Fusarium wilt     (Fusarium oxysporum)

Introduction

The disease may appear at any stage of crop development, depending on inoculum density, temperature and host susceptibility at high inoculum density or when infection initiates from seed  or the soil.  The diseased plants may be killed at the seedling stage itself. 

Symptoms

The symptoms first appear on the cotyledons vein starts darkening, followed by peripheral chlorosis. The cotyledons become progressively more chlorotic and then necrotic before being shed. In older plants, the first external evidence of infection is yellowing of margin of one or more lower leaves. As the disease progresses within the plant, more leaves develop chlorosis, which characteristically portion of appears in patches between the main veins where as rest of the leaf remaining green. Under the optimal conditions for disease development, all the affected plants succumb and shed before the stem dries- out and dies. 

Management

• Fields with long history of disease should be avoided for growing the crop.

• Fields should be deeply ploughed and left for solarization.

• Seed treatment with Carbendazim @ 2 g/kg seeds should be given.

• Use of nitrogen fertilizers, particularly ammonium nitrate should be discouraged while use of potassium fertilizers should be encouraged.

• Resistant varieties such as DB-312 , AKA-5 , Sanjay , Virnar, Daulat, Jyoti, Jayadhar, Vijalpa, Sujaya, Digvijay,  G cot-11, G cot-13 , PA-32  should be preferred over others.