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(Art Agnello ama4@nysaes.cornell.edu, Entomology, Geneva)

The San Jose scale (SJS) is a pest of tree fruit that attacks not only apple, but also pear, peach, plum, and sweet cherry. The minute SJS adult males emerge in the spring from beneath scale covers on the trees, usually during bloom, and mate. The first of this year's adults started showing up on May 8 in our traps at Geneva. The females produce live crawlers within 4—6 weeks of mating; these are bright yellow, very tiny insects resembling larval spider mites. About 24 hours after birth, the crawlers have walked or drifted to new sites and settled in by inserting their mouthparts into the tree and secreting a white waxy covering that eventually darkens to black.

San Jose scale crawler

SJS infestations on the bark contribute to an overall decline in tree vigor, growth, and productivity. Fruit feeding causes distinct red-purple spots that decrease the cosmetic appeal of the fruit. Control measures for SJS are recommended when the scale or their feeding blemishes have been found on fruit at harvest during the previous season. Insecticidal sprays are most effective when directed against the first generation crawlers, specifically timed for the first and peak crawler activity, which are usually 7—10 days apart.

Red and purple discolorations marking San Jose scale feeding sites on fruit

The most reliable method of determining first appearance of the crawlers in your specific area is by putting sticky-tape traps on the tree limb near encrusted areas and checking them at least twice a week, starting about the second week of June. Alternatively, a degree-day accumulation of 310 (50°F base) from the date of first adult catch has also been shown to be reliable if the degree-days are known with some accuracy. In the Geneva area, first crawler emergence has tended to occur sometime around mid-June, which should make their appearance due any day now (we've reached 448 degree days as of this writing).

Effective materials for SJS control include Lorsban 50WP, Guthion, and Imidan. These sprays may also variously help in the control of OBLR, apple maggot, and codling moth. Coverage and control are generally better if the pesticide is applied dilute and in every row. SJS is frequently more of a problem in larger, poorly pruned standard size trees that do not receive adequate spray coverage. Dormant or delayed-dormant sprays of oil, or half-inch green applications of Lorsban 4EC or Supracide will have helped prevent populations from getting established. Early season pruning is important for removing infested branches and suckers, as well as for opening up the canopy to allow better coverage in the tree tops where SJS are often concentrated.

(Art Agnello ama4@nysaes.cornell.edu, Entomology, Geneva)

Infestations of European Corn Borer (ECB) in orchards are not very common, but when they do appear, as has been the case occasionally in N.Y., they can be quite serious. Considerable feeding damage will be noted in late June in terminals of newly planted apple and cherry trees, and early fruit feeding on apple is often evident by this time of the year. Infestations of this pest on apple are spotty and unpredictable; incidence in an orchard one year has no correlation with its likelihood of occurrence the next season. The ECB is present as two separate strains in N.Y., usually designated by their pheromone chemistry. The univoltine "Z" race (peak flight normally in mid-July), can be found almost continuously from Buffalo to Albany. The bivoltine "Z" race (peak flights in mid-June and mid-August) is present from Buffalo to about Rochester, and the bivoltine "E" race (also with peak flights in mid-June and mid-August) picks up from Rochester to Syracuse or thereabouts. In the Hudson Valley, all 3 races are probably present. What this means to most apple growers is that most places have flights in the middle of June, July AND August. Susceptible orchards (young non-bearing, and others in proximity to sweet corn populations) must therefore be protected almost continuously during the summer, using something that's relatively long-lasting.

Damage to newly planted, non-bearing trees is caused by larval tunneling in the current season's growth. Browning of terminal leaves is a good indication of corn borer larval presence. The feeding will kill the terminal and disfigure the tree.

ECB & SHOOT ENTRY

ECB TERMINAL DAMAGE

Non-bearing, newly planted orchards normally do not receive the intensive cover spray program bearing orchards do; therefore, corn borer infestations can build up more easily in young orchards. Corn borer attack on young trees can occur from June through August. Damage to the fruit usually shows up in late summer, when the August flight of the bivoltine strain is active.

Bearing orchards are more likely to show some early corn borer damage on the fruit if growers relax their spray program in June or early July. However, most fruit feeding occurs between the last cover spray (mid-August) and harvest. Weedy sites provide plenty of alternative hosts for this insect, especially those containing broadleaf dock, ragweed, pigweed, smartweed, and barnyard grass. Lannate, Lorsban and Asana can give very good control of ECB larvae, provided application is made before the caterpillars become concealed in the plant tissue. Potential problem plantings should be checked periodically in August for shoot infestations of this caterpillar, which is cream colored with a dark head.

Just a brief reminder to help you coordinate your pest control sprays with the right time of the season, to take advantage of recommended efficacy windows for a given pest's developmental stage. For those concerned with codling moth injury, our degree days (base 50°F) since 1st catch currently stands at 328, which is well into the preferred period for a preventive insecticide spray. For OBLR control using Confirm or a B.t. product, the recommended window for the 1st spray is 200—300 DD (base 43°F) after 1st catch, which corresponds to this week in western N.Y. In orchards where SpinTor or Lorsban are elected, waiting until approximately 350 is appropriate. Also, speaking of timing, we should point out the little-publicized change in the Carzol SP label since the winter, which now makes it illegal to use Carzol after petal fall -- another bit of fallout from the FQPA-generated pesticide review. It's not likely that too many orchards are in trouble with mites yet, but this information should be incorporated into seasonal spray programs before the moment when an acaricide might be necessary.

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