Preliminary Research On Prevention Mechanism Of Cyhalodiamide Trunk Injection Against Pine Wilt Disease

For a long time,because of the nosogenesis of pine wilt disease is not clear,there has not found an effective method to prevent the disease.The lack of effective measures lead to the spread of pine wilt disease widely,which has a huge impact on forest ecosystem.The preliminary experiment in woodland shows that trunk injection with cyhalodiamide has a better sffect.Based on the research at home and abroad,this paper has a systematical research which aims at the prevention of pine wilt disease,researching on Cyhalodiamide about toxicity assay and the effect of reproduceon Bursaphelenchus xylophilus,the effect of on needles of Pinus massoniana in physiological and biochemical,conduction distribution of cyhalodiamide in the pine tree after tranking injection,the precaution and treatment test against Pine Wilt Disease in woodland,the results are as follows:1)Filter out the chemical named cyhalodiamide which has a better nematicidal activity.Methods the median lethal concentration(LC₅₀)of seven nematocides for Bursaphelenchus xylophilus was determined by the impregnation method,after 24h‘s treatment,the median lethal concentration(LC₅₀)in order from largest to smallest is imidacloprid>isofenphos-methyl>methomyl>terbufos>emamectin>abamectin>cyhalodiamide.Among them,the median lethal concentration(LC₅₀)of cyhalodiamide is 0.0190 mg/L,the median lethal concentration(LC₅₀)of abamectin is0.0213 mg/L,the median lethal concentration(LC₅₀)of emamectin is 0.0214 mg/L.The effects of the reproduce on Bursaphelenchus xylophilus is positive correlation with their nematicidal activity of these seven chemicals.Experiment on inhibiting ability of the reproduce on Bursaphelenchus xylophilus of seven chemicals shows that cyhalodiamide is the best,abamectin and emamectin are the second.Separated300-900 head Bursaphelenchus xylophilus every dishs from the medium which full of Botrytis sp.after the Bursaphelenchus xylophilus acquisition feeding end which was treatment by cyhalodiamide,abamectin and emamectin alone.The other four are geeater than 15000.2)It is safety trunk injection with cyhalodiamide.Five physiological and biochemical indexes in needles of Pine massoniana changed in varying degrees after trunk injection with cyhalodiamide and emamectin.Two treatment both have significant effect on chrophyll a,insignificant on chrophyll b,while the effect on the soluble sugar content both are suppressive.Two treatment also cause the increase of MDA content in the same system.Two treatment both can lend to the activity increased of PAL,and the effect of cyhalodiamide is more significant.Two treatment both lend to the activity increased rapidly of PAL,then restore to normal level nearly in 16 days.3)Chemical distribute all the plant after the trunk injection of cyhalodiamide,effective treatment and prevention pine wilt disease.Tested the content of cyhalodiamide in Masson pine in different height with high-performance liquid chromatography.The recovery rate was between 84.35%-94.58%,relative standard deviation was between 7.82%-9.37%.The concentration of 2m,4m,6m were 1.25、4.35、0.31μg/g upon the trunk injection point,more highly of the median lethal concentration(LC₅₀)of cyhalodiamide（0.0190 mg/L）,more than that the east and the south had a higher concentration than the west and the north.Field trial showed that cyhalodiamide has better inhibition and toxicity on Bursaphelenchus xylophilus,the dose of cyhalodiamide injection rate had a positive correlation with the surviving rate of masson pine.