English abstract
The rapid expansion of greenhouse crop production in northern Oman in the last 5 years has been mirrored by an equally rapid increase in disease problems associated with the crops produced. Farmers are relying almost exclusively on cucumber production with three or four monoculture crops per year. Although damping-off is the principal disease constraint, flower and fruit rots cause largely unquantified, but significant losses each season. Isolations made from infected fruits indicated that the principal cause of the disease were Fusarium species. Plants were infected systemically with Fusarium being isolated from sections made at nodes throughout the stem. In addition to Fusarium, Alternaria spp. and Helminthosporium spp. were occasionally isolated from diseased fruits.
Symptoms of the disease start with gradual yellowing of the fruit from the flower end toward the petiole. As the disease progresses, infection with secondary invaders promotes fruit rot. Diseased fruits are not dropped from the plant, increasing the chance of further infection.
During the winter cropping seasons in 2003 and 2004 a commercial greenhouse was used to evaluate the effectiveness of foliar and soil-applied fungicides in reducing losses due to immature fruit rot. The first treatment consisted of weekly, foliar applications of carbendazim, the second treatment consisted of weekly, soil applications of carbendazim at and the third treatment served as a control, with no fungicide applications. In both seasons, the final percentage diseased fruits were significantly reduced both by foliar and chemigation applications of carbendazim.
Over two successive seasons, a commercial greenhouse was also used to evaluate the effectiveness of foliar applications of nutrients and fungicides, alone or in combination, in reducing the losses caused by fruit rots. The first treatment consisted of applications of carbendazim, the second treatment involved applications of foliar feed nutrients, in the third treatment, fungicide and nutrient applications were both applied, one day apart. The final treatment was a control, where plants received water sprays on the same day as treatment one. In 2003 the percentage diseased fruit was significantly reduced both by fungicide only treatment and by the combined foliar fungicide plus foliar nutrient treatments. For the foliar
feed only treatment, the level of diseased fruits was not significantly different from the control. In 2004, the highest percentage diseased fruit per plant was in the control, significantly different from the fungicide only treatment and the combined foliar fungicide plus foliar nutrient treatment. The percentage diseased fruit për plant in the nutrient only treatment was not significantly different from the control.
