Control Effect of 35%Thiamethoxam-prochloraz FS to Plant Diseases and lnsect Pests at Rice Seedling Stage and Safety Evaluation

Shanliang YAO，Hongyang Ll，Jiachun ZHOU，Junxi ZHANG，Huiling GU，Xingxing SUN

Institute of Agricultural Sciences in Jiangsu Coastal Area，Yancheng 224002，China

Control Effect of 35%Thiamethoxam-prochloraz FS to Plant Diseases and lnsect Pests at Rice Seedling Stage and Safety Evaluation

Shanliang YAO，Hongyang Ll*，Jiachun ZHOU，Junxi ZHANG，Huiling GU，Xingxing SUN

Institute of Agricultural Sciences in Jiangsu Coastal Area，Yancheng 224002，China

The prevention and control effect of 35%thiamethoxam-prochloraz FS to rice thrips and rice bakanae disease and its influence on the quality of rice seedlings were studied.The results show that when 100 kg of rice seeds were coated with 200 g of 35%thiamethoxam-prochloraz FS，the control effects to rice thrips were 93.0%and 84.7%15 and 20 days after sowing，and the control effect to rice bakanae disease was 90.8%30 days after sowing.As 100 kg of rice seeds were coated with 250 g of 35%thiamethoxam-prochloraz FS，the control effects to rice thrips were 98.2%and 94.9%15 and 20 days after sowing，and the control effect to rice bakanae disease was 94.6%30 days after sowing.35%thiamethoxamprochloraz FS is safe to rice seedlings and can effectively promote the growth of rice seedlings.

Thiamethoxam；Prochloraz；Seed coating；Rice thrips；Rice bakanae disease；Prevention

R ice bakanae disease and rice thrips are a main plant disease and an insect pest at seedling stage. In Yancheng region，rice bakanae disease has become more serious in recent years，which has affected the safety of rice production greatly.Rice thrips has a short life cycle and overlapping generations，and it occurs frequently in summer with low temperature and much rainfall，so it is one of major pests at seedling stage. Coating rice seeds with agents can not only kill germs on rice seeds but also prevent rice from suffering bakanae disease and rice thrips at seedling stage，so it is a cost-effective method of control plant diseases and insect pests at rice seedling stage［1］.Therefore，studying a seed coating to control plant diseases and insect pests at rice seedling stage as well as its control effect，rational dose and use security has great significance to rice production.

Thiamethoxam，the second generation nicotinic efficient and low-toxic insecticide with a new structure，can selectively inhibit niacin acetyl cholinesterase receptors ofcentral nervous system of insects and then block normal conduction of the central nervous system，thereby leading to paralysis and death of the insects.It is efficient and safety and has a broad spectrum and a long period of preserving effect，so it can control rice aphid，thrips，plant hopper and other resistant insects［2］.Prochloraz，also a broad-spectrum insecticide，can control ascomycetes and imperfect fungi of many crops effectively through inhibiting biosynthesis of ergosterol，so it can be used as seed coating to control rice bakanae disease and other diseases at seedling stage，and it is also one of main agents used to control rice seed borne diseases［3］.Here the controleffectof35% thiamethoxam prochloraz FS to plant diseases andinsect pests at rice seedling stage and safety evaluation were studied to explore its safe usage technology.

Materials and Methods

Experimental agents

35% thiamethoxam-prochloraz FS，30%thiamethoxam FS，and 0.5% prochloraz FS are from Shaanxi Thompson Bio-Technique Co.，Ltd.，Syngenta Suzhou Crop Protection Co.，Ltd.，and Jiangsu Huanong Seed Coating Co.，Ltd.respectively.

Experiment methods

Experimental treatments

There are six treatments in the experiment，namely mixing 100 kg of rice seeds with 166.6 g of 35%thiamethoxam-prochloraz FS，200 g of 35% thiamethoxam-prochloraz FS，250 g of 35%thiamethoxam-prochloraz FS，200 g of 35%thiamethoxam FS，250 g of 35%prochloraz FS respectively（named A，B，C，D and E），while CK was named F.

