台灣土傳性疫病之防治及抑病土壤

Abstract

經測定土壤對胞囊發芽力的影響，發現柑桔疫病菌（Phytophthora parasitica, P. palmivora)，及甜椒疫病菌(P. capsici)之抑菌土壤在本省西部的分佈非常普遍，但並不一定十分均勻的分佈在同一塊田土中，有些抑菌土壤樣品之週邊土壤並不抑菌。所有已發現之P. capsici抑菌土壤均為P. parasitica及P. palmivora之抑菌土壤，但反之並不亦然。抑菌土壤與地上部耕作物之種類，土壤之質地、顏色似無關係。大部分抑菌土壤之酸鹼值均在pH5.0以下，但酸鹼值在pH5.0以下之土壤並不一定是抑菌土壤。大部分抑菌土壤經100℃蒸氣處理15分鐘後，仍具抑菌性。但是抑菌土壤經KOH調節酸鹼值在pH5.0~8.0時，即失去抑菌性。二鹽基或三鹽基之單價陽離子磷酸鹽類有抑制疫病菌胞囊發芽之能力。 When spore germination was used to assay pathogen suppression, soils suppressive to Phytophthora parasitica, P. palmivora and P. capsici were found to be widely distributed in the western Taiwan. Soil sample collected from the same general areas showed considerable variation in pathogen suppression. These three species of Phytophthora behaved similarly in regard to sporangial germination in most of the soils tested. The degree of pathogen suppression was not correlated with soil texture, soil color or vegetation. Allof the soils suppressive to P. capsici and most soils suppressive to P. palmivora and P. parasitica were with pH value lower than pH 5.0. However, some soils with pH lower than 4.0 still supported more than 80% germination of sporangia of all three Phytophthora species. When the pH was adjusted to 6-8 the suppressive soils tested became conducive. Most suppressive soils remained suppressive to Phytophthora after being steamed at 100 ℃ for 15 mm. The conducive soil became suppressive to sporangial germination when it was amended with dibasic or tribasic phosphate monovalent cation salts.