Pests and Diseases

 

My camellia leaves have yellowed markings on the upper leaf surface and under the leaf is all white. Is this an insect or disease?

This is an insect called Tea Scale and it is the worst pest on camellias. It is difficult to treat with contact insecticide because total coverage with the insecticide on the underside of the leaves is necessary. Therefore, treating with a systemic insecticide or horticultural oil is recommended.

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Suddenly two pots of our impatiens have fine webs and a washed-out look to the foliage. What pest is present and what can we do to get rid of it?

Spider mites have found a home in your impatiens plants. This often happens when the plants are given a protection free of the rains that tend to wash the mites away. The pests are pencil-point size, piercing, sucking arachnids that cause the bleak look as they suck the juices from leaves and stems.

Start control by using a strong stream of water to wash the mites away. Then apply an insecticidal soap spray. Follow the label instructions, and repeat applications every 5 to 7 days for a few weeks to prevent reinfestation.

If the plants have been severely infected they may not recover.

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What is a good spray program to control lawn pests?

There was a time when gardeners sprayed every other month, March through October to control lawn pests. University of Florida studies found most lawns flourished without the frequent pesticide treatments. They also revealed many beneficial insects help control the pests. Good bugs include earwigs, spiders, and big-eyed bugs. The pesticides kill these as well.

Most gardeners scout their yards and stay alert for declining turf. Problem areas are checked for pests and sprayed as needed. Lawns also decline because of drought, diseases, nematodes and lack of sun.

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I was surprised with your diagnosis of leafhoppers in a recent column. I thought the problem was sod webworms. How can you tell the difference, and how should the webworms be treated?

Sod webworms chew the grass blades. At first they nibble, producing a skeletonized leaf, but as they grow older, the entire leaf is consumed. Often when they are feeding, gardeners remark that the lawn appears to be mowed too closely. Leafhoppers suck juices from the blades and cause yellowing of the turf when the population is high.

Gardeners can usually ignore leafhoppers, but they like to control the webworms. However, they cause minimal damage to a healthy turf, which simply grows new leaf blades when damaged by the insects. If needed, a natural Bacillus thuringiensis-containing insecticide available at garden centers give good control of webworms. Synthetic insecticides are also available.

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My ferns have small white scales. What can I spray them with?

 Ferns are so sensitive to insecticide that most chemicals may do more damage to the plant than the insect. Even some of the appropriate sprays may cause phytotoxicity. Ivory soap may help as insects are repelled as well as killed.

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My petunias are wilting and collapsing even though I have watered adequately. What is the problem?

Damping off is a disease that commonly affects petunias and other bedding plants. This soil home disease characteristically causes a browning and collapsing of the stem at the soil level. Soil fumigants, applied prior to planting according to label directions, have proven effective. Several fungicides are labeled but may be difficult for homeowners to find.

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My ferns have brown spots on the underside of the foliage. Is this an insect or disease?

These brown spots are spore masses, not insects or disease. These spores are the equivalent to seeds in higher plants. Fern propagation from these spores is very difficult since exact and controlled conditions are difficult to simulate for most home gardeners. Division of the parent plant is recommended for fern propagation, except tree ferns.

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What causes hard white or colorless spots around the outside of my tomatoes?

This damage may be done by stinkbugs. These pests insert their mouthpart below the tomato skin and suck out the tomato sap. These empty cells create a hard, colorless spot. Stinkbugs do cause fruit to have a poor aesthetic quality, but the fruit is still edible. Whiteflies cause a similar disorder, but the colorless area is broader and more generalized. Other similar spots are known as ghost spots, cause unknown.

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My poinsettia is showing spots on the foliage and creamy colored scab-like lesions on the stem. What is this and how can I get rid of it?

This is a disease called poinsettia scab. The diseased tissue must be pruned out. Once the poinsettia begins to flush out with new growth, spray with appropriate fungicide and repeat on the next two growth flushes.

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My roses have black spots with irregular edges on the leaves. Some spots have yellow rings around them. The leaves are even dropping now. How do I treat this?

Black Spot is the most common foliage disease of roses. The disease can only get established when the foliage stays wet for 6 hours each day or longer, and is spread by splashing rain.

Control is accomplished by keeping the foliage dry and spraying weekly with a recommended fungicide.

