Rapid Detection Method For Capsicum Anthracnose And Screening Of Synergistic Effective Fungicides

Pepper anthracnose is one of the main fungal diseases in pepper production,which seriously affects the yield and quality of pepper.This study identified the types of pepper anthracnose in Guizhou Province,established a rapid detection method based on LAMP technology,developed a rapid selection kit of fungicides based on color reaction,and screened out highly efficient new synergistic combinations to prevent and control different pathogens.Designed to provide a reference for the scientific medication of pepper anthracnose.The main conclusions of this article are as follows:1.The types of pepper anthracnose pathogens in Guizhou Province were isolated,and establish a rapid detection kit of pepper anthracnose pathogens based on LAMP.Tissue separation method was used to isolate and identify the pepper anthracnose samples collected from Guiyang and Zunyi by Koch’s rule,colony morphology and r DNA-ITS sequence analysis.They were identified as capsicum anthracis,which were Colletotrichum acutatum,Colletotrichum scovillei and Colletotrichum sp.Colletotrichum acutatum,respectively.Colletotrichum sp.was a suspected new species.Based on the LAMP technology,four LAMP primers were designed with the ITS sequence of the transcribed spacer in the anthracnose of pepper as the target gene,and the conditions such as the ratio of primers,reaction time and reaction system were optimized.The specific test results of the test kit for pepper anthracnose showed that the LAMP system was amplified for 60 min at the optimal reaction temperature of65℃.The pepper anthracnose showed green and blue under the action of indicators calcein and hydroxynaphthol blue,respectively.The reaction result was positive.While the other 8 tested strains and the blank control showed orange yellow and purple,respectively,all were negative reactions,no amplified bands appeared,indicating that the LAMP detection primer had strong specificity,which provides an efficient method for the detection of anthracnose Convenient,specific and visual detection method.2.A rapid drug selection kit for pepper anthracnse was developed.According to the principle of normal distribution of fungicide sensitivity of pepper anthracnse pathogens,the sensitivity baselines of pepper anthracnose to prochloraz and thiophanate-methyl in Guizhou Province were established,which were 0.0710±0.0133 mg/L and 0.7641±0.1508 mg/L,respectively.Based on the sensitive baseline,using bromocresol purple as an indicator,a rapid selection kit for pepper anthracnose fungicide was developed,consisting of 2%bromocresol purple solution,0.088 mg/L or 0.175 mg/L or 0.35 mg/L kit of prochloraz and PDA medium,reagent consisting of2%bromocresol purple solution,0.45 mg/L or 0.9 mg/L or 1.8 mg/L thiophanate-methyl and PDA medium box.The results show that field pathogens of pepper anthracnose showed yellow on the kit of 0.35 mg/L prochloraz,indicating that they had developed resistance,and orange red on the kit of 0.088 mg/L prochloraz,indicating that they were more sensitive;at 1.8 mg/L The yellow color on the thiophanate-methyl kit indicates that resistance has been developed,and the orange red on the 0.45 mg/L thiophanate-methyl kit indicates they were more sensitive.3.In order to screen of synergistic effective fungicides,the sensitivity of three pathogens of pepper anthracnose 17 fungicides was investigated by the mycelial growth rate method.The results show that 17 fungicides had a certain inhibitory effect on pepper anthracnose.The inhibition effect of prochloraz,fenoxan,pyraclostrobin,and tebuconazole was higher with the EC₅₀ values of 0.06 mg/L,0.49 mg/L,0.51 mg/L and 0.68 mg/L,respectively,followed by syringare and pyraclostrobin,with the EC₅₀values of 1.34 mg/L and 1.38 mg/L.But the inhibition effect of oximetrobin,pyraclostrobin,and fluoxastrobin was lower,with the EC₅₀ values of 12.01 mg/L,13.42 mg/L and 14.24 mg/L,respectively.The synergistic combination showed that the obviously active component ratio of tebuconazole and pyraclostrobin,picoxystrobin and prochloraz was 1:1 and 1:3,with the EC₅₀ values of 0.37 mg/L and0.05 mg/L,the SR of 2.06 and 1.72,respectively.