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Pesticide Types

Several examples of pesticides available for backyard plantings are described below. Since various suppliers provide the same active ingredient under various trade names, the compounds below are listed using their common chemical name.

Not all insects or diseases appear on all labels for all crops. Always consult the label before making pesticide applications. Labels vary greatly between commercial products of the same material. It is important to refer to the label for the best timing and application rates when applying pesticides.

Table 2.4: Pesticides available for home garden use on various fruit crops is referenced in some of the listings below.

Azadirachtin

This azadirachtin-based biological insecticide, repellent, antifeedant, and insect growth regulator is used mostly in soft, organic insect-control programs. It controls pests on contact and ingestion. Azadirachtin can be applied using standard spraying equipment up to the day of harvest. This pesticide is toxic to fish and aquatic invertebrates.

Bacillus thuringiensis or Bt

Bacillus thuringiensis (Bt--many products) is a selective microbial insecticide formulation using a byproduct of the naturally occurring bacterium Bacillus thuringiensis as its active ingredient. This bacterium is able to exist as a spore until temperature, moisture, and available nutrients are conducive to the reinitiation of the life cycle. Bt exhibits a unique insecticidal activity when eaten by susceptible larvae, specifically those of the insect order Lepidoptera (moths and butterflies).

Bt does not have any of the hazards sometimes associated with chemical insecticides. It has been shown to be incompatible, however, with mixtures with a high pH such as Bordeaux mixtures. In orchards, Bt should provide excellent control of variegated leafroller, tufted apple bud moth, red-banded leafroller, oblique-banded leafroller, green fruitworm, and most forest-orchard species (gypsy moth, tent caterpillar, webworm). If mixing Bt with other products, always add Bt first. Good mechanical agitation is important to quickly mix Bt.

Captan

Captan is a fungicide with protective and curative action. Many of the general purpose product mixes contain captan (see Table 2.4). Captan is effective against scab, black rot, white rot, bitter rot, Brooks spot, and blossom end rot on apples. It is effective against sooty blotch and flyspeck if the last spray application is not more than 30 to 40 days before harvest. It is not effective against the rusts, fire blight, or powdery mildew.

Where the early season apple scab control program fails and scab becomes established in the trees, captan at low rates cannot be expected to provide control. This fungicide is highly effective, however, in reducing spore germination. Use at least 4 to 5 T per 2.5 gal applied at intervals of no more than 10 to 14 days.

On stone fruits, captan is a good fungicide for the control of brown rot and scab when adequate spray schedules are followed. Captan plus wettable sulfur can be used on peaches when brown rot, scab, and mildew are present. Captan is effective against cherry leaf spot and brown rot on tart cherries if the diseases are at a low level and the spray intervals do not exceed 2 weeks.

Captan has caused a necrotic spotting, yellowing, and dropping of leaves when used under poor drying conditions or in combination with sulfur, especially on Delicious, Stayman, Baldwin, and King apple varieties. Foliage of d'Anjou pears has been stunted and cupped. Necrotic spots on fruit and foliage have occurred on both plums and prunes where captan was used from petal fall until the fruit begins to ripen. Its use usually results in acceptable fruit finish on apples, peaches, and nectarines. Captan residues on peaches at harvest may cause increased skin discoloration from abrasions that occur during picking and packing. The leaves of some sweet cherry varieties may be injured by repeated captan applications. A full-season program of captan may require the use of miticides or close adherence to a pest management program. Captan is not registered on pears.

Captan has few spray incompatibilities, but it should not be used with oil, lime, or other alkaline materials. Using captan within a week either before or after an oil application may result in leaf injury on apple trees. Combinations with sulfur might result in increased injury under high temperatures and high relative humidity. The preharvest interval for captan is 0 days. Please remember to check the label for rates and application times for best disease control.

Carbaryl (Sevin)

Carbaryl (Sevin) is a relatively safe, carbamate insecticide. It is highly toxic to bees and should not be used near bloom. When applied 2 to 3 weeks after bloom, carbaryl acts as a fruit thinner on many varieties. Mite populations usually build up rapidly following carbaryl applications because of its toxicity to mite predators. Thus, it is not recommended for most applications where mites are a threat.