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The trunk of my oak tree is covered with a silky web and there are little tiny insects under this web. How do I get rid of these before they kill my tree?

These insects are called Psocids. They do not damage trees or ornamentals. They only feed on the decaying organic matter that is trapped in the crevices of the bark. Once these insects are mature, they will move out of the web that once provided them with protection. No control measures are necessary. If they are unsightly, spray the webbed area with a strong spray of water to disperse the insects.

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My oleander is covered with reddish-orange colored worms with black hairs. They are stripping my plant of its foliage. What should I do?

Oleander caterpillars can strip a plant completely in one week. Oleander caterpillars are best controlled before they migrate over the entire shrub. The eggs are laid in the tips of the leaves. When the eggs hatch, all the little caterpillars are clustered on the branch tips. It is best to prune out these tips and then step on the caterpillars before they migrate throughout the entire shrub. All labeled insecticides have proven equally effective if applied when caterpillars are still small.

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It looks like something is pruning the twigs on my oak, dogwood, or maple tree. Every day I find more twigs under the tree and they have all been cleanly cut. What is doing this?

An insect called a twig girdler is the culprit. It lays its eggs in the twigs of popular trees like maple, oak, pine and pecan, then chews it off so it drops to the ground where the life cycle will be completed. The only control measure is to clean up the fallen twigs and burn them. This makes completion of the life cycle impossible and eliminates the next generation.

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My crape myrtle has a powdery-like substance on the leaf surface. The leaves then curl up and die. Is this a fungus?

This is a fungus called powdery mildew. Many crape myrtles are very susceptible to this disease. Repeated appropriate fungicide applications will be needed throughout the growing season. Resistant hybrids and/or increased air circulation around the plant have also been shown to be beneficial.

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This year my azaleas and sycamore leaves got a bleached-out appearance and the underside of the leaves was covered with black tar-like spots. What causes this?

Both azaleas and sycamore are susceptible to damage caused by an insect called a Lace Bug. Damage results from the insect sucking out cell sap, resulting in mottling of the leaf. The black tar spots are actually the insect's excrements. Control on azaleas can be accomplished with recommended sprays. Control on sycamore may be impractical if the trees are large. If no action is taken, the trees will defoliate early, but no permanent damage will result.

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I have a stand of pines on my property. One after another is turning brown and is dead within two weeks. There is some sawdust at the base of the tree and sap on the trunk. Can I save my trees?

 A serious pest of pine species is the Ips engraver beetle and other pine borers. They attack trees weakened by natural or man-made conditions such as drought, lightning or root damage during construction. The adult beetle attacks the pine by chewing through the bark and laying their eggs. The young larvae feed on the cambium tissue, which girdles and kills the tree.

Insecticide sprays on the trunk will probably not save the tree because of the short developmental period of the insect and the pre-existing weakness from some stress. Remove the affected tree and spray nearby uninfested trees with appropriate sprays to help protect them from attack. The best protection is to keep the pine healthy to avoid attack.

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The limbs of my East Palatka holly tree are declining on one side of the tree. What could be the cause and how to control it?

Both scale insects and fungus are attacking East Palatka hollies. The scale appears as slight to dark bumps that can be easily rubbed off with your finger. The fungus forms swollen areas near the end of the branches, which causes the limbs to decline.

The scale insect is the easiest to control. First prune out all the dead and dying tree portions. Then apply an oil spray to the insects. It takes some time for the scale to dislodge and drop from the tree.

There is no good control for the fungus except to prune it from the tree. When pruning, make sure you sterilize the pruners between cuts so you won't spread the disease.

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I cannot get rid of the wasps living in my podocarpus bush even though I have applied insecticides. What should I do?

Wasps often appear to be nesting in shrubs, but they are only visiting. Sometimes they are attracted to moisture adhering to the leaves and limbs and to the excreta from piercing sucking insects called honey dew.

If you can see a nest, then you know the wasps are making your podocarpus a home, and a wasp and hornet spray should be effective. More likely the wasps are feeding on the honeydew from aphids feeding on your shrub. Try controlling the aphids with a soap or oil spray. This normally eliminates both problems.

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When I am out in the yard, I find roaches in the bark of trees and shrubs. Can I get rid of the roaches?

