Kate Everts, Vegetable Pathologist, University of Delaware and University of Maryland; keverts@umd.edu
The weather based forecasting program MELCAST has begun for 2008. MELCAST is a weather-based spray scheduling program for anthracnose and gummy stem blight of watermelon. If you received a report in 2007 by fax, you should have received the first 2008 report last week. We are still working on the email addresses, but look for your email report today (Friday, May 30). If you are not receiving reports and would like to, please call Jeri Cook at (410) 742-8788 and give us your name and fax number or e-mail address. We have “migrated” the information to a new website, so bookmark the new site at http://mdvegdisease.umd.edu/. Click on the watermelon picture. (We are still in the process of moving the MELCAST-cantaloupe and the Tomcast reports.)
To use MELCAST for watermelons, apply the first fungicide spray 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 each overhead irrigation applied. After a fungicide is applied, reset your counter to 0 and start over. If a spray has not been applied in 14 days, apply a fungicide, reset the counter to 0 and start over. Please call Kate Everts if you have any questions on how to use MELCAST on your crop : (410) 742-8789.
Because of widespread resistance to Quadris in our area, chlorothalonil (Bravo, etc.) or Pristine plus chlorothalonil alternated with chlorothalonil is recommended when spraying according to MELCAST. If a serious disease outbreak occurs in your field, return to a weekly spray schedule.