Reduction of pre-emergence damping-off of peas caused by Pythium ultimum with calcium oxide

Publisher Website
Google Scholar
Abstract
Calcium oxide (CaO) and calcium hydroxide [Ca(OH)2] significantly reduced pre-emergence damping-off of peas and othe crops caused by P. ultimum in naturally infested soils in the greenhouse. Disease reduction was comparable to that achieved with thiram seed treatment. Damping-off of 5 additional pea cultivars [Alaska 423, Target, Freezonian, Progress No. 9 and Thomas Laxton] in naturally infested soil and disease caused by several isolates of P. ultimum in artificially infested soils were also reduced by 0.2% CaO. In both years of a field study with the pea cv. Perfected Freezer, stands were significantly greater when thiram-treated seed was planted in CaO-amended soil than when either treatment was used individually. CaO reduced populations of Pythium spp. in a naturally infested soil, and of P. ultimum and P. aphanidermatum in an artificially infested soil. Germination of sporangia of P. ultimum and oospores of P. aphanidermatum was almost completely inhibited in CaO-amended soils after 1 wk of incubation. Adjustment of corn meal agar to high pH values, similar to those of CaO-amended soils, did not affect radial growth or propagule germination of either fungus. However, ammonia vapors arising from ammonium hydroxide solutions or from inorganic N salts in a soil made alkaline with CaO killed the propagules.