Vegetables

 

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

 

Lima Beans

With the recent increase in corn earworm catches, be sure to watch for earworms in fields with pin pods. You should also sample for 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. Lannate, Mustang or Capture can be used to control all 3 insects on lima beans.

 

Melons

Spider mite populations continue to increase in many fields. In our field trials this season, Agri-Mek and Capture have provided 3-4 weeks of control with 2 applications. A few growers have tried dimethoate this season with varying degrees of success. If you have not used dimethoate in a few years and you are having limited success with other products, you may want to consider one application of dimethoate. You should not use it more than once, especially if you experienced poor control or resistance in past years. If you have not used it for 3 or more years and you had reduced efficacy when you stopped using it, we often find you can make one application and get good control. However, multiple applications usually result in a quick reversion to resistance and an explosion in populations.  The maximum rate for dimethoate 4EC on melons is 1 pt/acre.

 

Peppers

At the present time, all peppers that have fruit ½ inch in size or larger should be sprayed on a 7-day schedule for corn borer, corn earworm and pepper maggot control. With the recent increase in corn earworm catches, chemical selection will be important. Remember Orthene or Address will not provide satisfactory earworm control. A pyrethroid or Lannate will be needed for earworm control. Also, a continuous pyrethroid program should not be used to avoid aphid explosions.

 

                                                                                                                                                                                             R. Bessin, Univ. of Kentucky

 

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. Once corn earworm trap catches reach 20 per night in your area, a pyrethroid should be added to the pin spray. After the pin stage, Lannate, Capture or Mustang should be used. After the pin spray, sprays will be needed on a 7-day schedule from the pin spray until harvest except in the Bridgeville and Laurel areas where sprays are needed on a 5-6 day schedule. 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 our link to http://www.udel.edu/IPM/thresh/snapbeanecbthresh.html). You should treat fresh market snap beans for corn borers on a 7-day schedule from the pin stage until harvest. Lannate, Capture or Mustang should be used.

 

Sweet Corn

Fresh market silking sweet corn should be sprayed on a 3-day schedule in all areas of the state. Be sure to also sample late-planted fields for fall armyworm larvae. No controls will be needed until 15% of the plants are infested. Sap beetles are also starting to show up silking sweet corn. Warrior, Penncap-M and diazinon have provided the best control.

 

 

 

 

 

 

 

 

 

 

 

Scorch on Sweet Corn -Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu

 

Several fields of processing sweet corn have exhibited small percentages of scorched tissue and tassles.  High temperatures (99 degrees and above) can cause scalding of corn leaf tissue.  Hybrids differ in their tolerance, and the stage of development of the tassel also influences the plant’s reaction to those temperatures.  The emerging or recently emerged tassles may appear “blasted or bleached.”

Usually, the percentage of affected plants is small and the effect on total yield is neglible.

 

 

Scorch on Sweet Corn

 

 

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

 

Cucurbits

Cucurbit powdery mildew is now present in Delaware and the Eastern Shore of Maryland.  Scout your fields of pumpkin, squash or susceptible muskmelon for this disease.  When one lesion is found on the underside of 45 old leaves, begin fungicide applications for powdery mildew.  You may already be on a schedule for general disease control with broad-spectrum materials such as chlorothalonil (Bravo, Equus or Echo) or maneb and copper.  These materials are contact fungicides and will protect against powdery mildew primarily on the upper leaf.  Where the threat of powdery mildew is severe, susceptible cultivars are planted, and economics support it, improved control can be achieved by alternation of these contact fungicides with Nova, Flint, Quadris, or Procure (a new product labeled to control powdery mildew at 4 to 8 oz/acre). 

 

 

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           07/17/02  07/16/02  07/15/02  07/14/02  07/13/02  07/12/02  07/11/02  07/10/02

  Bridgeville, DE           0               0               5               5               1               0               0

  Charles Co.                0               0               9               2               0               0               0

  Collins Farms             1               2               4               4               0               0               0

  Galestown, MD          1               3               4               4               0               1               0

  Georgetown, DE        1               3               2               4               0               1               2               2

  Glenville, MD              0               0               8               3               0               0               0

  Hebron                        1               3               4               3               0               0               0

  Hog Creek Rd.           0               0               9               3               0               0               0

  Salisbury, MD            2               3               4               3               0               1               2               0

  Vincent Farms           1               2               5               5               1               0               0

  Westminster               0               0               10            3               0               0               0

  White Marsh               0               0               10            3               0               0               0

  The first fungicide spray should be applied when the watermelon vines meet within the row.  Additional sprays

  should be applied using MELCAST.  Accumulate EFI (environmental favorability index) values beginning the

  day after your first fungicide spray.  Apply a fungicide spray when 30 EFI values have accumulated by the

  weather station nearest your fields.  Add 2 points for every overhead irrigation.  After a fungicide spray, reset

  your counter to 0 and start over.  If a spray has not been applied in 14 days, apply a fungicide and reset the

  counter to 0 and start over.  The first and last day listed above can be partial days so use the larger EFI value

  of this report and other reports for any specific day.

 

If, for some reason, a serious disease outbreak occurs in your field, return to a weekly spray schedule. 

More detailed information concerning MELCAST and sample data sheets are available on the web at http://www.agnr.umd.edu/users/vegdisease/vegdisease.htm.

 

 

 

 

 

 

 

 

 

Vegetable Diseases -  Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

 

Potato Disease Advisory.

 

Late Blight Advisory

 

Disease Severity Value (DSV) Accumulations as of July 18, 2002 are as follows:

Location: Joe Jackewicz Farm, Magnolia, DE. Greenrow: April 10, 2002

Remember that 18 DSV’s is the threshold to begin a spray program for late blight.