WNC Orchard Insect Pest Populations – August 10, 2021

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Brown marmorated stink bug trapBrown Marmorated Stink Bug: As shown in the chart below, emergence of first generation adults is well underway in the Cleveland/Lincoln County (about 60% complete) and Wilkes County (18% complete) areas, so the threat for damage will continue to increase over the coming weeks at both locations. Cooler temperatures in Henderson County and at higher elevations has delayed emergence, but the model predicts initial emergence Friday (8/13). Based on temperature forecasts, emergence in Henderson County will be about 10% complete next Tuesday (8/17), at which time control on susceptible cultivars should begin.

Chart showing brown marmorated stink bug emergence

Codling Moth and Oriental Fruit Moth:  With only a few exceptions, populations of the two key lepidopteran pests have been relatively low this year in managed orchards. Based on the degree-day model, in Henderson County (2016 DD) we are nearing the end of the second generation egg laying period, while in Lincoln County (2605 DD) emergence of the third generation is about 25% complete. While oriental fruit moth populations remain low in most commercial orchards, populations often begin to increase this time of the year in orchards not using mating disruption. However, pyrethroids applied for BMSB are highly effective at controlling this pest.

Apple Maggot:  As of 9 August we have caught only 2 apple maggot flies on traps on the research station and 0 in our abandoned orchard. These captures are lower and later than previous years.

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

2021 Average Weekly Trap Captures

Insects per trap
Jul 26 Aug 2 Aug 9
Codling moth  1.5 2.0 0.5
Oriental fruit moth 18.0 19.5 20.0
Tufted apple bud moth 1.0 1.0 0.0
Redbanded leafroller 0.0 4.0 0.0
Obliquebanded leafroller 3.0 2.0 2.0
Lesser appleworm 0.0 0.0 0.0
Apple maggot (abandoned and research orchards) 0.0 0.0 0.7
Brown marmorated stink bug (commercial) 7.0 3.0 7.5
Brown marmorated stink bug (unsprayed) 5.0 3.4 3.9
Spotted tentiform leafminer 2.0 4.0 0.0
Dogwood borer 24.0 21.0 25.0
Peachtree borer 27.0 3.0 15.0
Lesser peachtree borer 13.0 9.0 15.0
San Jose scale 0.0 0.0 2.5

*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.

2021 Accumulated Degree Days

Jul 26 Aug 2 Aug 9
Codling moth (Biofix: April 10)
1678 1858 2000
Oriental fruit moth (Biofix: March 27)
2279 2491 2668
Tufted apple bud moth (Biofix: April 30)
1920 2132 2309

About degree-day models

2021 Pest Trends (click to enlarge)

Chart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trendsChart showing insect population trends

Visit WNC Orchard Insect Populations for archived posts.

Additional Resources