Fungicide Screening And Field Application For Moldy Core And Core Rot And Sooty Blotch And Flyspeck Of Apple

With the structural adjustment of China’s apple planting industry and the continuous increase increase in labor costs,the demand for labor-saving no-bagging orchard management technology is increasing gradually.With the application of no-bagging cultivation technology,fruit diseases such as apple sooty blotch and flyspeck,anthracnose,black spot and moldy core will gradually increase in their incidences.In recent years,research has found that apple diseases have diverse and complex pathogens,and the phenomenon of one disease with multiple pathogens is common,which have increased the difficulty of disease control.To address these issues,this study aims to conduct indoor screening of fungicides against various pathogens of major apple fruit diseases in China,and to study the application techniques for controlling different diseases.The main results are as follows:1 Screening of fungicides for apple fruit diseases including sooty blotch and flyspeck,anthracnose,black spot,and moldy coreThe virulences of 9 fungicides against 12 pathogens of 4 diseases,including sooty blotch and flyspeck,anthracnose,black spot and moldy core were determined using the mycelial growth rate method and spore germination method.The results showed that(1)tebuconazole,difenoconazole,carbendazim and mancozeb had strong inhibitory effects on the pathogen of sooty blotch and flyspeck,and pyraclostrobin had a good inhibitory effect,while the inhibition effects of captan,iprodione,thiophanate-methyl and trifloxystrobin were poor.(2)Tebuconazole and difenoconazole had good inhibitory effects on five apple anthracnose pathogens,including Colletotrichum alienum,C.fructicola,C.gloeosporioides,C.siamense and C.orientalis.The inhibitory effects of captan and mancozeb are both poor.Pyraclostrobin had a good inhibitory effect on all Colletotrichum isolates except for its poor inhibitory effect on C.alienum.Carbendazim,trifloxystrobin,thiophanate-methyl and iprodione had better inhibitory effects on only two or three kinds of Colletotricum species.Inhibition assay of spore germination showed that pyrazolidinoxystrobin,trifloxystrobin and mancozeb had good inhibitory effects on C.siamense and C.orientalis,whereas thiophanate-methyl and carbendazim had poor inhibitory effects.(3)Tebuconazole and difenoconazole had good inhibitory effects on the mycelial growth of six black spot and moldy core disease pathogens,including Trichothecium roseum,Alternaria malicola,A.alternata,A.arborescens,A.tenuissima and Phoma glomerata;the inhibitory effects of captan and mancozeb were relatively poor;six fungicides,including iprodione,carbendazim,pyraclostrobin,trifloxystrobin,thiophanate-methyl and captan had good inhibitory effects on two or three kinds of black spot and moldy core pathogens.Spore germination inhibition assay showed that pyraclostrobin and mancozeb had a strong or good inhibitory effect on four pathogenic fungi including T.roseum,A.malicola,A.alternata and A.arborescens.The inhibitory effects of iprodione and thiophanate-methyl on the spore germination of these four pathogens were poor;trifloxystrobin,captan and carbendazim had good inhibitory effects on only two or three of the four pathogens.These results indicate that difenoconazole and tebuconazole have good inhibitory effects on the pathogens of sooty blotch and flyspeck,anthracnose,black spot and moldy core diseases.Pyraclostrobin has good inhibitory effects on the most pathogens.while mancozeb has good inhibitory effects on pathogen spore germination of anthracnose,black spot and moldy core diseases.It is recommended to use difenoconazole,tebuconazole,pyraclostrobin and mancozeb as candidates for the prevention and control of major apple fruit diseases.2 Research on the application technology of fungicides for the prevention and control of apple fruit diseases including sooty blotch and flyspeck,black spot and moldy core diseaseSeven fungicides were selected to be applied once every 15 d,with a total of 5 times,for field experiments on the prevention and control of sooty blotch and flyspeck.The results showed that the control effects of the seven fungicides,including 80% captan WG,70%thiophanate-methyl WG,50% trifloxystrobin WG,10% difenoconazole WG,25%pyraclostrobin SC,25% azoxystrobin WG,and 43% tebuconazole SC,were all above 90%.A field experiment was conducted on the prevention and control of organic sooty blotch and flyspeck.Eight available fungicides were selected and applied once every 15 d,with a total of5 times.The results showed that the control effect of 80% bordeaux mixture WP was 87.52%,99% potassium bicarbonate was 46.90%,80% sulfur WG was 39.63%,whereas control effects for 46% copper hydroxide WG,0.3% matrine AS,10% polyoxin WG,1% cnidiadin AS,100 billion CFU/g Bacillus subtilis WP and 0.5% berberine AS were no more than 25%,indicating poor efficacy.Four fungicides were selected for the interval experiment of sooty blotch and flyspeck prevention and control,including captan,trifloxystrobin,difenoconazole and bordeaux mixture.The results showed that the control effects of difenoconazole and bordeaux mixture were equivalent between 15 d and 20 d of spray interval;The control effect of captan and trifloxystrobin is better for 15 d interval than that for 20 d interval.The control effects of apple black spots and moldy core disease were evaluated after flowering and in the later stage of fruit development.20% pydiflumetofen.difenoconazole EC,25% pyraclostrobin SC and 10% polyoxin WG were selected to be sprayed after flowering for the prevention and control of black spot and moldy core disease.The results showed that the fruit rates of black spot disease were 11.53%,21.89% and 36.04%,respectively,and the fruit rates of moldy core disease were 12.13%,15.60%,and 29.42%,respectively,indicating that pydiflumetofen · difenoconazole have significantly improved the prevention effect against black spot and moldy core disease compared with polyoxin,The preventive effect of pyraclostrobin was also better than that of polyoxin.In order to clarify the effectiveness of fungicides in controlling black spot and moldy core disease in the later stage of fruit development,43% tebuconazole SC and 25% pyraclostrobin SC were selected for control from mid July.The results showed that both tebuconazole and pyrazolin can improve the control effects on the two diseases.Compared with the control group,tebuconazole had a46.09% and 50.07% higher control effect on black spot disease and moldy core disease,respectively.These results indicate that both post flowering and post fruit chemical control can affect the effectiveness of controlling moldy core and black spot disease.