WNC Orchard Insect Pest Populations – July 20, 2021
2nd Generation Codling Moth in Higher Elevations, BMSB in Lower Elevations
Codling Moth: In higher elevation orchards such as Henderson County, second generation codling moth DD accumulations average about 1512, compared to 2056 in lower elevation Cleveland County. The 1512 cumulative DD in Henderson correlates with about 15% egg hatch of the second generation. If not using mating disruption, now is an excellent time for insecticidal control of this generation. While pheromone trap captures should be used to judge population abundance and the need for additional applications, one application is usually sufficient against in low-population orchards.
In lower elevation orchards (i.e., about 1000 ft elevation), second generation egg hatch is about 75% complete, and if populations have not been an issue up to this point it is doubtful problems will start now. However, there are some locations where moth captures in pheromone traps remain high, so insecticidal control may still be necessary in these orchards.
Brown Marmorated Stink Bug: In lower elevation orchards, first generation adult emergence is now underway. Cumulative BMSB DD accumulations in Cleveland County are at 761, which coincides with emergence of 5% of the population. However, emergence will increase to 25% complete in the next week, so insecticidal control is important at this time.
In higher elevations, DD accumulations range from 530 in Henderson County (2100 ft) to 600 in Wilkes County (1400 ft). We are still at least two to three weeks away from initial emergence (750 DD) in these locations.
(Apple Maggot captures on traps remain extremely low in Henderson County. It is typically early August when emergence begins, but insecticides recommended for BMSB are also effective against this pest. Also, emergence patterns can vary among sites, so individual trapping is recommended.)
Insecticide Recommendations for Brown Marmorated Stink Bug: For the past 7 years there has been a Section 18 label for bifenthrin and dinotefuran for control of the brown marmorated stink bug (BMSB) on apples and peaches in North Carolina. A Section 18 is an emergency exemption request submitted by states to the EPA to control a pest(s) (often new) for which there are no or few effective pesticides registered on the target crop. We have learned much about the efficacy of various insecticides for control of BMSB since it first became a pest in North Carolina, and there are numerous other pyrethroids and neonicotinoids that control BMSB (see table below). In view of the large selection of insecticides that control this insect, a Section 18 for bifenthrin and dinotefuran was not requested for 2021. Below is a list of insecticides that will provide excellent control of BMSB on apples.
Insecticides recommended for control of BMSB on apples in North Carolina
|Common name||Trade Name||Rate/A||PHI(days)||Maximum per acre/season|
|*Thiamethoxam||Actara 25WDG||4.5 oz||35||16.5 oz|
|Chlothianidin||Belay 2.13SC||4 to 6 fl oz||7||12 fl oz|
|Beta-cyfluthrin||Baythroid 1EC, Sultrus||2.4 fl oz||14||2.8 fl oz|
|Cyfluthrin||Tombstone 2EC||2.4 fl oz||7||2.8 fl oz|
|Fenpropathrin||Danitol 2.4EC||16 to 21 fl oz||14||42.6 fl oz|
|Gamma-cyhalothrin||Proaxis 0.5EC, Declare||2.6 to 5.1 fl oz||21||20.5 fl oz|
|*Lambda-cyhalothrin||Warrior II 2.08CS, many generics||1.3 to 2.5 fl oz||21||12.8 fl oz|
|Zeta-cypermethrin||Mustang Maxx 0.8EC, Respect||2 to 4 fl oz||14||24 fl oz|
|6 to 12 fl oz||21||31 fl oz|
|5 to 6 fl oz||35||21 fl oz|
*A maximum of 0.2 lbs AI of lambda-cyhalothrin and 0.258 lbs AI of thiamethoxam per acre per season may be applied, regardless of the formulation used.
Learn more about southeastern apple insect pests at the Apple Insect Management page.
2021 Average Weekly Trap Captures
|Insects per trap|
|Jul 6||Jul 13||Jul 19|
|Oriental fruit moth||33.5||22.0||28.0|
|Tufted apple bud moth||0.0||0.0||0.0|
|Apple maggot (abandoned and research orchards)||0.0||0.0||0.0|
|Brown marmorated stink bug (commercial)||2.8||1.9||5.5|
|Brown marmorated stink bug (unsprayed)||4.0||0.5||2.1|
|Spotted tentiform leafminer||13.0||4.0||5.0|
|Lesser peachtree borer||29.0||14.0||17.0|
|San Jose scale||0.0||5.0||5.0|
*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
|Jul 6||Jul 13||Jul 19|
|Codling moth (Biofix: April 10)
|Oriental fruit moth (Biofix: March 27)
|Tufted apple bud moth (Biofix: April 30)
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