Evaluation of Alternaria alternata as a biological control agent of redroot pigweed (Amaranthus retroflexus L.)

Abstract

Biological control agents, especially some plant pathogenic fungi have the potential of weed control. To evaluate the efficacy of Alternaria alternata on the biological control of red root pigweed, an experiment was conducted based on Randomized Complete Block Design with three replications and different concentrations of the isolates A. alternata (104 ,107 spore ml-1 with distilled water and 104 ,107 spore ml-1 with surfactant and tween 40) at three temperature regimes (20/10, 25/15, 30/20 % c) during different growth stages (2, 4, 6 and 8 leaf). The results showed that the disease severity was increased by surfactant and enhanced temperatures. The inoculation of pathogen caused a significant reduction in dry weight at 2, 4 and 8 leaf growth stages and decreased plant height at 2,4 and 6 leaf stages and also reduced leaf area at 2 leaf stages. The results of this reaserch showed that this fungus has potential effectiveness and mycoherbicidal ability for red root pigweed control.