Management effects of disease-suppressive rotation crops on potato yield and soilborne disease and their economic implications in potato production

Authors: Larkin, Robert - Bob; Halloran, John

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2014
Publication Date: 1/24/2014
Citation: Larkin, R.P., Halloran, J.M. 2014. Management effects of disease-suppressive rotation crops on potato yield and soilborne disease and their economic implications in potato production. American Journal of Potato Research. http://dx.doi.org/10.1007/s12230-014-9366-z.

Interpretive Summary: Soilborne potato diseases are persistent problems in potato production. Rotation crops that have specific capabilities for reducing various soilborne diseases are referred to as disease-suppressive crops, and may be useful in potato cropping systems, but more information is needed to determine how to best use them within potato production systems. In this research, potential disease-suppressive crops were evaluated under different types of production management (grown as a cover crop, green manure, or harvested crop) in rotation with potato, and their effects on disease, yield, and economic viability determined. Results demonstrated that disease-suppressive crops, such as mustard, rapeseed, and sudangrass, grown as green manures or as harvested rotation crops, significantly reduced certain soilborne diseases, increased subsequent potato yield, and also provided an enhanced economic return relative to a standard rotation crop. All rotation crops grown as green manures provided disease and yield benefits compared to management as a cover crop, indicating the benefits of green manuring. Although the mustard blend green manure provided the most substantial benefits to disease reduction and increased potato yield, based on economic returns, mustard or rapeseed grown as a harvestable cash crop and residues incorporated provided the most productive and profitable management approach for using disease-suppressive crops in potato production. This research demonstrates that utilization of disease-suppressive crops within potato cropping systems can provide highly beneficial and economically productive results, as well as potentially enhance sustainability of potato cropping systems through improved soil health, reductions in soilborne disease, and increased crop yield.

Technical Abstract: Soilborne potato diseases are persistent problems in potato production. Use of disease-suppressive rotation crops, such as Brassica spp. (mustards, rapeseed) and sudangrass, has shown potential for management of soilborne diseases and enhanced yield. However, how to best implement these crops into productive potato cropping systems has not yet been determined. In this research, potential disease-suppressive crops were evaluated under four different management practices (each crop grown as a cover crop, green manure, harvested crop-w/residue incorporated, and harvested crop-w/residue not incorporated) in rotation with potato in field trials in Maine, and their effects on disease, yield, and economic viability determined. Mustard blend, sudangrass, and rapeseed rotations all reduced the potato tuber disease black scurf and increased yield relative to a barley rotation control, but only mustard blend consistently reduced common scab. In general, all rotation crops managed as green manures produced lower disease (by 15-26%) and higher yields (by 6-13%) than other management practices. Rotation crops that were harvested and then incorporated also provided significant benefits, but rotations managed strictly as cover crops were least effective. Overall, the combination of mustard blend managed as a green manure was most effective, reducing scurf by 54% and increasing yield by 25% relative to a soybean cover crop. When economic considerations were factored in, use of mustard or rapeseed as a harvested crop w/incorporation provided the best return, increasing net income by more than $860/ha, with mustard blend grown as green manure or non-incorporated harvest crop also increasing net income by $600 to $780/ha.