Wheat High plains virus can be transmitted by seeds of sweet maize
Research has been done in USA to assess the potential for seed transmission of Wheat High plains virus (EPPO Alert List). It is recalled that, in 1993, an unknown disease was noticed in maize crops (Zea mays) in Colorado, Idaho, Kansas and Texas (US). Electron microscopy and molecular data then supported the involvement of a new virus in this disease. In Idaho, the disease was observed in 8 fields of sweet maize (304 ha) with an incidence ranging from 30 to 85%, and 145 ha were abandoned due to the disease. From 1994 to 1996, the disease also developed in several sweet maize fields in southwestern Idaho. It was considered that this was essentially due to natural spread by the wheat curl mite (Aceria tosichella). Sweet maize seeds from 13 infected fields and research plots in Idaho, Colorado and Nebraska were collected and sown in pots in the glasshouse. Precautions were taken to avoid the presence of Aceria tosichella (e.g. experiments done in winter and early spring when mites are not likely to be present). Leaf samples were then collected from plants and tested by ELISA. Out of 46,600 seeds planted, 38,473 seedlings emerged, and 3 were found positive. The presence of Wheat High plains virus was confirmed by further tests. The authors felt that these results show that Wheat High plains virus can be transmitted by seeds of sweet maize under controlled conditions, although at a very low level.
Sources
Forster, R.L.; Seifers, D.L.; Strausbaugh, C.A.; Jensen, S.G.; Ball, E.M.; Harvey, T.L. (2001) Seed transmission of the High plain virus in sweet corn.
Plant Disease, 85(7), 696-699.