Chlorothalonil (Bravo)

Chlorothalonil formulations are nonsystemic foliar fungicides with protective action registered for the control of brown rot blossom blight; leaf curl of stone fruits; scab on peaches, nectarines and apricots; and cherry leaf spot. There are many formulations of chlorothalonil available to the home gardener (see Table 2.4). Please remember to check the label for rates and application times for best disease control

Copper Compounds - Bordeaux

Copper compounds are widely sold as fungicides for orchard and garden use. Copper is a foliar fungicide with protective action. These compounds can be highly phytotoxic to many fruit crops and must be used with extreme care. Check the label for type of copper and any cautions that accompany its use. Please remember to also check the label for rates and application times for best disease control. Many formulations of copper are available to the home gardener (see Table 2.4).

Copper was first used in the mid-1800s in grape vineyards in France to discourage theft of the grapes. Copper sulfate and lime were mixed in a slurry and spread over the grape vines. In 1882 a French scientist observed that this antitheft treatment was effective in reducing a disease called downy mildew. This observation was made near the town of Bordeaux, so the mixture of copper sulfate and lime became known as Bordeaux mixture.

Copper sulfate is readily soluble in water. This high degree of solubility is the fundamental cause of the toxicity problems, which copper sulfate can cause to all fruit crops. Fixed coppers have been developed that are relatively insoluble and therefore less toxic to plants; however, fixed coppers can also result in phytotoxicity under certain conditions. Fixed coppers include basic copper sulfate, basic copper chloride, copper oxides, and copper hydroxide.

The fungicidal activity of copper is based on its ability to destroy proteins in plants. This is true for all plants, fungi, and fruit plants. When lime is combined with copper compounds, it reacts with the copper, making it more stable. Thus, copper compounds in the presence of lime would generally produce lower, more uniform concentrations of free copper, which in turn would be less apt to injure plant tissues than if no lime were used. Because copper has the ability to kill all types of plant tissues, the use of copper fungicides carries with it the risk of causing injury to fruit plants. Ideally, copper on the leaf or fruit surface should be in high enough concentration to kill the fungus or bacteria but low enough not to cause injury to the plant.

Factors that can promote injury include failure to use enough lime; cold, wet weather conditions that apparently increase copper's solubility, allowing more into the plant and resulting in toxicity; and application of excessive rates of copper. Even when no injury is evident on the plant, subtle effects of the copper on the plant may be occurring. In addition, to reduce growth and yields, it has been shown that the use of copper fungicides can reduce the maturity of the fruit as well as that of the shoots. Copper fungicides can have subtle, chronic negative impacts on fruit plants.

Copper will provide low to moderate control of many of the diseases. Bordeaux may be used on pears during bloom for fire blight control when temperatures are above 70°F and drying conditions are rapid. Fixed coppers, plus lime, are safer than Bordeaux. They may be used for leaf curl control on stone fruits and pre- and postharvest leaf spot control on tart cherries. These compounds are useful in plant nutrition since they supply copper to the plant. Strawberries are very sensitive to copper. Never apply copper to strawberries because severe phytotoxicity will result under almost any conditions.

Do not apply any of the copper compounds without adding lime. Lime should be used at a rate one to two times that of the copper. If a copper material is applied without lime and yellowing and leaf drop occur, an application of lime within 2 to 3 weeks of the copper application may prevent further yellowing and leaf drop. Again, check the label of the product you intend to use to see if lime has already been added in the formulation or if it is advised to add lime and at what rates. Do not use copper in cool wet weather. Do not use immediately before or after using ferbam. Most insecticides are not compatible with lime.

Esfenvalerate

Esfenvalerate is a broad-spectrum pyrethroid insecticide with contact and stomach action. Esfenvalerate is very toxic to fish and other aquatic organisms. Esfenvalerate is also highly toxic to bees exposed to direct treatment and residues on plants. Use recommendations are generally limited to before bloom in Pennsylvania to conserve Stethorus and other predators of European red mite. Do not feed pomace to livestock.

