Read and Follow all Label Directions

In the following tables, the quantity of materials to mix to apply to apples is the amount of spray volume needed to cover one acre of well pruned, standard size trees. In Oklahoma, application rates will vary from 25-200 gallons per acre. Effectiveness of spray volumes will be determined by several factors including: tree sizes, tree densities, canopy density, and nozzle type. Irrespective of the amount of liquid per acre applied, use the amount of chemical per acre listed below as a guide for mixing. Numerous insecticides are labeled for use and are effective against insect and mite pests on apples. See the list of labeled insecticides for materials we have been able to determine are labeled for current use. However, registrations and use patterns are constantly changing and all recommendations should be offered with the advice to READ THE LABEL of any and all pesticides to be used on any crop.

Table 1. Amount of Materials Needed

* Horticultural oils are physical toxicants which act as suffocant and entrapment insecticides. r Restricted Use Pesticide.

MOA Group Tables start on page 43 of the handbook.

1. Check Table 1 for date of last application prior to harvest.
2. Scale insects may not be a problem if trees were regularly sprayed in cover applications with Guthion in the previous year. Horticultural oils act as suffocant and entrapment insecticides.
3. Mating disruption dispensers are only recommended in orchards with low codling moth populations and not in blocks of less than 5 acres. Isomate CT releases pheromone for a minimum of 100 days, but Checkmate CM dispensers release pheromone for only 75 days. Two applications of Checkmate CM per season should be made.
4. Avoid use of Sevin from bloom to 30 days after full bloom, unless fruit thinning is desired, then follow directions on the label. Avoid use of Sevin in areas exhibiting heavy mite infestation.
5. Do not exceed 20 fl oz per acre per application or 40 fl oz per acre in a growing season. Do not make more than 2 applications per growing season. Do not apply in less than 40 gals of water per acre. If second application is needed, do not re-treat within 21 days. See label for additional precautions about certain varieties.
6. Imidan is very sensitive to alkaline hydrolysis; therefore, check the pH of the tank mix and add a buffering agent if necessary, to adjust the pH to 6.0 or lower. Do not attempt to acidify solutions containing copper compounds.

Table 2. Days From Last Application to Harvest

**See labels for other limitations.
r Restricted use pesticide.

MITES.  The most important mites of this region are red spider mites and two spotted spider mites.  Red mites pass the winter as somewhat spherical eggs of a bright red to orange color on twigs and smaller branches of the tree.  Two spotted mites generally over winter as orange, hibernating females in protected locations of cover crops or other debris.  They then migrate to the foliage of the trees in the spring and summer.  Mites overwintering on the tree may be controlled by delayed dormant oil sprays.  In the event control is not satisfactory, one should rotate between Kelthane, Omite or Guthion sprays.

WOOLY APPLE APHID.  The winter is spent as eggs and young nymphs on elm trees.  After two spring generations on elm, they migrate to apples, usually in late June or early July.  Several generations are produced on apples during the remainder of the summer.  These aphids are purplish and characteristically covered with white, waxy secretion.  Their presence can be detected by visual observations of the scaffold limbs.  They are usually found where there are wounds from pruning or at the base of water sprouts.  Chemicals, such as Guthion, applied to control other aphids usually suppress populations of this pest as well.

For detailed information on using pesticides safely, see OSU Extension Fact Sheets EPP-7451, “Agricultural Pesticide Storage;” EPP-7454, “Check Your Pesticide Labels;” and  EPP-7457, “Toxicity of Pesticides.” 

* See labels for other limitations.
r = Restricted use pesticide.

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Phil Mulder
Department Head, Entomology and Plant Pathology