If you have any gardening questions please call us at (858) 694 - 2860 or E-mail Us Questions.
Can you recommend a company where I can buy beneficial insects?
Q: I want to release some beneficial insects in my garden to help control aphids and other insect pests. Can you recommend a company where I can buy some?
A: Some retail nurseries sell lady beetles and a few other beneficial insects. You can also find a list of suppliers of beneficial organisms in North America at:
SUPPLIERS OF BENEFICIAL ORGANISMS IN NORTH AMERICA.
Most gardens and landscapes already have a complex of beneficial insects and other natural enemies which control pests. You can increase the effectiveness of these beneficial biological control agents by not applying insecticides which leave a persistent toxic residue on plant foliage. If you need to use an insecticide, try insecticidal soap or horticultural oil which kill pests on contact and are less harmful to beneficial insects. Plants should also be washed periodically with a forceful spray of water to remove dust and other debris which interferes with the activity of beneficial insects. Ants may also interfere with biological control and make pest populations worse. They feed on sugary secretions of aphids, whiteflies and other sap sucking pests and drive off or kill beneficial insects which help control the pests. Ants can be controlled with toxic bait which they take back to their nests. Trees can be protected from ants with a sticky barrier like Tanglefoot which can be applied on a strip of paper wrapped around the trunk.
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What can I spray on a tree to keep it from producing fruit?
Q: A landscape tree in my yard produces a lot of seed pods that fall and make a big mess every year. Is there anything I can spray on the tree to keep it from producing fruit?
A: Olives and other trees planted in landscapes usually flower and produce fruit every year. If this characteristic is undesirable, you should consider removing the tree and replacing it with another species that does not have this characteristic. Olives and some other trees can be sprayed each year to prevent fruit production. Florel Brand Growth Regulator is registered to reduce or eliminate undesirable fruit development on many ornamental trees and shrubs. A list of specific plants which can be treated and more information about the product can be found online at Monterey Lawn and Garden Products Company. You may be able to treat a small tree yourself. Special equipment is required to treat large trees and the services of a commercial pesticide applicator is usually required.
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What is making my Italian Cypress turn brown?
Q: I have an old Italian cypress that is turning brown at the top. I have not watered the tree since spring and it's late summer now. Does the cypress need more water or is something else making it turn brown?
A: The Italian cypress is very drought tolerant after it becomes established in the landscape. Mature trees prefer an occasional deep irrigation during dry weather, but they can survive without summer irrigation if winter rainfall is adequate. Mature trees are tough and can survive almost anything except for a fatal disease known as cypress canker.
Leyland cypress is especially susceptible to the disease as are Italian and Monterey cypress when they are planted away from the coast. Fungal spores that carry the disease are spread by the wind and also spread within plants by splashing water. Resinous lesions form on infected bark and can girdle limbs as they enlarge. Infected branches or tree tops turn yellow or faded and then die. There is no chemical treatment for cypress canker and the disease often progresses until the tree is killed.
Pruning out the diseased parts of the tree may prolong its life, but this should be done when symptoms are first observed. Make pruning cuts in healthy wood, well beyond any apparent cankers. When the top of the tree is infected, you may have to remove the top several feet below the damaged area. Pruning is of little value when the lower portion of the main trunk is infected.
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How can I get rid of ivy ground cover in my yard?
Q: I want to get rid of some ivy ground cover in my yard. I sprayed it with round-up, but the ivy did not die. What can I do?
A: Round-up will not kill all plants. The mature leaves of Algerian ivy have a very waxy surface which prevents round-up from entering the plant tissue. One way to get rid of ivy is to cut back the foliage and then dig up as many of the large roots and stems as you can. If you want to use an herbicide on ivy, apply it on new light-green leaves that are about 2/3 size of mature foliage. You may have more success with the herbicide triclopyr (Ortho Brush-B-Gon) which is more effective than round-up on some woody plants.
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Should I treat my lawn with beneficial nematodes or an insecticide?
Q: I used a product containing beneficial nematodes on my lawn last May, but it did not seem to work. Should I use an insecticide product instead?
A: You might try treating your lawn with beneficial nematodes again. Insect-attacking nematodes are safe and effective for controlling grubs (beetle larvae) and caterpillars (moth larvae) in lawns. The beneficial nematodes are very perishable and should be ordered from a mail-order company. Use the product as soon as it arrives or store it in a refrigerator and use it as soon as you can. Soil temperature should be about 70 degrees F when nematodes are applied to a lawn. Nematodes become inactive when the soil temperature is below 60 degrees F. Because nematodes are killed by light and heat, apply them in the evening, especially in hot climate locations. Soil should be moist but not soggy when the nematodes are applied. Several irrigations may be necessary during the two weeks after application to keep soil moist.
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Can I replant the same kind of ice plant in an area of my yard where a large area of it died?
Q: A large area of ice plant in my yard started to die last spring and is now completely brown. I treated it with "soil soup" but that didn't help. Can I replant the area with the same kind of ice plant?
A: Certain water-mold fungi can infect and kill the roots of some types of ice plant. This usually occurs on poorly drained soil after a prolonged period of heavy rain or excess irrigation. The disease often damages the small-leafed ice plants Disneyland and rosea. The fungi that caused the disease can remain in the soil for several years. It would be best to plant another kind of ice plant or a different type of ground cover. If you replant the area with the same type of ice plant, it may grow well for a while, but the planting could be killed again when the soil becomes too wet.
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Is a disease turning the leaves on my oleander yellow?
Q: Leaves are turning yellow on some of the branches of my large Oleander. Is this a disease, if so how can I treat it?
A: Your oleander may have a disease called oleander leaf scorch. This disease is caused by a bacteria. It is spread from infected plants to healthy ones by a leaf hopper -- the glassy winged sharp shooter. The bacteria enter a plant's stem and grow in the water-conducting tissue. This blocks the flow of water and nutrients from the root system to the plant's foliage. The affected leaves gradually turn yellow and die. Unfortunately there is no treatment which will cure an infected plant. You can prune out stems with dying leaves to improve the plant's appearance, but the infection will eventually kill the entire plant. The bacteria does not survive in the soil, but replanting oleanders again is not recommended, since grassy winged sharpshooters are likely to feed on them and could effect the new plants.
For more information please visit UCIPM and read the pest note on oleander leaf scorch.
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Can you recommend a professional arborist?
Q: I want to find out if a large tree on my property needs to be pruned. Can you recommend a professional arborist?
A: I do not have enough information on local arborists to give you a recommendation. Companies in your area are listed in the telephone Yellow Pages under "Tree Service". You can also find arborists on line at the International Society for Arboriculture web site. The San Diego Professional Tree Care Association also has a web site which lists members who provide tree service.
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Is there a beekeeper I can call to remove a swarm of honeybees from my yard?
Q: A swarm of honeybees flew into my yard and made a big cluster on a tree limb. I know honeybees are beneficial and I don't want to kill them. Is there some beekeeper I can call to pick them up?
A: Commercial beekeepers usually will not collect a swarm or nest of feral honeybees. The time it takes to collect the swarm would cost a bee keeper more than the bees are worth. Also most feral swarms in San Diego County are Africanized honey bees and the bee keeper who collected the feral swarm would have to destroy the queen in the feral colony and replace it with a European honey bee queen. If this were not done, the colony would remain Africanized and would be difficult to manage.
