WNC Orchard Insect Pest Populations – June 9, 2020

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Apple orchard with mountain laurel on borderCodling Moth

At lower elevations, less than about 1200 ft, cumulative codling moth degree days (DD) now exceed 1000, indicating that the first generation is complete. Insecticides targeting codling moth are probably unnecessary until at least 1400 DD; the exception being in those orchards with high populations that are still capturing more than 5 moths per week in pheromone traps.

In Henderson County (2100 ft), codling moth degree-day accumulations are at about 560 DD, so this pest should still be considered a potential threat in this area. If pheromone trapping is not being conducted, it would be wise to assume a potentially damaging population exists in an orchard. Populations have been low this season, and it has been possible for many to minimize insecticide applications when using pheromone traps to verify low populations.

In orchards using mating disruption for codling moth and where insecticides for lepidopteran pests have probably not been necessary thus far, note that is now time for control of tufted apple bud moth (below), since codling moth/OFM mating disruption does not control TABM.

Tufted Apple Bud Moth

Tufted apple bud moth DD accumulations in Henderson County average about 710 as of today (June 9). However, degree days are accumulating quickly and 800 DD, optimum time for an insecticide targeting TABM, is expected to occur Saturday (June 13). Excellent control of TABM can be achieved with a single recommended insecticide applied anytime between now and the next two weeks. In those orchards where codling moth is also a concern, Altacor, Verpedryn, and Delegate are recommended. Where codling moth populations are low, Intrepid at 8 oz/acre will provide excellent TABM control, although it is not as efficacious against codling moth as the aforementioned products.

Aphids, Leafhoppers, and Mites

Now is also a time when green apple aphid, potato leafhopper, and European red mite populations traditionally appear in apples. While populations have been low thus far, these are secondary pests to keep an eye on when scouting orchards. There are a wide array of selective insecticides that control both aphids and leafhoppers, so check the Southeastern Apple Manual for those recommendations.

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

2020 Average Weekly Trap Captures

Insects per trap
May 26 Jun 1 Jun 8
Codling moth  0.1 0.5 0.4
Oriental fruit moth 0.2 0.4 1.1
Tufted apple bud moth 25.5 81.0 27.0
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 7.0 20.0
Lesser appleworm 0.0 7.0 8.0
Apple maggot (abandoned and research orchards) set 0.0
Brown marmorated stink bug (commercial) 0.8 0.6 1.5
Brown marmorated stink bug (unsprayed) 1.8 1.3 5.0
Spotted tentiform leafminer 0.0 0.0 10.0
Dogwood borer 14.0 37.0 58.0
Peachtree borer 0.0 0.0 0.0
Lesser peachtree borer 16.0 48.0 68.0
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.

2020 Accumulated Degree Days

May 26 Jun 1 Jun 8
Codling moth (Biofix 4/20) 299 DD 402 DD 541 DD
Oriental fruit moth (Biofix 3/30) 631 DD 765 DD 938 DD
Tufted apple bud moth (Biofix 4/27) 374 DD 507 DD 680 DD

About degree-day models

2020 Pest Trends (click to enlarge)

Graph of insect population trendsGraph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends Graph of insect population trends

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