Diseases in Summer / Alfalfa / Agriculture: Pest Management Guidelines / UC Statewide IPM Program (UC IPM)

Several diseases and disorders occur in alfalfa in the summer. Compare field symptoms to the photos below and keep records of diseases you see. Adjusting irrigation practices can reduce some diseases and disorders. Names link to more information on identification and management.

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Field view	Close-up view
Phytophthora root and crown rot Identification tip: Leaves of infected plants turn yellow or tan and drop. Phytophthora can infect large areas of alfalfa in a field.	Phytophthora root and crown rot Identification tip: Red-orange to yellow streaks spread up from infected root tips.
No photo available.	Rhizoctonia Root Canker Identification tip: Brown rotted roots caused by seedling disease known as damping off, due to Pythium sp., Rhizoctonia sp., or Fusarium sp.
Scald Identification tip: Plants that sustain waterlogging combined with high soil temperatures will uniformly turn yellow and wilt. This condition, called scald, can also occur with soils that remain saturated for long periods under cooler temperatures.	No photo available.
Anthracnose Identification tip: Infected plants' stems eventually become bleached and bent.	Anthracnose Identification tip: Southern anthracnose stem lesions (right) are darker and lack the distinct fruiting bodies that appear in Stagonospora lesions (left).
Stagonospora crown and root rot Identification tip: Stagonospora leaf spots are irregularly shaped tan lesions with brown borders.	Stagonospora crown and root rot Identification tip: Stagonospora lesions are spotted with tiny, round, black fruiting bodies.

Agriculture: Alfalfa Pest Management Guidelines

Diseases in Summer

Text Updated: 11/06