Survey ofBarley Yellow Dwarf VirusandCereal Yellow Dwarf Viruson Three Perennial Pasture Grasses in Florida

Abstract

Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV) are two important aphid-vectored viruses of small grains worldwide. In the Southeastern U.S., there is an absence of wheat, oat and barley during summer months. Thus, the availability of alternative summer hosts for the viruses and their vectors in the field is potentially critical for yellow dwarf epidemiology in the southeast. A 2-year survey of bahiagrass (Paspalum notatum Flugge), limpograss [Hemarthria altissima (Poir) Stapf & Hubb.], and eastern gamagrass (Tripsacum dactyloides L.) populations from the North Florida Research and Education Center, Marianna, FL. showed that bahiagrass and limpograss can act as alternative summer hosts of BYDV-PAV and CYDV-RPV. Additionally, bahiagrass also was shown to harbor BYDV-MAV. The finding of BYDV and CYDV on bahiagrass and limpograss indicates the potential of these perennial pasture grasses to act as “green bridges” between small grain seasons for yellow dwarf viruses. For bahiagrass and limpograss to act as sources of inoculum in yellow dwarf epidemiology, one or more aphid species will have to transmit the virus from these grasses to commercial small grains. However, very few aphids were collected and no known B/CYDV vector was found on these grasses in the 2 years of sampling. Sipha flava (Forbes), an aphid not listed as B/CYDV vector, was the only species collected on bahiagrass. Additionally, in B/CYDV transmission studies reported here, winged R. padi did not survive on bahiagrass and failed to transmit B/CYDV from bahiagrass to oats or from oats to bahiagrass.