WNC Orchard Insect Pest Populations – July 6, 2021
With the exception of the second generation coding moth flight, overall insect activity remains low throughout the region.
Codling moth degree-day accumulations since biofix range from about 1215 in Henderson County to almost 1700 in the Cleveland County area. The 1700 DD in lower elevations correlates with about 70% emergence of moths and 30% egg hatch, so this is an important time to be monitoring to determine the need for insecticide sprays. While in most situations a single insecticide application at about 1450 DD is sufficient for second-generation codling moth, two applications may be needed under higher population pressure. If traps are capturing more than 5 to 7 moths per week, an insecticide is recommended. Remember to use an insecticide with a different mode of action than was used against the first generation.
In Henderson County and higher elevations (≥2000 ft), the optimum timing for second-generation codling moth control (1400 to 1450 DD) is expected to occur in about 7 to 10 days.
It should be noted that it is rare for insecticides to be needed against second-generation codling when mating disruption is being used. A supplemental insecticide is recommended in mating disruption orchards only if the weekly cumulative moth capture exceeds 3 moths per trap.
Regarding oriental fruit moth, we are currently at the beginning of second and third generation egg hatch period in Henderson and Cleveland Counties, respectively. This typically coincides with relatively high moth captures in traps in orchards with high populations, such as at our research blocks at the Mountain Horticultural Crops Research Station. However, populations remain low in most commercial orchards.
Brown marmorated stink bug nymphs are becoming common on pheromone traps, but we remain at least 10 to 14 days away from first generation adult emergence in Cleveland County, and even longer in higher elevation orchards.
Learn more about southeastern apple insect pests at the Apple Insect Management page.
2021 Average Weekly Trap Captures
|Insects per trap|
|Jun 21||Jun 28||Jul 6|
|Oriental fruit moth||34.0||36.0||33.5|
|Tufted apple bud moth||4.0||1.0||0.0|
|Apple maggot (abandoned and research orchards)||0.0||0.0||0.0|
|Brown marmorated stink bug (commercial)||1.8||1.7||2.8|
|Brown marmorated stink bug (unsprayed)||2.0||4.0||4.0|
|Spotted tentiform leafminer||20.0||27.0||13.0|
|Lesser peachtree borer||48.0||25.0||29.0|
|San Jose scale||0.0||2.5||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
|Jun 21||Jun 28||Jul 6|
|Codling moth (Biofix: April 10)
|Oriental fruit moth (Biofix: March 27)
|Tufted apple bud moth (Biofix: April 30)
2021 Pest Trends (click to enlarge)
Visit WNC Orchard Insect Populations for archived posts.