A rapid seedling based screening technique to assay tobacco for resistance to Phytophthora nicotianae

AbstractBlack shank caused by Phytophthora nicotianae is a serious root and stem disease of cultivated tobacco worldwide. In this study, a rapid seedling‐based screening technique was developed to evaluate tobacco cultivars for resistance to P. nicotianae. This technique was compared with a stem inoculation technique commonly used on adult plants. The overall aim was to develop an improved and rapid technique that could also be used to characterize races of P. nicotianae. A strong positive correlation was found between results of the seedling assay and adult plant trials for all isolates and cultivars tested. Furthermore, P. nicotianae isolates could be characterized as race 0 or 1 using both stem inoculation and the rapid seedling assay. This assay will facilitate rapid and large‐scale screening for black shank resistance and therefore has the potential to reduce yield losses because of this disease in the field.