How do fungicides increase yield of spring barley when disease is low or absent?
Field experiments were conducted at two sites over several seasons to investigate how fungicides increase the yield of spring barley when visible disease is low or absent. The fungicide active ingredients prothioconazole (Proline®), pyraclostrobin (Comet 200®) and chlorothalonil (Bravo 500®), believed to differ in their potential physiological effects, were compared. All fungicides increased mean grain weight through the control of visible disease when disease was present post-anthesis, but only prothioconazole and pyraclostrobin significantly increased grain numbers. The increase occurred in the absence of visible disease pre-anthesis and could not be explained by the control of asymptomatic pathogen infection, control of leaf surface saprophytes, increase in leaf growth, or delayed leaf senescence. The evidence points to other direct effects of the fungicides on plant metabolism. A single application of prothioconazole plus pyraclostrobin at T2 can elicit the response and may be justified economically even if disease fails to develop post-anthesis.
Other Titles/Title of Conference
Crop Protection in Northern Britain - Environmental Management and Crop Protection, Dundee, UK
Journal Title/Title of Proceedings
The Dundee Conference: Crop Protection in Northern Britain 2014