EFFECTS OF CROP ROTATIONS AND A FALL COVER CROP ON RHIZOCTONIA CANKER, BLACK SCURF, AND COMMON SCAB OF POTATO, 2004

Authors: Larkin, Robert - Bob; Griffin, Timothy; Honeycutt, Charles

Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2006
Publication Date: 4/17/2006
Citation: Larkin, R.P., Griffin, T.S., Honeycutt, C.W. 2006. Effects of crop rotations and a fall cover crop on rhizoctonia canker, black scurf, and common scab of potato, 2004. Biological and Cultural Tests for Control of Plant Diseases. Vol. 21: V009

Interpretive Summary: Soilborne diseases of potato are persistent and recurrent problems causing substantial yield losses and reductions in tuber quality. These diseases are caused by soilborne fungal pathogens, and two of the most important are Rhizoctonia solani, causing stem and stolon canker and black scurf on tubers, and Streptomyces scabies, causing common scab of tubers. These diseases are very difficult to control. Chemical pesticides are often not very effective or economically feasible, and alternative approaches are needed. Crop rotations and cover crops are important for maintaining and improving soil conservation and soil quality, and may also reduce soilborne disease problems. In ongoing research, several potential rotation crops are being evaluated both with and without the presence of an additional fall cover crop in 2-yr rotations with potato, for their effects on soilborne diseases. In this report, results from the 2004 potato cropping season are presented. The rotation crops canola, sweet corn, and rapeseed significantly reduced Rhizoctonia canker compared with a continuous potato control. Rotation crops barley, soybean, and rapeseed significantly reduced black scurf and rapeseed reduced common scab on tubers. Cover crop did not significantly affect canker, but addition of a winter rye cover crop reduced black scurf and common scab diseases across all rotation crops. This information can be used by scientists, extension agents, and ultimately growers for the development of beneficial crop rotations and sustainable approaches to plant disease control.

Technical Abstract: Six different rotation crops (barley/clover, canola, green bean, rapeseed, soybean, and sweet corn) planted in 2-yr rotations with potato (and a continuous potato nonrotation control) were evaluated both with and without a fall cover crop of winter rye for their effects on the development of soilborne diseases of potato. This report represents the results from the potato crop year of 2004. Rotations, but not cover crop, significantly affected stem and stolon canker development. Rapeseed rotation reduced the incidence and severity of stem and stolon canker on potato plants relative to the continuous potato control. Canola, sweet corn, and rapeseed significantly reduced average canker severity (stem and stolon canker combined). Both rotation crop and cover crop significantly affected incidence and severity of black scurf and common scab on potato tubers. Rapeseed, sweet corn, barley/clover, and soybean rotations reduced the incidence of severe disease relative to continuous potato, and rapeseed, barley, soybean, and canola reduced disease severity (% surface coverage), with rapeseed resulting in the lowest disease levels among all rotations. Winter rye cover crop also significantly reduced black scurf incidence and severity compared to no cover crop across all rotations. Incidence of severe common scab was reduced with rapeseed rotation compared to all other rotations, and cover crop reduced incidence compared to no cover crop across all rotations. Total yield was comparable among all rotations as well as with and without cover crop. These results indicate that rapeseed and other rotation crops can significantly reduce soilborne diseases and addition of a fall cover crop such as winter rye can also reduce black scurf and common scab disease problems.