Fusarium wilt disease of cucurbits - its importance and management

Fusarium wilt is a devastating disease of cucurbits which are an important group of vegetable crops. Fusarium wilt is primarily a soil-borne disease and is responsible for causing great yield losses and quality decline in cucurbits. It is currently a major limitation to cucurbit cultivation around the globe. Cucurbits provide several edible and useful products to humans as well as animals. The crop is rich in nutrition and the infection due to the pathogen hampers its nutritional value. Fusarium wilt is caused by the fungus, Fusarium oxysporum which is highly host-specific. The host specificity of the fungus is classified by its formae speciales also known as f. sp. and the different hosts which they infect includes muskmelon, watermelon, cucumber, bitter gourd, etc. There are races also within the same f. sp. Three kinds of spores are produced by the fungus namely, chlamydospores, macroconidia and microconidia. The fungus causes wilting symptoms as it colonizes the xylem vessels of the plant and forms tylosses inside it which prevent the movement of water.
The pathogen eventually causes retardation of growth, yellowing as well as necrosis of leaves. When the disease is highly severe, it may cause death of the plant. Since the fungus causes huge losses in the quantity as well as quality of cucurbits due to which its market value decreases, hence it is very much essential to manage the disease. Management of fusarium wilt is very challenging due to persistent nature of the chlamydospores for several years and the development of new physiological races. Use of resistant varieties help in protection of plants against Fusarium wilt disease to a greater extent. The management of Fusarium wilt could also be achieved through several approaches including chemical control using the fungicides, solarization, crop rotation, bio-fumigation, nanoparticles etc. In addition, biological control strategy also offers an attractive and efficient method for the management of Fusarium wilt disease of cucurbits.
Keywords: Fusarium wilt, cucurbits, Fusarium oxysporum, management