Severely stunted cowpea plants have been found in similar to those observed on field plants. When inoculated Georgia fields in each of the last 4 yr, 1974 to 1977. Leaves of singly, each virus caused a relatively mild disease; leaves had the stunted plants were small, mottled, blistered, and a mild mottle, and plants displayed moderate stunting during malformed. The causal agent was sap-transmitted to the early infection period and almost no stunting at cowpeas. Several other hosts were susceptible and back senescence. In a greenhouse study, CMV reduced yield of inoculation from Cucumis sativus and Cassia obtusifolia to California Blackeye seed by 14.2% and BICMV by 2.5%. cowpeas established the presence of two viruses: cucumber Yield on doubly infected plants, however, was reduced mosaic virus (CMV) from C. sativus and a potyvirus, later 86.4%. Furthermore, the double infection reduced leaf identified as blackeye cowpea mosaic virus (BICMV), from weight, stem weight, and root weight by 94.3, 89.3, and C. obtusifolia. When seedlings of California Blackeye 87.3%, respectively. Seed and aphid transmission studies cowpeas were inoculated simultaneously with CMV and showed that the viruses can be transmitted from doubly-BICMV, a strong synergistic reaction occurred; the primary infected plants to cause single or double infections in and first two trifoliolate leaves became necrotic within 5-10 cowpeas. The name cowpea stunt is proposed for the disease days and usually abscised. Subsequent leaves were severely caused by the synergistic interaction of CMV and BICMV. diseased but free of the necrosis; the symptoms then appeared

SUMMARY Groundnut (Arachis hypogaea) plants from Nigeria with chlorotic rosette disease contained a manually transmissible virus, considered to be a strain of groundnut rosette virus (GRV(C)). GRV(C) infected nine out of 32 species in three out of nine families. It caused local lesions without systemic infection in Chenopodium amaranticolor, C. murale and C. quinoa, and systemic symptoms in Glycine max, Nicotiana benthamiana, N. clevelandii and Phaseolus vulgaris as well as in groundnut. Some ‘rosette‐resistant’ groundnut lines were also infected. GRV(C) was transmitted by Aphis craccivora, but only from groundnut plants that were also infected with an aphid‐transmissible second virus, which was not manually transmissible and was considered to be groundnut rosette assistor virus (GRAV). Plants infected with GRAV contained isometric particles c. 25 nm in diameter which were detectable by immunosorbent electron microscopy on grids coated with antisera to several luteoviruses, especially with antisera to bean leaf roll, potato leafroll and beet western yellows viruses. No virus‐like particles were observed in extracts from plants infected with GRV(C) alone. A single groundnut plant obtained from Nigeria with symptoms of green rosette contained luteovirus particles, presumed to be of GRAV, and yielded a manually transmissible virus that induced symptoms similar to those of GRV(C) in C. amaranticolor but gave only mild or symptomless infection of N. benthamiana and N. clevelandii. It was considered to be a strain of GRV and designated GRV(G).

No abstract

No abstract