Vegetable Crop Insects – August 20, 2010

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

The potential for corn earworm and corn borer pressure remains high in fall vegetable crops statewide. Trap catches remain high throughout the state and moths can be found laying eggs in fields so you may need to scout fields at least twice a week as well as check local trap catches (http://ag.udel.edu/extension/IPM/traps/latestblt.html or call the Crop Pest Hotline in state: (800) 345-7544; out of state: (302) 831-8851).

Cabbage
Continue to sample for cabbage looper, diamondback larvae, beet armyworm, fall armyworm and Harlequin bug. Although the pyrethroids will provide control of Harlequin bugs they are not effective on diamondback or beet armyworm in our area. So be sure to scout and select controls options based on the complex of insects present in the field.

Lima Beans
Continue to scout for stink bugs, lygus bugs, beet armyworm and corn eaworm. With the high corn earworm moth catches, moths can be readily found laying eggs in fields. Be sure to sample for corn earworm larvae as soon as pin pods are present. A treatment will be needed if you find one corn earworm larvae per 6 ft-of-row. At this time of year, we have also found soybean loopers in lima bean fields. If soybean loopers become a problem again this year, remember that they are a migratory pest, difficult to control and pyrethroid resistance has been documented in states to our south. The Belt SC federal label was recently expanded to include legume vegetables and soybean looper is on the label. However, it is not included on the DDA’s state registration list as of Aug 17. Materials must be labeled both federally and in-state to be used on a crop. We will let you know when it has received a state label as well or you can check their website ( http://www.kellysolutions.com/de/pesticideindex.htm ). The Lannate LV label lists loopers on the label. Be sure check the label for rates, restrictions (including plant back restrictions) and days from last application to harvest.

Peppers
At this time of year, corn borer, corn earworm, beet armyworm and fall armyworm are all potential problems in peppers. So be sure to select the material that will control the complex of insects present in the field. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (n state: (800) 345-7544; out of state: (302) 831-8851) or our webpage at http://ag.udel.edu/extension/IPM/traps/latestblt.html. We are also starting to see aphid populations increasing, especially in fields where pyrethroids have been used on a weekly basis. Treatments for both of these pests will need to be applied before populations explode.

Snap Beans
With the high trap catches, you will need to consider a treatment for both corn borer and corn earworm. You should also watch for beet armyworms. Sprays are needed at the bud and pin stages on processing beans for worm control. With the diversity of worm pest that may be present in fields, be sure to scout fields and select materials that will control the complex of insects present. For the most recent trap catches in your area and to help decide on the spray interval between the pin stage and harvest for ECB control in processing snap beans, you will need to call the Crop Pest in state: (800) 345-7544; out of state: (302) 831-8851 or check our website http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html.

Spinach
As the earliest planted spinach emerges from the ground, be sure to watch for webworms and beet armyworms. Both moths are active at this time and controls need to be applied when worms are small and before they have moved deep into the hearts of the plants. We are seeing an increase beet armyworm populations being found in vegetable crops – so it will also be important to select a material that will provide beet armyworm control. As a reminder, the pyrethroids have not provided effective beet armyworm control in past years. It also appears that webworm populations may be heavier than normal (typical during hot, dry seasons) so it is important to apply controls before any webbing occurs. Remember that both insects can produce webbing on the plants. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm.

Sweet Corn
With the continued high corn earworm trap catches, be sure that a spray is applied as soon as ear shanks are visible on plants. If fall armyworms are present in the whorl, you will need multiple whorl sprays for this insect before the ear shank spray to achieve effective control and to prevent larvae from dropping into the ear zone. Once fields are silking, you will need to check both blacklight and pheromone trap catches for silk spray schedules since the spray schedules can quickly change. (http://ag.udel.edu/extension/IPM/traps/latestblt.html or call the Crop Pest Hotline in state: (800) 345-7544; out of state: (302) 831-8851). Be sure to check all labels for days to harvest and maximum amount allowed per acre.

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