When honeybees swarm, they often form a cluster on a branch or other object and stay over night. These bees are usually not aggressive and will not sting if you leave them alone. The bees will usually leave in a day or two if they can find a hollow space nearby to build a nest. If the bees cannot find a good nest site, in a few days they will start to build honeycomb where the swarm is resting. When feral honey bees begin to build a nest, you should hire a pest control company to get rid of the bees. It is dangerous when Africanized honeybees nest near a home, and removal of the colony is the responsibility of the property owner.
You should inspect the walls and roof of your home and plug any openings where honey bees might enter. Honey bees only need an opening 1/4 inch in size to enter a wall or attic. If honey bees build a nest inside your home, hire a pest control company to get rid of them. After the bees are dead, you should open the wall or roof and clean out all the wax and honey. This may require the services of a building contractor. If the wax is not removed, its odor will attract other feral swarms to the area and honeybees may make another nest in your home or in another location nearby.
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Can you recommend a good consulting arborist?
Q: I want to find a consulting arborist, can you recommend a good one?
A: We cannot recommend a person, but you can locate consulting arborists certified by the International Society of Aboriculture, who work in your area. Some local arborists are also listed in the phone directory yellow pages. You can also obtain a membership list for the Professional Tree Care Association of San Diego by calling their office (619) 443-6202.
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Why has my 7 year old avocado tree never borne fruit?
Q: I planted a dwarf avocado in 1999. The tree is now 25 feet tall and has never borne fruit, what shall I do?
A: Avocado trees in small nursery containers usually begin to flower three to five years after they are planted. Several conditions can interfere with fruit set. Flowers may be damaged by frost or honeybees may not be present to pollinate the flowers. Insufficient soil moisture can also prevent fruit from setting or cause it to drop. Soil beneath an avocado tree should not be allowed to dry completely, especially when they are flowering and setting fruit. Avocados have shallow feeder roots which are most abundant in the top 6 inches of soil. It is usually best to water avocado trees with sprinkler irrigation about twice a week during dry weather if the trees are growing in from near the trunk to several feet from the spread of the branches. Also allow fallen leaves to remain on the soil under the tree or apply a layer of woodchips or other coarse mulch to conserve moisture. Avocado trees should be given a fertilizer containing nitrogen periodically during the spring and summer.
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How can I identify which tree roots are growing into my sewer pipe?
Q: Tree roots are growing into my sewer pipe. Can someone look at the roots and tell me which tree they belong to?
A: It would be very difficult to tell you which tree the roots in your sewer pipe are growing from by look at a sample of the roots from the pipe. You may have to locate where the roots have entered the pipe and trace them back to the tree they grew from. Removing the offending tree may not solve your problem though, because roots from another tree may also grow into the pipe if it is broken. The best solution would be to repair or replace the broken pipe. If water is leaking out of a sewer line, roots will follow the moisture and grow into the pipe. Roots will not enter a sewer line that is not broken and small roots cannot break a properly installed pipe.
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Can I spray my nectarine tree for leaf curl after it starts blooming?
Q: I live in Escondido and my nectarine tree and all of the others in the neighborhood started to bloom during the rain storm in early January. I did not apply dormant spray yet because the trees had not dropped all of their leaves. What should I do to prevent leaf curl? I can strip off the remaining leaves, but would spraying the tree now affect the fruit? Should I simply prune them and hope for the best?
A: Nectarines and some other fruit trees that have a low winter chilling requirement bloomed earlier than usual this year. Cool weather last fall and early rains in October may have satisfied the trees' chilling requirement, and this would allow the dormant buds to grow. Flower buds usually open first because they require less cold than leaf buds. Deciduous fruit trees may also bloom during the fall after early rain if the trees were not watered enough during a period of hot weather in late summer. The heat and water stress breaks down chemicals in the buds that keep them dormant.
It's too late now to spray your tree for leaf curl since it is already blooming and starting to set fruit. You can still prune your trees but the new leaves may be attacked by leaf curl especially if we have lots of rainy weather.
The fungus disease, leaf curl, can infect peaches and nectarines when new leaves emerge in spring. They must be sprayed with an effective fungicide while they are dormant to kill spores that overwinter on bark surfaces. Trees can usually be sprayed in December and again in January if weather permits. Fungicides used to control leaf curl include lime sulfur (usually sold as dormant disease control) daconil (Ortho multi-purpose fungicide) and fixed copper (a powdered copper fungicide). Trees should not be sprayed after buds begin to open since the spray can damage the flowers. New leaves will also become infected as soon as they emerge from dormant buds.
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When should I fertilize my eastern red bud tree?
Q: New leaves are starting to grow on my eastern red bud tree. (Cercis Canadensis) Should I give it some fertilizer now?
A: Wait until the leaves have grown to about half their normal size then apply fertilizer that contains nitrogen. The tree will be able to use the fertilizer better when it has more foliage. Also, if you wait a while before you apply fertilizer, the weather will be a little warmer and there will be less chance of frost damage to the new leaves. If you use a soluble fertilizer, scatter it lightly on the soil under the tree's dripline (at the edge of the branches) then irrigate to dissolve the fertilizer and carry it into the soil. Do not apply fertilizer close to the trunk, since this may injure the tree.
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Where can I get information about free shade trees?
Q: I heard on the radio that people could get five free shade trees to plant in their yard, but I did not hear who to contact. Do you know where I can get more information about this program?
A: People who live in the City or County or San Diego and have an account with San Diego Gas and Electric may qualify to obtain five free shade trees to plant on private property through the Cool Communities Shade Tree Program. You must first obtain and read a booklet and planting guide then submit an application. You can obtain the booklet on line at the San Diego Regional Energy Office. Click on programs, then select the Cool Committee Shade Tree option, and then click on the Planting Guide and Booklet icon. This will give you a printable pdf file.
The booklet can also be ordered by calling 1-888-831-8620.
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What tree can I plant that a pine bark beetle will not kill?
Q: Pine bark beetles killed my Monterey pine tree. What other trees can I plant, that the beetle will not kill?
A: Pine bark beetles, especially the western pine beetle and the engraver beetles (Ips spp.) attack pines weakened by old age, severe drought, root rot, or other stress factors. The Monterey pine is very susceptible to attack when it is planted in San Diego County because this tree is native to the central coast of California which receives more rain and has cooler weather than we experience in southern California. Pine species like the Italian stone pine and Aleppo pine which tolerate a drier, hotter climate are better adapted in southern California and are less susceptible to attack by pine beetles. However, all pines including these species may be killed by bark beetles when the trees are under sufficient stress and when a large population of beetles is present. If you want to plant another pine, make sure it is planted in a deep well-drained soil and provide adequate irrigation during dry weather.
Pine bark beetles do not attack other conifers including deodar cedar and incense cedar. They also do not attack cypress; however, these should not be planted in our area since they are susceptible to a deadly fungus disease cypress canker. Beefwood (casuarinas spp.) a tree native to Australia is not a pine, but it has a similar appearance and is not susceptible to attack by bark beetles. Bark beetles that attack pines do not attack other broad leaf evergreen and deciduous trees; however, other bark beetles like the eucalyptus long-horned borer may attack specific trees.
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What are some drought tolerant, low maintenance, plants?
Q: Can you recommend some drought tolerant, maintenance free plants that I can plant in my landscape?