Ferbam (Carbamate)

Ferbam (Carbamate) is effective on apples for rust and scab control, on stone fruits for leaf curl, on cherries and plums for clear spots and black knot, and on pears for leaf and fruit spot control. Do not use with lime. Ferbam may produce unsightly residues on leaves and fruit. On Golden Delicious, Jonathan, and other varieties that russet easily, injury may result from using ferbam, especially if it is applied in the pink through mid-June. The best time to use it is in the prepink period or in later summer sprays after mid-June.

Garlic (Guardian)

A 10 percent formulation of garlic is registered on apples and a number of apple pests are on the label. However, during the 1995 studies conducted at the Cornell University, no efficacy was observed when the compound was applied to control fruit pests listed on the label.

General Purpose Products

General purpose products (GP-Products) vary depending upon the manufacturer. Generally, the products will contain both a fungicide and an insecticide mixed in appropriate ratios for general control of most diseases and insects (see Table 2.4).

Glyphosate (Roundup)

Glyphosate (RoundUp) is registered for use on apples and pears up to 14 days before harvest and in stone fruit orchards up to 28 days before harvest. It is effective in controlling many emerged annual and perennial grasses and broadleaved weeds. Best results occur when it is applied as a 2 percent solution. It is labeled as a directed spray on apples and pears. In stone fruits it must be applied through a wick applicator. Glyphosate has no preemergence activity; therefore, it should be combined with a preemergent material for residual activity.

Caution: Avoid all contact with tree foliage. The chemical is not readily metabolized by plants, and accidental coverage could cause injury the following year. Glyphosate should not be stored or applied in galvanized steel or unlined steel (except stainless) containers or tanks. It can react with these containers to produce highly combustible hydrogen gas mixtures.

Granulosis Virus (Cyd-X, Carpovirusine)

The naturally occurring codling moth granulovirus belongs to the subclass B of the baculoviridae. Infection with granulosis virus is an acute insect disease with a short, rapid course. Incubation is rapid and death occurs 4 to 6 days after ingestion of virus particles. However, as with other baculovirus infections, the length of the incubation periods is influenced by temperature. As the disease progresses the dorsum of the integument turns intense pink; larvae become swollen and flaccid; shortly before or soon after death the integument ruptures. The applied virus is not very persistent in the environment and frequent applications may be necessary to achieve effective control of codling moth.

Imidacloprid

Imidacloprid is a systemic, synthetic insecticide with contact and stomach action. Its mode of action is similar to that of nicotine. Imidacloprid is used postbloom in apples for control of leafhoppers, leafminers, and aphids. For first-generation spotted tentiform leafminer, imidacloprid should be applied while the larvae are still in the sap-feeding stage, or within about 5 days after pollination is complete. For second and succeeding generations, apply 2 weeks after peak of pheromone trap catch for each generation. A second application may be required if severe pressure continues or if generations are overlapping. For white apple leafhopper, target nymphs of the first and, if necessary, the second generation. Imidacloprid is toxic to bees. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.

Kaolin Clay (Surround)

Surround (kaolin clay) is a novel, nontoxic material that forms a mechanical barrier film to protect fruit against insect and solar damage. Surround is registered for use on pears, apples, and stone fruit. Surround suppresses insects by creating a protective white particle barrier on plant surfaces, which repels and irritates insects. For best results, the material should be first used before expected insect appearance and reapplied every 7 to 14 days throughout the season. Uniform and consistent coverage is essential for effective insect suppression and control. Special washing may be required at harvest to remove residue from fruit.

Lime Sulfur

Lime sulfur is good for pre-bloom powdery mildew control on apples and for leaf curl control on peaches and nectarines during the dormant season. High rates will also control scale insects on stone fruit trees. Several formulations are available. Lime sulfur is incompatible with most pesticide formulations and should be used alone (see Table 2.4).

Malathion

Malathion is the most widely used home-planting insecticide because of its broad range of activities and safety for mammals. It is effective, however, for only 2 to 3 days. It is effective against aphids and moderately effective against mites, leafhoppers, and scale crawlers. It is available in wettable powder and liquid forms. The liquid form, however, may be injurious to the foliage of sensitive plants, such as raspberries. Phytotoxicity has been reported on McIntosh and Cortland apples, sweet cherries, European grapes, and Bosc pears.

