Resumen de Dead mycelium of Penicillium chrysogenum protects transplanted cotton plants agains fungal wilts in a saline field

H. J. Zhang, H. Z. Dong, W. J. Li

• Previous studies have shown that the dead mycelium of Penicillium chrysogenum at 900-1,500 kg ha�1 effectively controlled Fusarium and Verticillium wilt of cotton. Our objective was to determine if the dead mycelium is also effective at lower rates under a cotton seedling transplanting system. Columned soil blocks (500 g each), made of fertile soil alone in the first experiment, and both soil and dead mycelium at varying rates in the second experiment, were sown with cotton seeds in 2006 and 2007. Seedlings in the mycelium-free blocks were drenched with aqueous extract of the dead mycelium after full emergence, and then transplanted to a saline field. The disease severity of Fusarium oxysporum f.sp vasinfectum and Verticillium dahliae, leaf chlorophyll and malondialdehyde concentrations, leaf photosynthetic rate and lint yield of the transplanted plants were determined. The aqueous extract at a rate of 1 to 5% provided 18.6 to 25.6% protection against Fusarium wilt but not against Verticillium wilt. Lint yield was slightly increased with the aqueous extract in 2006, but not in 2007. The incorporation of the dead mycelium to soil blocks before sowing was effective in controlling both the Fusarium and Verticillium wilts of cotton. Dead mycelium applied at 1 to 3% (w/w) provided 26-30% protection against Fusarium wilt and 48-50% protection against Verticillium wilt, and increased lint yield by 13-14%. Such incorporation also delayed leaf senescence as indicated by the increased leaf photosynthetic rate and chlorophyll content, and reduced malondialdehyde concentrations. Incorporation of the dead mycelium of P. chrysogenum into soil blocks at a relatively lower rate (270 kg ha�1) would be an effective application mode for wilt control in sustainable cotton production.