A: All plants require some maintenance and even drought tolerant plants must be watered for awhile
(1 to 3 years) until they establish a good root system in the native soil which can supply the water they require. Picking out plants, much like picking out clothes, is a personal experience. One person may like a plant and another may hate it. For this reason I suggest you visit the water conservation garden in El Cajon or another demonstration garden where you can see well established plants and decide which suit your taste and need. You may also wish to visit the fire-safe demonstration gardens next to the Elfin Forest volunteer fire station located on Elfin Forest Road between Elfin Forest Lane and Fortuna del Este. It is set up for self-guided tours and is open daily. The fire-safe exhibit at Quail Botanical Gardens includes approximately 100 plant specimens. The exhibit is near the Ecke Building and is open daily with an admission fee.
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Can I use Roundup to kill some grass growing near my roses?
Q: I want to kill some grass growing near my roses. I was told that Roundup works well and I could plant in the soil the next day. Is this true?
A: Glyphosate, the herbicide in Roundup, will kill many weeds including most grasses, although you should be very careful if you use it near roses. The herbicide is not selective and can damage or kill roses and other desirable plants if it is sprayed on them. Glyphosate is systemic, it is absorbed by green foliage and green bark, even dormant roses can absorb the herbicide if they are sprayed. Once the herbicide is absorbed by a plant it can remain in the tissue for several months. Glyphosate is transported to growing parts of the plant and it keeps the plant from producing certain amino acids which are necessary for growth. The foliage of treated plants will turn yellow or wilt and die.
Glyphosate is not usually absorbed by plant roots, the herbicide is held very tightly on clay particles in the soil and is eventually broken down by micro organisms. You should be able to safely replant an area that was sprayed within a few days.
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I harvested an acorn squash from a volunteer plant but the fruit was too bitter to eat?
Q: I harvested an acorn squash from a volunteer plant but the fruit was too bitter to eat. What could have caused this?
A: The female flowers of an acorn squash plant can be pollinated with pollen from another plant in the squash family. If the hybrid seed are planted the resulting fruit will not have the same characteristics as the original acorn squash parent and may be of poor quality. If this was the cause of the bitterness in the fruit you picked then all of the fruit from the plant would have this characteristic. Bitterness can also occur on certain fruit from a squash plant if it was stressed by lack of water or some other condition. To avoid this problem only plant seed of a known variety and provide good growing conditions, especially regular and thorough irrigation.
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Are seeds from the California Pepper Tree the same as the Pink Peppercorns sold at herb stores?
Q: Are seeds from the California Pepper Tree the same as the Pink Peppercorns sold at herb stores and can I use the seeds from my own tree?
A: The Pink Peppercorns you saw at the herb store could be from a Pepper Tree, but I can't tell you for sure. You should ask if the store manager knows what plant the seeds come from.
Seeds of both the California Pepper Tree, also called Peruvian Pepper Tree (Schinus molle) and the Brazilian Pepper tree (Schinus terebinthifolius) are poisonous according to the AMA Handbook of Poisonous and Injurious Plants 1985. Eating large amounts of the berries causes gastro enteritis, vomiting and diarrhea according to another source Poisonous Plants of California , University of California Press, 1986. It states "the red berry like fruit of the Brazilian Pepper Tree sometimes were sold and used as an imported spice called Pink Berries or Pink Peppercorns. No information is available regarding the toxicity of these berries when used in small amounts as a spice" Both trees also cause contact dermatitis, the symptoms from the Brazilian Pepper Tree are more severe. California Pepper Tree leaves emit a distinct odor of black pepper when crushed, leaves of the Brazilian Pepper Tree also emit a pepper-like odor but it is not as pronounced as with the California Pepper Tree.
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What are the small worms on my olive tree?
Q: I found small worms in the fruit on my olive tree. What are they and is there anything I can do to get rid of them?
A: Your olives are infested with larvae of the olive fly, a fruit fly pest native to the Mediterranean region. It was discovered in California in 1996 infesting olives on landscape trees in Los Angeles County. By October 2001 the olive fly had spread along the coast from San Luis Obispo south into Baja California and into the southern San Joaquin Valley.
The olive fly is a major pest of olives. The larvae feed on olives and cause early fruit drop. Infested fruit are not suitable for pickling and they do not produce top quality olive oil.
The adult olive fly is about 3/16 of an inch long and has a brown body with a yellowish to light brown head. The wings are clear with dark veins and a small black spot at the wing tip. The female flies begin laying eggs in August. They pierce the skin of an olive and deposit a single egg in the pulp. Eggs hatch into yellowish-white maggots that feed throughout the olive, growing to a length of about 1/5 of an inch then enter the resting stage and pupate just beneath the skin. Adult flies emerge in as little as 30 days during warm weather. Subsequent generations follow the same pattern until fall when larvae abandon the fruit to pupate in the soil. Adult flies may not emerge from the over-wintering pupae for five to six months. In mild climates adult flies may also over-winter near olive trees.
Studies must be conducted on management of olive flies before a control can be recommended. No insecticides are currently registered in California for control of olive flies in home gardens. Insecticides not labeled for use on olives should not be used since they may leave a harmful residue on fruit when it is harvested. Contact insecticides will not control eggs or larvae inside the fruit.
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Why are my navel oranges splitting?
Q: Some fruit on my navel orange tree are splitting. What causes this and what can I do to prevent it?
A: Splitting in navel oranges often occurs on green fruit between September and November. In some years, splitting may occur in Valencia oranges but it usually is less of a problem than in navel oranges. Splitting is a long-standing problem in most areas where navel oranges are grown. In some years, the percentage of split fruit is high; in other years it is low.
Splitting is not known to result from any single factor. Studies indicate that changes in weather including temperature, relative humidity and wind may have more effect on fruit splitting than anything else.
The amount of water in a citrus tree changes due to weather conditions and this causes the fruit to shrink and swell as water is lost or gained. If the water content changes too much or too rapidly the rind may split. Good cultural practices can help reduce fruit splitting but may not eliminate it completely. Proper irrigation of citrus is very important. A large area of soil around a tree should be watered since roots normally grow somewhat beyond the edge of the canopy. Wet the soil to a depth of at least 2 feet then allow it to become somewhat dry before irrigating again. Do not keep the soil constantly wet or allow it to become excessively dry. When trees are fertilized , apply the correct amount of plant food and water thoroughly after it is applied. If soil is dry, irrigate before trees are sprayed with insecticidal soap, horticultural oil or other pesticides and delay treatment if the weather is hot, windy or dry. Promptly control gophers that feed on tree roots and do not cut or damage roots.
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Do pumpkins and squash easily cross breed?
Q: Do pumpkins and squash easily cross breed? Do I need to plant them far apart to prevent this from happening? Also, my pumpkin leaves are covered with mildew. Is this because I water the leaves? Can mildew be prevented?
A: Pumpkins and squash belong to the genus cucurbita. There are six different species and different varieties within the same species will cross easily, but crossing does not occur between different species. Some squash are in the same species as pumpkins and can cross pollinate each other; however, this will not affect the fruit produced by either plant. Cross pollination is not a concern for gardeners unless they want to save seed of a particular variety to plant. Cross pollination between two varieties will produce hybrid seed resulting in plants with some characteristics of both parents. Planting several varieties in separate locations may not prevent bees from cross pollinating flowers. Most natural crosses produce offspring with less desirable characteristics than the parent plants. This can be prevented by hand pollinating flowers of an individual plant. The procedure for doing this is described in the book Seed to Seed by Suzanna Ashworth, The Seed Saver's Exchange, 1991 (We are ordering a copy for the library). Many cucurbit varieties are subject to powdery mildew. Spores of the fungus do not require free water to germinate and infect leaves. Overhead irrigation should be avoided though, because high humidity favors powdery mildew. Planting mildew resistant varieties is the best way to avoid the disease.
