WNC Orchard Insect Populations for June 12, 2018

— Written By and last updated by

Image of codling moth flightJune 12, 2018

First generation codling moth flight has subsided in both the mountains and piedmont locations. The only location where codling moth remains a threat, and where insecticidal control should continue, is where populations are historically high. This includes orchards adjacent to poorly managed orchards or where wooden apple bins (originating from other states) are stored.

We are in the midst of second-generation OFM flight, but as mentioned last week, this generation is usually of little threat where the first generation was adequately controlled. Based on recent observations in commercial orchards, there is very little if any damage by first-generation codling moth or OFM.

If an insecticide effective against TABM, such as Altacor (or Voliam Flexi), Delegate or Intrepid, has not been applied within the last two weeks, an application should be made within the next week.

Finally, we’re approaching that time of the year when apple aphids and potato leafhopper populations are beginning to appear. Both insects prefer to feed on new shoot growth. Now is a good time to scout orchards to determine the need for control. They are easily controlled with a range of neonicotinoids or closely related compounds, such as Admire, Assail, Actara, Closer, or Sivanto.

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

2018 Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
May 29
 June 4
 June 11
Codling Moth 3.5 0.3 0.8
Oriental Fruit Moth 5.7 13.0 16.0
Tufted Apple Bud Moth 12.0 11.0 1.0
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 1.0 2.0 0.0
Lesser Appleworm 0.0 1.0 0.0
Apple Maggot 0.0 0.0 0.0
Brown Marmorated Stink Bug (commercial – mountains) 1.3 1.7 1.5
Brown Marmorated Stink Bug (commercial – upper piedmont) 3.7 2.0 0.7
Brown Marmorated Stink Bug (research – unsprayed) 0.3 2.0 2.5
Spotted Tentiform Leafminer 0.0 0.0 40.0
Dogwood Borer 31.0 18.0 18.0
Peachtree Borer 1.5 7.5 16.0
Lesser Peachtree Borer 25.0 20.5 42.5
San Jose Scale 0.0 0.0 7.5

*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 May 29
 June 5
 June 11
Codling Moth Apr 30 501 654 797
Oriental Fruit Moth Apr 2 883 1071 1249
Tufted Apple Bud Moth May 4 564 752 929
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.