Roaches can be beneficial insects in landscapes. They help reduce the organic matter that often accumulates in lawns, gardens and under trees. Often the loose bark of trees gives them a good hiding place. It would be impossible to eliminate the roaches from your landscape, but you can keep them from entering the home if this is also a concern.

First make sure all potential entrances around the outside of the home are properly sealed and caulked. Then if roaches are still a problem, apply a barrier with an insecticide labeled for perimeter treatment for household pests as instructed on the label. Most likely the applications will be infrequent, but usually when roaches are driven inside by unfavorable weather.

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After my seeds germinate and start growing the little seedling just turns brown and collapses at the soil level. What is the problem and how can I treat it?

This is a disease called damping off. It is caused by soil borne fungi such as rhizoctonia and pythium. There is no treatment for this disease once the seeds are planted. Soil sterilization is one form of prevention and treatment against this disease. Soil sterilization can be accomplished by solarization. Use seeds treated with a fungicide for further prevention. Crop rotation also helps.

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Our viburnum hedge has a whitefly problem that results in lots of sooty mold on the foliage. I have tried soap sprays with little success. What do you suggest?

Soap sprays can help control whitefly infestations, but you have to be persistent and hit the undersides of the leaves where the immature stages are well-hidden. Repeat sprays during several weeks.

Whitefly is also controlled by natural oil sprays available from garden centers. Besides eliminating this pest, the product also helps loosen the sooty mold. If you would rather try a synthetic pesticide, there are several formulations with Merit, a systemic insecticide, available to spray on the plant or to drench the ground and be absorbed by the roots. When the whitefly is under control, the sooty mold slowly disappears from the foliage.

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My neighbor moved away and gave me his pepper and tomato plants, plus a container of caterpillar spray. How often do I treat the plants?

Wait until you see signs of caterpillar damage, which should be quite obvious. Caterpillars chew holes in leaves when small and devour entire stem and fruit portions as they reach maturity. Check the plants every day or two for the pests.

Often a caterpillar or two can be handpicked from the plants, and sprays are not needed. When the caterpillars are too numerous to count, it's time to use the spray, following label instructions. Moisten the entire plant and note the waiting period between the last spray and harvest to pick your red, ripe tomatoes.

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I added several new houseplants to my home and noticed little gnats flying around that I think may be whiteflies. What should I use to treat the plants?

If the insects taking flight are white, then you have made the correct diagnosis and whiteflies are likely feeding on the foliage. They should also be easy to see on the backs of the leaves and can be controlled with a soap or oil spray available from your garden center.

But when you catch one to get a close-up look, and it's really a dark color, you may have fungus gnats flies that live in damp places such as your soil. These insects have an immature wormlike stage that when mature produces the winged adults. If this is the case, it's probably best to take the plants outside and treat them with an insecticide made for use with houseplants that can be drenched on the soil. When the treatment dries and the odor dissipates, you can move the plants back indoors for display.

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I caught an inch-long tan caterpillar feeding on my rose-buds. Is this a job for the natural Bacillus insecticide?

Caterpillars can find all parts of a rose plant a tasty treat, especially the tender buds. Usually they are not that numerous and can be hand picked from the plant and destroyed as needed. If there are too many to easily remove, the Bacillus thurigiensis insecticides--often sold as Dipel, Thuricide or BT products-- could be applied to obtain control. They are a little slow to eliminate the caterpillars, but they usually stop feeding shortly after an application

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I have a pot of English ivy growing at my front door that has developed a black sooty covering on the older leaves. May I apply a spray to control the black growth?

You have made a good diagnosis by identifying the sooty mold as fungus. It looks bad but usually causes little harm to your ivy. Much more devastating is the scale insects likely hiding under the leaves or around the stems of your plant providing excreta to encourage the sooty mold growth. These insects may be green or brown and hard to see.

Control of both the scale and sooty mold is not that difficult. Often both can be loosened and washed off with a soapy water solution using a soft rag or old toothbrush. Repeated washes may be needed. Another natural control is to take the plant outside under the shade of a tree and apply an oil spray available at your garden center. Follow label instructions.

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I have been at war with small metallic blue beetles eating my Mexican heather and I am losing. What can I do to get rid of them for good?

Persistence may help to control these pests, but you must apply a pesticide when damage from the beetles is noted. The presence of the appropriately named blue metallic beetles is easily detected from the semicircle chewing mark on the leaves of heather, camellias, crape myrtles and persimmons.

