WNC Orchard Insect Pest Populations – July 14, 2020

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Brown marmorated stink bug nymphOverall direct insect pest populations remain relatively low throughout the region, while populations of key secondary pests such as European red mite and leafhoppers are becoming more prevalent. In lower elevations of the piedmont, first generation brown marmorated stink bug will begin emerging later this week.

Codling Moth

In lower elevations near Cleveland and Lincoln Counties, codling moth degree day accumulations average 1830 DD since biofix, which coincides with about 60% egg hatch of the second generation. If trap captures remain low and there is no evidence of damage, the potential for populations to flare up at this time are very low. In Henderson County at an elevation of about 2100 ft, cumulative DD since biofix are only about 1275. Emergence of second generation adults picks up between 1400-1450 DD, which is predicted to occur early next week. For those using mating disruption for codling moth and OFM, it is unlikely that insecticides are needed for this generation, although pheromone trap captures should be the determining factor.

Brown Marmorated Stink Bug

As shown in the figure below, first generation BMSB adult emergence is predicted to begin by the end of this week in the Cleveland/Lincoln County area (1,000 ft elevation). Emergence begins at about 700 DD (predicted in this area for July 18), and by July 21 predicted DD accumulations are 735, which coincides with emergence of about 7% of the population. Insecticide applications for BMSB (see below) should be considered next week in those areas with a history of BMB problems.

Emergence of first generation adults is still at least three weeks away in higher elevations (>2000 ft). Degree-day accumulations at the MHCREC in Henderson County (2080 ft) is only at 435 DD as of July 14, and is predicted to be 495 in a week.

Figure of brown marmorated stink bug development

Insecticides effective against BMSB include several neonicotinoids (Actara and Belay) and most pyrethroids (i.e., Brigade, Bifenture, Baythroid, Danitol, Warrior/Karate, Mustang Max, Tombstone). It should be noted that neither neonicotinoids or pyrethroids are recommended for codling moth, so in those orchards where both BMSB and codling moth are of concern, either a tank mix with one of the above materials plus an insecticide effective against codling moth, or the premixes Besiege (chlorantraniliprole + lambda-cyhalothrin) or Voliam Flexi (chlorantraniliprole + thiamethoxam). Where Altacor (chlorantraniliprole) was used for first generation codling moth control, the above-mentioned premixes should not be used.

While the approval of the Section 18 request for bifenthrin was in last week’s update, it should be noted that this year’s request for dinotefuran (Venom, Scorpion) on apples has not been approved by the EPA.

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

2020 Average Weekly Trap Captures

Insects per trap
Jun 29 Jul 6 Jul 13
Codling moth  0.7 0.6 0.5
Oriental fruit moth 1.0 4.4 3.3
Tufted apple bud moth 4.0 3.0 0.0
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 1.0 1.0
Lesser appleworm 0.0 0.0 0.0
Apple maggot (abandoned and research orchards) 0.7 0.3 0.7
Brown marmorated stink bug (commercial) 1.5 0.8 1.1
Brown marmorated stink bug (unsprayed) 1.9 2.8 1.8
Spotted tentiform leafminer 31.0 34.0 15.0
Dogwood borer 14.0 42.0 28.0
Peachtree borer 9.0 19.0 21.0
Lesser peachtree borer 33.0 42.0 35.0
San Jose scale 190.0 1895.0 785.0

*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

Jun 29 Jul 6 Jul 13
Codling moth (Biofix 4/20) 919 DD 1088 DD 1246 DD
Oriental fruit moth (Biofix 3/30) 1421 DD 1626 DD 1818 DD
Tufted apple bud moth (Biofix 4/27) 1163 DD 1368 DD 1560 DD

About degree-day models

2020 Pest Trends (click to enlarge)

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