MELCAST Update

(www.melcast.info)

Editor: Cesar Escalante                                                                                              June 04, 2026

Extension Plant Pathologist

escalac@purdue.edu

812-886-0198

The MELCAST system is now working, and you can visit to see data updates at https://melcast.ceris.purdue.edu/ or www.melcast.info. This past week, many locations in Indiana received fewer rain events based on available weather observations. As a result, MELCAST data from May 28 to June 3 indicates that spray intervals have generally lengthened at several locations, with some approaching a 14-day schedule. Please visit the MELCAST website for more information and updates.

I have made a few visits to watermelon fields here in southwest Indiana, and the fields that were affected by bacterial diseases (mainly Pseudomonas) appear to have recovered. I believe that prompt applications of copper-based products, along with fewer rainy and humid days, have helped.

Now, I would like to provide a breakdown for selected locations in Indiana where spray intervals have been shorter and may warrant closer attention, depending on when the last fungicide application was made:

For cantaloupe, data for the period of May 28 through June 3 indicates relatively short spray intervals across several Indiana locations. At Ft. Vallonia, Merom Station, Oaktown, Princeton, Starlight, and Washington, cantaloupe spray intervals ranged from approximately 5 to 12 days based on accumulated Environmental Favorability Index (EFI) values during this period. At Williamsburg, EFI accumulation was somewhat slower, resulting in spray intervals closer to 7 to 10 days until May 29. Growers should continue to schedule fungicide applications using the 20-EFI threshold and adjust timing according to the rate of EFI accumulation at their nearest MELCAST station.

For watermelon, MELCAST data from May 28 through June 3 shows a similar pattern of spray intervals across Indiana locations. Spray intervals at Ft. Vallonia and Starlight were approximately 8 to 13 days, reflecting consistent EFI accumulation during the reporting period. Fungicide applications should continue to be timed using the 35-EFI threshold, with spray timing adjusted according to the accumulation of EFI values at each location.

If you have any questions, please feel free to reach out.

Sincerely,
Cesar Escalante
Extension Plant Pathologist