Mancozeb

Mancozeb has a protective effect for controlling black rot, downy mildew, and phomopsis cane and leaf spot of grape (see Table 2.4).

Maneb

Maneb has a protective effect for the control of black rot, downy mildew, and phomopsis cane and leaf spot of grape (see Table 2.4).

Mating Disruption - Last Call CM, Last Call OFM

Insect sex pheromone-based mating disruption is widely adapted by commercial fruit growers to prevent male and female moths from mating and therefore from producing viable eggs. Since mating disruption does not kill insects, it needs to be applied on large areas (minimum 5 acres) in order for it to be effective. For smaller growers, a different kind of mating-disruption technology called "attract and kill" is recommended. A formulation of insect sex pheromone and insecticide sold under the name of Last Call OFM or Last Call CM proved to be effective in controlling Oriental fruit moth or codling moth in small orchards. Multiple droplets of insecticide/pheromone solution need to be applied to the tree branches and trunk before the flight of each generation of Oriental fruit moth/codling to provide effective control. It is important to remember that mating-disruption technology, in contrast to most insecticides, is effective only against the target insect species and will not control other species of insects. In order to control both Oriental fruit moth and codling moth, separate applications of Last Call OFM and Last Call CM need to be applied.

Methoxychlor

Methoxychlor is a chlorinated hydrocarbon insecticide with fairly long residual activity. It is relatively safe to use since it is not very toxic to mammals and is not known to be phytotoxic. It can be purchased separately but is commonly an ingredient in orchard general purpose mixes.

Myclobutanil (Nova)

Myclobutanil (Nova) is a systemic fungicide with protective and curative action for many of the diseases of fruit.

Permethrin

Permethrin is a nonsystemic, broad-spectrum synthetic pyrethroid insecticide with contact and stomach action, having a slight repellent effect. The compound is active against: leafrollers, plum curculio, plant bugs, rosy apple aphid, and leafhoppers. Permethrin is not recommended after bloom to prevent outbreaks of European red mite.

Pyrethrum

Pyrethrum is a natural insecticide produced by several species of Chrysanthemum sp. and is the precursor of the synthetic pyrethroid insecticides. Pyrethrum is available as an emulsifiable concentrate, in combination with rotenone, or alone as a wettable powder. Pyrethrum is labeled against a large number of pests: grape leafhopper, potato leafhopper, leaf curl plum aphid, blueberry flea beetle, blueberry thrips, and blueberry sawfly. Pyrethrum is quickly broken down in the environment and may be used up to and including the day of harvest.

Rotenone

Rotenone is derived from the root of various plants of the Derris or Lonchocarpus species from Southeast Asia and Central and South America. Rotenone is a broad spectrum botanical insecticide with expected activity against a broad range of pests: codling moth, plum curculio, European apple sawfly, apple maggot, pear psylla, European red mite and two-spotted spider mite, Japanese beetle, and tarnished plant bug. Rotenone is nontoxic to syrphid flies that feed on aphids, and to honeybees. Due to the fact that rotenone is rapidly degraded by sunlight it needs to be reapplied frequently (every week or less). Rotenone is also highly toxic to fish and birds.

Ryania

Ryania is a botanical insecticide made from the ground stems of Ryania speciosa, a plant native to tropical America. Ryania is toxic to moth pests such as codling moth.

Safer Insecticidal Soap

Safer insecticidal soap is a "natural" pesticide for insect and mite control on fruit trees. This soap-like material, consisting of long-chain fatty acids, is thought to disrupt the cellular metabolism of insects and mites. It has been used to control a variety of insects on various crop and noncrop plants. Safer insecticidal soap is effective only in the liquid state as it contacts the insect or mite. Once dried, it is not toxic to the pest. In certain situations, this pesticide can be an effective alternative to traditionally used insecticides. Moreover, it is extremely safe for humans and other animals. There are no reentry restrictions, and sprays can be applied up to the day of harvest. There is a lingering concern, however, about fruit russeting associated with the product, especially in dilute applications. Moreover, it may be toxic to Stethorus, the black ladybird beetle used as a mite predator. Therefore, we currently recommend Safer insecticidal soap only for nonbearing apple and pear trees and other fruit crops.

