WNC Orchard Insect Pest Populations – August 8, 2023

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Apple orchardWe are approaching that time of the year when codling moth and oriental fruit moth (OFM) populations become less important, and when the risk of damage by brown marmorated stink bug increases.

Codling moth has or is near completion of the 2nd generation throughout the region, and OFM has completed its third generation. While there is time for another generation of each insect, the risk of damage from hereon is low in those orchards that have not experienced problems up to this point in time. In those orchards that have experienced infested fruit, the risk is likely to remain into September.

Overlapping generations of OFM can lead to increased populations in August and September. In the past this was often avoided with an application of sprayable OFM pheromone (CheckMate OFM-F) in mid August and early September, but increased use of pyrethroids for BMSB (see below) has led to suppressed late-season OFM in recent years.

Brown marmorated stink bug DD accumulations in Cleveland, Wilkes and Henderson County average about 900, 708, and 694, respectively. Based on the model predicting emergence of F1 adults, emergence is about 35-40% in Cleveland County, so risk for damage is high. However, BMSB populations have been relatively low this year, so the risk factor is likely lower.

Initial emergence of F1 adults occurs at about 750 DD, which is predicted to be early next week in Henderson and Wilkes Counties.

Finally, remember that the Mountain Hort Field Day is this Thursday, August 10, at the Mountain Horticultural Crops Research and Extension Center in Mills River. This field day includes several apple presentations in the research orchards as well as talks on tomatoes, vegetables, specialty crops, and alternative crops. More details are in the MHCREC announcement.

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

2023 Average Weekly Trap Captures

Insects per trap
July 24 Aug 1 Aug 8
Codling moth  1.0 4.5 1.0
Oriental fruit moth 18.0 13.5 11.0
Tufted apple bud moth 0.0 1.0 0.0
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 0.0 2.0
Lesser appleworm 0.0 1.0 0.0
Apple maggot (abandoned and research orchards) 0.0 0.0 0.0
Brown marmorated stink bug (commercial) 1.9 1.7 1.1
Brown marmorated stink bug (unsprayed) 0.0 1.0 0.7
Spotted tentiform leafminer 0.0 0.0 0.0
Dogwood borer 17.0 11.0 20.0
Peachtree borer 5.5 7.5 3.5
Lesser peachtree borer 3.0 2.5 0.0
San Jose scale 15.0 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.

2023 Accumulated Degree Days

July 24 Aug 1 Aug 7
Codling moth (Biofix: April 7) 1605 1802 1938
Oriental fruit moth (Biofix: March 24) 2275 2506 2673
Tufted apple bud moth (Biofix: April 21) 1922 2153 2320

About degree-day models

2023 Pest Population Trends

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