Two new 'legumoviruses' (genus Begomovirus; family Geminiviridae) naturally infecting soybean (Glycine max L. Merr.) in Nigeria were molecularly characterized. Based on characteristic symptoms in soybean, the two viruses are provisionally designated as Soybean mild mottle virus (SbMMV) and Soybean chlorotic blotch virus (SbCBV). SbCBV has a bipartite genome, whereas SbMMV has only a DNA A component. The DNA A component of SbMMV is 2,768 nucleotides (nt) long and the DNA A and DNA B components of SbCBV are 2,708 and 2,647 nt long, respectively. In pairwise comparisons, the DNA A component of SbMMV and SbCBV showed 62% nt sequence identity, indicating that these two viruses are distinct. Whereas the DNA A of SbMMV contains two virion- and four complementary-sense open reading frames, that of SbCBV lacks the virus-sense AV2, a signature gene present in 'Old World' begomoviruses. A pairwise comparison with the corresponding nucleotide sequence of other begomoviruses in the databases indicated that SbCBV had a maximum of 74% identity with cowpea golden mosaic virus and SbMMV had a maximum of 65% identity with mungbean yellow mosaic India virus and kudzu mosaic virus. Phylogenetic analysis of the DNA A component of SbCBV and SbMMV together with those of other begomoviruses available in the databases showed clustering of the two viruses within the 'legumovirus' clade of the begomovirus phylogenetic tree. In addition, the DNA A and B components of SbCBV from Centrosema pubescens Benth were found to be identical to those from soybean, indicating that leguminous wild species are a potential alternative host for the virus. Since soybean is an introduced crop, the identification of two distinct begomoviruses naturally infecting soybean in Nigeria suggests the occurrence of 'legumoviruses' in plant species indigenous to Africa and underscores their potential threat to sustainable cultivation of soybean on the African continent.

Integration of alleles for bacterial canker resistance into new sweet cherry cultivars requires information on the sources of resistance in the germplasm. Five market-leading sweet cherry cultivars, 'Rainier', 'Sweetheart', 'Bing', 'Regina' and 'Chelan', advanced selections 'AA', 'BB', 'CC', 'DD', 'EE', 'GG', and 'PMR-1' used as breeding parents in the Washington State University's Sweet Cherry Breeding Program were evaluated. Comparative genotypic disease severity was obtained with three methods of inoculation (leaf wounding with carborundum, cut wounds in leaf mid-rib and shoot tip) on whole plants. Additionally, genotypic data on susceptibility of detached leaves versus fruit and an assessment of the movement of Pseudomonas syringae pv. syringae (Pss) population in inoculated shoots were obtained. Genotype susceptibility was significantly (P B 0.05) influenced by inoculation method, with shoot inoculation providing the best separation of resistance levels among genotypes. A low correlation (r = 0.26, P = 0.21) was observed between disease responses measured on detached leaf versus fruit, while a moderately high correlation (r = 0.50, P = 0.10) was found among bacterial populations in the tissues and in the degree of symptoms expressed. By all comparative methods, the advanced selections, as well as, 'PMR-1', were less susceptible than the market-leading cultivars. Also, movement of Pss from shoot tip inoculation points to the shoot base was not detected for advanced selections 'AA', 'BB', 'DD', and 'EE'. This study reveals that the advanced selections could be potential sources of resistance alleles to bacterial canker. This is the first evaluation of the advanced selections for bacterial canker disease.

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Root rot caused by Fusarium species is a major problem in the pulse growing regions of Montana. Fusarium isolates (n=112) were obtained from seeds and/or roots of chickpea, dry pea, and lentil. Isolates were identified by comparing the sequences of the internal transcribed spacer region and the translation elongation factor 1-α in Fusarium-ID database. Fusarium avenaceum was the most abundant species (28%), followed by F. acuminatum (21%), F. poae (13%), F. oxysporum (8%), F. culmorum (6%), F. redolens (6%), F. sporotrichioides (6%), F. solani (4%), F. graminearum (2%), F. torulosum (2%) and F. tricinctum (0.9%). The aggressiveness of a subset of 50 isolates that represent various sources of isolation was tested on three pulse crops and two cereal crops. Nonparametric analysis of variance conducted on ranks of disease severity indicated that F. avenaceum and F. solani isolates were highly aggressive on pea and chickpea. In lentil, F. avenaceum and F. culmorum were highly aggressive. In barley, F. avenaceum, F. solani, F. culmorum, and F. graminearum were highly aggressive. In wheat, F. avenaceum, F. graminearum, and F. culmorum were highly aggressive. Two F. avenaceum isolates were highly aggressive across all the crops tested and found to be cross pathogenic. One isolate of F. culmorum and an isolate of F. graminearum obtained from chickpea and lentil seed were highly aggressive on barley and wheat. The results indicate that multiple Fusarium spp. from seeds and roots can cause root rot on both pulse and cereal crops. Rotating these crops may still lead to an increase in inoculum levels, making crop rotation limited in efficacy as a disease management strategy.

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