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Why are my citrus trees losing their leaves?
Q: I thought citrus were not deciduous, but my trees are losing a lot of leaves. Is this normal or could it be caused by how I water or fertilize my trees?
A: Citrus are evergreen. They retain foliage throughout the year, although the oldest leaves continually drop. Unusually heavy leaf fall can occur when a tree is stressed, which may be caused by a variety of factors, including improper irrigation (which keeps soil too dry or too wet), conditions that increase water loss from foliage (like high temperature, wind and low humidity), high soil salinity (from over fertilization or high salts in irrigation water and root damage due to poor drainage, disease and pests, like gophers).
With mature citrus, water and fertilizer should be applied in a doughnut shaped area around the trunk extending a little beyond the edge of the canopy. Enough water should be applied to wet the soil at least 2 feet deep and trees should not be irrigated again until soil in the top few inches begins to dry. Soluble fertilizer should be applied evenly to soil around the tree. Sufficient irrigation should follow to dissolve fertilizer and carry it into the root zone.
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What is difference between wasp, hornets and bees?
Q: What is the difference between wasps, hornets and bees? Can I safely chase them away with my hose?
A: There are many kinds of wasps and bees. Some species are solitary insects and others like honeybees, bumblebees and yellow jackets are social insects which live in colonies. Honeybee colonies can survive for years, but bumblebee and yellow jacket colonies usually die out in late fall and are reestablished the next year by fertile females. Honeybees and yellow jackets defend their nests and will sting intruders. Honeybees have a barbed sting which remains in the skin. Each bee can only sting once and dies. Yellow jackets have a smooth sting which does not stay in the sting. Each wasp can sting multiple times and can also bite. Some yellow jackets make nests in cavities in the ground and other species make nests in walls or buildings. Yellow jackets that build aerial nests are commonly called hornets. Yellow jackets look somewhat like honeybees. Their bodies are black with jagged bands of bright yellow (or white in the case of hornets) on the abdomen and have very short, narrow waists.
You should not spray wasps or bees with water or swat at them since the insects are more likely to sting when disturbed or injured. Yellow jackets and honeybees which build nests near homes can pose a hazard to people nearby. Nests should be destroyed by a commercial pest control company.
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Can I fertilize my eucalyptus tree to fight off the red gum lerp psyllid?
Q: My eucalyptus is being attacked by the red gum lerp psyllid. Will the tree get stronger and fight off the psyllid if I fertilize it and water heavily?
A: No. Practices that stimulate new vegetative growth can weaken eucalyptus trees and hasten their decline when psyllid populations are high. Trees defoliated by the red gum lerp psyllid must use food stored in woody tissues to produce new foliage. Psyllids quickly attack new leaves and cause them to drop during warm weather. Eucalyptus damaged by the red gum lerp psyllid should not be fertilized or heavily irrigated. Trees which have grown under irrigated conditions may benefit from periodic deep watering when soil is dry. Mature trees should be watered near the drip line, but not next to the trunk.
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How do you treat blossom end rot on tomatoes?
Q: How can you treat blossom end rot on tomatoes? Does it cause a plant to lose leaves from the top or bottom of the plant?
A: A lack of calcium in developing tomato fruit causes blossom end rot. Cells at the blossom end of green tomato fruit are damaged creating an area with dark, sunken leathery tissue. The unaffected portion of ripe fruit can safely be eaten if secondary decay has not occurred. Blossom end rot does not cause foliage symptoms; however, diseases or pests that damage foliage may also contribute to blossom end rot.
Soils in our area usually contain enough calcium; however, in some situations tomatoes may benefit from an application of gypsum (calcium sulfate) prior to planting. Blossom end rot can usually be prevented with good cultural practices. Select varieties resistant to soil diseases and nematodes. Avoid planting beefsteak varieties if blossom end rot has been a problem since they often develop the disorder. Plant tomatoes in good garden soil where they will receive sun all day. Mix in a complete fertilizer high in phosphorus prior to planting and do not over fertilize with nitrogen during the growing season. Excess nitrogen stimulates lush vegetative growth which competes with developing fruit for available calcium. Irrigate a large area around each plant to encourage the development of a large root system. Wet the soil at least a foot deep when surface soil begins to dry out.
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Should I prune my citrus shoots?
Q: My citrus tree has 2 very tall shoots. Should I prune them now? I heard you should never prune citrus.
A: Citrus trees can be pruned, but they do not require extensive pruning to produce fruit. Any shoots which grow from below the graft union (suckers) should be removed whenever they appear. The best time to prune citrus trees is in late winter or early spring after the danger of frost has passed. Dead, diseased or broken branches can be removed at any time. Young trees should be pruned as little as possible since the removal of leaves slows their growth. Pruning of mature trees may include thinning out unwanted growth and shortening or removing low branches to keep them from touching the ground.
Vigorous upright shoots called water sprouts often grow on the trunk above the graft union and on branches on the tree's canopy. These shoots should be retained if they are in a good location since they increase the tree's size and its fruit bearing capacity. Shoots that grow up through the center of a tree can be pulled outward into an open area of the tree or pruned out if they are not needed. Water sprouts can be left unpruned and they usually produce lateral branching within a year or they can be shortened if desired.
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My ground cover is dying?
Q: I planted Myoporum parvifolium ground cover on a bank in my yard 6 years ago. It grew well at first but large patches have died during the past 2 years. I don't know why the plants died. There was no sign of gopher activity and I don't think I was overwatering the ground cover. My soil is decomposed granite and I run the sprinklers for 15 minutes 3 times a week. New plants grow well when I plant them in areas where old plants have died. What can I do to keep the ground cover from dying?
A: Myoporum is very susceptible to root and crown rot caused by phytophthora, a soil born fungus. There is no way to eliminated the fungus from the soil, but you may be able to reduce the damage it causes with careful irrigation. Frequent irrigation maintains a high soil moisture content which favors water molds like phytophthora. Myoporum is very drought tolerant and established plantings do not require frequent irrigation. The ground cover may only need to be irrigated once every 2 to 4 weeks depending on weather conditions. Watering deeply and allowing the soil to dry out as much as possible between irrigations should help control the phytophthora and keep your ground cover healthy.
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What fertilizer should I use?
Q: What fertilizer should I use when I plant vegetables and flowers?
A: Some fertilizer should be mixed into garden soil before you seed or transplant annual vegetables and flowers. When you buy fertilizer, look at the package label to find out how much nitrogen(N), phosphorus(P) and potassium(K) it contains. The percent of N-P-K is listed in this order on every fertilizer package. Ammonium phosphate fertilizer 16-20-0 contains 16% nitrogen, 20% phosphorus and 0% potassium. A starter, or pre-plant fertilizer should contain more phosphorus than nitrogen. Products that contain 2 or 3 times as much phosphorus will provide annuals with enough phosphorus for the entire growing season. Many California soils are not deficient in potassium, but fertilizer containing this element may be beneficial in some soils. Products which contain as much potassium as nitrogen, will supply enough potassium for the growing season. Apply soluble chemical fertilizers at the rate given on the label. Scatter the fertilizer evenly over the area to be planted and mix it into the top 6 to 8 inches of soil. If you use an organic fertilizer apply it 2 to 4 weeks before planting and mix it into the soil. If poultry manure manure is used, apply it at the rate of 20 pounds to 100 square feet of garden soil several weeks before planting and thoroughly irrigate the soil to leach out harmful salts. If steer manure is used, do not apply more than 50 pounds to 100 square feet of soil. Steer manure contains less nutrients than poultry manure and it has a high salt content.
