水稻种衣剂防治稻瘟病研究

旱圃接菌测定表明，６种水稻种衣剂防治稻瘟病的效果都十分明显，除种衣剂１号的防病效果为６９．３５％外，其余５种种衣剂的防效均达９１％－９８％，田间不上区接菌试验胞衣稻种水育秧４７天，种衣剂２号，３号，４号，６号的防效为７２．９６％－８４．８９￥％，１号，５号为５５５左右。

STUDIES OF THE TREND OF RICE BLAST EPIDEMICS ON HYBRID RICE CROPS IN ZIZHONG COUNTY AND THE STRATEGY FOR ITS CONTROL

An analysis of the historical records of rice blast and meteorological data in Zizhong county has shown that climate factors affected the severity of the disease but they had no close correlation with its epidemics. The presence of virulent races and their percentage in the population seem to have been the key factors for the development of the disease. In Zizhong county, the development of blast on hybrid rice varieties showed a nine year cycle. In other words, a resistant rice variety maintained its resistance to rice blast in the first seven years of cultivation. In the eighth and ninth years, rice blast would be epidemic and cause great yield losses. However, the damage caused by the disease would not be serious enough to be a disaster in the tenth year even if the original variety still accounted for a certain percentage of the rice varieties grown in the region. The key measure for the control of the disease is considered to be timely replacement of the current varieties with new resistant ones.