Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Lima Beans
Be sure to watch carefully for spider mites. Economic levels continue to be detected and controls are only effective if treatments are applied before populations explode. Labeled materials include bifenthrin and dimethoate. We are starting to see an increase in stink bug and plant bug populations. As soon as pin pods are present, be sure to watch carefully for plant bug and stink bug adults and nymphs. As a general guideline, treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps.
Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. Although aphid populations still remain low in most fields, we have had a report of a localized economic infestation. At this time of year, early detection is critical since populations can quickly explode. We continue to find fields with yellow striped armyworm, cabbage loopers and cucumber beetle adults feeding on the rinds of watermelons. In addition, cucumber beetle larvae have been found feeding on the undersurface of melons. We can also continue to find high levels of beet armyworm moths in some of our pheromone traps so you will need to check carefully for this insect since populations can quickly explode. With the complex of rind feeders present, it will be important to determine which insect is causing the damage to select the best treatment option. The pyrethroids have not provided effective beet armyworm control so be sure to select a material that is labeled for this insect on melons such as Coragen, Avaunt, Intrepid, Radiant, Synapse or Vetica. Since harvest is well underway in the earliest planted fields, be sure to check all labels for days between last application and harvest.
Peppers
As soon as the first flowers can be found, be sure to consider a corn borer treatment. Depending on local corn borer trap catches, sprays should be applied on a 7 to 10-day schedule once pepper fruit is ¼ – ½ inch in diameter. 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 visiting our website at http://ag.udel.edu/extension/IPM/traps/latestblt.html. You will also need to consider a treatment for pepper maggot. Be sure to 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 (http://ag.udel.edu/extension/IPM/traps/latestblt.html and http://ag.udel.edu/extension/IPM/thresh/snapbeanecbthresh.html). Once pins are present on fresh market snap beans, a 7 to 10-day schedule should be maintained for corn borer and corn earworm control.
Sweet Corn
Be sure to sample all fields from the whorl through pre-tassel stage for corn borers, corn earworms and fall armyworm. We are starting to see an increase in whorl infestations of fall armyworm. A treatment should be considered when 12-15% of the plants are infested. 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 for corn earworm 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 (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 (in state: 1-800-345-7544; out of state: 302-831-8851).