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How do we control ants entering the house?
Q: We have lots of ants in the garden and they occasionally come into the house. What is the safest way to control them?
A: Most ants build nests outdoors in the ground. Workers leave the nest to search for food throughout the landscape and occasionally in homes. Storing food securely and good sanitation helps make homes less attractive to foraging ants. Sealing cracks and openings where ants may enter a home also helps to keep them outdoors. When ants invade your home wipe them up with soapy water. If ants continue to enter your home apply an insecticide labeled for ant control at the spot where they are entering. Using ant stakes and other bait products is the safest way to control ants outdoors. Baits are formulated as solids or liquids and applied in stations or in the case of granules by broadcasting them. Ants are attracted to the bait and carry small portions of it back to the nest where it is given to other workers, larvae, and reproductive forms. To achieve wide distribution of the bait so the entire colony will be killed, the bait toxicant must be slow acting. Some examples of toxicants used in ant baits are hydramethylnon, boric acid, and fipronil. Hydramethylnon is photodegradable, so if it is broadcasted in granular form it should be applied in the evening. Boric acid is most effective at concentrations of 1 percent or lower. Fipronil is a new class of toxicant that is effective against ants at ultra-low doses.
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How do I grow geraniums from cuttings?
Q: I want to grow geraniums from cuttings. A friend told me to just cut off a piece of stem and plant it in the ground. Another friend told me to put the stem in a glass of water until it made roots. Another person told me to just plant the cutting in a container filled with potting soil. Which method works best?
A: All geraniums can be grown from stem cuttings although some varieties are easier to propagate than others. Cuttings can be taken any time of the year in areas where the climate is mild. Cuttings should be taken when plants are vegetative and not when they are in full bloom. Take cuttings from a healthy plant free of disease and pests. Use a hand pruner or sharp knife and remove a 4 to 6 inch long cutting from the tip of the stem. Make a straight cut across the stem just below a node (the swollen area on the stem where leaves are attached to the stem). If you take cuttings from more than one plant disinfect your shears after each plant with a solution of equal parts rubbing alcohol and water. Remove all leaves from the bottom half of each cutting and stick the cuttings in a small clean container filled with sterile potting soil. To provide better drainage use equal parts potting soil and perlite. Cuttings can be planted immediately and do not have to be treated with a rooting hormone or fungicide. Plant several cuttings in the container then water until the potting mix is thoroughly wet. Place the container in an area that receives bright light but not direct sun. Water when the surface of the soil is slightly dry. Do not cover the cuttings with a plastic bag since this can promote decay. When cuttings are well rooted transplant them to a larger container or to the garden and provide midday shade for about two weeks. If you prefer to plant cuttings directly into the garden first place them in a cool and dry location for one or two days until callus tissue forms on the cut surface. This will help protect the cutting from decay.
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Can bananas grow in San Diego?
Q: Can bananas be grown in San Diego County? Which varieties grow best and what kind of care do they need?
A: Bananas can be grown successfully in San Diego County near the coast and in some inland areas where winter temperatures usually remain above freezing. Bananas need 10 to 15 months of frost-free conditions to produce a flower stalk. Freezing temperatures will kill the foliage. Plants grow best where they are sheltered from strong winds and where summer temperatures do not rise much above 80 degrees Fahrenheit. They should be planted in a sunny location in well-drained soil, enriched with composted organic matter. Bananas require frequent irrigation and monthly application of fertilizer during warm weather. Additional information on the culture of bananas is available from the California Rare Fruit Growers (Click on 'CRFG Fruit Facts on-line'). Hybrid varieties of banana that have performed well in the San Diego area include "Ice cream" which is also known as "Blue Java", "Orinoco" and "Cardaba". Information on these varieties and where to purchase them can be obtained by calling the CRFG 'Banana Lady' at 760.753.6757 (best evenings).
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Bamboo is spreading into my yard. What can I do?
Q: Bamboo is spreading into my yard from a neighbor's property. What can I do to kill the bamboo in my yard, and how can I keep it from growing back again?
A: Bamboo spreads by underground stems called rhizomes. Clumping bamboos have short rhizomes and spread slowly, but running bamboos produce very long rhizomes which give rise to leaf stalks called culms far from the main clump. To prevent a running bamboo from spreading, a "rhizome barrier" is essential. A barrier two or three feet deep is effective. It should be slanted at a 45 degree angle outward at the top so that when the rhizomes hit the barrier they will bend upwards. A barrier does not stop a running rhizome, it only deflects it. The barrier should project an inch or two above ground level. Check the barrier once a year, and cut off rhizomes that arch over the top.
Barriers can be concrete, or metal, or plastic. The usual recommendation is high-density polypropylene, 40 mil or heavier, glued or taped at junctions, or clamped with stainless-steel clamps. This material comes in rolls, or as hinged sections and is available from some landscape suppliers and bamboo nurseries, frequently termed "root barrier." More elaborate barriers with corner posts that hold the material at the proper angle are also available.
To remove the bamboo that has grown into your yard, first cut the underground rhizomes where they enter from an adjacent property. They usually grow in the top foot of soil and can be cut with a spade and mattock or saw. If only a few rhizomes and culms are present they can be dug up and removed. A large mass of bamboo can be killed by cutting off all of the culms at ground level and continually removing new culms as they appear. Preventing any foliage growth will deplete the plant's stored food and eventually kill the clump, although the clump may take a year or more to die. The herbicide glyphosate (Round-up) can also be used to kill bamboo. A concentrated solution can be painted on the end of culms immediately after they are cut, or foliage can be sprayed with a dilute solution if nearby plants will not be damaged by spray drift. Glyphosate is absorbed by plant tissue and transported within the plant. The herbicide inhibits new growth, but more than one treatment may be required to kill well established clumps of bamboo.
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Could bark beetles attack the pine trees at my home?
Q: When I recently drove through the Laguna Mountains, I saw a lot of dead pine trees. A resident told me that bark beetles were killing the trees. Could this pest also attack the pine trees at my home in San Diego? What can I do to protect my trees?
A: Bark beetles are one of the most destructive pests of pines. Trees weakened by lack of water or other kinds of stress are initially killed, but even healthy trees may be killed when a large number of beetles are present.
Adult bark beetles are about the size of rice grains. Most species are dark red, brown or black and have strong, scoop-like jaws well suited for boring. Larvae are cream or white in color and grub-like.
Adult beetles bore through a tree's bark and make galleries or tunnels beneath it where eggs are laid. When larvae hatch they begin to feed and create their own galleries. The larvae reach maturity in several weeks to months, then change into adult beetles and chew out through the bark to begin the cycle again. Up to four complete generations are produced each year in warm regions.
When bark beetles attack a pine the first insects that bore through the bark emit odors (called agrigation pheromones) into the air that attract a large number of beetles of the same species. Feeding by the beetles and their larvae damages the tree's cambium, the tissue that produces new growth. The beetles also carry fungi on their bodies, which grow rapidly and clog the water-conducting tissue of the tree, hastening its death.
The needles on infested pines fade from a normal green color to light green then straw yellow and finally to red or brown. The fading starts at the top of the tree and spreads downward.
Bark beetles typically begin their attack on a single usually weakened tree. As beetle numbers increase, adjacent trees, even healthy ones, are attacked and may be overwhelmed. This situation often gives rise to group kills where several to more than a dozen trees may be killed at a particular site.
