Fungicide application improves seed yield of perennial ryegrass upon infection with stem and crown rust fungi

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Rust epidemics may have detrimental effects on seed yield in perennial ryegrass (Lolium perenne L.). Field trials comprising two cultivars of perennial ryegrass were established to evaluate the impact of stem rust (Puccinia graminis subsp. graminicola) and crown rust (Puccinia coronata f.sp. lolii) on seed yields. Two or three applications of a mixture of fungicides (epoxiconazole plus boscalid mixed with pyraclostrobin) provided effective control of both stem rust and crown rust and positive seed yield responses, although differences were observed between cultivars. For stem rust, two fungicide applications led to variable levels of disease control (from 86% to 100% for cv. Esquire and from 15% to 98% for cv. Calibra), whereas three applications resulted in 100% disease control in both cultivars. Two fungicide applications were sufficient for an appropriate control of crown rust on both cultivars (approx. 98–100% disease control). Generally, two fungicide applications resulted in an increase in seed yield for both cultivars. On average, an increment of 4% and 15% was observed in Esquire and Calibra equivalent to 86 kg/ha and 352 kg/ha, respectively. Three fungicide applications provided an increase of 2% and 17% in Esquire and Calibra equivalent to 45 kg/ha and 434 kg/ha, respectively. Significant differences were only observed in Calibra after two or three fungicide applications. Additionally, results from semi-open field trials testing for preventive and curative effects showed that tebuconazole, pyraclostrobin, picoxystrobin, azoxystrobin, and a mixture of epoxiconazole, pyraclostrobin, and boscalid fungicides resulted in high efficacy in reducing stem rust occurrence, the latter resulted in the largest preventive and curative effect. Experiences from field and semi-open field trials indicated that fungicide mixtures with contrasting modes of actions, e.g., triazoles, strobilurins, and SDHIs, and applied close to the time of inoculation provided an effective control of rust fungi and increased seed yield in perennial ryegrass.

TidsskriftCrop Protection
Antal sider7
StatusUdgivet - 2020

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