Pennsylvania Flower Growers #250
In some greenhouse operations it is necessary to reuse clay or plastic pots. If a crop affected with a fungus or bacterial disease has been growing in these pots, the threat of the next crop becoming affected with the same disease is great. The pathogenic fungi or bacteria may grow into the pores of clay pots or may be in soil particles clinging to plastic pots. When these pots are refilled with soil and the new crop is planted, serious disease out breaks may result. Steaming clay pots is very effective in killing any pathogens in or on clay pots. However, some growers do not have facilities for steaming. In addition, many plastic pots may melt if subjected to a temperature high enough to kill the pathogens. Disinfestant soaks may be used if steam is not available or if plastic pots are involved. Formaldehyde is very effective in eliminating pathogens from pots but it has an offensive odor, the solution is irritating to the hands of workers, and the fumes may be toxic to workers and are phytotoxic to plants. Walton (1) compared the effectiveness of Clorox and L-F 10 with formaldehyde against Thielaviopsis basicola, Rhizoctonia solani, Fusarium oxysporum f. sp. lycopersici. Verticillium albo-atrum and Pythiumsp. He found that Clorox did not eliminate Fusarium but did eliminate the other fungi at a concentration of 1.05& L-F 10 at a concentration of 0.43% controlled all fungi in a 10 minute soak and at a concentration of 0.22% gave complete control in a 60 minute soak. Formaldehyde also gives complete control.
Keywords: Fungi or bacteria Disinfestant soaks Formaldehyde PG-141, PG-142 concentrations