Current Western NC Orchard Pest Populations

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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

JUNE 15, 2015

Throughout most of the mountain and piedmont production regions, we are currently in a period of low lepidopteran activity – first generation codling moth and tufted apple bud moth flight is complete, and second generation oriental fruit moth populations are very low in most locations.

Scouting at this time should be focused on green apple aphid, potato leafhopper and European red mite. Biological control can often provide necessary levels of control of aphids and mites, but there are few effective natural enemies of potato leafhopper.

In those orchards where dogwood borer may be a concern – younger trees in their first three to five years – now is a good time to begin inspecting for evidence of larval burrowing in either the graft union or burr knots on the lower part of the tree. When burrowing into the trunk, larval frass and sawdust will be evident on the surface of the bark or on the ground below the larval entry point. The window of opportunity to control DWB is fairly wide, extending from June through mid-July. Annual insecticide applications targeting DWB are not necessary, with anecdotal evidence indicating that one application every two to three years during the first five to six years after planting maintains populations at low levels.

What insecticides should I spray on apples with little or no fruit?  With a light crop in certain areas, there have been some questions about what insecticides are necessary in orchards with little or no fruit.

  • Do not spray for direct pests, such as codling moth, OFM, TABM, or apple maggot. These insects all require fruit to complete development and increase in numbers; hence, the absences of fruit will actually help to suppress populations for next year.
  • On young trees where vigorous growth is desired, key indirect pests including potato leafhopper and European red mite can suppress growth and result in early senescence of leaves. These are probably the two most important insect pests to consider on trees without fruit. On mature trees with no fruit, potato leafhopper damage is inconsequential, and mite populations will probably be suppressed by biological control agents, so it is unlikely that populations will build to high numbers.
  • As mentioned above, dogwood borer should also be monitored and controlled if necessary on young trees without fruit, because repeated infestations over several years can kill trees.

Average Weekly Trap Captures*

Insects per trap
June 1
June 8
June 15
Codling Moth
3.7 4.7 0.7
Oriental Fruit Moth
3.0 5.3 2.8
Tufted Apple Bud Moth 18.0 15.0 8.5
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 2.0 4.0 0.5
Lesser Appleworm 0.0 0.0 0.0
Apple Maggot 0.0 0.0 0.0
Brown Marmorated Stink Bug 0.3 0.0 0.3
Spotted Tentiform Leafminer 7.0 42.0 23.0
Dogwood Borer 55.0 48.0 38.0
Peachtree Borer 9.0 18.5 22.0
Lesser Peachtree Borer 41.0 35.0 53.5
San Jose Scale 7.5 0.0 0.5

*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 June 1
June 8
June 15
Codling Moth April 23 548 677 828
Oriental Fruit Moth Apr 6 983 1147 1330
Tufted Apple Bud Moth April 23 723 887 1070
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.

  • 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.

  • 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.

  • 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.