Three pea seedborne mosaic virus later unless otherwise mentioned. pathotypes from pea and lentil germ plasm. Plant Disease 70:783-786. Virus and CIP purification. The method of Yeh and Gonsalves (18) was Three isolates of pea seedborne mosaic virus (PSbMV), P-l and P-4 from pea (Pisum sativum) and used to purify CIP from plants infected L-l from lentil (Lens culinaris) germ plasm accessions, were distinguished by their capacity to infect with isolates P-1 and L-I. The two virus pea genotypes. Resistance in peas was isolate-specific. Resistance to the L-l isolate was associated with bean yellow mosaic virus resistance and also with a delayed reaction to isolate P-4. Several pea isolates were purified according to the germ plasm accessions were resistant to all three isolates. All isolates were infective to 26 genetic method of Dougherty and Hiebert (5) lines of chickpea (Cicer arietinum), a new host, but not to 12 accessions of pigeon pea (Cajanus with some modifications. Infected shoots cajan). Antisera produced against the cytoplasmic inclusion protein induced in peas by P-l and L-I of Ranger pea were harvested and frozen were useful in detecting infections by the indirect ELISA method and were generally more sensitive 24-28 days after inoculation. Tissues than antisera to the viral protein. were homogenized in cold potassium phosphate buffer (0.5M, pH 7.5, with 0.1% Na 2 SO 3 and 0.01 M ethylene

In Pisum sativum, two independently inherited single recessive genes were found to confer resistance to the same pathotype of pea seed-borne mosaic virus from lentil (PSbMV-L1). The gene sbm-2, present in the domestic cuttivar Bonneville, was determined to be closely linked to mo, which conditions resistance to bean yellow mosaic virus and watermelon mosaic virus 2 and is known to be located In Pisum linkage group 2. The second gene, sbm-3, was found in PI 347492, a bean yellow mosaic virus-susceptible line from India, and apparently is located in a different linkage group. Both genes, independently of each other, confer resistance to PSbMV-L1, but whether they are repetitive entities remains to be determined. Pea seed-borne mosaic virus (PSbMV) was characterized by Musil in Czechoslovakia and by Inouye in Japan. 1518 In 1968, this virus was found in the United States, 917-22 and since then, its presence has been ascertained in several other countries. 13 In searching for sources of resistance to PSbMV, Stevenson and Hagedorn, Baggett and Hampton, and Hampton and Braverman screened hundreds of accessions of Pisum sativum L. with the standard strain (PSbMV-ST) and found resistant germ plasm among foreign introductions. 312-23 Hagedorn and Gritton determined that, in PI 193586 and PI 193835 accessions from Ethiopia, resistance was conferred by a single recessive gene (sftm). 8 Recently, Goodell and Hampton and Ashby et al reported that PSbMV isolates from lentils (PSbMV-L) and from New Zealand peas (PSbMV-NZ) were unable to infect pea cultivars possessing mo, the gene for resistance to bean yellow mosaic virus (BYMV). 26-24 Alconero et al demonstrated that resistance to PSbMV-Pl and PSbMV-P4 (from pea), and to PSbMV-Ll (from lentil), was pathotype specific. 1 Consequently, it appears that in P. sativum, there are distinct genetic entities for resistance to PSbMV, with each factor capable of controlling only a specific pathotype of the virus. Alone or in combination, these resistance factors were found in a number of plant introductions (Pis), mostly from. India and Ethiopia. 1 '"

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Eighty-one Trifolium ambiguum accessions, representing the germ plasm collection for that br omide t soil wa and wit species, and selected accessions of T. alpestre, T. hybridum, T. medium, T. pratense, and T. repens methyl bromide at 76.4 kg/ha and kept were evaluated in the field from 1981 through 1983 for overall vigor, persistence, yield, and covered with plastic for 48 hr. Threedays susceptibility to virus infections. Infections by bean yellow mosaic virus, clover yellow vein virus, before planting, disulfoton, fensulfothion, white clover mosaic virus, and red clover vein mosaic virus were common in many accessions. and benomyl were incorporated into the Accessions of T. ambiguum and T. medium were the least affected by virus infections and persisted soil at 1.1, 8.4, and 48.9 kg/ha, better than other species. Symptoms of virus infection appeared early and spread rapidly in respectively. Foliar sprays of triadimefon, accessions of T. hybridum, T. pratense, and T. repens and were associated with loss of vigor and applied monthly, and methoxychlor, death of most of the plants by 1983. T. alpestre accessions were only moderately affected by viruses malathion, and benomyl applied biweekly, but showed neither the rapid growth of T. hybridum, T. pratense, or T repens nor the persistence of were used throughout each growing T. ambiguum or T. medium. Several accessions of T. ambiguum compared favorably with season at 0.14, 3.4, and 0.51 kg/ha, developed cultivars of T. pratense after 2 yr of field exposure.respectively. Disulfoton was broadcast