الملخص الإنجليزي
Muskmelon late season vine decline (MLVD) has become more predominant in muskmelon cultivation in Oman. A survey conducted in the Al Batinah region showed that more than one soilborne pathogen is associated with MLVD disease. Pythium aphanidermatum, Fusarium spp., Rhizoctonia sp. in addition to nematodes were isolated from infected roots, crowns and stem tissues. Disease symptoms were similar in all fields included in the survey. Wilting of the plant canopy about two weeks before harvest was common. Brown to Dark brown lesions were scattered over primary, secondary and tap roots. Sloughing-off of cortical tissues of the root system in advanced disease stages was associated mainly with P. aphanidermatum. Fusarium species were involved in strangled crown areas and with discolored vascular tissue of roots, crowns and stems. In most cases, a short tap root was a distinctive symptom.
Two field experiments were conducted in different locations with different soil characteristics to evaluate different control measures in their efficacy in reducing the density of inoculum and AUDPC and consequently increasing yield. At Al Sawadi, metalaxyl was added at the rate of 100ml/plant via a separate drip irrigation system throughout the growing season. Metam sodium was applied as preplant treatment in aqueous form at the rate of 226ml/2m2 via a drench method. Cabbage residue was burried as a preplant treatment at the rate of 20 kg/2m2. At Wadi Al Abiath, cabbage residue was added at the same rate as in the first trial. Metam sodium was applied using the same method but at an increased rate (250ml/2m2). A fungicide mixture (Tachigaren, Hymexazole, Tolclfos Smethyl and Thiram, Topsin, Thiophonate methyl was applied via a drench method around the root zone. Oxamyi 10% was added as granules prior to and after sowing.
In both trials, metam sodium showed the best results in reducing inoculum levels. At Wadi Al Abiath, metam sodium significantlly reduced AUDPC. In both trials, none of the treatments showed a significant impact in increasing fruit yield. Moreover, both varieties examined were susceptible to MLVD disease. Out of thirty two exotic varieties evaluated, Panna, Canal261 and Kurooger showed tolerance to MLVD.
