WNC Orchard Insect Pest Populations – August 11, 2020

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Insect trap in apple orchard

Brown marmorated stink bug adult emergence is becoming more widespread, while apple maggot and oriental fruit moth numbers increased in the past week.

Brown Marmorated Stink Bug

Emergence of first-generation BMSB adults is approximately 50% complete in the Cleveland/Lincoln County area, while in Wilkes and Alexander Counties about 20% of the population has emerged (see emergence figure below). BMSB poses a threat to crops in these areas that have significant populations. Emergence is just beginning in Henderson County, so the threat of damage will increase significantly in the next week or so. In Haywood County and similar elevations, emergence is still at least a couple of weeks off.

Chart of brown marmorated stink bug emergence times

Codling Moth, Oriental Fruit Moth, and Apple Maggot

Second generation codling moth is essentially complete throughout the area, and third generation populations are only expected in areas that have experienced problems up to this point. Both OFM and apple maggot trap captures increased over the past week, which is expected at this time of the year. Although numbers of these latter two pests were not particularly high at our monitoring sites, populations can vary considerably from orchard to orchard.

Below is a summary of the activity of various insecticides against the key pests of concern at this time, albeit those with a preharvest interval of no more than 21 days:

Insecticide range of activity against key insect pests of apple during August and September. (X = has activity)

Common name Brand name Pre-harvest interval BMSB OFM Codling moth Apple maggot
  Bifenthrin* Brigade, Bifenture 14 X X X
  Beta-cyfluthrin Tombstone 7 X X X
  Cyfluthrin Baythroid 7 X X X
  Fenpropathrin Danitol 14 X X X
  Gamma- cyhalothrin Proaxis 14 X X X
  Lambda-cyhalothrin Karate 21 X X X
  Zeta-cypermethrin Mustang Maxx 14 X X X
  Chlothianidin Belay 3 X X
  Dinotefuran* Venom, Scorpion 3 X
  Lambda-cyhalothrin + chlorantraniliprole Besiege 21 X X X X

*Bifenthrin and dinotefuran have Section 18 emergency exemption labels.

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

2020 Average Weekly Trap Captures

Insects per trap
Jul 27 Aug 3 Aug 10
Codling moth  0.7 0.7 0.6
Oriental fruit moth 4.8 4.2 3.6
Tufted apple bud moth 0.5 0.0 5.5
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 1.0 1.0 0.0
Lesser appleworm 0.0 0.0 0.0
Apple maggot (abandoned and research orchards) 0.0 0.7 1.7
Brown marmorated stink bug (commercial) 1.7 2.0 3.2
Brown marmorated stink bug (unsprayed) 3.5 3.3 2.8
Spotted tentiform leafminer 16.0 8.0 0.0
Dogwood borer 6.0 25.0 7.0
Peachtree borer 31.0 22.0 29.0
Lesser peachtree borer 28.0 22.0 22.0
San Jose scale 265.0 72.5 17.5

*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.

2020 Accumulated Degree Days

Jul 27 Aug 3 Aug 10
Codling moth (Biofix 4/20) 1581 DD 1781 DD 1917 DD
Oriental fruit moth (Biofix 3/30) 2218 DD 2459 DD 2625 DD
Tufted apple bud moth (Biofix 4/27) 1960 DD 2201 DD 2367 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 Graph of insect population trends

Visit WNC Orchard Insect Populations for archived posts.

Additional Resources