Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Corn Earworm Alert
The potential for corn earworm pressure in fall vegetable crops is high statewide. Trap catches remain high throughout the state and moths can be found laying eggs in fields, so be sure to scout 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
We continue to find economic levels of fall armyworm, cabbage looper, diamondback moth larvae and harlequin bugs. Be sure to apply treatments before larvae move deep into the hearts of plants. Also, be sure to select a material for the pest complex present at treatment time.
Lima Beans
Continue to scout all fields for spider mites, lygus bugs, stinkbugs and corn earworm. The higher labeled rates of insecticides will be needed for stinkbug control. For corn earworm, higher rates will also be needed if population levels are high and worms are large at the time of treatment. As trap catches continue to increase, multiple treatments may be needed for earworm control. 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. Therefore, you will need to consider an application of Lannate LV at the higher rate for soybean looper control. Be sure check the label for rates and days from last application to harvest.
Peppers
In areas where corn borers are being caught in local traps, fields should be sprayed on a 7-day schedule for corn borer control. In areas where corn borer catches are above 10 per night, a 5 to 7-day schedule may be needed. Since trap catches can increase quickly at this time of year, be sure to check local moth catches in your area at http://ag.udel.edu/extension/IPM/traps/latestblt.html. With the high corn earworm pressure, you will also need to watch for corn earworms infesting peppers. Be sure to select a material that will control corn borers and corn earworm as well as beet armyworm if they are present.
Snap Beans
At this time, you will need to consider treatments for both corn borer and corn earworm from the bud stage through harvest on processing snap beans. After the pin sprays, you will need to check our website for the most recent trap catches to help decide on the spray interval between the pin stage and harvest for processing snap beans (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html). The highest labeled rates of insecticides will be needed if population pressure is heavy in your area. Remember, Orthene (acephate) will not provide effective earworm control. Be sure to scout fields at least twice a week for corn earworm to be sure that a tighter schedule is not needed between the pin spray and harvest. Once pins are present on fresh market snap beans, a 5 to 7-day schedule should be considered for corn borer and corn earworm control.
Spinach
Be sure to watch for both webworms and beet armyworm moths as soon as plants emerge. Controls should be applied when worms are small and before they have moved deep into the hearts of the plants or produced webbing. Remember that both insects can produce webbing on the plants. Generally, at least 2 applications may be needed to achieve control of webworms and beet armyworm.
Sweet Corn
With the high corn earworm catches throughout the state, all fresh market silking sweet corn should be sprayed on a 2-day schedule. Trap catches are generally updated on Tuesday and Friday mornings (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/silkspraythresh.html). You can also call the Crop Pest Hotline for current trap catches (in state: 800-345-7544; out of state: 302-831-8851). In addition, you will need to combine a fall armyworm material with a pyrethroid for at least the first 2-3 silk sprays for fall armyworm control. Be sure to check all labels for days to harvest and maximum amount allowed per acre.