WNC Orchard Insect Pest Populations – August 3, 2023

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Apples on tree.I apologize for the delayed update this week, but travel and field work has set us behind. The pest complex of greatest importance remains the internal lepidopteran complex (codling moth and oriental fruit moth) and brown marmorated stink bug, the latter of greatest importance in lower elevations.

Second generation codling moth has completed egg laying in lower elevation areas, and is more than halfway complete in higher elevations (e.g., ≥2000 ft). Unless codling moth damage exists in orchards, the potential for new damage from this point on is minimal.

We are approaching that time when 3rd and 4th generations of OFM are beginning to overlap, which contributes to increasing populations later in the year. If pheromone trap captures increase to greater than 7 to 10 moths/trap, an insecticide spray should be considered. In those areas where BMSB is emerging and pyrethroids will be sprayed, OFM will also be controlled.

First generation BMSB adult emergence is underway in lower elevation orchards (about 1000 ft and lower). In Cleveland County, 821 DD have accumulated since biofix, which is equivalent to emergence of about 25% of the adult population. DD accumulations are considerably behind in Henderson (641 DD) and Wilkes Counties (655 DD), and adult emergence is not expected for another 10 to 14 days. However, as mentioned in last week’s update, Granny Smith apples have been shown to be highly attractive to BMSB beginning in late July to early August, so an insecticide application should be considered on that cultivar.

Finally, remember that the Mountain Hort Field Day is on 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 17 July 24 Aug 1
Codling moth  1.0 1.0 4.5
Oriental fruit moth 15.5 18.0 13.5
Tufted apple bud moth 0.0 0.0 1.0
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 0.0 0.0
Lesser appleworm 1.0 0.0 1.0
Apple maggot (abandoned and research orchards) 0.0 0.0 0.0
Brown marmorated stink bug (commercial) 1.9 1.7
Brown marmorated stink bug (unsprayed) 1.3 0.0 1.0
Spotted tentiform leafminer 0.0 0.0 0.0
Dogwood borer 20.0 17.0 11.0
Peachtree borer 7.5 5.5 7.5
Lesser peachtree borer 4.0 3.0 2.5
San Jose scale 225.0 15.0 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 17 July 24 Aug 1
Codling moth (Biofix: April 7) 1451 1605 1802
Oriental fruit moth (Biofix: March 24) 2086 2275 2506
Tufted apple bud moth (Biofix: April 21) 1733 1922 2153

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2023 Pest Population Trends

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