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Pea seed-borne mosaic virus (PSbMV), a nonpersistently aphid-transmitted potyvirus, has been reported in field pea (Pisum sativum L.)-growing regions worldwide. In 2014, PSbMV was first identified in field peas in North Dakota, U.S.A. Susceptibility and yield losses attributed to PSbMV infection are influenced by viral pathotype and host genotype. Isolate ND14-1, recovered from North Dakota infected seed and identified as pathotype 4 (P4), was mechanically inoculated onto 20 field pea cultivars under greenhouse conditions. PSbMV susceptibility, number of seeds and pods per plant, yield, symptom expression, and PSbMV seed transmission rates were assessed by cultivar. A risk assessment was developed based on cultivar susceptibility, yield reduction, and PSbMV seed transmission. Risk factors were weighted based on perceived importance to commercial field pea producers. Three cultivars were classified as low risk, seven cultivars were classified as intermediate risk, and 10 cultivars were classified as high risk. Two of the low-risk cultivars, Aragorn and Cruiser, were confirmed to be resistant to this isolate of PSbMV. Cultivar Arcadia was susceptible to PSbMV infection with mild expression of symptoms, but was classified as low risk based on a low seed transmission rate and diminished yield losses. This risk assessment could prove a useful tool for growers in field pea cultivar selection where PSbMV is prevalent.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is a damaging seed-transmitted disease of dry beans that causes reduced seed quality and yield. Seed-to-seedling transmission of C. lindemuthianum has been documented as high as 15% in asymptomatic seeds under greenhouse conditions. Increasing pathogen colonization in seeds has been correlated with increasing anthracnose seed symptoms via quantitative PCR (qPCR), but stem colonization has not been quantified. Previous studies also have characterized seed yield and quality losses caused by planting C. lindemuthianum–infected seeds, but none evaluated the effect of growing asymptomatic seeds on disease and plant development under field conditions. A real-time qPCR assay was developed in this study and used to detect C. lindemuthianum in the stems of seedlings as early as 15 days after planting. Field trials measured the seed-to-seedling transmission of C. lindemuthianum across levels of anthracnose symptoms in seeds ranging from healthy to severely discolored. Results from these two field trials indicated that emergence and yield decreased and foliar symptoms, pathogen detection, and incidence of symptoms on progeny seeds increased as the severity of infection in planted seeds increased. In both years, planting asymptomatic seeds resulted in higher anthracnose severity than planting healthy seeds. Yield, seed weight, and incidence of symptoms on progeny seeds were not higher in asymptomatic seeds than in healthy seeds in 2014, when moderate disease pressure was observed. However, these factors were significantly different in 2015, when anthracnose severity was driven up to 75% by conducive weather conditions. This serves as a strong warning to growers that planting seed grown in a field where anthracnose was present, even if those seeds are asymptomatic, can result in yield and quality losses. Planting certified dry bean seed is always recommended.