Fungicides applied directly to the seed protect against seed-borne disease, but are limited in their ability to protect the plant from soil-borne pathogens. In the absence of an in-furrow fungicide, the plant may encounter soil-borne pathogens as the root and stolon structures expand beyond the area protected by the seed treatment.
Rhizoctonia solani attacks tubers, underground stems and stolons of plants, causing diseases such as black scurf and stem canker. The pathogen is typically introduced into fields on potato seed tubers or through contaminated soil. Sclerotia in soil or on seed tubers germinate, and the resulting mycelium colonizes plant surfaces where nutrients are available. Cold and wet soils also favor disease development. The most damaging phase of the disease occurs underground and often goes unnoticed. Severe lesions are large and sunken. If the fungal lesion expands quickly, relative to the growth of the plant, the stolon or stem can be girdled and killed.
Soil applied fungicides, such as Elatus fungicide, can help protect potatoes from diseases such as black scurf and stem canker. Elatus applied in furrow can help prevent stand loss, post-emergence sprout death, disproportionate tuber sizing, early loss of stolons and girdling.