WNC Orchard Insect Pest Populations - August 26, 2026 - Southern Appalachian Apples

WNC Orchard Insect Pest Update - August 26, 2026

— Written by Jim Walgenbach — Contributors: Stephen Schoof | August 26, 2026 (Updated: Aug. 26, 2026, 4:28 p.m.)

As apple harvest comes into full swing, the opportunity for insecticide applications become less convenient due to preharvest intervals and workers in orchards.

Hopefully most orchards will not require additional sprays from this point on, but oriental fruit moth (OFM) and brown marmorated stink bug (BMSB) are the two most likely insects to require control at this time. If insecticides (or mating disruption) targeting these pests have occurred in the past week or 10 days, the likelihood for damage is low. BMSB degree-day accumulations have reached about 1,000 in Henderson County, which predicts about 55% emergence of first generation adults. While weekly pheromone trap captures have gradually increased over the past few weeks, numbers are still relatively low compared to 4 to 5 years ago (see Figure below). Almost all first generation adults have emerged in lower elevation orchards.

Chart showing declining August numbers of brown marmorated stink bug captures from 2019 through 2026

OFM pheromone trap captures continue to be low in most of our monitoring sites in Henderson County, but there are a few locations with consistently higher numbers. If not using pheromone traps to monitor populations, consider applying an insecticide effective against OFM on cultivars that will not be harvested by mid-September. The preharvest interval for insecticides recommended for OFM are:

Preharvest interval (days) for OFM insecticides
Delegate	7
Altacor	5
Exirel	3
Verdepryn	7
Zivalgo	7
Pyrethroids: Baythroid Brigade Danitol	7 14 14

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

2026 Average Weekly Trap Captures - Henderson County

	Insects per trap
Insect	Jul 20	Jul 27	Aug 3	Aug 10	Aug 17	Aug 24
Codling moth	3.0	4.5	4.0	3.0	1.5	2.0
Oriental fruit moth	7.5	17.5	12.0	9.5	7.0	7.5
Tufted apple bud moth	0.0	4.0	2.0	0.0	5.0	0.0
Redbanded leafroller	1.0	0.0	5.0	0.0	9.0	1.0
Obliquebanded leafroller	0.0	1.0	1.0	0.0	0.0	0.0
Lesser appleworm	0.0	2.0	0.0	0.0	0.0	0.0
Apple maggot (unsprayed/research)	0.0	0.0	0.0	0.0	0.0	0.0
Apple maggot (abandoned orchard)	7.5	2.0	0.0	2.5	0.5	0.0
Brown marmorated stink bug - ADULTS (commercial)	0.8	0.6	1.9	1.9	5.6	6.2
Brown marmorated stink bug - NYMPHS (commercial)	2.1	0.3	2.8	3.9	14.0	6.0
Brown marmorated stink bug - ADULTS (unsprayed/research)	6.0	6.0	4.0	9.5	1.5	9.5
Brown marmorated stink bug - NYMPHS (unsprayed/research)	13.5	9.5	22.5	11.5	17.0	35.0
Spotted tentiform leafminer	4.0	0.0	0.0	0.0	0.0	0.0
Dogwood borer	37.0	43.0	46.0	78.0	90.0	80.0
Peachtree borer	20.0	24.0	37.0	31.0	27.0	28.0
Lesser peachtree borer	2.0	3.0	8.0	2.0	3.0	13.0
San Jose scale	22.5	2.5	2.5	65.0	342.5	27.5
*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.

2026 Degree Days - (MHCRS) Mills River

	Accumulated Degree Days
Insect	Aug 10	Aug 17	Aug 24
Codling moth (Biofix Apr 11)	2297	2486	2663
Oriental fruit moth (Biofix Mar 21)	3100	3325	3528
Tufted apple bud moth (Biofix Apr 17)	2700	2924	3128

About degree-day models

Degree-day (DD) models predict adult emergence and egg hatch of each generation. They do not predict the intensity of populations, which can be assessed by using pheromone traps. Hence, the models should be used to help gauge the time period when control is most likely needed, and pheromone traps provide information on the need for and frequency of insecticide applications. For full details, read “IPM Practices for Selected Pests” in the Orchard Management Guide.

Codling Moth:

1st generation: Egg hatch begins at about 350 DD after biofix and is completed by 1050 DD. The most critical period for insecticidal control is from 350 to about 750 DD.
2nd generation: Egg hatch of the second generation can extend from about 1300 to 2600 DD after biofix, but the most critical period for insecticidal control is 1400 to about 2500 DD.
3rd generation: Adults begin to emerge at about 2500 DD after biofix, but the model is less accurate in predicting late-season populations.

Oriental Fruit Moth:

1st generation: Only one insecticide application between 400 and 500 degree days is usually necessary, as 1st generation egg-laying is usually low on apple.
2nd generation: Effective 1st-generation control may eliminate the need for 2nd-generation control. If trap captures remain high, insecticides may be needed around 1100 to 1400 DD.
3rd generation: Insecticide may be needed at 2200 DD after biofix.
4th generation: Overlapping generations late in the season make it difficult to predict when 4th-generation egg hatch begins, but continuous egg-laying can occur from August through October. Use traps to determine the need for further insecticide applications.

Tufted Apple Bud Moth:

1st generation: One well-timed insecticide application between 800 and 1200 DD after biofix will often eliminate the need for further control of TABM.
2nd generation: Only if trap captures exceed 25 moths per trap by 2600 DD is an insecticide application recommended. NOTE: Insecticides targeting 2nd generation TABM are usually not necessary if 1st generation populations were successfully controlled.