American wildrice (Zizania
palustris) cultivars grown in Minnesota can
be affected by stem rots caused by Nakataea sigmoidea (=Sclerotium
oryzae) and Bipolaris oryzae. Genetic differences between cultivars have not
previously been characterized. Likewise, neither heritability nor gain from
selection have been estimated. Variety trials were inoculated with both of
these fungal organisms to estimate broad-sense heritability for stem rot
symptoms. Replicated half-sib families were inoculated and rated for stem rot
severity. Heritability and gain from selected were estimated for both stem rot
and foliar disease, and correlations between these and other traits were
estimated. Alternative inoculation methods were compared for effectiveness in
producing consistent results for severity ratings. Methods of evaluating stem
rot severity are compared and discussed. Since Sclerotium oryzae also causes stem rot in rice (Oryza sativa), methods of inoculating and evaluating stem rot in
wildrice may have applicability to rice.