Plot layout

The test was conducted in the testing ground of Institute of AgriculturalSciences in Jiangsu Coastal Area.The fertility of loam in the test field is medium，and rice variety is“Teyou 559”.There are six treatments and each treatment has four repetitions，so there are 24 plots with randomized block arrangement，and each plot has an area of 10 m2.Before seeding，the agents were diluted with water and mixed with rice seeds completely（the ratio of agents to rice seed is 1:50）until the agents were distributed on the surface of rice seeds，and then the seeds were dried in the air.The seeds were germinated on May 19 and then sowed on May 21 in 2014.

Table 1 Control effect of 35%thiamethoxam-prochloraz FS to rice thrips

Survey on the control effect of rice thrips［4］

Ten samples were collected from each plot using parallel jump method，and the area of each sampling point was 0.1 m2.Number of live thrips left were surveyed 15 and 20 days after sowing，while the quantity ofrice seedlings suffering from rice thrips was surveyed 20 days after sowing through sampling 50 plants from each point.

lnvestigation of the control effect of rice thrips［5］

100 plants in each point were chosen to investigate number of diseased plants，plant height，root quantity and length，and their fresh weight.

Calculation of pesticide effect

The formulas of pesticide effect are shown as follows:

Emergence rate（%）=（Emergence number/Seeding number）×100

Rate of diseased plants （%）=（Number of diseased plants/Number of investigated plants）×100

Control effect（%）=（1-PT0/CK0）× 100

Insecticidal effect（%）=（1-PT1/ CK1）×100

Proportion of affected seedlings（%）=（Quantity of affected seedlings/ Total quantity of investigated seedlings）×100

Protection effect of seedlings（%）=（1-PT2/CK2）×100

where PT0is rate of diseased plants in treatments；CK0is rate of diseased plants in CK；PT1is number of live insects in treatments；CK1is number of live insects in CK；PT2is proportion of affected seedlings in treatments；CK2is proportion of affected seedlings in CK.Statistical analysis of experimental data was conducted using DMRT method.

Results and Analysis

Control effect of 35%thiamethoxam-prochloraz FS to rice thrips

Results of variance analysis show that F values of insecticidal effect 15 and 20 days after sowing and protection effect of seedlings 20 days after sowing were 840.02，580.78 and 825.94 respectively，higher than F0.01value （5.41），showing the differences between various treatments were extremely significant.As shown in Table 1，15 days after sowing，the insecticidal effect of treatment C （98.2%）was significantly higher than other treatments；the insecticidal effects of treatments B and D were medium，namely 93.0%and 92.5%；the insecticidal effect of treatment A （88.0%）was very significantly lower than treatment A；the insecticidal effect of treatment E was very low.20 days after sowing，the insecticidal effect of treatment C（94.9%）was very significantly higher than other treatments；the insecticidal effects of treatments B and D were medium，namely 84.7%and 82.3%，very significantly higher than treatment A but very significantly lower than treatment C；the insecticidal effect of treatment A was low（75.5%），very significantly lower than treatments C，B and D；the insecticidal effect of treatment E was extremely low.As for the protection effect of seedlings 20 days after sowing，the control effectof treatment C （89.6%）was very significantly higher than other treatments；the control effects of treatments B and D were medium，namely 78.3%and 77.3%，very significantly higher thantreatment A but very significantly lower than treatment C；the control effect of treatment A was low（67.6%），very significantly lower than treatments C，B and D；the control effect of treatment E was very low.

Control effect of 35%thiamethoxam-prochloraz FS to rice bakanae disease

Results of variance analysis indicate that F value of control effect 30 days after sowing was 20.60，higher than F0.01value（5.41），showing the difference between various treatments was extremely significant.According to Table 2，the emergence rate of treatment C was the highest，and its control effect was the best（94.6%），significantly higher than that of treatment A （84.5%）；the control effect of treatment D to rice bakanae disease was very small.

