Relationships among symptoms of spotted wilt disease of peanut and their potential impact on crop productivity and resistance breeding

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.