Current Western NC Orchard Pest Populations Weekly Summary, July 13 2015

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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

JULY 13, 2015

lady beetle

A beneficial insect in the orchard, a lady beetle

Codling Moth:  In Henderson County and other elevations above 2000 ft, codling moth degree-day accumulations since biofix average about 1500. Although this timing coincides with the mid-flight period of the second generation, and pheromone trap captures did increase slightly this past week, overall, codling moth populations have been low this year. Last week we surveyed numerous orchards in Henderson County for insect damage, and codling moth damage was extremely low. In most mating disruption orchards it is unlikely that insecticides will be needed against second generation codling moth, and in most other orchards it is unlikely that more than one application will be necessary. However, pest control decisions should be based on pheromone trap captures in individual orchards.

In lower elevations, such as Cleveland and Lincoln County, degree-day accumulations since biofix average about 2100, which indicates that the end of second generation flight is nearing. If pheromone trap captures have been low in recent weeks, it would be very unusual for populations to increase over the next several weeks.

Oriental Fruit Moth:  Despite the fact that very little OFM damage has been observed up to this point in time, pheromone trap captures did increase by about 4-fold this past week – although overall numbers remain fairly low, averaging about 8 moths/trap. As mentioned in recent weeks, OFM populations often gradually increase from late July through September, and insecticidal control can be difficult in September when harvest is underway. Also remember that mating disruption is highly effective in managing OFM, so this is rarely a problem in orchards using dual pheromone dispensers (codling moth and OFM) for mating disruption. In those orchards not using mating disruption, one or two applications of sprayable pheromone have worked very well in past years. The first application should be made when pheromone trap captures increase to >10 moths per trap per week, and a second application 3 to 4 weeks later.

As with codling moth, OFM populations can vary considerably among orchards, and there is no substitute for the use of pheromone traps to detect potentially damaging populations.

Apple Maggot:  Historically, apple maggot flight usually begins in mid to late July and remains a potential threat through early August. We have kairomone-baited red spheres in several abandoned orchards in Henderson County, but as of yet we have not consistently captured any flies.

Brown Marmorated Stink Bug:  First generation adults are becoming more abundant throughout the region. These are individuals that developed from eggs laid by overwintering adults in May and June. Typically, emergence begins at about 450 DD (°C) from 13 May, and peak emergence occurs between 600-700 (°C). As of Monday (July 13) DD accumulations in Henderson County were 435, so first generation adults should begin to emerge this week. Off the mountain where temperatures are considerably warmer, we are near 600 DD – as of July 13, 560 had accumulated in Cleveland County. First generation adults tend to readily move from the edge of wooded habitats into orchards and other fields, so scouting for BMSB will be important over the next several weeks. Based on pheromone trap captures thus far, populations appear to be much higher in the piedmont compared to most mountain areas.

Average Weekly Trap Captures*

Insects per trap
June 29
July 6
July 13
Codling Moth
2.7 2.0 4.3
Oriental Fruit Moth
4.3 2.3 8.3
Tufted Apple Bud Moth 1.5 0.5 0.5
Redbanded Leafroller 0.5 1.0 0.5
Obliquebanded Leafroller 1.0 0.0 0.0
Lesser Appleworm 1.0 0.0 5.0
Apple Maggot 0.0 0.0 0.0
Brown Marmorated Stink Bug 0.8 0.8 20.5
Spotted Tentiform Leafminer 27.0 30.0 0.0
Dogwood Borer 84.0 14.0 29.0
Peachtree Borer 32.0 33.0 30.0
Lesser Peachtree Borer 42.0 14.5 20.0
San Jose Scale 7675.0 7412.5 10005.0

*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.

Accumulated Degree Days

Henderson County
 Biofix June 29
July 6
July 13
Codling Moth April 23 1176 1311 1480
Oriental Fruit Moth Apr 6 1771 1903 2098
Tufted Apple Bud Moth April 23 1476 1643 1839
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.