Category Archives: Pest Group

Insect update for Aug. 31, 2017

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This week, corn earworm (bollworm) moth captures in the black light trap were down at most locations (steady at Chesapeake and Prince George-Templeton), perhaps partly due to the rainy weather, but some “down” numbers are still pretty high (Suffolk, for example). The table is here: BLT_31_Aug_2017

We had no reports of any brown marmorated stink bugs captured in the black light traps this week.

We have vial-tested close to 1,000 corn earworm moths in Dr. Taylor’s pyrethroid resistance monitoring program in 2017, with an average of 38% survival.

Insect update for Aug. 17, 2017

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Corn earworm moth captures in the black light traps ranged from 2 to 45 moths per night; brown marmorated stink bug catches ranged from zero to 2.6 per night. Here are the data tables: BLT_17_Aug_2017

In our corn earworm (bollworm) vial tests, we are averaging 39% moth survival, with 832 moths tested to date.

Insect update for Aug. 10, 2017

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Black light trap captures of corn earworm/bollworm ranged from 5 to 78 moths per night this week. Brown marmorated stink bug captures ranged from zero to 2 per night. Here are the data tables: BLT_10_Aug_2017

Resistance monitoring of corn earworm/bollworm shows that this season in Suffolk, an average of 39% of moths survived the 24-hour exposure period to the pyrethroid, cypermethrin.

Plant Bug Update – 4 August 2017

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Twenty-three representative cotton fields in eight Virginia counties were scouted weekly for mean plant bug density. Data for the July 17th to August 3rd sampling period is represented in the distribution map below (follow link to view). Red dots on the map represent fields that have averaged at or above the spray threshold for plant bug during the sampling period. Plant bug densities for multiple fields has increased substantially since the last update in mid-July. Nineteen of the 23 sampled fields have reached the spray threshold at least once this season since sampling began in late-June. Plant bugs are present in every county sampled and are likely present in at least low numbers in all cotton growing counties in the state. Therefore, we recommend scouting your cotton fields regularly for plant bug.

The spray threshold for plant bug in Mid-Atlantic cotton is eight plant bugs (i.e., adults and nymphs) per 100 sweeps in addition to square retention below 80 percent. We recommend conducting four to eight random 25-sweep samples throughout each field. Once flowering begins, we recommend continuing sweep net sampling and also looking for dirty blooms (pictured below) or sample dime to quarter size-bolls from 25 random plants for internal feeding damage (e.g., warts, stained lint, punctures). Spray treatment may be warranted if dirty blooms and or internal damage exceeds 15 percent and plant bugs are also active in the field. Please refer to the Virginia Cotton Production Guide (pg. 23)  or Pest Management Guide (sect. 4, pg. 88) for spray recommendations if spray threshold is reached.

“Dirty bloom” indicative of plant bug feeding.

When viewing the distribution map in full-screen mode, click on the left arrow icon to view map legend. Click on individual fields represented by colored dots on the map to view mean plant bug density for the sampling period as well as total mean density for the season. Mean plant bug densities were calculated by sampling four sweet net samples (25 sweeps per sample) and four drop cloth samples across each field. Total adults and nymphs in a single visit were totaled and averaged for each visit within the sampling period.

View full-screen distribution map

Plant bug distribution map for the July 17th to August 3rd sampling period.

 

Insect update for Aug. 3, 2017

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Black light trap catches of corn earworm (aka bollworm) moths increased at most reporting stations, ranging from 5 to 58 per night this week. The pheromone traps at Suffolk also caught about 20 moths per night. Mike Arrington reported that he was seeing cotton fields (Bt and conventional) very close to egg threshold for bollworm in Suffolk and Southampton Counties.

Brown marmorated stink bugs ranged from zero to 1.7 per night. The data tables for corn earworm and BMSB are here: BLT_3_Aug_2017

Corn earworm moth survival in the cypermethrin vial tests was 36% for the week, and 40% for the seasonal average (to date).

Insect update for July 27, 2017

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Corn earworm/bollworm moth captures in the black light traps increased this week, with averages ranging from 2 to 65 moths per night. Suffolk and Hanover had high numbers. Brown marmorated stink bugs ranged from zero to 10 per night across our reporting stations (high numbers in Hanover). More details can be found in the tables here: BLT_27_Jul

Be sure to scout your fields to keep aware of your pest situation. The 2017 Virginia Cooperative Extension Field Crops Pest Management Guide contains thresholds, sampling procedures, and products/rates for soybean (pages 4-61 to 4-76), peanut (pages 4-77 to 4-86), cotton (pages 4-87 to 4-100) and other crops. There is also an online threshold calculator for corn earworm in soybean

Results (to date) from Dr. Taylor’s corn earworm survey of field corn are as follows:  Accomack= 29% infested ears; Northampton=38%; Henrico=37%; Chesapeake=19%; Dinwiddie=19%; Greensville=19%; Prince George=20%; Southampton=53%; Sussex=26%; Amelia=18%; Lancaster=4%; Northumberland=7%; Richmond County=4%; Westmoreland=6%; and Franklin County=46% infested ears.

Insect update for July 20, 2017

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This week, our black light trap operators reported a range of zero to 8.5 corn earworm/bollworm moths per night and zero to 2.7 brown marmorated stink bugs per night. The tables are in this pdf file: BLT_20_Jul_2017

The corn earworm/bollworm pyrethroid resistance monitoring program is averaging about 36% moth survival. These are pheromone trap-collected moths from Suffolk, Virginia. The pyrethroid is cypermethrin at 5 micrograms per vial.

Virginia Cooperative Extension ANR Agents, Virginia Tech personnel, interns, and others have started our annual field corn survey for corn earworm/bollworm larvae. It can be an indicator of the pressure that we’ll see in other crops (e.g., soybean) when the moths emerge and fly out of corn fields. We’ll have a full report in the beginning of August (including data from many more counties), but here are the average ear infestations from those surveys already completed (based on sampling 50 ears per field, 5 fields per county): Accomack=29%; Henrico=37%; Southampton=53%; Amelia=18%; Westmoreland=6%.