STUDIES ON BASAL ROT DISEASE OF ONION IN EGYPT

Abstract

The present investigation was planned to study the variability among different isolates of Fusarium oxysporumfsp. cepae ( Hanz.) and snyd and Hanz. ' Also, varietal reaction was studied. The effect of microelements, growth regulators, some cultural practices and fungicides in greenhouse, field and storage on disease incidence and yield of onion bulbs was also studied. li' Results obtained could be summarized as follown: 1. Six isolates of F. oxysporum fsp. cepae, were isolated form diseased bulbs and transplants collected from different Governorates of Egypt were pathogenic to Giza-20 onion variety causing basal rot symptoms. Isolates varied in their virulence. Isolate VI was the most virulent, while isolate I was the least virulent .On the other hand, isolate IV was moderately virulent. 2. As for, interaction between local varieties and three isolate (virulent) was moderately virulent and least virulent. Giza-6 variety was susceptible while Shandawill-1 was highly susceptible with all tested isolates. 3. Laboratory experiment: Cichocel was no inhibition effect on radial growth of F. oxysporumfsp. cepae, but increasing the radial. 4. In field spraying onion plants with growth regulators Gibberellic acid (GA3), Cichocel (CCC) and Naphthalin acetic acid (NAA) decreased the percentage of infection by increasing the concentration except CCC increased by increasing the concentrations. The yield increased by increasing the concentrations of GA3 and CCC except concentrations (200 ppm. of ,while of NAA the yield decreased by increasing the concentration in both two seasons.