An investigation of the Barley Yellow Dwarf Virus as a primary or associated cause of premature ripening or "Deadheads" in wheat

Abstract

In two controlled experiments conducted in 1960 and 1961 respectively, the ability of recognized root pathogens to induce premature ripening ("deadheads") of wheat was compared with that of the barley yellow dwarf virus, a hitherto uninvestigated factor in this regard.

In both experiments the heads of virus-infected plants ripened earlier than those of plants inoculated with fungal pathogens, and grain in heads which were not completely sterile was extremely shrivelled. However, it was impossible to decide by visual observation when normal ripening commenced. To overcome this difficulty a formula for the classification of prematurely ripened heads, on a weight per floret basis, was used for the statistical analysis of the results.

On this quantitative basis it was found that the virus significantly reduced the yield of grain (l% level), but there was no interaction between the virus and any of the root-rot fungi. The fungus, Rhizoctonia solani, Kuehn, also significantly reduced the yield in both experiments (5% level) and Fusarium culmorum (W.G.Sm.) Sacc. caused a reduction (5% level) in the 1960 experiment. There was a significant interaction (5% level) between these fungi in the 1961 experiment.

The fungi Ophiobolus graminis Sacc., Helminthosporium sativum Pamm., King & Bakke, and Curvularia ramosa (Bainer) Boed., did not significantly reduce grain yield in either experiment.

All fungi were recovered, but to a varying degree, from the roots of inoculated plants.