石刁柏病害之病原學的調查(第一報)

Abstract

1.民國五十六年度，本省石刁柏常見之病害有莖枯病、褐斑病、灰色黴病等。 2.所發生病害之中，尤以莖桔病最爲嚴重，此病在所調查地區之範圍內均有發生，發病莖率有高至100%者，被害程度達3.54，影響石刁柏產量、品質至鉅。 3.褐斑病亦甚普遍，除三重市一地之外，其餘地區均有發生，其發病莖率有高至99%者，被害有至3.89之高者。 4.灰色黴病祗在雨天連續時及排水缺佳之園地時可見及其發生，而發病莖率尚低。 5.石刁柏莖枯病病原菌雖在有傷或無傷之植株上均能感染，而在有傷口之組織上較易並迅速感染。 6.供試殺菌劑中Dithane M-22, Dithane stainless, Arasan, Suzu tablet等對莖枯病病原菌柄胞子發芽之毒效良佳，在2.5p.p.m.之濃度尚能抑制其發芽。 7.各殺菌劑對石刁柏莖枯病病原菌菌絲之殺減效果以Suzu tablet爲最佳，在25p.p.m.之濃度浸漬10分鐘能殺減其菌絲，其次Dithane M-22, Dithane stainless, Arasan等亦稍有效果。 8.在室內藥劑試驗所選對石刁柏莖枯病病原菌抑制有效藥劑，在盆栽植株或田間實際應用上之效果，仍待日後之進一步研究探討。 The present experiment deals with etiological surveys of incidence, distribution and severity of the major diseases of asparagus throughout the island, and study on the infection of causal fungus of asparagus stem blight in greenhouse, and fungicidal test, in order to evaluate control measure of the stem blight. The results will be summarized as follows: 1. In 1967, stem blight caused by Phoma asparagi Sacc., Cercospora blight caused by Cercospora asparagi Sacc., gray-mold rot caused by Botrytis spp. etc. were noticed frequently to cause considerable damages to asparagus plants in some asparagus growing areas. 2. Among them, stem blight was the most wide-spread and serious disease of asparagus plants, this disease occurred in all of the asparagus growing areas. Percentage of diseased stem was noticed frequently up to 100 percent, the degree of disease severity was at index, 3.54, thus lowering both the quantity and quality of the asparagus production. 3. Cercospora blight was the very widespread asparagus disease also. The disease occurred in all asparagus growing areas, except in San-chung City. The percentage of diseased plants was noticed frequently up to 99 per cent. 4. Gray-mold rot occasionally occurred in continuous rainy climate and in poorly drained fields. The percentage of disease infection was not high yet. 5. The infection of the causal fungus of stem blight takes place on either wounded or unwounded asparagus plants, while it takes place more easily and rapidly on wounded tissue. 6. Toxic effect of various fungicides on pycnidiospore germination of Phoma asparagi sacc. was conducted in laboratory. Dithane M-22, Dithane stainless, Arasan, and Suzu tablet were found to be more effective, inhibiting the pycnidiospore germination at the concentration of 25 p.p.m. 7. In the fungicidal test with the fungus mycelium, Suzu tablet at concentration of 250 p.p.m. was the most effective ones, the mycelium are killed by dipping for 10 minutes, and Dithane M-22, Dithane stainless, Arasan showed some effectiveness. 8. Effective fungicides on inhibiting the development of causal organism screened by laboratory test are expected to be checked by green-house and field experiment.