Field studies were conducted during the 2003 through 2005 growing seasons to evaluate postemergence herbicides and timing of application for horse purslane, smellmelon, and Palmer amaranth control in peanut. Acifluorfen provided inconsistent control of the three weed species. Bentazon failed to control Palmer amaranth, horse purslane, and smellmelon (< 65%), whereas 2,4-DB controlled horse purslane and smellmelon less than 70%. Diclosulam applied early postemergence (EPOST) controlled Palmer amaranth at least 77% but horse purslane control varied from 27 to 73% when applied EPOST and was less than 50% with the late postemergence (LPOST) application. Diclosulam controlled smellmelon less than 65%. Imazethapyr and imazapic controlled Palmer amaranth and smellmelon at least 70% but controlled horse purslane less than 65%. Lactofen controlled Palmer amaranth and horse purslane at least 93% with the EPOST application but had inconsistent control (40 to 100%) when applied LPOST. Smellmelon control with lactofen was also inconsistent. Removal of weed interference with all herbicides except bentazon provided peanut yields greater than the nontreated check.

Periodic surveys were conducted to seek potential indigenous fungal agents for development as mycoherbicides against horse purslane, a major weed of agricultural fields in India. Pathogenic fungal species were isolated and identified from naturally infected horse purslane. The biocontrol potential of these pathogens for horse purslane was evaluated by studying their host range and virulence under growth chamber and greenhouse conditions. Three candidates, Alternaria alternata, Fusarium oxysporum, and Phoma herbarum, were identified as potential candidates for biological control of horse purslane. Preliminary host-range tests and pathogenicity studies, conducted using 45 crop and weed plants belonging to 18 families, demonstrated that P. herbarum provided effective weed control and was safe to most of the plant species tested. Further mycoherbicidal application of P. herbarum as plant spray under field condition caused mortality of horse purslane 60 d after application of the inoculums. Phoma herbarum is a good mycoherbicide candidate against horse purslane.