Vol. 43 No. 1 (2004): 3rd IWGTD - Special issue on Grapevine Trunk Diseases
Research Papers

Sensivity of Jordanian Isolates of Alternaria solani to Manchotane

Published 2004-04-01

How to Cite

[1]
K. Al-Mughrabi, “Sensivity of Jordanian Isolates of Alternaria solani to Manchotane”, Phytopathol. Mediterr., vol. 43, no. 1, pp. 14–19, Apr. 2004.

Abstract

Early blight of potato, caused by Alternaria solani, poses a significant risk to potato crops worldwide. Fifty A. solani isolates representing a population were collected from the Jordan Valley, purified, and tested for their sensitivity to the fungicide mancothane. The isolates were tested against a series of concentrations of 0, 0.1, 1, 10, 100, and 1000 mg mancothane ml-1 in 5% sodium dodecyl sulfate (SDS). Some A. solani isolates tolerated up to 1000 mg mancothane ml-1. Isolates treated with the various concentrations were divided into 5 groups based on the percentage of A. solani growth achieved despite treatment: group 1 comprised isolates with mycelial growth of 0.1– 20.9%; group 2, 21–40.9%; group 3, 41–60.9%; group 4, 61–80.9%; and group 5, 81–100%. Ninety-seven percent of all isolates grew at 0.1 mg mancothane ml-1, 94% at 1 mg ml-1, 86% at 10 mg ml-1, 66% at 100 mg ml-1, and 16% at 1000 mg ml-1. Isolates appeared to be distributed normally at 10 mg mancothane ml-1. Eight isolates were highly resistant to mancothane and grew even at the highest test concentration. An A. solani population collected from potato fields in the Jordan Valley exhibited a moderate level of resistance to mancothane. Growers should be careful and vigilant when using this fungicide to control early blight.

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