Phytophthora Fruit Rot

 

HOSTS

  • Melon
  • Pumpkin
  • Squash

BIOLOGY

Phytophtora fruit rot is caused by various Phytophthora species. It is a concern whensoil remains saturated for at least five hours toward harvest time.

  • The pathogen survives in soil up to two years on infected plant debris.
  • In saturated soils, spores form and may infect nearby fruit that is close to harvest stage.

SYMPTOMS

Water-soaked spots form where fruit touches the ground, eventually turning into a white, yeast-like growth, and finally becoming a soft decay. The fruit will collapse.

GENERAL MANAGEMENT

Phytophthora fruit rot is rare in Utah.

  • A few weeks before harvest, inspect fruits each week, by checking where they touch the soil.
  • Rotate with non-host crops for two years.
  • Plant only in well-drained soils and allow soil to dry between irrigations.
  • Clean equipment and tools between fields.
  • Remove infected fruits.

Under good preventive practices, fungicides are not necessary in Utah.

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.