Chapter 50 - Cucurbitaceous vegetables-II

Abstract

Virus diseases are major problems in cucurbit production worldwide. These diseases have increased their prevalence and emerged in the various crop production areas particularly affecting squash or pumpkin, bitter gourd, bottle gourd, sponge gourd, and ridge gourd. Known diseases are caused by virus species belonging to various genera such as Potyvirus, Cucumovirus, Tobamovirus, Begomovirus, Polerovirus, Orthotospovirus, Crinivirus, and Nepovirus. Diseases include mosaic caused by Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), andZucchini tiger mosaic virus; cucumber mosaic caused by Cucumber mosaic virus (CMV); cucumber green mottle mosaic caused by Cucumber green mottle mosaic virus (CGMMV) squash leaf curl (Squash leaf curl virus,Squash leaf curl Philippines virus, Squash leaf curl China virus); chlorotic curly stunt, yellow mosaic and yellow vein mosaic (Tomato leaf curl New Delhi virus): beet pseudo-yellows, cucurbit aphid-borne yellows Cucurbit aphid-borne yellows virus, melon yellow spot Melon yellow spot virus), and tobacco ringspot Tobacco ringspot virus (ToRSV). These viruses are mostly transmitted by insect vectors, except CGMMV that is mechanically and seed-transmitted. ZYMV and CMV are also seed transmitted. These diseases induce a range of symptoms such as mosaic, mottling, chlorosis, vein banding, crinkling or wrinkling, curling, puckering, chlorotic spots, necrotic spots, interveinal chlorosis, severe yellowing, distortion and thickening of the leaves, reduction in leaf size, and stunting of infected plants depending on the causal virus.