摘 要：
根据紋枯病的特点,确定防治以化学保护为主,寻找有效药剂并探討其施用方法。室內試驗,在测定的81种药剂中,阿莫尼亚、多硫化鋇、西力生、磺原酸鋅、硝酸銀及多种有机錫等都有很好的杀菌作用,但在大田应用时,由于药力不能持久,都无实际效果。五氯硝基苯效果不稳定,在适于发病的环境下卽无效。土习脫有高效,但其成分复杂,且药害严重,难于广泛应用。只有“苏化911”有很好的防病效果,而无显著的药害。經过連續三年间在南京等地示范試驗結果,用100—200 p.p.m.在水稻孕穗前噴布一次卽可将稻株的发病率从82.6—100％压低到6.2—0％,产量視病情的輕重增加6.3—49.2％。“苏化911”也有一定药害,但如使用方法适当,也可以減免。“苏化911”的合理用法:1.剂型:“苏化911”不溶于水,必須制成乳剂或悬浮液作噴布用或用填充物稀释作撒布用。在喷布时必須使用适当的噴雾器,使药液均匀分佈稻株表面。在撒布时,虽徒手操作,也可得到如期效果。撒布药土的效果較之噴粉、噴雾毫无逊色。使用毒土浓度虽高达1000 p.p.m.,仍无明显药害。2.浓度:初步看出用30％可湿性“苏化911”粉剂1份加滑石粉100份或者加风干細土300份已有满意的效果。在嘖雾时乳剂或可湿剂浓度均以100—200p.p.m.为宜。3.用量:100p.p.m.的乳剂或悬浮液,每公頃施用1500公升,可奏全效,而无药害,如用量增加,最好減低浓度,否則有严重药害。4.使用时期:以水稻生育前期(分蘖末到孕穗初)为宜,过迟,特别抽穗以后效果小,且对产量不利。5.用药次数:“苏化911”的残效可以持續数十天,噴布一次就能收到完全或近完全的效果。
译 名：
CONTROL OF SHEATH BLIGHT OF RICE BY "K.C.I. 911"
作 者：
Vongmay Chu, Chen Yu-ling (Kiangsu Branch, the Academy of Agricultural Sciences of China)
摘 要：
Trials have been made at the Kiangsu branch of the Chinese Academy of Agricultural Sciences since 1958 to investigate chemical treatment against the sheath blight of rice incited by the fungus Pellicularis sasakii, which causes serious damage throughout all the principal rice-producing regions of southern China, especially in those places where the paddy crops grow thrivingly and give good harvests. Among 81 fungicides tested, quite a few chemicals, such as ammonium hydroxicide, barium polysulphide, ethyl mercury chloride, ethyl-zinc xanthate, silver nitrate, and several organotinny compounds were found to have good fungicidal activity in laboratory experiments. Nevertheless, most of these chemicals did not give significant evidence in controlling the disease in field trials owing to the fact that recidues of these chemicals persist on the paddy plant for only a very short period. Pentachloronitrobenzen, known as a Rhizoctoniocidal agent, showed some effect in field control, but the results with this fungicide were variable and unreliable under the conditions favouring high levels of infection. Tuzet (T.U.Z.), the well-known specific agent for controlling sheath blight of rice, was highly effective, but both phytotoxicity and the complicated constituents lead it to be doubtful whether it would be practical for a large scale application. On the other hand, however, "K.C.I. 911" (methylarsine sulphide) has been proved to be promissing, as it always gave excellent disease control without marked injurious effect to the plant. In field tests conducted over 3 years at Nanking and other 2 dis- tricts, it showed that a single spray of "K.C.I. 911" at the concentrations of 100-200 p.p.m. at or before boating of the paddy plant reduced the number of diseased plants to 0-6.2% as compared with 82.6-100% in untreated plots. Consequently, the grain yield was increased 6.3—49.2% depending upon the degree of infection. Since "K.C.I. 911", like the most of the arsenical compounds, consists of high fungitoxicity with high phytotoxicity, extreme care must be excised in its application. Basing upon the results obtained from extensive observations made over 3 years, considerable knowledge and experience concering the correct use of this special fungicide for eradicating the sheath blight of rice have been accumulated, which are summerized as follows. 1) Method of application: "K.C.I. 911" is insoluble in water. It should be either prepared as an emulsion or a suspension for spraying, or diluted with various inert materials such as talc or air dried soil for dusting. For spraying, an adequate sprayer is essential so as to wet the plants evenly. For dry treatments, it is also better to employ a mechanical spreader, although it may even be achieved by bare hands. Both pot experiments and field trials have proved that scattering the mixture of the fungicide and air dried soil by bare hands is fully as effective as spraying with the agent in liquid form by machinary. Moreover, it should be especially noticed that when "toxic soil" is used, there showed no injurious effect on the plant even though the concentration of the chemical is as high as 0.1%. 2) Limits of concentration: No definite experiments were made to determine the optimum dosage of "K.C.I 911" applied in the dry form, but it was experienced that a mixture of 1 part of "K.C.I. 911" wettable powder at 30% active ingredient with 100 parts (by weight) of talc, or with 300 parts of air dried soil gave satisfactory results. As to be diluted with water, the concentration of the active ingredient should be limited to 100-200 p.p.m. Higher concentrations may seriously injure the crop, and the yields will thus be greatly reduced, while lower concentrations result poor disease control. 3) Amount required: Both the efficacy in disease control and the degree of injury to the plant tissues depend upon the amount of liquid acctually used. Applling the 0.01% "K.C.I. 911" either emulsified or suspended in water at a rate of approximately 1500 liters per hectare, a complete control was obtained with negligible damage. Higher rates, unless using a more diluted liquid, definitely injure the rice plant. 4) Time of application: Best results were obtained when the rice plant is treated at earlier growing stages of development, viz. from the ending of tillering to the period just before boating. Applications delayed up to heading induce adverse results, as the rice plant has already been severely infested, and the yound grains of the rice is particularly subject to the toxicity of this fungicide. 5) Time of application: Owing to the fact that recidues of "K.C.I. 911" may persist and remain active on paddy plant for several weeks, a single application of about 150 grams of this material (0.01% in water) per hectare at the proper time may bring about a 100% control of sheath blight of rice. Careful experimental trials indicated that there is no or little beneficial effect to make any additional applications.
