As of July 1, cumulative codling moth degree days (DD) were at 1375 in Henderson County and 1780 in Cleveland County. This coincides with the early stages of second generation egg hatch and about 50% egg hatch in the two areas, respectively.
With the current hot weather, DDs are accumulating quickly (>30/day), so an insecticide application this week or at your next spray in Henderson County is recommended where there is no pheromone trap monitoring or where a preventive application is desired. In low-population orchards, a single application at this time is usually sufficient for the second generation. As pointed out in previous updates, insecticides are usually not needed in orchards using mating disruption and with continued low pheromone trap captures.
With the second generation more advanced in lower elevation orchards, insecticidal control at this time should be based on pheromone trap captures. Historically, under low population densities (no damage present and low trap captures) one application at about 1400 DD is sufficient. If unsure or there is evidence of damage, chemical control should continue at this time. The situation in orchards with mating disruption is the same as described above.
Refer to last week’s update for recommendations on insecticide selection.
Aphids, Leafhoppers and Mites: As we enter July, aphid, leafhopper and European red mite populations are on the decline. If mites have not been an issue by early July, in most circumstances they will not develop into problem.
Plum Curculio: July is also a time when first generation plum curculio adults emerge. The vast majority of these adults do not reproduce, but they do feed on fruit, resulting in external damage. Usually this is only a concern in orchards with significant first generation damage. In those orchards falling under this category, an insecticide effective against plum curculio should be considered.
Brown Marmorated Stink Bug: We are still a couple of weeks from emergence of first generation BMSB in lower-elevation orchards. The degree-day model predicts initial emergence of first generation adults at about 750 DD; BMSB DD accumulations as of July 1 were 460 in Henderson County and 610 in Cleveland County. Based on forecast temperatures, 750 is predicted in about 2 weeks in lower-elevation orchards. It should be noted that there has been a significant decline in BMSB populations over the past three years, and the need for insecticidal control has also declined. Although it’s early, trap captures currently continue in that direction. It is noted that BMSB is not well suited to temperatures in the mid to upper 90s, so the current heat will suppress reproduction and survival of immatures.
