Plant Pathology: Extension: Plant Disease Library

Fusarium

Important diseases:   Fusaium wilt of tomato, Cereal head blight, Soybean sudden death

Fusarium causes root, stem, and crown rots, wilts, head blight, and leaf spots. The fungus is seen most often as a root and lower stem pathogen. Fusarium has a wide host range. It may act alone or more often is association with other soilborne pathogenic fungi, such as Rhizoctonia or Pythium.

Necrosis of roots often beginning with lateral roots. A red-pinkish discoloration is often associated with infected tissue. Infection generally moves upward through the plant.

Conidiophores are produced in a sporodochium (cluster of conidiophores) growing on surface of infected tissue. Conidiophores may be single or branched with conidia produced at the tips.

Three types of spores are produced; macroconidia, microconidia, and chlamydospores. Macroconidia can vary greatly in size and shape. Generally, macroconidia are colorless, slightly curved ("sickle"or "canoe" shaped), and multi-celled. Microconidia are colorless, small, oval to short cylindrical and one or two-celled. Chlamydospores are thick walled, rounded cells typically found in older mycelium. They are fungal survival structures.