VIRUS DISEASES OF AMERICAN PASTURE AND FORAGE CROPS

Authors: McLaughlin, Michael; Larsen, Richard; TREVATHAN, LARRY - MISSISSIPPI STATE UNIV; EASTMAN, CATHERINE - ILLINOIS NAT HIST SURVEY; Hewings, Adrianna

Submitted to: American Society of Agronomy Special Publication
Publication Type: Book / Chapter
Publication Acceptance Date: 10/19/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: This book chapter summarizes current knowledge of the viruses and virus diseases of pasture and forage crops in the contiguous 48 states of the USA. The legume and grass crops and the virus diseases of each are described according to the regions where they occur. Coverage of legume crops, with emphasis on alfalfa and true clovers, reflects the relative research effort in the USA on species of this large and diverse plant family. Similarly, coverage of grass crops is relatively greater for well researched cash grain crops like corn and small grains, which may be harvested as forage or grazed, than for pasture species which are exclusively harvested by grazing. Although more land in the contiguous 48 states is covered by forage crops than by all other crops combined, the value of forage crops harvested through grazing is difficult to reliably estimate. Similarly, although the incidence of virus diseases in forage and pasture crops, although studied relatively little compared to other crops, is relatively very high, especially among legumes. Despite the high incidence of virus diseases, little is known of the effects of most virus diseases on forage crops and even less is known of their economic impact. The potential impact of these largely unrecognized diseases is demonstrated by examples of a few diseases which have been studied more thoroughly. These inlcude peanut stunt virus disease which limits white clover persistence and productivity in the Southeast, alfalfa mosaic virus disease of alfalfa in the Northwest and Midwest, and barley yellow dwarf virus disease which affects important grass species throughout their range.

Technical Abstract: This book chapter summarizes current knowledge of the viruses and virus diseases of pasture and forage crops in the contiguous 48 states of the USA. The legume and grass crops and the virus diseases of each are described according to the regions where they occur. Coverage of legume crops (Family Leguminosae), with emphasis on alfalfa (Medicago sativa L.) and true clovers (Trifolium spp.), reflects the relative research effort in the USA on species of this large and diverse plant family. Similarly, coverage of grass crops is relatively greater for well researched cash grain crops like corn and small grains, which may be harvested as forage or grazed, than for pasture species which are exclusively harvested by grazing. The viruses affecting each crop are identified and described and the epidemiology and control of the diseases is discussed. Viruses of legume crops include alfalfa mosaic, bean leafroll, bean yellow mosaic, clover yellow mosaic, clover yellow vein, pea enation mosaic, pea streak, peanut stunt, red clover vein mosaic, soybean dwarf, and white clover mosaic. Viruses of grass crops include agropyron mosaic, barley yellow dwarf, brome mosaic, johnsongrass mosaic, maize chlorotic mottle, maize dwarf mosaic, panicum mosaic, ryegrass mosaic, soilborne wheat mosaic, sorghum mosaic, sugarcane mosaic, and wheat streak mosaic. The potential impact of these largely unrecognized diseases is demonstrated by examples of a few diseases which have been studied more thoroughly. These include peanut stunt virus disease which limits white clover persistence and productivity in the Southeast, alfalfa mosaic virus disease of alfalfa in the Northwest and Midwest, and barley yellow dwarf virus disease which affects important grass species throughout their range.