Try reapplying a general insecticide such as Diazinon, Sevin, or one of the new synthetic pyrethroids. This time add a spreader-sticker available from garden centers to the tank following instructions. The addition of this product ensures the pesticide is on the foliage when the beetles begin feeding. Some damage may still be noted, but you should win this war.

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I pulled a weed out of my yard today that resembled parsley. The instant I touched the weed, it gave me a burning sensation. What is the weed and how can I control it?

I hope you applied a soothing cream to help counteract the toxic sap from the appropriately named burning nettle. The weed began to appear in home landscapes about 30 years ago and has since become a common winter annual.

Burning nettle has the bright green and toothlike leaves of parsley, but it should be avoided and removed from the yard. Possibly the best ways to control this pest are to dig it out or spot-treat the foliage with a nonselective herbicide. Lawn-care products made for your turf type also can be used to take the sting out of the lawn.

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We found a rather large green bug on a railing that looks like a type of grasshopper. What can you tell us about this insect?

Your big burly insect is a katydid. The attached e-mail picture helped make this identification easy. They are relatives of the common grasshoppers also found in the landscape. Katydids have a pyramidal-shaped back and are usually bright green.

During the warmer months, male katydids produce serenades. The insects feed on landscape plants, including citrus-tree foliage and fruits. They also can be found feeding in vegetable and flower gardens. The insects are not numerous and seldom need control. The few that are spotted can be handpicked from the plants.

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Our crinum lily is getting red spots on the leaves, and then the leaves turn yellow. What is the cause and a cure?

This not-so-attractive look is called red blotch, a fungal disease that attacks crinums and amaryllis foliage. When the spots grow large and humerous, leaves yellow and decline. You never really eliminate the disease, but you can keep it under control.

Start by trimming the severely affected foliage to reduce the spread of fungal spores. This may be the only control needed to prevent rapid reinfection. If needed, a fungicide of Thiomyl or Halts Systemic Fungicide also can be applied. At best, the disease is prevented in the drier months, but new infections can be expected when the rains return.

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Every year I get little worms in my peaches, pears, guavas, and papayas. What are they and can anything be done?

These are probably the larvae of the Caribbean fruit fly. This pest is a problem on all fruits are fleshy and which stay on the tree a long time before opening. The fly deposits an egg just below the surface of the skin and the larvae feeds throughout the fruit as it matures. Upon maturity, a fly emerges from the fruit. The larvae are usually so numerous the fruit is inedible. Frequent and persistent appropriate sprays throughout the fruit period will give only poor results in controlling this pest.

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My fall squash and cucumbers have been attacked by worms that drill into the fruit. What are the pests, and how do you control them?

Melon and pickle worms love these crops and also cantaloupes. A moth lays eggs that hatch into larvae and they bore into the fruit to feed and grow. The first sign of attack is a hole in the fruit oozing with excreta from the insects.

Use frequent sprays of a bacillus thuringiensis-containing natural insecticide, such as Dipel or Thuricide, starting when the fruit forms, and repeat as suggested on the label.

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The tangerines and oranges on my trees and the ground are being hollowed out. What is the cause, and what should I do?

Citrus rats, also known as roof rats are dining on your fruit. They seem to know when they are ripe before we do. Control may be difficult when there is an abundant food supply, but you should try.

Rats can be lured to poison baits available from garden and hardware centers. Use tamper-proof containers to prevent access to small children and pets, available from bait suppliers or pest-control companies.

You can try using traps baited with dog food or peanut butter, but make sure they are not accessible by children or pets.

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Recently you wrote about citrus rats. Whatever is eating my fruit leaves pieces of peels and eats the fruit fairly neatly. Any ideas?

Have you seen any squirrels lately? They are much neater than rats, and may move the fruit from one area of the yard to another. Rats normally eat their fruit on the tree and feed through a large hole made on the side.

Squirrels peel the fruit and gradually consume it a portion at a time. You may find the peels in various places in the yard where they have taken the fruit with them. No good control exists for squirrels. In most urban settings you need a permit to use live traps and there are no baits available. You can call a critter-control company to trap them for you.

Most gardeners find squirrels less annoying than rats and tolerate the few that feed in the trees. Also squirrels appear less likely to establish a home in your house.

