5.6 Acaricides

Of the 5 species of mites found on fruit trees in New York State, only the European red mite and the twospotted spider mite are abundant and widely enough distributed to be major problems.

Mites are not insects, and because they are not affected by most insecticides, special chemicals, known as acaricides, have been developed for their control. With few exceptions, acaricides are not effective against insects. Therefore, growers who want to control mites in their orchards should (A) use oil during the half-inch green to tight cluster period, or an acaricide at the tight cluster to pink bud stage, and then (B) regularly monitor mite populations on the foliage from petal fall until harvest, applying an acaricide and/or an

insecticide that will provide some suppression when mite numbers exceed the threshold for that period (refer to Figs. 4-6). For further information on the use of these materials, their limitations, and the precautions to be observed, refer to the Comments sections in the spray recommendations.

Abamectin (*Agri-Mek). Refer to “Other Materials” section.

Acequinocyl (Kanemite) is registered for control of European red mite and twospotted spider mite in apples and pears. This material, which is a member of the quinoline family, represents new chemistry and a novel mode of action, against which no resistance has yet been demonstrated in mite populations. It has activity against all life stages and is recommended for use against threshold populations, normally those occurring in summer. Two applications per season are allowed; it is nominally safe to predatory mites and has a low bee poisoning hazard.

Bifenazate (Acramite, Banter) is a carbazate that acts as a contact acaricide against both the motile stages of mites and the larvae and nymphs that hatch from treated eggs. Because this represents a new class of chemistry, there is no cross-resistance of this material demonstrated with other currently used acaricides. It is effective against both European red mite and twospotted spider mite, exhibiting a rapid knockdown of contacted motile forms and a relatively long residual efficacy period. It is labeled in New York for use on apples, pears, peaches, nectarines, plums and prunes. Only one application per year is permitted. It is moderately toxic to honeybees upon direct contact, but low in toxicity by foliar residue: it therefore has a moderate bee poisoning hazard.

Clofentezine (Apollo) is a tetrazine compound used as a contact acaricide that acts primarily as an ovicide/larvicide; it is particularly effective against winter eggs of European red mite. Following early season applications, it gives excellent residual control. Its use in apples is restricted to no later than 45 days before harvest, but in pears, cherries, peaches and apricots it may be used up until 21 days before harvest. It is safe to bees (low bee-poisoning hazard), beneficial insects, and predatory mites. It is not an effective adulticide.

Etoxazole (Zeal) acts like an insect growth regulator by inhibiting molding, and has very good activity against all life stages of European red mite and twospotted spider mite when applied preventatively or at threshold. It stops egg, larva and nymph development on contact and sterilizes adults; its translaminar movement into the leaf tissue ensures longer residual activity and action against mites feeding on plant surfaces not directly contacted by the spray application. It is labeled for use on pome fruits and stone fruits; only one application per year is permitted. It has a low bee-poisoning hazard.

Fenazaquin (Magister) Magister SC miticide is labeled for use in pome and stone fruits. The active ingredient has shown good results against European red mite, twospotted spider mite, apple and pear rust mites, and plum nursery mite, as well as pear psylla and some unique activity on powdery mildew. This product has a METI (mitochondrial electron transport inhibitor) mode of action, the same as Nexter, Portal, and Kanemite and is in IRAC Group 21; therefore, rotation among products with different modes of action should be taken into consideration to avoid resistance issues. Magister has a 3-day PHI and a 12-hr REI; it has a high bee-poisoning hazard.

Fenpyroximate (Portal) is a phenoxypyrazole acaricide and insecticide labeled for control of European red mite, twospotted spider mite, pear rust mite, leafhoppers, mealybugs and pear psylla. Portal belongs to the METI (Mitochondrial Electron Transport Inhibitor) class of compounds. For effective resistance management, Portal should be used in rotation with other modes of action. The active ingredient in Portal, fenpyroximate, works by blocking cellular respiration, which gives it activity against all motile stages of mites: larvae, nymphs, and adults. Only 1 application may be made per growing season in pome fruit. Two applications per season allowed in stone fruit. It is classified as a reduced-risk material, and has a low bee-poisoning hazard.

Formetanate Hydrochloride (*Carzol) is a carbamate acaricide-insecticide used for control of European red mite and twospotted spider mite on pears, apples, and peaches and against phosphate-resistant white apple leafhopper, potato leafhopper, and spotted tentiform leafminer on apples. Suppression of tarnished plant bug has been achieved during some seasons with prebloom applications. *Carzol is quite susceptible to alkaline hydrolysis and should be freshly prepared before each application. This material may not be applied past the petal fall stage. *Carzol is toxic to birds and other wildlife and highly toxic to predatory mites. It has a moderate bee-poisoning hazard. Note that the most recently approved label in New York State has deleted all tree fruit uses for *Carzol. User must have product that’s labeled for use on apples, pears, peaches, and nectarines.

