Vegetable Crop Insects – July 31, 2009

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

Vetica Label
This newly registered insecticide (March 2009) from Nichino America Inc. just received a supplemental label (July 20, 2009) for use on Head and Stem Brassica (Cole) Leafy Vegetables. Please refer to the full federal label and supplemental labels for use directions, rates and restrictions: http://www.cdms.net/LabelsMsds/LMDefault.aspx?pd=9462&t. The supplemental label and the EPA approved container label must be in the possession of the user at the time of application.

Cabbage
As soon as plants are set in the field, be sure to sample for cabbage looper and diamondback larvae. Egg laying moths can be found laying eggs in fields. Treatment will be needed before larvae move into the hearts of the plants.

Cucumbers
Cucumber beetle populations have started to increase again in areas with historical problems. Be sure to scout all fields for cucumber beetles and aphids. Fresh market cucumbers are susceptible to bacterial wilt, so treatments should be applied before beetles feed extensively on cotyledons and first true leaves. Although pickling cucumbers have a tolerance to wilt, a treatment may still be needed for machine-harvested pickling cucumbers when 5% of plants are infested with beetles and/or plants are showing fresh feeding injury. With the warm weather this past week, we are starting to see an increase in aphid activity. A treatment should be applied for aphids if 10 to 20% of the plants are infested with aphids with 5 or more aphids per leaf.

Lima Beans
Continue to scout for spider mites, stinkbugs and lygus bugs. Early detection and treatment will be needed to achieve spider mite control. In addition, multiple sprays may be needed for mites, especially if populations are high at treatment time and/or numerous eggs are present. 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.

Melons
Continue to scout all melons for aphids, cucumber beetles, and spider mites. High levels of beetles are being found in fields causing damage to the rinds. Unfortunately, multiple applications will be needed to provide a reduction in populations. We are also starting to see an increase in aphid populations. Treatments should be applied before populations explode and leaf curling occurs.

Peppers
As soon as the first flowers can be found, be sure to consider a corn borer treatment. We are starting to see an increase in moth populations. 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 still 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 to beet armyworm feeding on leaves you should also watch for an increase in aphid populations. We are starting to find aphid populations increasing and they can explode quickly, especially where beneficial insect activity is low. As a general guideline, treatment may be needed if you find one or more aphids per leaf and beneficial activity is low.

Snap Beans
As corn borer and corn earworm populations start to increase, 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
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 armyworms feed 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).

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