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I've had white scale on my Indian hawthorn for several months and have applied sprays. The scale is still on the foliage. What should I do?

Don't expect the scale to disappear quickly. It is usually cemented firmly to the foliage and has to wear away. Sometimes it takes many months for the scale to drop off. No further control is needed unless new scale is seen. Then an oil spray available from your garden center is usually all that is needed. Follow the label instructions for repeated applications.

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I have a gardenia that was beautiful and just finished blooming. It suddenly has turned yellow and has ants on the underside of the leaves. What can be done to save this plant?

Ants are often a sign that scale insects are feeding on he gardenias. Look closely at the undersides of the leaves. They are usually a green or brown color.

If present, apply an oil spray to obtain control. Also make sure the plant has adequate water and feed lightly in March, June and September to keep the gardenia green and vigorous.

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The foliage on our hibiscus plants looks healthy and green, but they drop their buds before they open. What do we need to do?

Open a fallen bud or two to check for hibiscus midges. The small larva stages are yellow and often seen crawling among the flower portions. The feeding insects cause the buds to fall before opening. When present, control with a general insect herbicide labeled for hibiscus available from your local garden center.

If the insects are not present, the buds may be dropping because of the plant's rapid growth. Summer rains and frequent feedings can cause the plants to produce growth at the expense of flowers. Reduce the feedings or apply only blossom-booster type products to encourage flowers by fall.

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Something is wrong with my crape myrtles. The leaves are black, often turn yellow, and the flower buds are not opening. I noticed aphids recently. How can I save the plants?

Crape myrtles can look a bit ugly at this time of the year, and you can blame a lot of the decline on the aphids. The insects suck the juices from the new leaves and buds, producing excreta that is the food for the sooty mold fungus. The feeding also inhibits good bud formation and may affect opening.

Now that fall has returned, and the days are growing shorter, the plants are beginning to lose their leaves and stop flowering. It's too late to begin a spray program to control the aphids and prevent further leaf and bud damage. Gardeners usually ignore the damage. If needed earlier in the season next year, an oil spray available from garden centers can be applied to control the aphid and sooty mold problems.

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I think my gardenia has cottony cushion scale. How do I get it under control?

If the insects small but marshmallowlike, you probably do have a cottony-cushion scale infestation. Usually this pest is accompanied by a sooty mold covering on the surface of the leaves.

Both problems are easily controlled by an oil spray. It will take weeks for these tightly adhering pests to slough off the foliage and stems.

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We have noticed a rounded ball growth among our shrubs. When it opens, it's a reddish-pink in color and emits an awful smell. What can we do to eliminate this growth?

Perhaps the rancid smell is best described as dirty diapers coming from the appropriately named stinkhorns. These are fungal growths that have been living on the organic matter in the soils among the bushes. They might be considered beneficial because they help to break down the organic matter in the ground, but they do emit a terrible odor.

Stinkhorns send up the pink to orangy fruiting bodies you notice during warm, damp weather. Insects are attracted to the rancid smell, and they pick up spores and disperse the mushrooms to other sites. Regretfully, there is no good control except to collect the mushrooms when noted or just knock them over and wait for them to dry up.

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The leaves on my Indian hawthorns are developing dark spots and then falling off. What can I do to stop the decline?

These small spots are caused by a disease called entomosporium leaf spot. It also affects photinias, often called red tops, where it can be a devastating fungal problem: Normally attacks of Indian hawthorn are not as severe unless the plants are having other problems.

Make sure your plants receive proper watering and are fertilized several times a year to maintain good vigor. Then dig down and check for swollen roots, a sign of nematodes. Also, plants growing in areas with poor air movement may have more problems with this leaf-spot disease. First try to correct any cultural and pest problems that might affect growth. Then apply the fungicide Immunox, Thiomylor Fertilome Systemic Fungicide to control entomosporium leaf spot; follow label instructions.

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Our rose blossoms start to open and then develop a tan to brown discoloration at the edges of the petals. Some blossoms never open. What is happening to the flowers?

 The beauty of your rose blooms has been marred by tiny insects called thrips. Tap a damaged blossom over a white sheet of paper to dislodge these pests. They have rasping-sucking mouth parts used to feed on the flowers and cause the discoloration. Regretfully, thrips are one of the normal spring rose problems.

