WNC Orchard Insect Pest Populations – May 19, 2020

— Written By and last updated by

Apple orchardCodling moth pheromone trap captures increased somewhat this week with the return of warmer temperatures, and as of May 19 degree day accumulations ranged from about 220 in Henderson County to 500 in Lincoln and Cleveland County. In orchards with moderate to high codling moth populations, the 250 DD threshold for initial insecticide applications is predicted to occur later this week in Henderson County and other locations with a similar elevation. In orchards with low populations, an insecticide application can be delayed until at least 350 DD, which is predicted to occur in the middle of next week (May 27). Finally, those orchards using mating disruption and where codling moth populations are very low, it is likely that an insecticide targeting lepidopterans can wait until the optimum timing for tufted apple bud moth, which is between 600 and 800 DD.

In lower-elevation orchards where at least one insecticide application has been applied for codling moth, this pest will remain a concern for another couple of weeks, and the need for continued sprays should be based on pheromone trap captures.


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


2020 Average Weekly Trap Captures

HENDERSON COUNTY
Insects per trap
May 4 May 12 May 18
Codling moth  1.6 0.4 0.5
Oriental fruit moth 1.5 0.3 0.5
Tufted apple bud moth 14.0 11.0 8.0
Redbanded leafroller 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) 0.8 0.3 0.6
Brown marmorated stink bug (unsprayed) 0.3 0.1 1.8
Spotted tentiform leafminer 0.0 0.0 0.0
Dogwood borer 0.0 1.0 14.0
Peachtree borer 0.0 0.0 0.0
Lesser peachtree borer 51.0 20.0 16.0
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 4 May 12 May 18
Codling moth (Biofix 4/20) 90 DD 135 DD 202 DD
Oriental fruit moth (Biofix 3/30) 332 DD 400 DD 496 DD
Tufted apple bud moth (Biofix 4/27) 74 DD 142 DD 238 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.


Additional Resources: