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Hudson Valley Insect Management at Tight Cluster: April 28, 2014

Hudson Valley Insect Management at Tight Cluster – 2014

April 28, 2014

In terms of our weather, we are at a very similar growth stage in tree phenology to that of 2013 with tight cluster occurring at nearly the same calendar date in Highland (27th April). Forecasts for the next 3 days (NOAA) show daytime temperatures averaging in the lower 60’s (51-70oF) and evening temperatures in the mid-40’s (43-47 oF). If we follow a predicted extended cooling trend with temperatures in the mid-60’s, we will see McIntosh at bloom near the 9th of May with petal fall near the 16-20st of May, allowing for roughly 8-10 days of bloom (the average for McIntosh is 9.8 days).

As we approach the pink period of tree phenology the insect pest control options available to us are numerous. With more choices usually follows greater confusion. Although we have lost the use of azinphos-methyl (Guthion WP) and increasing resistance of some of the insect pests such as the obliquebanded leafroller, we are fortunate to have a number of insecticide options to contend with these issues. The petal fall application is likely to be the single most important application for insect pest management to pome and stone fruit in the Hudson Valley. High-pressure orchards can experience nearly 100% crop loss from a complex of fruit damaging insect pests in a matter of a few days to week or two. Needless to say, insect pest management is critical at this point in time. However, in orchards experiencing high pressure at PF, a pink application may be a wise choice if historical losses are experienced.

Most orchards have varying degrees of insect presence and scouting for these insects based on their pest status will allow for greater economic benefits and productive management. As we have stated in earlier text, San Jose scale found at harvest should, without question, be managed during this period to keep fruit from becoming infested a second year..

The Lorsban decision:
Pre-bloom management will play an import role in petal fall decision-making. A single yearly application of Lorsban (chlorpyrifos) can still be made to tree fruit. If chlorpyrifos (Lorsban or similar generics) is used in a pre-bloom foliar application, then it cannot be used in a post bloom foliar or trunk application. A pre-bloom chlorpyrifos application made at early pink will have a considerable impact on San Jose scale (SJS), rosy apple aphid (RAA), emerging obliquebanded leafroller larvae (OBLR), mullen and tarnish plant bug (MPB & TPB), European apple sawfly (EAS) and white apple leafhopper (WALH). Most importantly, if bees are brought into a block in a season of cooler temperature and delayed petal fall of later varieties, a pink application provides increased management of migrating plum curculio with less pressure to remove bees from a mixed block while active pollinators continue to work king flowers. It also provides a bit of insurance if beekeepers are delayed in removing hives from mixed variety blocks.

Be aware that the active ingredient in Lorsban and the Lorsban generics is chlorpyrifos, which has a high bee-poisoning hazard. Judicious use of this product near bloom is essential to reduce the risk to active pollinators.

Residual insecticide levels of foliar applications of chlorpyrifos during the delayed dormant period (dormant to ½” green) will likely have little or no impact on the OBLR established in the orchard. We typically see the insect emerge from its overwintering hibernaculum to actively feed on foliage from late tight cluster through bloom. For this insect pest, bloom applications of Bt (Dipell, , Agree, Javelin) at lower labeled rates using tight interval frequent applications, and or PF application of a specific OBLR insecticide, such as Intrepid or Proclaim, will be required for management when OBLR populations are high. Scouting will easily determine the population at bloom to assist in decision making using the OBLR scouting threshold of 3% infested terminals found in the Cornell Guidelines (pg. 71 ).

Dogwood borer (DWB): The dwarfing rootstock, M.9, creates an abundance of burr knots. These root initials provide ideal locations for the dogwood borer to lay eggs and for larfa to burrow and feed upon. Painting trunks can reduce the attractiveness of trunks to DWB.

M.9 rootstock painted to reduce borer infestation

M.9 rootstock painted to reduce borer infestation

The G.11 rootstock produces fewer root initials, however, flaking bark on this rootstock can also act as a location for borers and although there are fewer DWB in these varieties, they should not be overlooked during scouting as observed in this example.

G.11 rootstock with borer infestation

G.11 rootstock with borer infestation

Borer.G.11.2

A directed, coarse, trunk spray of Lorsban to control the trunk borers should be considered in orchards employing dwarfing rootstock of apple such as M-9 that produce a high number of burr knots attractive to trunk borers. In recent surveys throughout New York, dogwood borer, especially in Macoun, have been implicated in tree decline, often associated with phytophthora root, crown and collar rots.

Insect Pest Management for Pear:
Pear are approaching white bud stage in the Hudson Valley. We are seeing a very high number of eggs on pear stems and cluster buds and leaves. Newly emerging nymphs have moved down to the base of the flower bud stems, well hidden from view and insecticide sprays.

Pear psylla management: Continued applications of up to 1% oil to reduce pear psylla egg laying, nymph emergence and rust mite buildup is quite effective. Oil can be used at a 1% concentration at 14-day intervals for psylla nymph management throughout the season. However, higher rates will cause phytotoxicity. Oil for pear psylla control is NEVER CONCENTRATED. Use a 1 nymph per leaf threshold to help determine optimum timing to scout for egg laying that gives rise to each generation of nymphs. It’s important to note that if 1% oil is used for psylla management, it will have greater efficacy at application rate above 100 GPA. Larger droplet size and increased ‘dilute’ application rates have been found to impose greater impact on egg hatch and early instar mortality.

The movement of nymphs into the developing flower buds will make applications of contact insecticides (OP’s and pyrethroids) less effective for psylla control, even with excellent coverage. Insecticide options for nymph management should consider the inclusion of neonicotinoids, the more effective products being Actara or Assail. Their use in combination with 0.25 to 1% oil will increase translocation into leaf tissue and insect cuticle to improve efficacy.

Plum curculio (PC) are not as attracted to pear as to apple, however, management should begin at petal fall or first oviposition scar. The use of OP’s (Imidan), pyrethroids, the neonicotinoids Actara or Calypso will control PC. As temperatures increase the pyrethroids will become less effective on pear psylla populations. The neonicotinoids Actara or Calypso will have excellent efficacy against psylla nymphs when used at petal fall. Leverage 360 (imidacloprid, + cyfluthrin) used against PC will also have efficacy against the pear psylla adult and nymph at this timing.