Vegetable Crop Insects – July 19, 2013

July 19, 2013 in Vegetable Crops

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

Kudzu Bug on Succulent Beans
As indicated in past newsletters, initial findings from host preference studies from Georgia indicate that Kudzu bug does not prefer non-soybean beans, but will occur on them. We have sent samples of 3 lima bean varieties (C-elite Select, Cypress and Concentrated Fordhook) to the Georgia program to be evaluated so we will have more information as soon as it is available. In the one pole lima bean where the first adults were detected, the numbers of adults have dwindled and a few egg masses where found but no nymphs hatched. As a reminder, it is the nymph that is important in regards to treatment in soybeans once fields reach flowering and the pod development stage. Also, this insect is a slow feeder that will gradually drawing down plant vigor therefore it gives us plenty of time to sample fields and react with a treatment if needed. In the meantime, as I have indicated in past newsletters, you will want to scout succulent beans to see if this trend is true in our area. We may have to use the information developed for soybeans this season to help us make management decisions in succulent beans if the need arises. We will keep you posted of any new finds as well as new management information as it is developed.

Lima Beans
With the wet weather, spider mites problems have not occurred like last year but we do find an occasional mite in a field. 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 are starting 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.

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 reports of localized infestations. At this time of year, early detection is critical since populations can quickly explode. It is also the time of year to watch for beet armyworm, yellow striped armyworm, cabbage loopers and cucumber beetle adults feeding on the rinds of watermelons. 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
Depending on local corn borer trap catches, sprays should be applied on a 7 to10-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 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

http://extension.udel.edu/ag/insect-management/insect-trapping-program/ecb-and-cew-moth-catch-thresholds-for-processing-snap-beans/

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 You can also call the Crop Pest Hotline (in state: 800-345-7544; out of state: 302-831-8851). http://agdev.anr.udel.edu/trap/trap.php

http://extension.udel.edu/ag/insect-management/insect-trapping-program/action-thresholds-for-silk-stage-sweet-corn/)