Over the last week, black shank was reported in several tobacco crops across Georgia.
Weather conditions since prior to transplanting have resulted in repeated periods of wet soil conditions which have caused the soil temperatures to be slow to warm and creating a perfect environment for infection by and growth of black shank in water-damaged tobacco roots and stems.
Recent drier soil conditions and daytime temperatures in the 90s have resulted in wilting of infected plants and sunscald of the wilted tissue without the typical yellowing of the leaves.
Protection from the 8 oz. / A of Ridomil Gold applied in the transplant water has been subject to numerous rainfall events and more than six weeks since transplanting for most Georgia tobacco.
Growers with any history of black shank in selected fields to be planted this year were encouraged to make additional applications of one pint of Ridomil Gold or equivalent rates of generic materials to be applied to the soil following transplanting with an additional application prior to the last cultivation.
Application to the plants is not curative and does not provide protection. The chemical must be taken up by the roots prior to infection.
Additional rainfall will further reduce the efficacy of any remaining material in the soil.
Previous race determination work in Georgia indicated that nearly all black shank in the state is Race 1. Most of the varietal resistance available to growers is for Race 0. Long term control of black shank will depend on development of new varieties with new sources of resistance, long rotations of tobacco in diseased fields and use of preventive chemicals to help control the incidence of disease.