Spotted wilt disease of peanut (Arachis hypogaea L.), caused by tomato spotted wilt virus (TSWV), has impacted peanut production for growers in the southeastern United States since the mid‐1990s. No single intervention can manage the disease sufficiently, but when used together, planting date, plant population, and cultivar selection can minimize risk of losses. The effects of planting date, plant population, and cultivar on spotted wilt were assessed in a field experiment over three consecutive years (2010–2012) near Marianna, FL. Evaluation included three visual measures of disease symptoms (rating scale 1–10, disease intensity rating 0–30, and testa symptomology), two measures of stand counts (emerged plants and tap root counts), and immunological assessment of the presence of TSWV in root crowns, pod yield, and grade. There was no effect of planting date on spotted wilt symptoms on foliage, on the testa, or on TSWV infection. Foliar symptoms of spotted wilt were found in all peanut cultivars, with ‘Georgia Green’ displaying more symptoms than the other three cultivars and ‘UFT‐312’ less than other cultivars. Immunological results found 10% or fewer plants of ‘Florida EPTM ‘113’’ and UFT‐312 infected with TSWV compared with 44% for ‘Florida‐07’ and 67% for Georgia Green. Immunological results showed that TSWV is present in about 50% of the plants of the moderately resistant cultivars Georgia Green and Florida‐07, which represent those commonly grown in the southeastern United States. This may indicate high risk for disease loss in those cultivars compared with Florida EPTM ‘113’ and UFT‐312, which possess a different source of resistance and had ≤10% infected plants. The cultivars Florida EPTM ‘113’ and UFT‐312 display a superior level of resistance that may override other factors, such as planting date and plant population, in years with high disease pressure.

Symptoms of spotted wilt of peanut were evaluated in a field experiment over three years (2010–2012) near Marianna, Florida. Assessment included three visual measures of disease and ImmunoStrip (a form of ELISA) testing of root crowns for the presence of Tomato spotted wilt virus (TSWV), the causal agent of spotted wilt in peanut. Foliar symptoms of spotted wilt on a 1 to 10 scale and on a disease incidence rating (DIR) were highly correlated (r = 0.88; p < 0.001). Foliar symptoms were moderately correlated (0.45 < r < 0.54; p < 0.001) with TSWV infection. However, symptoms on the testa were highly correlated with TSWV infection (r = 0.78; p < 0.001). These results indicate that foliar symptomology is less reliable in assessing TSWV infection than testa symptomology. Regression analysis showed that foliar symptoms underestimated the proportion of plants infected by TSWV. Seed inspection may be a good predictor of plant infection and therefore useful in breeding programmes because it is much less expensive than ELISA. Resistance to TSWV infection is characteristic of some resistant peanut genotypes and a lack of testa symptomology could help to identify those genotypes.

Therapeutic/Care Management study, Level IV.

No abstract

SS-AGR-331, a 5-page illustrated fact sheet by B.L. Tillman, M.W. Gomillion, J. McKinney, G. Person, W.D. Thomas, and C. Smith, presents ideas for comparing the performance of varieties on a “farm scale” that will give peanut growers tools to accurately evaluate peanut varieties on their own farm. Published by the UF Department of Agronomy, March 2010.