POWDERY MILDEW OF GRAPEVINE IN EGYPT: PREVALENCE, TEMPERATURE, HUMIDITY, CULTIVARS AND CHEMICAL AND BIOLOGICAL CONTROL

Radwan, Fatma M.; Radwan, M.A.; Hassan, M.S.S.

doi:10.21608/mjppf.2015.331524

POWDERY MILDEW OF GRAPEVINE IN EGYPT: PREVALENCE, TEMPERATURE, HUMIDITY, CULTIVARS AND CHEMICAL AND BIOLOGICAL CONTROL

Document Type : original papers

Authors

Plant Pathol. Res. Inst., ARC, Giza, Egypt

10.21608/mjppf.2015.331524

Abstract

Field studies were conducted to clarify the period of the disease appearance and its successive development. Thompson seedless, Crimson seedless, Red Roomy and Flame seedless cultivars in four Egyptian governorates, i.e. Kalyoubia, Gharbia, Beheira and Minia were examined during 2012 and 2013seasons to calculate the disease severity %.The disease occurrence was more prevailing during the season 2013 than 2012. Flame seedless was the least susceptible cultivar, Thompson seedless, Red roomy and Crimson seedless were very susceptible under field conditions. In the contrary, the highest disease severity was recorded in Gharbia on Red Roomy and Crimson seedless but the lowest was on Thompson seedless and Flame seedless. The highest disease severity percentage was recorded in Minia governorate with all cultivars, followed by Beheira and Kalyoubia, while Gharbia governorate recorded the lowest occurrence. The temperatures which were correlated with the intensity of powdery mildew indicating that as temperatures increase, the intensity increased. The pathogenic activity of the fungus began when the temperature was 22°C with a relative humidity more than 50%.The temperature of 25.0-32.0°C, relative humidity of 55-90% were the most favourable conditions for the peak incidence of the disease. Interestingly, the disease severity subsided with the increasing the temperature degree above32°C. The fungicides and biocides were sprayed 5 times at 15-day intervals at two programmes on grapevine cv. Thompson seedless in Nobaria-Beheira . All treatments in early spraying programme which started with three protective sprays of sulfur after bud break were more effective on leaves and bunches as compared with treatments were used in late spraying programme which started after the appearance of disease symptoms. Topas, Bayfidan and Punch were the most effective treatments, followed by Topsin M and AQ10. On the contrary, Bio Arc, Bio Zeid and Micronized soreil were the least in minimizing the incidence of powdery mildew.The efficiency of sulfur declined when the pressure of the disease was high

Keywords