Studies On Occurrence Regularity And Integrated Control Of Walnut Anthracnose

In this study,based on investigation of the occurrence of walnut anthracnose and the reasons of breaking,then combine the means of chemical prevention,determine the effect of fungicide against walnut isolates by mycelial growth rate test and spore germination assay in laboratory.At the same time,conduct test to prevent walnut anthracnose in the fields.The purpose of the study is to clear the regularity of walnut anthracnose occurrence and the reasons,and screen out the effective fungicide to prevent walnut anthracnose.The study results are as following:(1)From the results of the survey that the extent of walnut anthracnose in Xinmian Town Shimian County,the area of walnut anthracnose's damage is great,the disease is serious.Before July,the range of damage is small;after July,the disease rate is increasing quickly,especially on fruits and leaves.According to investigation on 25 August,the rate of the disease is 76.74 percent on fruits,70 percent on leaves,33.31 percent on twigs;the disease index is 53.76 on fruits,30 on leaves,16.92 on twigs.(2)By investigating the reasons of the occurrence of the walnut anthracnose,we find it is related to the height altitude,environment,walnut varieties,cultivation and management,growth and development.? the height is higher,the disease of walnut anthracnose is more serious.the disease rate:the low altitude(26.67%)<the intermediate altitude(43.33%)<the high altitude(53.33%);the disease index:the low altitude(22)<the intermediate altitude(26.67)<the high altitude(31.33).? the environment is the worse,the disease of walnut anthracnose is more serious.the disease rate:the good environment(23.33%)<the better environment(30%)<the bad environment(56.67%);the disease index:the good environment(26)<the better environment(30.67)<the bad environment(39.33).? the walnut varieties have the lower resistance,the disease of walnut anthracnose is more serious,the disease rate:the walnut variety“Yanyuanzao"(23.33%)<the walnut variety"Chuanzao 1"(33%)<the walnut variety "Chuanzao 2"(33.33%)<the walnut variety "Shimianjuxing"(40%)<the walnut variety "Xiangling"(66.67%);the disease index:the walnut variety "Yanyuanzao"(16.67)<the walnut variety"Chuanzao 1 "(19.33)<the walnut variety“Chuanzao 2"(23.33)<the walnut variety "Shimianjuxing"(33.33)<the walnut variety "Xiangling"(40.67).?the cultivation and management is more extensive,the disease of walnut anthracnose is more serious.the disease rate:the good cultivation and management(26.67%)<the better cultivation and management(33.33%)<the extensive cultivation and management(60%);the disease index:the good cultivation and management(16.67)<the better cultivation and management(20.67)<the extensive cultivation and management(33.33).? the growth and development is more weaker,the disease of walnut anthracnose is more serious.the disease rate:the strong growth and development(30%)<the general growth and development(33.33%)<the weak growth and development(43.33%);the disease index:the strong growth and development(14.67)<the general growth and development(21.33)<the weak growth and development(30).(3)Twenty-five fungicide formulas screening was determined in the laboratory,the result shows that:five fungicide formulas including 100%streptomycin 3 000 times diluted,25%prochloraz 500 times diluted,25%prochloraz 1 000 times diluted,70%thiophanate-methyl 500 times diluted,50%thiram 500 times diluted strongly affected the growth of mycelium.Among which,four fungicide formulas including 100%streptomycin 3 000 times diluted,25%prochloraz 500 times diluted,70%thiophanate-methyl 500 times diluted,50%thiram 500 times diluted were most efficient on exhibiting spore germination.100%streptomycin 3 000 times diluted,25%prochloraz 500 times diluted,70%thiophanate-methyl 500 times diluted,50%thiram 500 times diluted strongly affected both the growth of mycelium and exhibiting spore germination.(4)From the experiment results of using three kinds of fungicide formulas and three periods to prevent walnut anthracnose of three walnut varieties in the fields.The result shows that:concluding from the result of the study,formula one and formula two are the best fungicide formulas to prevent walnut anthracnose.If combining with economic cost and the influence of environment,this study's best period of using fungicide is one month.The best fungicide formula to prevent walnut anthracnose is formula two,which is the group of 70%thiophanate-methyl(WP)22 g+50%thiram(WP)30g.