Current Western NC Orchard Pest Populations

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

DSC_7596July 21, 2014

Based on the codling degree-day model, second generation egg laying is about 15% complete in Henderson County, but populations have generally been low throughout the region.  Off the mountain in Polk County, the model predicts that egg laying of the second generation is about 65% complete, but densities have been also been very low in Polk.  Under low-density populations, a single application targeting the second generation should be sufficient, and the window of opportunity for making that application is generally wide – generally from about 1500-1800 DD.  However, in those orchards with damage or where pheromone trap captures have been greater than 5 to 7 per week, at least two applications are likely necessary.

Oriental fruit moth populations remain high in some, but not all locations.  Numbers continue to remain very low in orchards using mating  disruption, including sprayable OFM pheromone.

Apple maggot trap captures increased abruptly in one abandoned orchard, but remained low in another.  In the absence of monitoring for this insect, it would be wise to assume a potentially damaging population exists.


 2014 Average Weekly Trap Captures*

HENDERSON COUNTY POLK COUNTY
Insects per trap Insects per trap
Jul 7
Jul 14
Jul 21
Jul 7
Jul 14
Jul 21
Codling Moth
3.8 3.5 3.4 0.4 0.1 0.1
Oriental Fruit Moth
42.3 35.8 31.6 4.8 2.3 0.5
Tufted Apple Bud Moth 3.0 0.5 2.0 0.0 0.0 1.0
Redbanded Leafroller 0.5 0.0 0.0 0.0 0.0 0.0
Obliquebanded Leafroller 0.5 1.0 0.0 3.0 1.0 7.0
Lesser Appleworm 0.5 0.0 0.5 12.0 0.0 1.0
Apple Maggot 0.5 0.0 1.0 - - -
Brown Marmorated Stink Bug 0.0 0.3 0.0 - - -
Spotted Tentiform Leafminer 88.0 46.0 34.0 - - -
Dogwood Borer 35.0 20.5 34.0 - - -
Peachtree Borer 35.5 46.5 43.0 - - -
Lesser Peachtree Borer 22.0 18.0 3.5 - - -
Plum Curculio 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.


2014 Accumulated Degree Days


Henderson County      Polk County
  Jul 7
Jul 14
Jul 21
  Jul 7
Jul 14
Jul 21
Codling Moth Biofix 5/2 1172 1325 1441 Biofix 5/2
1485 1675 1819
Oriental Fruit Moth Biofix 4/7 1785 1973 2127
Biofix 4/2
2221 2447 2626
Tufted Apple Bud Moth Biofix 4/28
1549 1737 1891 Biofix 4/21
1962 2187 2366

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.

2014 Pest Trends (click to enlarge)

UPDATED July 21

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