WNC Orchard Insect Populations for July 10, 2018

— Written By and last updated by

photo of applesJuly 10, 2018

Codling moth DD accumulations range from about 1480 in Henderson County to 1770 in Lincoln County, indicating that egg hatch of second generation codling moth is beginning in Henderson County and is about 40% complete in lower elevation orchards. Depending on population intensity, one or two applications of an insecticide effective against codling moth are recommended at this time. It should be noted that with a few exceptions, codling moth populations appear to be very low this year. There is minimal damage from the first generation and pheromone trap captures have been very low throughout the year.

In orchards using mating disruption for coding moth, insecticides targeting second generation codling moth are not necessary unless pheromone trap captures (orchard average per trap) exceeds a cumulative of 3 moths per trap over successive weeks when using CML2 or CMDA lures. In orchards that have used mating disruption for more than 3 or 4 years, insecticides are usually not necessary against the second generation. However, pheromone traps should be used to confirm low population pressure.

Emergence of first-generation adult brown marmorated stink bug is now beginning in lower elevation orchards including Lincoln, Cleveland, and Burke Counties. First generation adult emergence in Henderson County is not expected for at least another two weeks.

In orchards where BMSB is a concern, an insecticide effective against this insect should be considered at this time. This includes most pyrethroid insecticides except Asana, the neonicotinoids Venom/Scorpion and Actara (35-day PHI), and the premix Besiege. The premixes Endigo and Voliam Flexi are also effective, but both have a 35-day PHI due to the thiamethoxam component.

Finally, in those orchards that had significant plum curculio damage earlier in the year, emergence of first-generation adults occurs during July. These adults can feed on apples and peaches before seeking overwintering sites. Again, this is primarily a concern where a sufficient number of individuals completed development in fruit, which is usually very low in this region.


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


2018 Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
June 25
July 2
July 9
Codling Moth 0.5 0.3 1.0
Oriental Fruit Moth 19.3 15.7 11.0
Tufted Apple Bud Moth 0.0 0.0 0.0
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 2.0 0.0 0.0
Lesser Appleworm 0.0 0.0 0.0
Apple Maggot 0.3 0.0 0.0
Brown Marmorated Stink Bug (commercial – mountains) 0.4 0.3 0.2
Brown Marmorated Stink Bug (commercial – upper piedmont) 0.6 1.3 2.2
Brown Marmorated Stink Bug (research – unsprayed) 0.8 1.0 0.8
Spotted Tentiform Leafminer 30.0 0.0 0.0
Dogwood Borer 48.0 20.0 23.0
Peachtree Borer 28.0 30.0 37.0
Lesser Peachtree Borer 13.5 7.0 4.0
San Jose Scale 0.0 2.5 17.5

*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.


2018 Accumulated Degree Days

  Henderson County
 Biofix June 25
July 3
July 10
Codling Moth Apr 30 1124 1323 1488
Oriental Fruit Moth Apr 2 1636 1876 2071
Tufted Apple Bud Moth May 4 1317 1556 1752
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)

codling moth trend graph oriental fruit moth trend graph tufted apple bud moth trend graph redbanded leafroller trend graph
dogwood borer trend graph

codling moth trend graph oriental fruit moth trend graph tufted apple bud moth trend graph redbanded leafroller trend graph lesser appleworm trend graph obliquebanded leafroller trend graph spotted tentiform leafminer trend graph dogwood borer trend graph peachtree borer trend graph lesser peachtree borer trend graph apple maggot trend graph Brown marmorated stink bug trend graph San Jose Scale trend graph