Plant bugs continue to be a problem in some Virginia fields with ¼ of those scouted by the entomology team above threshold for the first two weeks of bloom. In anticipation of the upcoming bollworm flight, Monsanto sponsored a meeting last week at the TAREC to discuss mid-season insect management in cotton. Here is a summary of our discussion:

1. For 2 gene cotton (Widestrike, Bollgard II, Twinlink): scouting for eggs is recommended. Sample 100 terminals and leaves. Aim for 10 in 10 locations in the field. If you find 25 eggs, spray an insecticide. I recommend Prevathon unless stink bugs or plant bugs are an issue in your field. In that case, use Besiege. Bollworm (Helicoverpa zea aka corn earworm) and tobacco budworm (Heliothis virescens) eggs are indistinguishable and budworms are 100% controlled by Bt cotton. There is some risk that you are spraying unnecessarily. Very low numbers (<3%) of larvae sampled in non-Bt cotton were budworms in 2016 and 2017.
2. For 3 gene cotton (Widestrike 3, Bollgard III, and Twinlink Plus): scouting for 2^nd stage larvae  (1/8″ or larger) is recommended. This gives in-plant toxins time to kill small worms. Sample 100 bolls, blooms, and/or squares. Aim for 10 in 10 locations per field. If you find three larvae in one trip, two larvae in two consecutive trips (two larvae in each trip), or one larva in three consecutive trips (one larva in each trip), spray insecticides. I do not anticipate damage in 3 gene cotton unless we have very high pressure.
3. Pyrethroids have performed poorly in cotton in 2016 and 2017 tests (15-50% control). I think that pyrethroids are too risky in cotton. Some growers are satisfied with the control that they have been achieving. Last year, worm specific products ran out in some Virginia locations. I recommend Steward as an alternative to Prevathon and Besiege for bollworm control in cotton.
4. Weekly scouting is recommended for all pests. Bollworm eggs hatch fast (2-3 days) and worms cannot be controlled by any product once they are inside of the boll.
5. Spray bugs only at threshold. Bloom threshold for plant bugs is 2-3 per drop cloth sample. For stink bugs, use damaged fruit thresholds: Week of bloom 1 = 50% internal boll damage; week 2 = 30%; weeks 3, 4 and 5 = 10%; week 6 = 20%; week 7 =30%; week 8 = 50%. About a dozen beneficial insects are common in Virginia cotton. Ambush bugs, big-eyed bugs, minute pirate bugs, green lacewings, two species of ladybird beetles, and several types of spiders are examples. They are of two types: 1) predators that prey upon an insect pest (see examples below), or 2) parasites that live within the host insect. These insects, particularly the predators, reduce the number of eggs and larvae of bollworms, plant bug nymphs and aphids. Because these allies lessen the impact of pest insects, common sense dictates that producers use them as a management tool. Their presence often means that growers can delay and, on occasion, eliminate some insecticide applications. However, the rapid increase in pest populations will often overwhelm the beneficial population and applications become necessary. Do not hesitate to spray pest insects at recommended thresholds.

A big thank you to Seth Dorman and his scouting crew and to Glenn Roundtree for initiating and organizing our recent pest management discussion.

Moth trap monitoring

We are monitoring corn earworm and fall armyworm moth activity levels on sweet corn farms in 17 different counties in Virginia. Moth Trap Catch Data are being recorded by: Kuhar Vegetable Entomology lab (Montgomery Co.); Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.). Data are posted weekly.

Trap Catch

Below are some trap catch results (moths per night) for some of the locations around Virginia for this week. In summary, we are observing a slight drop off in corn earworm moth activity at most locations, except Amelia County, which posted the highest corn earworm activity this week.  Very little fall armyworm activity has been observed at this point, and numbers are so low that they are not presented.

We are monitoring corn earworm and fall armyworm moth activity levels on sweet corn farms in 17 different counties in Virginia. Moth Trap Catch Data are being recorded by: Kuhar Vegetable Entomology lab (Montgomery Co.); Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.). Data are posted weekly.
Below are some trap catch results (moths per night) for some of the locations around Virginia for this week (note we do not have data for all locations yet).  In summary, we are observing the highest corn earworm activity in the eastern portion of the state including Virginia Beach and Exmore on the Eastern Shore.  Pest pressure is considered high in those locations.  Above threshold trap catch of corn earworm is also being observed on some farms in the southwest region of the state (Franklin County and Montgomery County).  Very little fall armyworm activity has been observed at this point.

Region County        Field                      CEW/night     FAW/night
Eastern Accomack Painter
Eastern Accomack Painter
Eastern Virginia Beach Northridge    3.4                       2.9
Eastern Virginia Beach Pungo            4.3                          0
Eastern Virginia Beach Creeds           5.9                       0.1
Eastern Northampton Capeville         1.0                        0
Eastern Northampton Cheriton          1.9                        0
Eastern Northampton Eastville           0.7                        0
Eastern Northampton Exmore            7.4                        0
Eastern Westmoreland Field                0.2                       0
Central Amelia Field
Central Hanover Wiblin
Central Hanover Haynes
Central Halifax
Central Halifax
Central Charlotte
Northern Loudoun Field1                    1.0                         0
Northern Loudoun Field2                    <.2                        0
Northern Loudoun Field3                    <.2                        0
Northern Rappahannock
Northern Page
Northern Frederick Field1                     0.3                      0
Northern Frederick Field2                     0                         0
Northern Rockingham
Southwest Montgomery Whitethorne   0.0                    0
Southwest Montgomery Homefield       0.0                    0
Southwest Montgomery Wall                  2.0                    0
Southwest Franklin Wirtz                         1.4                    0
Southwest Carroll
Southwest Washington Abingdon