Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Cole Crops
As soon as plants are set in the field, be sure to sample for cabbage looper and diamondback larvae. A treatment will be needed before larvae move into the hearts of the plants. In recent years, we have seen more Harlequin bug activity in cole crops. In general, most of the “worm” materials are not effective on Harlequin bugs. The pyrethroids have provided control in years past.
Lima Beans
With the wet weather, spider mites problems have not occurred like last year but we continue to find very low levels in isolated fields in Kent and Sussex counties. Be sure that you continue to sample for mites in your routine sampling each week. Early detection and control before populations are exploded is necessary to achieve effective control. We continue to see an increase in stinkbug and plant bug populations. As soon as pin pods are present, be sure to watch carefully for plant bug and stinkbug adults and nymphs. As a general guideline, treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. Also be sure to begin sampling the earliest planted fields for corn earworm. A treatment will be needed for corn earworm if you find one corn earworm larvae per 6 foot-of-row.
Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. We continue to see an increase in aphid populations as well see rind feeding from cucumber beetle adults and a variety of caterpillars. If beet armyworm is in the mix, it is important to select a material that is effective on this insect (refer to the Commercial Vegetable Recommendations) – the pyrethroids do not provide effective control.
Peppers
Sprays will be needed on a 7 to 10-day schedule once pepper fruit is ¼ – ½ inch in diameter for the complex of worms present. Be sure to check local moth catches in your area by calling the Crop Pest Hotline (instate: 800 345-7544; out of state: 302 – 831-8851) or visit our website at http://agdev.anr.udel.edu/trap/trap.php. At this time, you will also need to consider a treatment for pepper maggot. Be sure to also watch carefully for beet armyworm larvae since they can quickly defoliate plants. In addition, be sure to use a material that provides beet armyworm control – the pyrethroids will not control this insect.
Snap Beans
As corn borer and corn earworm populations start to increase again, you will need to consider treatments for both insect pests. Sprays are needed at the bud and pin stages on processing beans for corn borer control. As earworm trap catches increase, an earworm spray may also be needed at the pin stage. 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. Once pin pods are present on fresh market snap beans, a 7 to 10-day schedule should be maintained for corn borer and corn earworm control.
http://agdev.anr.udel.edu/trap/trap.php
Sweet Corn
Be sure to sample all fields from the whorl through pre-tassel stage for corn borers, corn earworms and fall armyworm. A treatment should be considered when 12-15% of the plants are infested in the whorl stage. Since fall armyworm feeds deep in the whorls, sprays should be directed into the whorls and multiple applications are often needed to achieve control. The first silk sprays will be needed as soon as ear shanks are visible. Be sure to check both blacklight and pheromone trap catches for silk spray schedules since the spray schedules can quickly change. Trap catches are generally updated on Tuesday and Friday mornings You can also call the Crop Pest Hotline (in state: 1-800-345-7544; out of state: 302-831-8851). http://agdev.anr.udel.edu/trap/trap.php