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

April 20, 2015

MHCRS rainbow 019

With most orchards now in the petal fall or slightly later stage, the key insect pests of primary concern on apples (and peaches) are oriental fruit moth and plum curculio.

OFM pheromone trap captures have been quite high in numerous orchards in recent weeks, which is not unusual at this time of year.  Hence, in those orchards not using mating disruption and where pheromone traps are also not being used, one should assume that insecticidal control of this generation is necessary.  Despite the high trap captures at this time of year, egg production is much lower than later in the season when trap captures are typically lower.  Consequently, a single insecticide application applied between petal fall and first cover usually does an excellent job in controlling first generation OFM.  This generation of OFM can be controlled with thinning sprays of Sevin when applied at a minimum of 1 lb AI/acre.  See the table below if additional insects need to be controlled.

In those orchards where plum curculio is a concern, it is important to remember that many weevils probably entered orchards during bloom, and additional ones will be entering over the next few weeks.  Hence, petal fall is typically the most important time for insecticide sprays to control curculio.  While several different insecticides will control this pest, the choice of which insecticide to spray should be based on additional insects that may require control.  Listed below is a table of relative effectiveness of insecticides against insects commonly present at petal fall.

This week we also observed initial emergence of San Jose scale adults. In orchards that have experienced scale problems in recent years, an insecticide targeting scale should be applied when crawlers are active, which occurs between 500 to 600 degree-days (50°F base temperature) after peak pheromone trap capture of adults. Based on historical temperatures, crawler activity is not expected until late May or early June.

Relative Effectiveness of Insecticides for Insect Control at Petal Fall

(E=Excellent, G=Good, F=Fair, — =No Activity)
Insecticide
Active Ingredient
Oriental Fruit Moth
Plum Curculio
Rosy Apple Aphid
Actara
Thiamethoxam
F
E
E
Assail
Acetamiprid
E
F
E
Avaunt
Indoxacarb
E
E
Belay
Chlothianidin
G
G
E
Calypso
Thiacloprid
E
G
E
Imidan
Phosmet
E
G
Voliam Flexi
Thiamethoxam + Chlorantraniliprole
E
E
E

Average Weekly Trap Captures*

HENDERSON COUNTY
Insects per trap
Apr 6
Apr 13
Apr 20
Codling Moth
0.0
0.0
0.3
Oriental Fruit Moth
3.0
85.5
108.3
Tufted Apple Bud Moth
0.0
0.0
0.5
Redbanded Leafroller
3.0
7.0
2.0
Obliquebanded Leafroller
-
-
-
Lesser Appleworm
-
-
-
Apple Maggot
-
-
-
Brown Marmorated Stink Bug
-
-
-
Spotted Tentiform Leafminer
4.0
10.0
1.0
Dogwood Borer
-
-
-
Peachtree Borer
-
-
-
Lesser Peachtree Borer
0.0
0.0
0.0
San Jose Scale
0.0
0.0
99.5
*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
Apr 6
Apr 13
Apr 20
Codling Moth
-
-
-
-
Oriental Fruit Moth
Apr 6
Biofix
118
232
Tufted Apple Bud Moth
-
-
-
-
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.

Pest Trends (click to enlarge)

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