Gain control and some better looking blossoms by removing any buds showing color. Then apply an insecticide to the planting; be sure to hit the new flower buds. Products giving control of thrips include insecticidal soaps, natural pyrethrin sprays and the new synthetic pyrethroids found in many general insect-control products for use with landscape plantings. Follow the label for best and safe application. Weekly sprays are usually needed until the thrips are under control.

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I am having one of my best years with roses, but the stems are covered with green aphids. I have used a spray, but the insects have persisted. What should I try next?

A soap spray may be the simple answer to your aphid problems. These pests have avoided some insecticides, but the soaps available at garden centers still seem to work. You have to hit the insects with the sprays because soaps are contact insecticides.

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I found dozens of tiny caterpillars chewing the leaves of my desert rose plant. What should I do, and will the plant recover?

If the caterpillars are orange with black hairs, your desert rose is hosting a collection of oleander caterpillars. It might be hard to believe, but this different looking plant is in the same family as oleanders and mandevillas. Sometimes the caterpillars just skip over for a little visit on each of these.

One defoliation won't bother a healthy plant. In fact, it's not abnormal for the desert rose to drop its leaves because of drought and cool temperatures; so a few hungry caterpillars should be of little bother. It's a plant that's built for survival with thick storage stems stocked with food and water for the tough times. With a little care, the plant should leaf out and be in bloom again for fall.

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Our hibiscus looks healthy and green but never blooms. It produces what looks like buds, but they never open. Should I cut it back?

Hibiscus can be shy bloomers, but if big, plump buds are forming, most should open. Recently, an insect known as a midge has been causing the buds to drop prematurely to spoil the flower displays. It's a small critter but can be seen in the yellow larva stage within the buds that fall to the ground without opening.

When the larva are noted, one of the synthetic pyrethroid sprays available from your garden center can be used to obtain control. These are marketed as general-use insecticides for the landscape.

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In a recent column, you mentioned a disease that affected hollies, just when we were thinking of planting a short hedge of the Burford type. The plants we selected look healthy. Will this variety be affected?

Starting with healthy plants is one secret to controlling the witches broom disease, also known as sphaeropsis, which is affecting many local hollies. But yes, it can affect the Burford selection of the Chinese holly, too. Much of the disease is spread through pruning, so if you have pest-free plants and use clean pruners when trimming is needed, the chances of getting a witches broom infection is minimal.

Of the common hollies, only the yaupon selections seem to have resistance, and the dwarf forms would make a good hedge, too.

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The flower buds on my hibiscus and gardenia plant drop before they open. What could cause the problem?

Premature flower bud drop is often a problem with both of these plants and can indicate an insect problem, cultural/environmental problems, or a varietal characteristic.

Insects called thrips can damage the unopened bud. These may go undetected until considerable damage has occurred and the buds drop.

Too much or not enough fertilizer or water can stress the plant - resulting in bud drop. Nematodes can parasitize the root system, creating a water and nutritional stress on the plant, also resulting in bud drop.

Some varieties of hibiscus, especially doubles, are characterized by premature bud drop. Some varieties bloom well during one period of the year and consistently drop their buds at all other times.

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We have a large hibiscus plant that blooms most of the year. It's still blooming but has lost most of its leaves. It has small, hard, brown bumps on the branches. How do I treat this plant?

It sounds as if it's pruning time. Now is a good time to remove the tall shoots to bring the plant back in bounds. Remove any shoots that are heavily encrusted with the brown bumps; these are scale insects.

Also reduce the height of the plant to allow for growth. Complete the spring care by applying a low-toxicity oil spray available from your local garden center; follow label instructions to finish controlling the scale.

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Some of the fruit on our Murcott tree have brown warts on the surface. Inside the fruit looks fine. Is this normal, or should we spray the tree with some thing?

The warts are normal for a tree affected with citrus scab, a fairly common disease of lemons, Minneola tangelos, Murcotts and Page oranges. Other selections can be affected too, but the damage is usually less noticeable. The disease infects the fruit and foliage loss from the trees.

As you noted, the internal fruit portion is fairly normal, and if the fruit remains on the tree until maturity, the fruit will have the desired flavor and texture. Where needed, scab can be controlled with a copper fungicide spray applied as the fruit and foliage form. Once they are infected and the warty growths are noted, it is too late to apply a spray.

