WNC Orchard Insect Pest Populations – May 5, 2020

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codling moth on leafCooler Temperatures Expected to Suppress Codling Moth Activity

With the warmer temperatures during the past week, there was an increase in codling moth trap captures compared to recent weeks. However, with cooler temperatures moving into the region in the next couple of days, and expected to stick around for a week, insect activity will likely be greatly reduced. Codling moth degree day (DD) accumulations across the region range from about 100 at the Research Station in Henderson County to almost 350 in Lincoln County. The initial insecticide application for first-generation codling moth is recommended at 250 DD, which is not expected for at least 10 to 14 days in Henderson County. Off the mountain in Lincoln County, most locations have probably applied at least one application for first-generation codling moth. Further applications, if warranted, can likely be delayed during this cold period.

Time is Approaching for San Jose Scale Crawler Emergence

For those growers concerned about San Jose scale and who have not yet applied an insecticide for this pest, the optimum timing for targeting crawlers is mid-May in Henderson County (see graph below), and about a week earlier off the mountain in the piedmont. In lower elevations now is a good time to target crawlers, while in Henderson County a week or two from now would be optimal. Three insecticides, including Esteem, Courier and Movento, have all demonstrated excellent season-long control when applied to coincide with crawler emergence.

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

2020 Average Weekly Trap Captures

Insects per trap
Apr 20 Apr 27 May 4
Codling moth  0.1 0.4 1.6
Oriental fruit moth 0.1 0.8 1.5
Tufted apple bud moth 0.0 1.0 14.0
Redbanded leafroller 0.0 0.0
Obliquebanded leafroller set 0.0 0.0
Lesser appleworm set 0.0 0.0
Apple maggot (abandoned and research orchards)
Brown marmorated stink bug (commercial) 0.1 0.0 0.8
Brown marmorated stink bug (unsprayed) 0.1 0.1 0.3
Spotted tentiform leafminer 0.0 0.0 0.0
Dogwood borer set 0.0
Peachtree borer 0.0 0.0 0.0
Lesser peachtree borer 0.0 7.0 51.0
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

Apr 20 Apr 27 May 4
Codling moth (Biofix 4/20) Biofix 34 DD 90 DD
Oriental fruit moth (Biofix 3/30) 185 DD 250 DD 332 DD
Tufted apple bud moth (Biofix 4/27) Biofix 74 DD

About degree-day models

2020 Pest Trends (click to enlarge)

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

Visit WNC Orchard Insect Populations for archived posts.

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