Some factors affecting the pathogenicity of Alternaria alternata against the weed Rumex dentatus
2009
Siddiqui, I., King Saud Univ., Riyadh (Saudi Arabia). Botany and Microbiology Dept. | Bajawa, R. | Javaid, A., University of Punjab, Quaid-e-Azam Campus, Lahore 54590 (Pakistan). Inst. of Mycology and Plant Pathology
Rumex dentatus L. is a problematic weed of wheat. Recently Alternaria alternata has been reported as a new pathogen on this weed, resulting in up to 70% mortality of the host plant. This study was conducted to optimize the conditions to maximize the potential of the pathogen for use as a mycoherbicide agent for the management of R. dentatus. Thus, the effect of spore concentration (10 sup3, 10 sup5 and 10 sup7 condinia/mL), host-plant growth stage (2-3 leaf, 4-5 leaf and 10-12 leaf or flowering stage), dew period (100% humidity for 12, 18 and 24 h) and temperature (20, 25 and 30 deg C) on the pathogenicity of A. alternata was investigated. To further enhance the disease potential of the pathogens, different formulations of infected propagules (1 and 2% gelatin, 1 and 2% carboxymetylcellulose (CMC), 1:1 gelatin and CMC, 10 and 20% canola oil emulsion) were also used. The pathogenicity of A. alernata increased with increasing spore concentration and length of dew period. A spore concentration of 10 sup7 condinia/mL in 20% canola oil emulsion under 100% relative humidity for 24h resulted in 100% mortality of R. dentatus plants at the 2-3 and 4-5 leaf stages. Infection and mortality in mature plants at the 10-12 leaf stage was lower. The maximum mortality of the host plant was observed at 25 deg C and 30 deg C.
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