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I have centipede grass in my yard, and within the past several weeks large brown areas have appeared. The grass is dying, and the ground seems to be soft. Can you tell me what the problem might be?

 A soft, spongy soil may be the result of a mole cricket invasion. This is not a common problem with this turf type, but it's possible. The easiest way to check for this root-destroying pest is with a soap flush. Mix 1½ fluid ounces of a mild dish detergent in 2 gallons of water, and sprinkle it over a 4 square foot area of turf at the edge of a good and bad area. If the mole crickets are present, they should come to the surface within a few minutes.

Mole crickets are about 1 inch, ¼ wide and brown at this time of year(September). They tunnel in the soil, destroying roots and causing the soft earth feeling. If you spot several in the soap flush area, treat with a mole cricket control available from your garden center.

Because centipede grass can have many other problems including nematodes, ground pearls, grubs and diseases, you may want to drop a sample of the sod by your local extension office. The agent needs about a square foot of turf with 2 inches of soil from an area bordering good an bad spots to make a diagnosis.

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A few of our impatiens plants are getting a whitish look to the leaves and a web is forming between the stems. What can I do to save them?

The webs are a sign spider mites are affecting the leaves by sucking juices from them to make them appear white. By the time you notice the webs, thousands of mites are present and the plant is sure to decline.

It's best to remove heavily infected plants to prevent further spread. Use soap sprays from your garden center, and a strong water stream to wash off light infestations.

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About five months ago, I planted several bougainvillea in containers. They grew fine but have now developed yellow leaves with dark spots. What is happening to the plants?

SSummer rains likely encouraged the growth of a bacteria or a fungal organism that caused leaf spot. Both are quite common on bougainvillea. Yellowing leaves affected with the spots are going to drop. As the drier fall weather returns, the leaf spotting should stop. If it continues, a natural copper-containing fungicide can be applied following label instructions.

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My okra and other vegetables were not growing well and when I pulled them up, the roots were covered with tumor-like growths? What is this?

The knots that you see are probably the result of a nematode infestation. Nematodes parasitize the plant by intercepting water and nutrients, which would normally support active, healthy plant growth.

The best treatment for nematodes is soil sterilization by solarization prior to planting. This may need to be repeated at the start of all gardening seasons. Adding liberal amounts of organic soil amendments helps, as does crop rotation. Some varieties are more tolerant to nematodes than other varieties. Examples are 'Better Boy' tomato and 'Califomia Blackeye #5' southern peas. Nodules on the roots of leguminous plants such as beans or peas probably are not from nematodes but rather from beneficial nitrogen fixing bacteria.

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I have two big pumpkins and both of them have a little hole with a white gel flowing from the opening. Will this cause permanent damage, and is there a control?

Insects known as pickle worms and melon worms are likely attacking your pumpkins. The eggs are laid on the foliage or surface of the fruit, and the larvae bore into the rind.

Take a close look at the hole, and if the damage is superficial it can be ignored. Older pumpkins may show injury, but only the outer portion is affected and the wound usually heals.

When the pumpkins are young and soft, the insects enter and feed inside, causing the fruit to rot. Where needed, a natural Bacillus thuringeiensis-containing insecticide or a synthetic spray of Sevin or a new pyrethroid may help. Follow the label instructions.

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Tiny green worms are feeding on my tomato leaves. I tried a homemade soap spray, but it burned the plants. What can I do that is natural?

Homemade pest controls give varying results, and sometimes, as you found, the concoctions damage the plants. Luckily, a natural bacterial extract of Bacillus thuringiensis is marketed for caterpillar control at local garden centers. It's often sold as Dipel, Thuricide or simply a BT insecticide. The products are slow to act but effective.

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I have two nice pecan trees in my yard; one has a pest that produces a stinky ooze from a crack in the side of the tree. How can I control the pest?

The smell and usually a dark-colored ooze is produced by bacteria living in the trunk of the tree. The bacteria may have entered with an insect or through some other injury to the tree trunk.

Many trees have these infected portions that emit the slimy substance, especially during the damper weather. There is no quick control except to encourage the tree to wall off the diseased portions over time. Make sure you apply the yearly feeding provided pecan trees in February to keep this tree productive and to encourage the wound-sealing growth.

