Zucchini yellow mosaic virus: characterization and management in Iraq

A disease characterized by severe yellow mosaic, plant stunting, leaf reduction and distortion, and knobbed fruits, suspected to be of Zucchini Yellow Mosaic Virus (ZYMV) was observed on summer squash growing areas at different sites in Iraq. Samples of symptomatic plants were collected and tested by bioassay and by serological DAS-ELISA, using anti-ZYMV polyclonal antibodies. Results showed that the virus infects; Cucurbita pepo, C. moschata, Cucumis melo, and Citrullus lanatus giving the same symptoms observed on squash plants. Mild mottling with slight deformation of fruit was observed on Cucumis sativus sap-inoculated by the virus. Chenopodium amaranticolor developed chlorotic local lesions on sap-inoculated leaves. Necrotic local lesions were formed on Euphorbia peplus leaves sap-inoculated by the virus. The susceptibility of these hosts to the virus was confirmed by serological DAS-ELISA test. Based on these results, it can be concluded that the virus could be a strain of Zucchini yellow mosaic virus (ZYMV). The foliar application of chemical product on squash plants at 50 ppm one week before virus inoculation confer a protection period against ZYMV infection for up to 30 days. No symptoms were developed on the treated plants, as well as no virus was detected by ELISA test. Meanwhile, when the product applicated after 2 weeks of virus inoculation at 75 ppm, the virus was detected in the old leaves only for 3 days of inoculation, then it disappeared for up to 30 days. These results indicate that the product may induce the synthesis of compounds in the plants leading to inactivate the virus and inhibit its replication locally at the penetration site or systemically throughout the plant.