16% Exianqing is the first choice for controlling rice "small panicle head"

For many years, in some major rice-producing areas such as Jiangsu, the phenomenon of "small panicle head" (also called small-grain distorted panicle) has appeared continuously over many years under multiple varieties, multiple planting levels, and multiple ecological conditions in large-scale production. Its characteristics are: small panicles, small glumes, cracking of the inner and outer husks after grain filling, partial exposure of rice grains, and small grains with dark brown color. It is especially severe in the Lixiahe area, coastal areas, along the Huai River, along the Yangtze River, and hilly areas of Jiangsu Province. It is estimated that in recent years the affected area in Jiangsu Province alone has been about 100,000 hectares each year, reducing rice output by more than 100 million kg, and cumulatively causing about 500 million kg of rice yield loss. It is generally believed that improper cultivation and management techniques and the influence of climate, soil, fertilizer, pesticides, and other conditions, as well as the occurrence of bakanae disease, rice blast, and stripe disease, either as a single factor or through the combined action of several factors, are the main causes of "small panicle head" formation. Some also believe that "small panicle head" is caused by variety degeneration or seed quality problems.

In recent years, Jiangsu Dahua Seed Group has carried out cooperative research with the Institute of Plant Protection of the Jiangsu Academy of Agricultural Sciences and the Zhenjiang Institute of Agricultural Sciences in the Jiangsu hilly region. After extensive field investigations and studies, and indoor testing and analysis of samples from multiple sites and multiple varieties, it was found that the difference in Fusarium infection rate between "small panicle head" grains and healthy panicle grains was not obvious, while "small panicle head" grains all carried nematodes and normal panicles did not carry nematodes, showing an extremely large difference between the two. Therefore, this indicates that damage from white-tip nematode disease is the direct cause of the "small panicle head" phenomenon.

Using the commercial seed-treatment agents commonly used in production, namely 25% Shibaike, 4.2% Jinfeng, 16% Exianqing, and 95% Padan, seed treatment was carried out on Wuyunjing 7, Zhendao 2, and Wuyujing 3, with conventional cultivation and management adopted. Field trial results showed that for control of "small panicle head," 95% Padan had the best effect, reaching more than 97%; the control effect of 16% Exianqing was about 95%; the control effect of 4.2% Jinfeng was about 90%; and after seed soaking treatment with 5% Shibaike, the control effect was below 15%. Because 16% Exianqing is a mixture of Padan and prochloraz, it has a combined controlling effect on white-tip nematode disease and bakanae disease. From the trial data, it appears to have a better control effect on rice varieties susceptible to white-tip nematode disease, such as Wuyujing 3. Therefore, in the spring rice seed @#@136@#@ season of 2003, Dahua Branch proposed the promotion and application of 16% Exianqing as a mandatory supporting measure for seed treatment. The application area was nearly 4 million mu. In fields treated with this agent, the occurrence rate of "small panicle head" was indeed very low, and there were no disputes caused by seed quality issues, achieving good social benefits.

The research results suggest that at present and for a relatively long period in the future, rice production should not only continue to attach importance to the control of bakanae disease, but also attach great importance to the control of white-tip nematode disease; neither should be neglected. At present, the most economical and effective control method should first be seed soaking treatment, among which 16% Exianqing is the first choice, and it can achieve the best goal of having significant control effects on both bakanae disease and white-tip nematode disease.