A formulated container medium suppressive to Rhizoctonia damping-off of cabbage

Ten agricultural wastes were tested for their suitability as substrates for the growth of cabbage seedlings. Spent forest mushroom compost (SFMC) and spent golden mushroom compost (SGMC) were found to be more suitable than raw spent forest mushroom growth medium (RFM), raw spent golden mushroom growth medium (RGM), rice hull, carbonized rice hull, peanut husk, coconut fiber, bagasse meal or wasted cotton. The optimum composting period for SFMC and SGMC was 10 and 6 weeks, respectively. A new container medium (SSC-06) was formulated using SFMC, carbonized rice hull, shrimp and crab shell meal, blood waste, and lime. The SSC-06 medium was suitable for growth of cabbage seedlings and was suppressive to Rhizoctonia solani AG-4. The suppressive effect of 20-day-old SSC-06 medium on colonization of cabbage seeds by R. solani AG-4 was reduced after it was steamed in 100 degrees C hot air for 15 similar to 30 min. However, the inhibitory effect was restored to the steamed SSC-06 medium by inoculation with Trichoderma harzianum isolate TH-05 at a concentration of 10(5) cfu/g dry medium. After the medium was steamed for 5, 10, 15, 25 or 30 min, no fungal colonies were recovered, but the colony-forming units of the bacterial population were maintained at >10(6)/g dry medium. The potential for SSC-06 as a container medium for commercial nursery industries is discussed.