Western NC Orchard Pest Populations Weekly Summary, June 22 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

JUNE 22, 2015

Brown marmorated stink bug

Brown marmorated stink bug

The warm weather is accelerating development of many insect pest populations, so do not be surprised if the timing of certain pest events is considerably earlier than in the past few years, which have had relatively cool summers.

Lepidopteran Pests:  In the higher elevation orchards such as Henderson County, we are in a period of reduced potential for damage by direct insect pests. Codling moth degree day accumulations are at about 1000, so we are between generations. We are beyond the time for control of first generation tufted apple bud moth, and second generation oriental fruit moth flight is ending. Off the mountain in lower-elevation orchards, second generation codling moth flight is now underway – estimated cumulative degree days since biofix for codling moth in Cleveland County is about 1500, and Bill Hanlin reported 1400 in the Wilkes area. In orchards with minimal signs of damage by first generation larvae, a single application between about 1450 or 1500 DD should be sufficient for the second generation.

Plum Curculio:  With plum curculio damage being quite extensive this year, growers should be prepared for emergence of first generation adults. Although these adults typically do not produce a second generation of offspring in this region, they can feed on apples and cause additional damage to fruit. Adults emerge from those fruit that were infested after bloom and fell from the tree – larvae generally do not complete development on apples growing on the tree, but they will on peach fruit on the tree. In past years, emergence of first generation adults has begun between 700 and 800 DD after first detection in an orchard in the spring, which occurs in early April. Estimated DD accumulations in Henderson and Cleveland Counties are currently about 650 and 840, respectively. Emergence can occur over a several-week period, so scouting for adults should be underway. Again, the potential for damage by these adults is greatest in orchards with damage evident by overwintering weevils at petal fall and first cover. In problem orchards, an insecticide active against PC should be applied within the next week in lower elevation orchards and in 1 to 2 weeks in higher elevation orchards.

Brown Marmorated Stink Bug:  We continue to capture brown marmorated stink bug in virtually all pheromone traps deployed in the mountains and piedmont regions. Some overwintering adults are still active and laying eggs, but the majority of the population consists of nymphs ranging from early to 4th instars. Using a biofix of 15 May, we have previously observed emergence of first generation adults (i.e., summer adults) to begin at about 650 degree days (celsius); we are currently at about 270 and 350 in Henderson and Cleveland Counties. Despite the warm temperatures, we are still probably a minimum of three weeks (piedmont) to five weeks (mountains) from reaching 650 DD. While there has been some nymphal activity observed in tree fruits (primarily peaches and Asian pears), migration of adults from wooded areas into adjacent orchards by summer adults will likely pose the greatest threat for damage to apples.

In those areas with tree fruit production near small grains, anticipate movement of brown and green stink bugs from the grains following harvest into adjacent fruit or vegetable crops. Jeremy Martin at the Sand Hills Research Station reported large numbers of stink bugs moving from harvested rye into adjacent peaches. Brown stink bugs have been a common occurrence in small grains sampled in the piedmont and mountain areas.

European Red Mite:  As often occurs with hot weather, mite populations are rapidly increasing on number crops. There have been reports of high European red mite populations on apples in several locations. Twospotted spider mite can also be a problem on apples and other crops (especially peaches and vegetables), particularly in piedmont production areas.

Average Weekly Trap Captures*

Insects per trap
June 8
June 15
June 22
Codling Moth
4.7 0.7 1.3
Oriental Fruit Moth
5.3 2.8 2.5
Tufted Apple Bud Moth 15.0 8.5 3.5
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 4.0 0.5 0.0
Lesser Appleworm 0.0 0.0 0.0
Apple Maggot 0.0 0.0 0.5
Brown Marmorated Stink Bug 0.0 0.3 1.5
Spotted Tentiform Leafminer 42.0 23.0 57.0
Dogwood Borer 48.0 38.0 59.0
Peachtree Borer 18.5 22.0 18.0
Lesser Peachtree Borer 35.0 53.5 42.0
San Jose Scale 0.0 0.5 1527.5

*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 8
June 15
June 22
Codling Moth April 23 677 828 1012
Oriental Fruit Moth Apr 6 1147 1330 1544
Tufted Apple Bud Moth April 23 887 1070 1284
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.