WNC Orchard Insect Pest Populations – September 1, 2020

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Apple maggot trapSeptember 1, 2020

During the past week both brown marmorated stink bug and apple maggot populations increased in number.

Brown marmorated stink bug

BMSB pheromone trap captures in Henderson County increased considerably during the past week, as noted below in the figure that compares trap captures during the past three years. This trend of increasing BMSB trap captures is expected to continue in higher elevation locations (Haywood, Henderson, and Wilkes Counties) where less than 50% of first-generation adults have emerged to date (see the updated emergence figure below). In lower elevations such as Lincoln County, over 80% of first-generation adults have emerged, so it is less likely that populations will rise significantly in those locations. The bottom line is that in these higher elevation orchards, late-maturing fruit will continue to be susceptible to damage for the rest of September.

Trap capture chart

Apple Maggot

A significant increase in captures of apple maggot flies was finally observed this past week in our abandoned orchard site. Blocks adjacent to non-managed orchards that also have a good fruit load are likely to be most susceptible to infestation. Fortunately, insecticides applied for BMSB will also control apple maggot.

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

2020 Average Weekly Trap Captures

Insects per trap
Aug 17 Aug 24 Aug 31
Codling moth  0.5 0.0 0.1
Oriental fruit moth 4.3 6.7 4.3
Tufted apple bud moth 5.0 5.0 0.5
Redbanded leafroller 0.0 0.0 0.0
Obliquebanded leafroller 0.0 0.0 0.0
Lesser appleworm 0.0 2.0 0.0
Apple maggot (abandoned and research orchards) 1.0 1.7 7.0
Brown marmorated stink bug (commercial) 3.1 2.4 3.7
Brown marmorated stink bug (unsprayed) 7.0 11.3 23.5
Spotted tentiform leafminer 2.0 0.0 0.0
Dogwood borer 17.0 20.0 27.0
Peachtree borer 18.0 30.0 18.0
Lesser peachtree borer 13.0 40.0 38.0
San Jose scale 117.5 260.0 225.0

*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

Aug. 17 Aug. 24 Aug. 31
Codling moth (Biofix 4/20) 2095 DD 2216 DD 2405 DD
Oriental fruit moth (Biofix 3/30) 2843 DD 2994 DD 3223 DD
Tufted apple bud moth (Biofix 4/27) 2585 DD 2736 DD 2965 DD

About degree-day models

2020 Pest Trends (click to enlarge)

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 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

Visit WNC Orchard Insect Populations for archived posts.

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