On apples, Safer insecticidal soap has proven effective against motile stages of mites and white apple leafhoppers. Apply one part Safer insecticidal soap concentrate and 50 parts soft water to foliage. Be aware that agitation in the spray tank can cause excessive foaming and require the use of defoamer (see label on Safer insecticidal soap container).

On pears, Safer insecticidal soap is effective against pear psylla and mites in postbloom applications at the same rate recommended for apples. However, it is not effective against many other pear pests during postbloom. It can be mixed with a one-half rate of another insecticide to provide a broader range of effectiveness.

Spinosad

Spinosad is a member of the new Naturalyte class of insecticides labeled for apples in 1998. Spinosad is recommended for control of leafrollers and thrips on peaches, plums, cherries, nectarines, prunes, and apricots. The compounds also possess some activity against Oriental fruit moth and codling moth. It is formulated as a suspension concentrate. This product, with both contact and ingestion activity, provides about 7 to 8 days of residual activity on the tree. Natural enemy toxicity is low. Spinosad can be used to manage various lepidoptera pests and also has activity against apple maggot. Control of spotted tentiform leafminer is very good with one application per brood. Excellent control can be achieved for tufted apple bud moth and obliquebanded leafroller with two applications per generation. Spinosad under the trade name Entrust is registered for use by organic fruit growers.

Streptomycin

Streptomycin is used for the control of fire blight on apples and pears. Bloom sprays are most effective when applied at night. See discussion of bloom sprays in apple and pear spray programs for amounts and timing.

Sulfur

Sulfur is very effective against powdery mildew of apples and cherries and scab on peaches and nectarines. Some varieties are easily injured by sulfur applications. Jonathan and Cortland are more tolerant than Stayman and Delicious. Rome Beauty is intermediate. Allow at least 7 days between oil and sulfur applications. Some of the newer sulfur formulations can be used in seasonal programs on apples without injury. Read the labels on these products for rates (see Table 2.4).

Summer Horticultural Oils

Summer horticultural oils are horticultural "superior oils" with a narrow 10 to 90 percent distillation range that permits relatively safe use on apple foliage during the summer months. In orchards under an effective pre-bloom mite-control program, a summer oil can effectively suppress mite and aphid populations when applied at petal fall timing and subsequently at 2 and 4 weeks after petal fall. Using oil at a concentrate rate higher than 1 percent solution increases the likelihood of phytotoxicity and is therefore not recommended. Apple variety and spray drying conditions should be taken into account to minimize any possible effects on fruit finish. The slow drying conditions and extremes of cool or hot conditions should be avoided when applying horticultural mineral oils. Treatment with other materials is generally not recommended.

Superior Oil

Superior oil with a 60- or 70-second viscosity is recommended as a control measure for preventing San Jose scale, European red mite, and aphids. The 60- or 70-second oil is not a dormant-type oil. It is lighter and more volatile than the original superior oil used as a dormant spray. The main advantage of the lighter 60- or 70-second oil is the reduced possibility of plant injury. It is safer because it is more volatile, resulting in less persistence on the tree. It remains on the tree long enough to kill the pest, but not long enough to interfere with vital plant processes or oil-incompatible pesticides that may be applied later. Because of this safety factor, the 60- or 70-second oil can be applied up to the prepink stage of apple tree development. Oil applied during silver tip to ¼-inch green is not nearly as effective on mites as it is when applied between 1/2-inch green and full pink.

2,4-D

2,4-D (various names) is a broadleaf contact herbicide that will not control grasses. It is particularly useful for controlling perennial weeds. It should not be applied to bare ground or under hot dry conditions. DO NOT use ester formulations of 2,4-D because they are extremely volatile and could vaporize and damage surrounding nontarget vegetation. Use with extreme caution if grapes or Solanaceous vegetable crops are in the immediate vicinity. Not recommended if the area to be treated contains a domestic well field.

 

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