Evaluation of eight novel fungicides against potato late blight based on CARAH warning system
[Objective]The study aimed to investigate the effectiveness of eight novel fungicides on the control of potato late blight and provide recommendations for rational use of these fungicides in effectively controlling the disease.[Method]Under the guidance of the optimized CARAH warning system,randomized block design was employed to assess the effectiveness of six chemical and two botanical fungicides a-gainst potato late blight in the spring potato planting regions of Yunnan,using the main variety Cooperation 88.The efficacy of various fungi-cides in controlling late blight on potato foliage and stems was evaluated.Late blight was sprayed once for each completed generation of infec-tion,starting before the earliest disease plant predicted by the system.[Result]According to the CARAH warning system,the emergence of the central late blight plant on Cooperation 88 was predicted around 2nd to 4th,July.In fact,field surveys showed that late blight of control plants occurred on 3rd,July.The optimized warning system could predict the emergence time of central disease plant with 100％accuracy.Under the guidance of the warning system,late blight was sprayed 9 times from the first spray on 1st,July to last spray on 30th,August.Com-pared with the standard control,the investigation of potato foliage and stem late blight showed all eight fungicides demonstrating significant control effectiveness against both potato foliage and stem late blight with exceeding 85.50％and 87.50％,respectively.The 31％famoxa-done-oxathiapiprolin recorded the highest efficacy at 95.00％and 96.75％,respectively.The 0.3％eugenol exhibited a higher efficacy of 90.50％and 92.50％,respectively.The application of 8 fungicides under the guidance of the CARAH warning system significantly increased potato yields.And the yield increase ranged from 116.29％to 257.69％.Although the commodity rate of control potato was only 38.27％,spraying different fungicides resulted in a higher commodity rate of Cooperation 88,ranging from 71.60％to 79.94％.[Conclusion]The pre-diction of CARAH warning system is highly consistent with the actual occurrence of late blight in the field,and can precisely guide the man-agement of late blight.All six chemical and two botanical fungicides are tested and found to be highly effective against potato late blight.These fungicides are recommended for potato production.Specifically,the botanical fungicide eugenol is found to be an excellent substitute for chemical fungicides,significantly reducing the dosage of chemical fungicides for late blight management.
Potato late blightChemical fungicidesBotanical fungicideControl efficacyCARAH warning system
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