Preventing infestation is the best way to protect pines from bark beetles because little can be done to control the insects once trees are infested. Trees should be given proper irrigation and good care to keep them vigorous. Healthy trees are less likely to be attacked by bark beetles and have a better chance of surviving the damage from a few insects. Beetles drown in pitch when they try to bore through the bark of a vigorously growing tree.
Pines need a steady supply of soil moisture and should be irrigated periodically during dry weather. Water deeply near the tree's outer canopy and apply a layer of coarse organic mulch on soil around trees to conserve soil moisture and control weeds.
Pines need little fertilization or pruning. A small amount of nitrogen applied during winter will stimulate vegetative growth. Healthy trees should not be severely pruned or topped. Trees can be pruned lightly if desired, but do not prune from February to October when adult beetles are flying. Unseasoned, freshly cut wood can harbor beetles and should not be piled near susceptible trees.
Any condition that decreases a tree's vigor makes it more susceptible to attack. Whenever possible try to reduce tree stress from man-made causes like excessively wet or dry soil, root damage due to soil compaction, excavation or addition of soil near trees, and overly crowded planting which increases competition for water.
Periodically, inspect pines for early signs of bark beetle activity. Check the bark of your tree for boring dust, a fine paprika colored sawdust-like material, which often collects in crevices and cobwebs. Some bark beetles also make pitch tubes, which are small masses of pitch and boring dust at the place they enter the tree. If beetles have only attacked a few branches in the top of the tree, prune them off. If the main trunk is heavily infested, promptly remove the entire tree to protect nearby pines from attack. Dispose of infested wood or strip off the bark if it is kept for firewood, to stop beetle development.
No contact or systemic insecticides are effective against beetles or larvae feeding beneath the bark. Healthy uninfested trees of high value located near infested trees are occasionally treated with certain insecticides that leave a persistent residue on the bark to protect them from beetles. Trees should be treated by commercial pesticide applicators since they can obtain the most effective materials and have special equipment needed to spray large trees.
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Why are my oranges turning brown and black?
Q: My oranges are turning brown and some are turning black. They look bad but the inside seems OK. Is the fruit OK to eat? I have had the trees for several years and have never had this problem before.
A: Your oranges were damaged by a tiny mite which uses its piercing mouth parts to remove fluid from cells on the surface of the rind. This causes the skin to dry out and discolor. The pest is called the citrus rust mite when it damages oranges, which turn a rusty to brown or black color. The pest is also called the silver mite when it damages lemons which turn gray and have a "shark skin" appearance.
Fruit damaged during its early development may drop from the tree or stop growing and not mature properly. Damage to fruit late in its development is primarily cosmetic. Discolored fruit can be eaten when they mature, but they lose water faster than undamaged fruit and do not store as long.
Citrus rust mites are very small and may be carried from one tree to another by wind, birds, rats, or other rodents and by people. Mites can only be seen with strong magnification (20X), but the damage they cause is easily detected if you look for it. Check developing fruit at several locations on a tree once or twice a month. Young fruit should have a uniform green color with a waxy surface. Colonies of rust mites produce small areas of dull, discolored skin where they feed.
If rust mite damage is detected treat the tree with a miticide product labeled for use on citrus. Seek advice from a knowledgeable garden center employee when selecting a product and read the label before you buy it. Horticultural oil like 'Sun Spray' and insecticidal soap control mites on contact, but do not have any residual activity and may need to be reapplied periodically. Products containing sulfur also control mites and have some residual activity after application. Good coverage of all plant surfaces is required for best control. If the soil is dry, water before treatment and do not spray trees during hot or windy weather.
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Why is my oak tree leaves drying up?
Q: The leaves on my oak tree are drying up and there are spider webs on the tree. Someone said I should spray the tree and another person said I should water more. I do not know what kind of oak I have.
A: You do not need to spray your oak unless it has a severe pest infestation. Insect and mite pests associated with oak do not kill healthy trees. Most pests are kept under control by natural enemies, which may be killed if a pesticide is used. Spiders also help control pests and should not be killed.
It is not unusual for an oak to have some brown leaves. Old leaves naturally turn brown when they die. Young leaves that have been damaged may also turn brown. It is unusual for a large number of young leaves to turn brown, but this can occur if a tree's root system has been damaged by a soil fungus disease, water logged soil, construction activity and other causes.
Native oaks are adapted to California's climate, which has wet winters and dry summers. Oaks should not be irrigated at all from spring through fall, because keeping soil moist during warm weather favors soil fungal diseases which can kill oaks. Trees can be given supplemental irrigation during late winter if there has not been enough rainfall to wet the soil to a depth of at least 2 feet. Do not apply water near the tree's trunk. Apply water to a broad band of soil around the tree beginning at the edge of the branches and extending out 10 feet or more. Apply water slowly until it penetrates to a depth of about 3 feet. Do not give oaks any nitrogen fertilizer since this will stimulate lush growth that is subject to damage by powdery mildew and will also increase the tree's water requirement during the dry season.
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Who do I call to have a eucalyptus tree removed?
Q: A large eucalyptus tree, near my house, blew down. I think the tree may be on city or county property. Who can I call to have it removed?
A: Trees growing on private property are the responsibility of the landowner. Government agencies will usually remove fallen or hazardous trees on public property. For tree removal on City of San Diego property call (619) 527-5465 and for trees on County property call (858) 874-4040.
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Should I fertilize my orange tree now?
Q: Some leaves on my citrus tree are turning yellow and dropping. Should I fertilize the tree now?
A: On citrus and some other sub-tropical plants it is common for older leaves to turn yellow and drop during winter months when the weather is cold. There is less root growth, at this time of year, and some nutrients may not be absorbed as well by roots until the weather warms again in spring or early summer. A fertilizer containing nitrogen is usually applied a few weeks before or when new leaf growth begins. The loss of green color between the veins on new foliage may be caused by a lack of zinc or other micronutrient. If zinc deficiency persists, when the weather remains warm, it may help to spray new, nearly developed, leaves with a chelated fertilizer containing zinc, such as Tru Green Citrus Growers Mix. A chelated fertilizer or zinc sulfate can also be applied to soil at the edge of a trees drip line. Iron deficiency may also occur even though most soils contain an adequate amount of iron. Iron may not be in a chemical form, which roots can absorb due to high soil pH or poor soil aeration (over irrigation or poor drainage).
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How can I get rid of the mushrooms and will they kill my tree?
Q: My fruit tree has mushrooms growing out of the trunk, about a foot above the ground, I remove the mushrooms when I see them, but they grow back again each year. How can I get rid of the mushrooms and will they kill my tree?
A: The mushrooms are probably produced by wood rot fungus that is growing in the non-living wood inside the trunk. This type of fungus does not kill the live tissue in the outer part of the trunk, but it will rot out the interior portion of the trunk. Your tree may live for several years but the trunk may eventually weaken and break. Removing mushrooms does not kill the fungus and there is no chemical treatment that will control the fungus without destroying the tree. You may want to plant a young tree in another part of your yard as a future replacement for the older tree.
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Will my Yucca tree roots die or keep growing?
Q: The roots of a large Yucca damaged my sprinkler system. I had the tree removed by cutting its trunk at the base. Will the roots die or will they keep growing and cause more damage?
A: To live and grow, roots need sugars and other compounds produced by plant leaves. Roots may survive for a while on starch stored in woody tissue, but they will eventually die if the top of the plant is removed. The roots of your Yucca will stop growing and eventually die if you promptly remove any new stems and leaves that may grow from the base of the trunk. The re-growth of sprouts can be prevented by treating the trunk with a herbicide product such as Ortho Brush-B-gon or Roundup. Use an axe to cut through the bark at a 45 degree angle around the base of the trunk and apply the herbicide to the open slits.
