Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Reminder – Warrior II is now present in the market place so be sure to read the label to be sure you are applying the correct rate. This new formulation is twice as active (2.08 lbs of active ingredient per gallon) as the old Warrior (1.04 lb of active ingredient per gallon) so be sure to read the label for the correct rates as well as restrictions. (http://www.cdms.net/LDat/ld8JD000.pdf).
Lima Beans
Be sure to watch carefully for spider mites. Economic levels are being detected and controls are only effective if treatments are applied before populations explode. Labeled materials include bifenthrin and dimethoate. We are staring 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. Bifenthrin (Brigade and a number of generics), Mustang MAX, Proaxis and lamda-cyhalothrin (Warrior and a number of generics) are labeled for both insects. The higher labeled rates will be needed if stinkbugs are the predominant insect present.
Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. We have heard reports of beet armyworms feeding on the rinds of watermelons. Since this insect is difficult to control, be sure to select a material that is labeled for beet armyworm on melons such as Spintor, Radiant, or Intrepid. The pyrethroids will not provide effective BAW control.
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 (in state: 1-800-345-7544; 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.
Potatoes
Continue to scout fields for Colorado potato beetle (CPB), aphids and leafhoppers. Controls will be needed for green peach aphids if you find 2 aphids per leaf during bloom and 4 aphids per leaf post bloom. This threshold increases to 10 per leaf at 2 weeks from vine death/kill. If melon aphids are found, the threshold should be reduced by ½.
Snap Beans
Continue to scout for leafhopper and thrips activity in seedling stage beans. As a general guideline, once corn borer catches reach 2 per night, fresh market and processing snap beans in the bud to pin stages should be sprayed for corn borer. Sprays will be needed at the bud and pin stages on processing beans. Additional sprays may be needed after the pin spray on processing beans. Since trap catches can change quickly, be sure to check our website for the most recent trap catches and information on how to use this data to make a treatment decision in processing snap beans after bloom (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 and corn borer trap catches are above 2 per night, a 7 to 10-day schedule should be maintained for corn borer control.
Sweet Corn
Continue to sample seedling stage fields for cutworms and flea beetles. You should also 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. 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).