Resistance Detection And Management Of Grape Ripe Rot Causing By Colletotrichunr Gloeosporioides

Ripe rot is one of the important fungal diseases on grape, mostly caused by Colletotrichumgloeosporioides. The main fungicides to control grape ripe rot are benzimidazole fungicides and steroldemethylation inhibitors (DMIs).A total of108isolates of C. gloeosporioides collected from grape fields in Lin’an, Zhuji andJinhua,the important grape producing regions in Zhejiang province for evaluating their resistances tothiophanate-methyl and tebuconazole by method of distinguishing dosage. And the β-tubulin gene ofthiophanate-methyl sensitive and thiophanate-methyl resistant strains were amplified and sequenced.The frequency of resistance to thiophanate-methyl is37.04%. All resistant isolates belong to high levelresistance(Ben HR), and showed double-resistance to carbendazim and diethofencarb. Sequencealignment indicated a substitution of TAC for TTC at codon200of β-tubulin gene in Ben HR isolates,which led to a substitution of tyrosine for phenylalanine at codon200. Thirty-three (30.56%) isolateswere detected belong to low-level resistance. Results suggested that C. gloeosporioides had seriousresistance to thiophanate-methyl and diethofencarb in Zhejiang. Moreover, resistance to tebuconazolealso developed quickly.Sensitivity of C. gloeosporioides to pyraclostrobin and kresoxim-methyl were determined byusing method of mycelial growth inhibition. Results indicated that the sensitivity to pyraclostrobin wassignificantly higher than to kresoxim-methyl. Further study was carried out to establish the sensitivitybaseline of C. gloeosporioides to pyraclostrobin.The EC50values of pyraclostrobin ranged from0.0753to7.6034μg/mL with the average value of4.7766±3.7237μg/mL. SHAM，a specific inhibitor ofaltemative oxidase, showed notable synergistic interaction with pyraclostrobin against mycelial growthof C. gloeosporioides. In presence of50μg/mL SHAM, the EC50(EC50Q+S) ranged from0.0753to7.6034μg/mL, with a average value of1.9147±1.6039μg/mL. The factor value (F1=EC50Q/EC50Q+S)for the impact of alternative respiration on sensitivity to pyraclostrobin ranged from0.35to31.43，witha average of3.78.These results showed that the alternative respiration plays an important role in C.gloeosporioides energy metabolism during mycelial growth..Randomly selected LA-38was parental strains. And three resistant mutants of C. gloeosporioidesto pyraclostrobin were obtained by UV-induced. Resistance level of risitant mutants R1, R2, R3were 2.7739，7.3785and4.3702,respectively, with the average value of4.8409. Further, comparisons inmycelial growth, sporulation,spore germination and pathogenicity showed that resistant mutants have ahigher fitness than parental strains. From the experiment results, we can infer pyraclostrobin has ahigher resistance risk in control grape ripe rot. We should prevent drug resistance strictly, and avoid thecontinuous use of a single agent in production.Control of C. gloeosporioides on grape fruits by several mixture of fungicides was tested.Resultsshowed that pyraclostrobin of20μg/mL mixed with Huai nongte of2000times have the best efficacy.The effect of pyraclostrobin mixed with Huai nongte is better than pyraclostrobin and prochloraz mixedin a3:1ratio.