Hexakis or Fenbutatin Oxide (*Vendex) is an organotin compound registered for the control of a wide range of plant-feeding mites on several fruit crops, including strains that are resistant to some other miticides. Where resistance to Plictran has been found, it is highly likely that resistance to this material is also present. *Vendex is nontoxic to honey bees, and is relatively nontoxic to predatory mites. It can be readily dispersed and can be used in conventional, dilute or concentrate, sprayers. Agitation is required during mixing and spraying. Thorough coverage of foliage and fruit is necessary for optimum mite control. This product is compatible with insecticides. It is not to be applied more than 4 times/season or more than 3 times between petal fall and harvest. This product is corrosive and may cause skin irritation, respiratory irritation, and eye damage. Use protective clothing and goggles as described on the label. Do not graze treated areas or contaminate food or feedstuffs. *Vendex is toxic to fish and has a low bee-poisoning hazard.

Hexythiazox (Savey, Onager) is a carboxamide compound used as a contact and stomach-poison acaricide. It is effective against eggs and larvae of European red mite; it will not kill adults. It is registered for a single application in all pome and stone fruits, and may be used up to 28 days before harvest. It provides excellent residual control, and is safe to bees (low bee-poisoning hazard), beneficial insects, and predatory mites.

Petroleum Oil Emulsions have been applied in the dormant and/or prebloom period for many years to control certain scales and other insects, as well as the European red mite. Although oil was once largely strongly recommended for red mite control, and has been used with increasing frequency during the past few years. Newer acaricides often prove unreliable as the mite populations develop resistance to them; mites are generally unable to develop resistance to oil. The type of oil, as well as its viscosity and other characteristics, has an important influence on its effectiveness in pest control and its phytotoxicity. Oils in the 60 to 70-second viscosity range have historically been recommended as the preferred products for effective mite control with supplemented or replaced by new pesticides, it is still minimum phytotoxicity to fruit trees. However, because of blending processes used by petroleum refiners, it now appears that the viscosity of a given product is a less reliable indicator of suitability than is the 50% distillation temperature, with a value of 412 +/- 8°F being preferred for prebloom use. Table 5.6.1 gives the specifications for narrow range plant-spray oils currently available that permit relatively safe use on apple foliage during the summer months. An oil is a physical pesticide, effective only when the film deposited covers every egg or young mite. Therefore,

thorough spraying and complete coverage of the entire tree are essential. A prebloom oil is recommended at 2 gal/100 from the 1/2-inch green to the tight cluster stage. A concentration of 1 gal/100 is advised from the tight cluster to the pink stage because mite eggs become more susceptible as the season advances. In apple orchards that have received an early season oil spray, a summer oil can effectively suppress mite populations when applied at petal fall and in subsequent cover sprays at rates of 1 to 2 gal/100 gal of finish spray solution. Although generally compatible with most crop protection chemicals, oil should never be mixed with fungicides containing sulfur, such as Captan or Bravo.

Refer to Section 17.3 for guidelines in determining potential compatibility. Apple variety, moisture stress, and spray drying conditions should be taken into account to minimize any possible effects on foliage quality and fruit finish. Summer oils can increase the incidence of scarf skin in varieties such as Red Rome, Jonathan, and Stayman. Oil has a low bee-poisoning hazard.

Use this procedure for mixing a fungicide-insecticide-oil combination:

Fill the spray tank 1/4 full with water and add the liquid or wettable powder pesticide.

Resume filling the tank and add the self-emulsifying oil. Continue agitation.

Do not allow mixture to stand without agitation.

When using the tank-mix oils, first combine the wettable powder or liquid pesticides with 100 gal of water containing the emulsifying agent. Then add the oil to the mixture. Agitate vigorously while spraying.

Pyridaben (†Nexter) is a pyridazinone compound used as a selective contact acaricide-insecticide in apples and pears, plus all stone fruits, with effectiveness against motile forms of mites and pear psylla; it does not kill eggs. It is recommended for use to control postbloom mite and psylla populations, and is an effective late season rescue material. †Nexter is toxic to fish and aquatic invertebrates, and has a high bee-poisoning hazard. Not registered for use in Nassau or Suffolk Counties.

Spirodiclofen (*†Envidor) This product, which is a member of the tetronic acid family, is labeled for use against mites, including European red mite, twospotted spider mite, and apple and pear rust mites, on pome fruits, under a FIFRA 24(c) Special Local Need label. The label must be in possession of the user at the time of application. A maximum of 1 application per season is allowed, with a PHI of 7 days; this product is not for sale, distribution or use in Nassau and Suffolk Counties. It is relatively harmless to beneficial species and has a low bee-poisoning hazard.