WNC Orchard Insect Populations for August 14, 2018

— Written By and last updated by

August 14, 2018Ladder beside apple tree

Overall insect pressure remains low in most areas. While degree-day accumulations coincide with early egg hatch of the third generation in lower elevation orchards (e.g., Cleveland, Lincoln Counties), this generation should not require control unless damage from previous generations is evident, which seems to be rare. In higher elevations (e.g., Henderson County), DD accumulations coincide with the tail end of second generation egg hatch, and pheromone trap captures remain low. OFM pheromone traps captures are also very low throughout the area.

Based on pheromone trap captures in multiple apple orchards, first-generation adult brown marmorated stink bug emergence continues in the mountains, and has slowed down considerably in lower elevation orchards (less than 1000 ft elevation). Populations to date do not appear to be especially high, so two-week interval applications should be sufficient in those locations where protection is of greatest need – i.e., fresh market production.

We continue to capture apple maggot flies on traps in abandoned orchards, which is to be expected this time of the year. However, dispersal from these sites usually declines considerably later in the season, so further insecticide application specifically targeting this insect are probably not needed moving into next week, with the exception being those orchards near abandoned sites.


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


2018 Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
July 30
August 6
August 13
Codling Moth 1.5 0.5 0.3
Oriental Fruit Moth 17.7 13.0 17.0
Tufted Apple Bud Moth 3.0 1.0 0.0
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 2.0 1.0 0.0
Lesser Appleworm 5.0 1.0 0.0
Apple Maggot (abandoned and research) 19.3 21.3 14.3
Brown Marmorated Stink Bug (commercial – mountains) 0.8 1.0 1.3
Brown Marmorated Stink Bug (commercial – upper piedmont) 2.2 1.8 1.1
Brown Marmorated Stink Bug (research – unsprayed) 1.8 1.3 5.2
Spotted Tentiform Leafminer 5.0 3.0 0.0
Dogwood Borer 60.0 19.0 5.0
Peachtree Borer 29.5 22.5 25.0
Lesser Peachtree Borer 10.5 10.5 3.0
San Jose Scale 2.5 5.0 2.5

*Note that averages presented here are intended only to illustrate the timing of insect emergence and fluctuations in population activity, and not as general indicators of population levels. Some orchards included in these averages have significantly higher or lower populations than most commercial orchards in the area, resulting in averages that are sometimes skewed from what is typical. The only way to have an accurate assessment of an individual orchard’s populations is to set up traps in that orchard.


2018 Accumulated Degree Days

  Henderson County
 Biofix July 30
August 7
August 14
Codling Moth Apr 30 1950 2100 2295
Oriental Fruit Moth Apr 2 2633 2819 3054
Tufted Apple Bud Moth May 4 2314 2500 2735
About degree-day models: The 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.

2018 Pest Trends (click to enlarge)

codling moth population trend graph oriental fruit moth population trend graph tufted apple bud moth population trend graph redbanded leafroller population trend graph lesser appleworm population trend graph spotted tentiform leafminer population trend graph dogwood borer population trend graph peachtree borer population trend graph lesser peachtree borer population trend graph apple maggot population trend graph brown marmorated stink bug population trend graph san jose scale population trend graph