Vegetables

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

BEET ARMYWORM ALERT

Beet armyworms can be found in many fall vegetable crops including cabbage, lima beans, snap beans and spinach. Moths can be readily observed laying eggs in fields. Identification is critical because pyrethroids will not provide control. Young larvae will often web the leaves together and larger larvae can produce significant amounts of defoliation. Please refer to the description of larvae under the field crops section of the newsletter. Labeled products will vary with the crop so please refer to controls under each vegetable. See page 9 for photos.

Cabbage.

Diamondback (DBM) and cabbage looper (CL) larval populations continue to increase. We are also seeing an increase in beet armyworm populations. The treatment threshold is 5% of the plants infested. If DBM and CL are present, Avaunt (3.5 oz/acre), a Bt, Proclaim (3 oz/acre), or Spintor (4-5 oz per acre) will provide control. If cabbage looper is the predominant species, a pyrethroid or Confirm (8 oz/acre) will also provide control. If beet armyworm is the predominant species, Avaunt, Confirm or Spintor should be used.

Lima Beans.

Be sure to sample fields carefully for corn earworm, beet armyworm, lygus and stinkbugs. A treatment should be applied if you find one corn earworm per 6 foot of row or 15 tarnished plant bugs and/or stinkbugs per 50 sweeps. There are no thresholds for beet armyworm; however, a spray should be considered when worms are small and you can find 20% of the plants defoliated. Lannate, Mustang or Capture can be used to control corn earworm, lygus and stink bugs. If beet armyworm is causing problems, Lannate will only work if worms are small at the time of treatment. Spintor is also labeled on lima beans and will provide good beet armyworm control.

Peppers.

At the present time, all peppers should be sprayed on a 5to7-day schedule for corn borer, corn earworm, and beet armyworm control. Orthene or Address will not provide satisfactory earworm control. A pyrethroid or Lannate will be needed for earworm control. If beet armyworms are present, Avaunt, Spintor, or Confirm will provide the best beet armyworm control. Depending on the pest complex present, a combination of products will be needed.

Snap Beans.

Processing snap beans in all areas of the state should be treated at the bud and pin stages for corn borer control. Orthene or Address should be used at the bud and/or pin stages for corn borer control. In all areas, a pyrethroid should be combined with Orthene at the pin spray for earworm control. Beet armyworm can also be found defoliating snap beans. There are no thresholds for beet armyworm; however, a spray should be considered when worms are small and you can find 20% of the plants defoliated. Orthene should provide good control of beet armyworm. Lannate will only provide control of small larvae. Spintor is also labeled on snap beans and will provide good reduction in beet armyworm numbers. After the pin stage, Lannate, Capture or Mustang should be used for corn borer and earworm control. Sprays will be needed on a 5-day schedule from the pin spray until harvest. Since this can change quickly, be sure to check our website for the most recent trap catches and information on how to use this information to make a treatment decisions in processing snap beans (http://www.udel.edu/IPM/traps/latestblt.html and http://www.udel.edu/IPM/thresh/snapbeanecbthresh.html). You should treat fresh market snap beans for corn borers, corn earworm and beet armyworm on a 5-7-day schedule from the pin stage until harvest. Lannate should be used if beet armyworms are small. Lannate, Capture or Mustang should be used if corn borer and corn earworm are the predominant species.

Spinach.

Fields should be scouted at emergence for webworm and beet armyworm larvae. Controls should be applied when worms are small and before they have moved deep into the hearts of the plants. Also, remember that both insects can produce webbing on the plants. Since beet armyworms are more difficult to control and populations are increasing in our area, chemical selection is important. Since Lannate cannot be applied before plants are 3-inches in diameter and it only provides control of small larvae, Confirm or Spintor will be needed for beet armyworm control. If webworms are the predominant species, Ambush, Pounce, Confirm (6-8 oz/acre) or Spintor (4-8 oz/acre) should be used. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm.

Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 2-3-day schedule in all areas of the state. Since corn earworm catches continue to be high and fall armyworm can be found in silk stage corn, you should consider combining Lannate LV at 1 to 1.5 pt/A with the highest rate of a pyrethroid. Be sure to check our website for the most recent trap catches and information on how to use this information to make a treatment decision in fresh market sweet corn.

(http://www.udel.edu/IPM/traps/latestblt.html and http://www.udel.edu/IPM/thresh/silkspraythresh.html ) .

Vegetable Diseases - Kate Everts, Extension Vegetable Pathologist, University of Delaware and University of Maryland; everts@udel.edu

MELCAST for Watermelons.

From the University of Maryland and University of Delaware

Latest EFI values from local weather stations

Any questions please call (410) 742-8788

EFI Values (Environmental Favorability Index)

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program.

Location 08/21/02 08/20/02 08/19/02 08/18/02 08/17/02 08/16/02 08/15/02 08/14/02

Bridgeville, DE 2 3 2 1 1 0 1

Charles Co. 0 0 0 3 0 1 0

Collins Farms 3 4 3 2 1 0 0

Galestown, MD 2 3 2 1 1 0 1

Georgetown, DE 1 3 3 1 1 0 4 1

Glenville, MD 0 3 0 0 0 0 0

Hebron 2 2 3 1 2 0 0

Hog Creek Rd. 0 0 0 0 0 0 0

Salisbury, MD 2 1 2 1 0 0 0

Vincent Farms 3 4 2 1 1 0 1

Westminster 0 3 0 0 0 4 0

White Marsh 0 0 0 0 0 0 0