Factors to Consider When Managing Phytophthora Fruit Rot in Watermelons

Clint Thompson Disease, Top Posts, Watermelon

Increased rainfall means conditions are favorable for the development of phytophthora fruit rot (Pcap) in watermelon, according to University of Georgia Extension Vegetable Blog and Extension plant pathologist Bhabesh Dutta.

UGA Extension photo/Shows Phytophthora Fruit Rot in watermelon.

There are several pre- and post-harvest considerations growers need to be mindful of in protecting their watermelon crop from the disease.

Dutta recommends:

  1. Avoid harvesting watermelons from low spots in your field.
  2. Pick healthy fields first followed by problematic fields.
  3. Pay attention to any water-soaked spots on fruit while harvesting and discard them.
  4. Once you’re done harvesting, grade the watermelons again for any water-soaked spots. These can be as tiny as a dime.
  5. Keep the watermelons for 48 hours to 72 hours under the shed after grading. Based on UGA research, symptoms start appearing within that time frame.
  6. Re-grade your watermelons for Pcap symptoms before shipping. This will help reduce post-harvest losses due to Pcap.

UGA also reminds producers that the most effective method of control for this disease is to prevent Phytophthora capsici from moving into a non-infested field.  It spreads by soil, water, and/or plant material. It is highly recommended to thoroughly clean all farm equipment that is used in an infested field before moving it to another field.  Also, avoid using water sources (i.e. ponds or reservoirs) that receive run-off water from an infested field.

High soil moisture favors the development of this disease, thus well-drained fields should be selected. Excessive irrigation should be avoided.