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What should I do with a 70 year old Avocado tree that might fall over?
Q: I am concerned that a large 70 year old Avocado tree may fall over, it has a 2 inch hole at the base of the trunk which leads to a large cavity. The tree is growing in a lawn and receives frequent irrigation. What should I do?
A: It is difficult to predict if a tree with a cavity in its trunk will fall. You should have an arborist, certified by the International Society of Arboriculture inspect the tree and determine its potential hazard to people and nearby structures.
To locate a certified arborist call companies listed under "Tree Service" in the yellow pages phone directory. You can also obtain a referral from the International Society of Arboriculture or from the San Diego County Professional Tree Care Assoc. (619) 443 6202.
You should prevent honeybees from building a nest in the cavity, if the tree is not removed. If Africanized honeybees nest in the cavity, the colony will be a hazard to people and pets in the area. You can bee-proof the cavity by filling it with expanding polyurethane foam, sold at home improvement stores. Covering the cavity entrance with one-eighth inch mesh hardware cloth will also exclude bees.
A tree that has a cavity in its trunk may continue to live for several years. Wood rot fungi destroy non-living wood inside the trunk, but do not kill the live tissue in the outer part of the trunk. There is no chemical treatment or other way to kill wood rot fungi inside a tree's trunk. The outer layer of wood in a tree's trunk provides most of its strength, but the trunk will become weaker as the size of the cavity increases.
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What kind of onions should I plant?
Q: I want to grow some sweet, mild flavored onion bulbs. Are the small onion sets sold at garden centers a good variety to plant, or should I use seed?
A: Onion sets can be planted to produce a quick crop of green onions, but they will not produce a good crop of bulbs. The onions sold as sets are pungent varieties which often go to seed before they produce a bulb in our area. The best way to grow a mild crop of onion bulbs in our area, is by planting seed of short or intermediate day length varieties. Grano, Granex and other short day varieties should be planted in early to mid November. Sweet Spanish, Italian Red and other intermediate day length varieties should be planted in early February. Mature bulbs will be ready to harvest in mid or late summer.
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What animal would strip the bark off branches on my bougainvillea?
Q: Some animal has stripped the bark off branches on my large bougainvillea. What animal would cause this damage and how can I protect the plant?
A: Roof rats like to hide and build nests in dense vines, shrubs and trees especially bougainvillea and climbing ivy. The rodents damage plants by cutting off small twigs at a 45 degree angle and by chewing bark off larger branches. Roof rats are often found in urban landscapes where there is adequate food, water and shelter. Information on roof rats and how to control them can be obtained from the county of San Diego vector control office. Phone: 858.694.2888. To discourage roof rats from nesting in plants, thin the canopy by removing selected branches. Also, eliminate possible sources of water and food in the landscape. Pick fruit and nuts as soon as they are ready to harvest and dispose of fruit that has dropped to the ground. You can use traps or poison bait to control rats, but be careful how they are used to avoid harming children, pets and non-target wildlife.
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How long do nematodes stay in the soil?
Q: The tomatoes I grew last year were attacked by nematodes. When I dug up the plants I noticed swollen areas on their roots. How long do nematodes stay in the soil? Can I plant tomatoes in the same area this year?
A: Nematodes are microscopic round worms. Some nematodes damage a variety of plants including tomatoes. Root knot nematodes feed on small roots and cause the tissue to grow abnormally producing galls. The damaged roots absorb less water and nutrients from the soil. Once nematodes have been introduced into a garden, there is no practical way to eradicate them. You can grow tomatoes in nematode infested soil by planting varieties resistant to root knot nematodes. The letter 'N' after a variety name indicates it is resistant to nematodes. This information is provided in most seed catalogs and on the plant label of some tomato varieties sold at garden centers. If you want to grow tomatoes that are not nematode resistant, plant them in another area of your yard. Also, do not move soil from areas infested with nematodes to other areas of your yard, and thoroughly clean garden tools after they were used in an infested area.
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How do you crack macadamia nuts?
Q: How do you crack macadamia nuts?
A: Macadamia nuts have a very hard shell, which is difficult to break with a standard nutcracker. A small quantity of nuts can be cracked with a vice. A special nutcracker designed for macadamia nuts can be purchased from the Gold Crown Macadamia Association. Phone: 760.745.4396 or write:
Gold Crown Macadamia Association,
P.O. Box 235, Fallbrook, CA 92088.
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What can we do to protect my fruit trees from borers?
Q: Borers killed an old peach tree in our yard. We removed the tree and planted an new bare root peach tree last winter. What can we do to protect it from borers?
A: Borers often attack fruit and ornamental trees that are weak or damaged by sunburn. Live tissue beneath the bark can be killed by heat from the sun on the south side of a tree's trunk and the top side of horizontal branches. The trunk and major branches of newly planted and container grown trees should be painted with whitewash to protect the bark from sunburn damage. You can use a commercial whitewash sold at some garden centers, or you can dilute white interior flat latex paint with an equal amount of water. Also, irrigate as needed to provide adequate soil moisture for young trees. Wait until leaves and shoots are actively growing, then feed lightly with a fertilizer containing nitrogen. Scatter a small amount of fertilizer around the tree at least one foot from the trunk and water well to dissolve.
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St. Augustine grass is invading my tall fescue lawn. Will Roundup kill the St. Augustine grass?
Q: St. Augustine grass is invading my tall fescue lawn. Will Roundup kill the St. Augustine grass or is there some selective herbicide which will kill the St. Augustine without killing the tall fescue?
A: Before you use an herbicide you should make sure that the grass invading your lawn is actually St. Augustine. The grass could be kikuyu grass which has a similar appearance. Both types of grass have thick runners about 1/4 inch diameter which spread on top of the soil. You can tell which grass you have by looking at the tip. Kikuyu grass has a pointed leaf tip and St. Augustine grass has a rounded blunt tip. St. Augustine grass does not produce seed and must be propagated vegetatively. Kikuyu grass produces seed which remain in the soil and can grow after the parent grass is removed. Roundup is a non selective herbicide which will kill either St. Augustine or kikuyu grass but it will also kill your tall fescue turf grass. If you use Roundup you will have to replant the treated area with tall fescue. If you kill existing kikuyu grass it will probably grow back from seed the following year. Kikuyu grass growing in a tall fescue lawn can also be controlled with the selective herbicide product Turflon Ester sold by Monterey Lawn and Garden. More than one application may be required to control established kikuyu grass. Turflon Ester is not registered to control St. Augustine grass, however, the herbicide will damage the grass according to the product label. Bermuda grass and zoysia grass are also damaged by the herbicide.
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If I use treated wood around my fruit trees, will the chemicals poison my fruit?
Q: I have 5 fruit trees. Around each tree I have a 4' square border of Redwood to keep water in, which I apply once a week. The borders are 25 years old and termites have eaten the boards. I would like to replace the Redwood with pressure treated wood which contains Chromated Copper Arsenate (CCA). The wood is sold with a health warning, but it does not cover my situation. If I use this wood around my fruit trees will the chemicals get into the soil and poison my fruit?
