WNC Orchard Insect Populations

— Written By and last updated by

May 15, 2018

We are approaching the time when insecticides for first generation codling moth will need to be initiated. Degree-day accumulations since biofix range from about 200 in Henderson County to 320 off the mountain in Cleveland County. In situations where moderate to high populations exist (i.e., probably observed some damage in 2017), the first spray should be applied at 250 DD. In orchards with low populations (low trap captures and no damage in 2017), the first application can be delayed until about 350 DD, which is predicted to occur next week in Henderson County. In orchards using mating disruption, it is highly unlikely that insecticides for lepidopteran pests (e.g., tufted apple bud moth, codling moth) will be needed until early to mid-June, although pheromone trap captures should be used to mitigate the unexpected. The cooler and rainy weather predicted for the coming days will help to reduce codling moth flight and egg laying.

For those planning to control San Jose scale post bloom with Esteem, Centaur or Movento  applications, sprays should be made by the end of this week for best results.

Finally, emergence of overwintering brown marmorated stink bug adults is about two-thirds complete in Henderson County, with emergence expected to be completed in the next two weeks. Emergence is complete off the mountain in lower-elevation orchards. To date, numbers have been fairly low in pheromone traps.


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


2018 Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
Apr 30
May 7
May 14
Codling Moth
0.5
4.5
1.0
Oriental Fruit Moth
38.0
16.0
6.7
Tufted Apple Bud Moth
0.0
13.0
6.0
Redbanded Leafroller
1.0
0.0
0.0
Obliquebanded Leafroller
0.0
0.0
0.0
Lesser Appleworm
0.0
0.0
0.0
Apple Maggot
Brown Marmorated Stink Bug (commercial – mountains)
0.0
0.0
n/a
Brown Marmorated Stink Bug (commercial – upper piedmont)
1.3
1.3
n/a
Brown Marmorated Stink Bug (research – unsprayed)
0.3
2.3
0.5
Spotted Tentiform Leafminer
0.0
0.0
0.0
Dogwood Borer
0.0
0.0
3.0
Peachtree Borer
0.0
1.0
1.0
Lesser Peachtree Borer
13.0
139.0
98.0
San Jose Scale
0.0
0.0
0.0
*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
Apr 30
May 8
May 14
Codling Moth
Apr 30
93
196
Oriental Fruit Moth
Apr 2
247
372
503
Tufted Apple Bud Moth
May 4
52
184

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)

Written By

Photo of Dr. Jim WalgenbachDr. Jim WalgenbachExtension Entomology Specialist (Fruits / Vegetables) (828) 687-0570 (Office) jim_walgenbach@ncsu.eduEntomology and Plant Pathology - NC State University
Posted on May 15, 2018
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