WNC Orchard Insect Pest Populations – May 4, 2021

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San Jose scale trap

With the uncertainty of fruit loads and extended bloom period, many growers are just now applying a petal fall spray. Recommendations for petal fall were outlined in the April 15 update, with an emphasis on control of plum curculio.

Codling Moth:  In lower elevation orchards such as Lincoln and Cleveland Counties, codling moth degree-day accumulations have increased to 300, while in Henderson County they are only about 180 DD. First egg hatch begins at about 250 in orchards with moderate to high populations. However, in orchards with low populations, which includes most commercial orchards, initial applications can be made at about 350 DD. In Henderson County, 250 and 350 DD are predicted to occur on May 9 and 15, respectively. In Lincoln county 350 DD is predicted for later this week.

San Jose Scale: Another insect on the radar at this time is San Jose scale. Targeting first generation crawlers at first or second cover has become a popular strategy in recent years, and has worked well for those employing this tactic. Two commonly used and excellent materials are Esteem and Centaur, and for resistance management it would good to alternate these materials yearly. Also, studies last year showed that Assail at 6 oz/A also provided good control of a large SJS population.

The reason for the recommended timing of applications at 1st or 2nd cover is illustrated in the figure below that shows population trends of a large SJS population in apples in 2015. Crawlers began to emerge in mid-May, which is the optimum timing of applications in Henderson County. In lower elevations (Cleveland County), applications this week or next would be ideal.

Chart of San Jose scale population trends in 2015

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


2021 Average Weekly Trap Captures

HENDERSON COUNTY
Insects per trap
Apr 19 Apr 26 May 3
Codling moth  7.5 5.5 15.5
Oriental fruit moth 20.0 4.0 11.5
Tufted apple bud moth 0.0 0.0 5.0
Redbanded leafroller 14.0 12.0 4.0
Obliquebanded leafroller 0.0
Lesser appleworm 0.0
Apple maggot (abandoned and research orchards)
Brown marmorated stink bug (commercial)
Brown marmorated stink bug (unsprayed) 0.0 0.0 0.5
Spotted tentiform leafminer 0.0 0.0 2.0
Dogwood borer 0.0 0.0 0.0
Peachtree borer 0.0 0.0 0.0
Lesser peachtree borer 3.0 4.0 42.0
San Jose scale 0.0 0.0 0.0

*Note that these averages illustrate only the timing of insect emergence and fluctuations in populations, and are not representative of population levels in any given orchard. The only way to have an accurate assessment of an individual orchard’s populations is to set up traps in that orchard.


2021 Accumulated Degree Days

HENDERSON COUNTY
Apr 19 Apr 26 May 3
Codling moth (Biofix: April 10)
67 86 177
Oriental fruit moth (Biofix: March 27)
216 251 372
Tufted apple bud moth (Biofix has not been established)

About degree-day models


2021 Pest Trends (click to enlarge)

Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends Chart showing insect population trends


Visit WNC Orchard Insect Populations for archived posts.


Additional Resources

 

Written By

Jim Walgenbach, N.C. Cooperative ExtensionDr. Jim WalgenbachProfessor & Extension Entomology Specialist (Fruits / Vegetables) Call Dr. Jim Email Dr. Jim Entomology & Plant Pathology
NC State Extension, NC State University
Updated on May 4, 2021
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