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Whiteflies have invaded my eggplant bush. What can I do to combat them?

A little soap might clean up this problem, but it's best to obtain the insecticidal type sold at garden centers. These are tested products and won't burn or otherwise damage your plants when applied according to the label.

Sprays give little control of the adults that fly away when the plants are disturbed, but they do control the next generation forming on the undersides of the leaves. It is important to thoroughly spray underneath the foliage. Some gardeners also hang sticky boards, available from garden centers, near their plants to capture the escaping adults.

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I have been battling a persistent vine that is climbing my oak trees and covering a hedge. It has big heart-shaped leaves. Is there a way to control the vine without affecting nearby plants?

Some gardeners call this weedy vine kudzu, but it's the tropical yam. You probably want to keep the tree and hedge; so the first step is to cut the vine to the ground and remove it from the desired plants.

Next, treat the growths with a herbicide that contains triclopyr. Products available at garden centers with this active ingredient include Bayer Brush Killer Plus, Roundup Poison Ivy & Tough Brush Killer and Ortho Brush B Gon. Treat only the foliage, and follow the label carefully to prevent injury to nearby trees and shrubs.

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I have slugs in the garden. I can see their slimy trails across the sidewalk. Why do I have them, and how do I get rid of them?

Consider your garden normal; slugs enjoy moist, cozy quarters provided by damp organic mulch layers. They also are going to like nibbling on the plants, and this is where the problems start. It's not nice seeing holes in your plants.

You do have the option of picking off the slugs. This is a nighttime or early-morning job when you can see the critters dining on your plants. You also could lure them into shallow trays of beer where they decline in delight. Or you can apply a low-toxicity bait containing iron phosphate, marketed as Sluggo at many local garden centers, that controls slugs while you sleep. Just follow the label.

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The bottoms of my tomatoes have dark brown, rotten spots. What is this and how can I prevent this problem?

This is a nutritional disorder called blossom end rot. The deficiency may result from:

  • Soils being deficient in available calcium. Soil pH should be 6.0-6.8. A pH lower than 6.0 may not supply enough available calcium, therefore, lime must be applied according to a soil test. When the pH is okay, but the level of calcium in the soil is low, a non-liming source of calcium (gypsum) may be helpful when applied.
  • Infrequent watering will disrupt the flow of soluble calcium to the developing fruit. Soil must be kept consistently moist to keep calcium in solution and available to plants.
  • Soluble sprays of calcium to the foliage can help correct the calcium imbalance.

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My cucumbers look great, but my cantaloupes wilt and are not growing. What is the problem?

Dig down and check the roots. Most likely you have a nematode problem. If the roots are swollen and knotty, the plants are being attacked and are not going to be productive.

Cantaloupes and cucumbers are susceptible to nematodes, which are microscopic round worms in the soil. Certain ones attack susceptible plants, causing wilting and nutritional problems. No control exists except to replace the soil or bake the roundworms out of the ground using solarization techniques.

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I have two desert rose plants. One has foliage that is covered with webs, and the other has yellow bugs on the leaves. What should I do about these pests?

May I ask you to check the plant with webs for mites? Desert rose plants that get the pretty pink blossoms also can harbor large populations of spider mites. Look within the webs and on the leaves for these almost pinpoint-size arachnids. Your second plant is playing host to clusters of aphids. These are common insects that feed in the soft tissue of new growths. Ones that affect the desert rose are commonly a yellow color, pinhead-size and pear-shaped. They are up to no good sucking juices from the new leaves and flower-buds.

Here is the good news: An insecticidal soap can cure both problems. Follow the label directions when mixing and make sure to hit the undersides of the leaves for mites and growing tips of the plants for the aphids.

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We have a 12-year-old orange tree with a black sootlike growth on the leaves, and the oranges appear dirty. The tree also has a white growth on the limbs. Should we remove the tree or is there a treatment?

Save the tree and apply a natural oil insecticide to remove the mold and the insects that encourage dark fungal growth on the leaves and fruits. The mold feeds on excreta from piercing, sucking insects including whitefly, mealybugs and cottony cushion scale. The white on the trunk of your tree is likely snow scale, another pest that is controlled with the oil. Be sure to treat all portions of the tree to eliminate these pests.

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