Prevalence, mechanical transmission and impact of environmental conditions on cucumber mosaic disease in Sindh

Abstract

Cucumber mosaic virus (Genus: Cucumovirus, Family: Bromoviridae) is major pathogen of cucumber (Cucumis sativus L.) in Pakistan and may cause up to 100 % losses. Therefore, this survey based study was planned to determine the disease intensity in fields, mechanical transmission for confirmation of virus and analysis of influence of environmental conditions on the disease development. The disease was monitored on 30 plants at each site in district Hyderabad, Tando Allahyar, Thatta and Shaheed Benazirabad. There were seven sites at each district for observations. Metrological data collected from Regional Agro Metrological Centre, ARI Tandojam Sindh was correlated with the disease intensity. The disease incidence was ranging, 40-77, 37-70, 63-100 and 30-90%, at district Hyderabad, Tando Allahyar, Thatta and Shaheed Benazirabad, respectively. District wise, there was highly significant variation among incidence of cucumber mosaic disease (Df= 3, F= 20.59, P= 0.0000). Maximum disease incidence was recorded at Thatta (81.0%). However, overall severity of cucumber mosaic in all the surveyed districts was 2-score. On mechanical inoculation, after 15 days necrotic lesions were only found on the leaves of Chenopodium amaranticolor inoculated with sap of symptomatic leaves. Maximum, minimum temperature (℃) and evaporation showed significant relation (r 2 = 0.883, P= 0.0053, r 2 = 0.664, P= 0.0482 and r 2 = 0.827, P= 0.0119, respectively) only with the disease incidence but not with severity. Cloudiness was highly significantly related with disease severity (r 2 = 0.975, P= 0.0002) but there was non-significant relationship with disease incidence (r 2 = 0.600, P= 0.0705).