Current Western NC Orchard Pest Populations, August 3 2015

— Written By and last updated by

We track local insect populations throughout the growing season using a system of traps, temperature-recording devices, and degree-day models. Traps and weather data are checked weekly, with results updated by Tuesday afternoon from April through September. Learn more about southeastern apple pests at the Apple Pest Management page.


Weekly summary

AUGUST 3, 2015

Codling moth:  Surprisingly, pheromone trap captures increased in a couple of areas where spray programs have been minimal. Based on degree-day accumulations (average of about 2000 in Henderson County), these probably represent later-emerging individuals of the second generation. It should be noted, however, that trap captures remain very low – essentially zero – in the majority of managed orchards.

Oriental Fruit Moth:  OFM pheromone trap captures have been somewhat lower than expected in recent weeks, although numbers have been trending higher during the past month. In orchards not using mating disruption, a preventive application of sprayable pheromone may be warranted if pheromone trap captures have exceeded about 5 moths per trap.

Although we are monitoring in only a few orchards where mating disruption for codling moth and OFM is being used, trap captures at these sites have been extremely low, and insecticides for either of these pests have not been necessary for most of the season.

Apple Maggot:  Trap captures in an abandoned orchard increased to 8 flies during the past week. This is the first significant capture this season, but it still represents a relatively low population. The dry weather conditions have not been conducive to emergence of flies from the soil. The need for apple maggot sprays is probably most important in orchards adjacent to abandoned sites.

Brown Marmorated Stink Bug:  Stink bug populations remain highest in the piedmont production areas, but numbers seemed to have leveled off during the past few weeks. First generation adults that emerged before August 1 will continue to lay eggs for several weeks, but egg laying should begin to decline within the next one to two weeks. Overall, numbers seem to be fairly low in most Henderson County orchards.


 Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
July 20
July 27
Aug 3
Codling Moth
4.7
9.0
13.7
Oriental Fruit Moth
5.3
5.3
7.0
Tufted Apple Bud Moth
1.5
2.0
3.5
Redbanded Leafroller
0.0
0.0
2.5
Obliquebanded Leafroller
0.5
0.5
2.0
Lesser Appleworm
2.0
0.0
2.0
Apple Maggot
2.0
0.5
4.0
Brown Marmorated Stink Bug
0.3
0.0
0.0
Spotted Tentiform Leafminer
0.0
0.0
18.0
Dogwood Borer
48.0
26.0
40.0
Peachtree Borer
47.5
41.0
52.0
Lesser Peachtree Borer
21.0
7.0
25.0
San Jose Scale
1697.5
2015.0
367.5
*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.

Accumulated Degree Days

Henderson County
 Biofix
July 20
July 27
Aug 3
Codling Moth
April 23
1662
1840
2014
Oriental Fruit Moth
Apr 6
2315
2518
2734
Tufted Apple Bud Moth
April 23
2055
2258
2474
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.