Incidence and management of virus diseases of cucurbits in Lebanon

Virus diseases are the major cause of economic losses in commercial cucurbit production in Lebanon. This survey revealed that Zucchini yellow mosaic Potyvirus (ZYMV) and Cucurbit aphid-borne yellows Polerovirus (CABYV) are the most common viruses of field-grown cucurbits in Lebanon. They are followed by Watermelon mosaic Potyvirus (WMV), Papaya ringspot Potyvirus-watermelon strain (PRSV-W) and to a lesser extent Cucumber mosaic Cucumovirus (CMV). Cross-protection with a mild strain of ZYMV-WK gave significant protection of squash plants against severe virus symptoms and resulted in significant yield increase as compared to the control. Silver plastic mulch also gave a significant protection against viral diseases and a higher total yield than controls. However, the best protection and highest total yield were obtained with floating row covers. The integration of cross-protection with silver mulch or with floating row covers improved the protection obtained with either approach. (C) 2000 Elsevier Science Ltd. All rights reserved.