A: Wood treated under pressure with Chromated Copper Arsenate is resistant to termites and decay, however it does contain arsenic, which is a carcinogenic. You should wear gloves, protective glasses and a dust mask when cutting and handling CCA treated wood. Some arsenic in the wood will leach out into the surrounding soil, but it quickly binds to clay particles and does not move very far. Most soils naturally contain some arsenic and roots growing near treated wood could absorb more arsenic than usual. I don't know how much arsenic the fruit from your trees may contain , but it would not be very much, and it should not be a significant health hazard.
CCA treated wood is being phased out for residential use and other compounds which do not contain arsenic will be used as a wood preservative.You may be able to obtain wood that is not treated with CCA from a local lumberyard. You could also use Redwood, which is naturally decay resistant but it can be damaged by termites.
If your fruit trees are 25 years old you probably need to water a larger area than just inside the 4' x 4' wood border. Roots of most trees grow out to and often beyond the edge of the trees canopy, which is called the "drip line". All of the soil under the trees' canopy should be irrigated when the soil begins to dry and enough water should be applied to penetrate at least 2' deep. Water should not be allowed to stand next to the tree's trunk as this could cause crown rot or gummosis. A fungus disease which attacks citrus.
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Why do my walnuts turn black?
Q: My walnuts turn black before they are ready to harvest, when I crack the nuts the meat is also black. Is there any way that I can prevent this from happening?
A: Your walnuts were damaged by the walnut husk fly. This insect lays eggs in the green husks. The larvae feed in the husk causing it to decay and turn black. The husks dry out and are difficult to remove when the nuts are harvested. The insect does not feed on the nut meat, although they may darken somewhat.
Unfortunately there is no chemical treatment which home gardeners can use to control the walnut husk fly. Most gardeners simply tolerate the damage since the nut meats can still be eaten.
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What is killing my grass and how can I control it?
Q: Small areas of my St. Augustine grass lawn began to die in August. By September large patches had turned brown and the dead areas kept enlarging. What is killing the grass and how can I control it?
A: The lawn was probably damaged by the chinch bug. You may not have noticed the insect because of its small size and habit of feeding on stems close to the ground. The insect removes sap from St. Augustine grass stems with its piercing mouth parts and also injects saliva which is toxic to the grass. A combination of these two activities causes rapid yellowing and death of the grass.
Chinch bugs are most active when the soil temperature is about 70 degrees F. Their feeding and reproductive activity increases as the temperature rises which explains why the insect usually damages lawns during summer and early fall months.
Chinch bug damage is usually first noticed when small irregular shaped areas of grass begin to die and grass around the margin of dead areas show symptoms of yellowing and wilting. The dead area will gradually increase in size until the entire lawn is destroyed or when cool weather decreases the insects' activities.
Mature chinch bugs are black and white or grayish winged insects, 1/8 to 3/16 of an inch in length. They are somewhat shield shaped and have a distinctive color pattern. Eggs laid by adult insects hatch into nymphs which are black and red in color and from a 1/16 to 1/8 inch long. Late stage nymphs are nearly all black and slightly smaller but similar in shape to the adult but without wings.
To check for chinch bugs, part the grass and inspect the base of the plant near the soil surface. Inspect the lawn at several locations where the grass is turning yellow and in adjacent areas of apparently healthy grass. You should find chinch bugs if they are damaging the lawn. If the lawn is dying during the spring time, causal agents other than chinch bugs should be suspected.
Since chinch bugs only feed on St. Augustine grass, you can avoid lawn damage by planting other kinds of turf grass. Infestation can be controlled with insecticides applied as a drenching spray which penetrates to the soil surface. Look for insecticide products at garden centers that are labeled for use on lawns to control chinch bugs.
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Why don't my bird-of-paradise plants bloom?
Q: My bird-of-paradise plants are not blooming, I water and fertilize them regularly and they look healthy. Is there something else I should do to make them bloom?
A: Your plant may not be mature enough to produce flowers. Young plants may not bloom for a few years after they are planted. Well established crowded clumps produce the most flowers. Large clumps can be divided during warm weather, but the divisions may not bloom for several years and flower production will initially be light.
The bird-of-paradise will grow in full sun to partial shade, but plants in full sun produce more flowers. Fertilize plants during the spring and summer and do not fertilize during fall and winter. If you want small plants to grow rapidly use a fertilizer with more nitrogen than phosphorous. Use a fertilizer with as much, or more, phosphorous than nitrogen to obtain more flowers on established plants. Water plants thoroughly when you irrigate, then wait until the soil is somewhat dry before you irrigate again.
When flowers are removed pull them from the plant, this keeps the base of the flower stem from crowding the lower part of the clump. Grasp the flower firmly below the flower head and pull up and outward. Do not pull flowers from young plants until they have had the time to develop a root system that will withstand a strong tug, usually several years.
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What is this white cottony substance on my pyracantha?
Q: Some branches on my pyracantha have areas which are rough and swollen. These areas are covered with a white, cottony substance. Is this a pest or a disease and what can I do to control it?
A: The woody galls and the white, cottony substance on your pyracantha branches are associated with an insect pest called woolly apple aphid. The insect feeds on leaves, stems, and roots of apple, cotoneaster, hawthorn, and pyracantha. It removes sap from plants and secretes a toxin which causes woody, gall-like swellings on branches and roots where the insect feeds. The aphid secrets clear and sticky honeydew on plant parts which promotes the growth of black sooty mold. The woolly apple aphid is a reddish insect less than 1/8 inch long, is covered with white cottony material and has sluggish movements. Aphids spend winter on roots and branches, with little visible cottony material. During summer and fall successive generations migrate simultaneously from roots to branches and vice versa. Bands of sticky substances (such as tanglefoot) around trunks and branches can help prevent migration. Dormant oil sprays will kill colonies on branches. Aphids are not easily washed off with soapy water solution. There is no chemical control for root colonies. Tiny parasitic wasps are important natural control agents. Aphids often become numerous when these wasps are killed by insecticides applied during the growing season.
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What does a tomato hornworm turn into?
Q: What does a tomato hornworm turn into?
A: The tomato hornworm, Manduca quinquemaculata, is the larvae of a sphinx moth which is also known as a hawk moth. Caterpillars of the tomato hornworm grow up to four inches in length when they are mature and then form a dark brown pupae in the soil. During this resting stage the larvae transforms into an adult moth. The life cycle from egg to adult can occur in less than two month during the summer but will remain in the soil for several months during winter. The adult moth, which has a wingspan over four inches, is a strong flier and is sometimes mistaken for a hummingbird. It may be seen at dusk hovering over flowers and sucking nectar. The female moth mates then lays eggs on tomato plants.
The adult moth is dark grey with a body length of about 2 inches. The front wings are grey with whitish and blackish wavy streaks and a distinct, white dot in the middle towards the leading edge. The hind wing is gray with indistinct white bands and the abdomen has 6 yellow spots along each side.
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What is the green powdery substance on the trunk and branches of my citrus tree?
Q: There is a green powdery substance on the trunk and branches of my citrus tree. Is this a disease?
A: The green powdery material is probably dry algae. It often grows on the surface of the bark on portions of a tree's trunk or branches when moisture is present. Algae does not harm citrus trees and does not need to be controlled.
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I think I have found Red Imported Fire Ants. What should I do?
Q: I think I have found Red Imported Fire Ants. What should I do?
A: Call 1-800-491-1899, the same phone number you'll find on our Diaprepes poster. There you can get more information about the Red Imported Fire Ant, and you can report your find to the agricultural authorities. They will verify whether the pest is the imported one (versus the indigenous one) and they will take appropriate measures. This imported pest threatens our multi-billion dollar agricultural industry, and your help is needed in bringing it under control.
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