ABSTRACT
194S-H mixture, developed and named by the authors, was effective against Fusarium wilt diseases and some other soil-borne diseases. The mixture consists of 4.4% bagasse; 8.4% rice husks; 4.25% oyster shell powder; 8.25% urea; 1.04% potassium nitrate; 13.16% calcium superphosphate; and 60.5% mineral ash (31% silicon dioxide, 44% calcium oxide, 1.7% magnesium oxide, 18% aluminum oxide, and 1% ferrous oxide). When infested sandy soil was amended with 1% (w/w) S-H mixture, the population of Fusarium oxysporum f. sp. niveum decreased 92% in 1 month compared with unamended soil, where the population decreased 55%. In unamended soil, 36% of chlamydospores of F. oxysporum f. sp. niveum germinated; in soil-amended S-H mixture, only 4% germinated. In artificially infested soil, S-H mixture inhibited disease incidence completely, compared with 94% of watermelon plants infected 38 days after planting in unamended soil. S-H mixture also enhanced plant growth by increasing root weight and root number about three and six times, respectively. Naturally, infested fields were amended with S-H mixture at a rate of 900 to 1000 kg/ha for watermelon wilt control. S-H mixture controlled 76 and 84% of Fusarium wilt of watermelon in soils which contained 600 propagules of F. oxysporum f. sp. niveum per gram of soil. In soil with high population (1200 to 3400 propagules per gram of soil), S-H mixture controlled 61 and 57% of the disease. The effect of S-H mixture in controlling radish yellows can be enhanced by adding chopped cabbage leaves in the amendment, but the effectiveness of S-H mixture can be nullified when the inoculum density is over 5 × 103 propagules per gram of soil, when soil pH is too low (5.0) or too high (7.8), or by use of ammonium sulfate or urea, the latter of which may cause toxic injury to germinating seeds because urea has been included in the S-H mixture.
