By Christy Sprague
Volunteer potatoes can be an issue in corn fields where potatoes were grown the previous year. It is not only important to control volunteer potatoes to preserve corn yield, but controlling volunteer potatoes is critical for the management of potato pests, such as late blight and other potato diseases and pests.
Currently, there are no herbicides available that will completely control volunteer potatoes. However, Michigan State University Extension says there are a few different options that will provide good suppression of volunteer potatoes and significantly reduce the number of daughter tubers per plant.
Michigan State University researchers (Renner, Lee, Long, and Powell) had evaluated the effectiveness of several different post-emergence options for control of volunteer potatoes in corn. Herbicide treatments were applied when volunteer potatoes were between 4 and 6 inches tall. From this research, Callisto (3 fl oz) + crop oil concentrate (1 percent v/v) + ammonium sulfate (17 lb/100 gal); Callisto (3 fl oz) + atrazine (0.5 lb ai = 1 pt) + crop oil concentrate (1 percent v/v) + ammonium sulfate (8.5 lb/100 gal); Status (10 fl oz) + non-ionic surfactant (0.125 percent v/v) + ammonium sulfate (17 lb/100gal); and Status (10 fl oz) + atrazine (0.5 lb ai) + non-ionic surfactant (0.125 percent v/v) + ammonium sulfate (17 lb/100 gal) were the best options available for controlling volunteer potatoes, 28 days after treatment (Figure 1). Additionally, these treatments stopped daughter tuber production, reducing the risk of transmitting disease to the next year's potato crop.
*Use glyphosate only on Roundup Ready corn.
Something to consider
Of the treatments that provided good suppression of volunteer potatoes, Callisto and Callisto + atrazine are the only treatments that can be applied to seed corn. Corn inbreds vary in their sensitivity to herbicides including Callisto, so it is important to consult the seed company on their inbred tolerances to Callisto.
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Sprague writes for Michigan State University Extension, Department of Plant, Soil and Microbial Sciences