Safety of 35% thiamethoxamprochloraz FS to rice seedlings

Results ofvariance analysis show that the agents had obvious effects on the plant height，root length and fresh weight of rice seedlings，and F values of various indicators 30 days after sowing among the treatments were 354.466，84.208 and 20.214 respectively，higher than F0.01value（4.100），showing that the differences between various treatments were extremely significant.However，the agents had no obvious effects on root quantity，andF valueamongthe treatments was 0.305，smaller than F0.05（2.710），showing that the difference between various treatments was not significant.As shown in Table 3，the plant height，root length and fresh weight of rice seedlings after coating were very significantly higher than that of treatment F.Among these treatments，the quality of rice seedlings in treatment C was the best，and the plant height （119.5 mm）and root length （46.17 mm）were very significantly higher than that of other treatments，while the average fresh weight was also the highest（35.4 g）.

Table 2 Control effect of 35%thiamethoxam-prochloraz FS to rice bakanae disease

Table 3 Effects of 35%thiamethoxam-prochloraz FS on the quality of rice seedlings

Conclusions and discussion

Results of test of pesticide effect for controlling rice thrips show that treatment C （mixing 100 kg of rice seeds with 250 g of 35%thiamethoxam-prochloraz FS）had the best effect for controlling rice thrips，and it had a long period of preserving effect.Results of test of pesticide effect for controlling rice bakanae disease reveal that treatments B and C （mixing 100 kg of rice seeds with 200-250 g of 35% thiamethoxam-prochloraz FS）could improve the emergence rate of rice seeds and control rice bakanae disease effectively.According to a survey on the safety of 35% thiamethoxam-prochloraz FS to rice seedlings，treatments A，B and C（mixing 100 kg of rice seeds with 166.6-250 g of 35%thiamethoxamprochloraz FS）had no obvious damage to rice seedlings and could enhance the emergence rate of rice seeds and the quality of rice seedlings.

In a word，coating 100 kg of rice seeds with 200-250 g of 35%thiamethoxam-prochloraz FS before sowing is safe for rice “Teyou 559”and could improve the emergence rate of rice seeds and prevent rice bakanae disease and rice thrips from occurring. As for seeds with resistance to prochloraz，it is needed to increase its dosage or use other fungicides［6］.The safety and effectiveness of 35%thiamethoxam-prochloraz FS to other rice varieties need to be studied further.

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Responsible editor：Yingying YANG

Responsible proofreader：Xiaoyan WU

35%噻·咪种衣剂对水稻苗期病虫害的防效及安全性评价

姚善良，李红阳*，周加春，张俊喜，顾慧玲，孙星星
（江苏沿海地区农业科学研究所，江苏盐城224002）

田间测定了35%噻·咪FS对水稻蓟马、水稻恶苗病的防治效果和对秧苗素质的影响。结果表明，35%噻·咪FS 200 g/100 kg包衣，播后15、20 d对水稻蓟马的防效分别为93.0%、84.7%，播后30d对水稻恶苗病的防效为90.8%，35%噻·咪FS 250 g/100 kg包衣，播后15、20 d对水稻蓟马的防效分别为98.2%、94.9%，播后30 d对水稻恶苗病的防效为94.6%，两者均对水稻秧苗安全无药害，且能够有效促进秧苗的生长。

噻虫嗪；咪鲜胺；种衣剂；稻蓟马；水稻恶苗病；防治

盐城市农业科技指导性计划（YKN2013018）。

姚善良（1960-），男，江苏盐城人，副研究员，从事农作物生产管理技术研究。*

2015-09-02

Supported by the Guiding Plan for Agricultural Science and Technology of Yancheng City（YKN2013018）.

*Corresponding author.E-mail:yclhy@sina.com

Received:September 2，2015 Accepted:December 7，2015

修回日期 2015-12-07