WNC Orchard Insect Pest Populations – May 27, 2020

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Ragwort flowers beside apple orchardrdCodling moth remains the insect of greatest concern throughout the region, with degree-day accumulations since biofix ranging from about 325 in Henderson County to 630 in Lincoln County. In orchards not using mating disruption, an initial application is recommended between 250 and 350 DD. Codling moth can remain a threat until about 900 DD, although this can vary considerably depending on population pressure. As a reminder, if making multiple applications against the first generation, insecticides with the same mode of action should be made throughout this time. Wait until second generation codling moth emergences (about 1400 DD) to switch to an insecticide with a different mode of action.

In orchards using mating disruption, an insecticide is usually not recommended until the timing is ideal for tufted apple bud moth (see below).

In Henderson County, where tufted apple bud moth (TABM) is of greatest concern, we are approaching 400 DD. A single application of either Altacor, Delegate, Intrepid, or Verdepryn (same mode of action as Altacor) between 800-1200 DD after biofix will provide season-long control of TABM. The timing of this coincides with about 650 DD for codling moth, which allows for control of both pests.

Apple aphid and potato leafhopper populations have not been observed up to this point, but they should begin to appear over the next couple of weeks. If control of these insects is needed, options include Voliam Flexi (same active as Altacor plus Actara), or addition of a neonicotinoid with one of the above-mentioned insecticides for codling moth or TABM.


Learn more about southeastern apple insect pests at the Apple Insect Management page.


2020 Average Weekly Trap Captures

HENDERSON COUNTY
Insects per trap
May 12 May 18 May 26
Codling moth  0.4 0.5 0.1
Oriental fruit moth 0.3 0.5 0.2
Tufted apple bud moth 11.0 8.0 25.5
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 0.0 0.0
Lesser appleworm 0.0 0.0 0.0
Apple maggot (abandoned and research orchards)
Brown marmorated stink bug (commercial) 0.3 0.6 0.8
Brown marmorated stink bug (unsprayed) 0.1 1.8 1.8
Spotted tentiform leafminer 0.0 0.0 0.0
Dogwood borer 1.0 14.0 24.0
Peachtree borer 0.0 0.0 0.0
Lesser peachtree borer 20.0 16.0 32.0
San Jose scale 0.0 0.0 0.0

*Note that these averages illustrate only the timing of insect emergence and fluctuations in populations, and are not representative of population levels in any given orchard. The only way to have an accurate assessment of an individual orchard’s populations is to set up traps in that orchard.


2020 Accumulated Degree Days

HENDERSON COUNTY
May 12 May 18 May 26
Codling moth (Biofix 4/20) 135 DD 202 DD 299 DD
Oriental fruit moth (Biofix 3/30) 400 DD 496 DD 631 DD
Tufted apple bud moth (Biofix 4/27) 142 DD 238 DD 374 DD

About degree-day models


2020 Pest Trends (click to enlarge)

Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends


Visit WNC Orchard Insect Populations for archived posts.


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