ABSTRACT
A simple method for in vitro production of sporangia by Phytophthora boehmeriae causing cotton boll blight in China was developed, and a method for dilution of zoospore suspensions was presented as well, Large amounts of sporangia were obtained when mycelial mats, produced from Potato extract-Dextrose Liquid (PDL) or Bean extract-Dextrose Liquid (BDL) at 24 ℃ for 48—72 hr ,were rinsed with Mineral Salt Solution (MSS) four times at 20—22℃ for 10—12 h with continuous fluorescent light (cool white), and incubated for additional 12 h after drained off MSS. Darkness favored oospore whereas suppressed sporangial production by P. boehmeriae. BDB is superior to PDB in the production of oospores and sporangia by P. boehmeriae as evidenced by the amount of sporangia or oospores and in particular the fact that the color change of mycelial mats from light orange to purple was synchronous with the sporulation of P. boehmeriae. Tris-succinate buffer(pH6.8, 5.0mmol/L, TSB) was the quantitatively excellent diluent for preserving motility of zoospores of P. boehmeriae in the dilution process.