The weed sicklepod, a problem in the cultivation of soybean, cotton, and peanut, can be controlled by the mycoherbicide, Alternaria cassiae. However, the presence of water (dew) for an extended period is required by the fungal spores to germinate and infect the target weed. Preliminary tests with invert (water-in-oil) emulsions containing paraffin wax, paraffin oil, lecithin, and water indicated that about 10% (w/w) water, maintained over an 18-h period, was necessary under laboratory conditions for significant germination of the fungus. The ability to maintain that amount of water in the invert emulsion depended upon spray deposit size, adjuvants, and oil phase: water ratio. Paraffin wax was an effective adjuvant for reducing water evaporation and increasing sicklepod mortality in the greenhouse.