Volunteer potato plants (potatoes growing from unharvested tubers) might be problematic in rotation crops during the 2019 growing season. These plants can be a competitive weed with most crops and act as a reservoir for diseases and insects. In general, winter conditions in Canada are severe enough to control most volunteers (soil temperature below -2 C or 28 F) but winter survival is dependant on tuber health, temperature, snow cover and burial depth. When unharvested tubers survive the winter, volunteer potatoes are difficult to control the following growing season, and no one measure will guarantee success. An integrated approach, including harvest methods, cultural control, tillage methods, pre-crop control, and in-crop herbicides is needed for proper volunteer management. Tips for Volunteer Potato Control:
- Minimize the number of tubers left in the field following harvest. If a large number of tubers remain in the field in the fall, be prepared to deal with volunteers the following season.
- Avoid deep fall tillage that buries tubers — leave tubers near the soil surface to be exposed to winter conditions.
- Delay planting the rotation crop to maximize volunteer emergence, then apply a herbicide or remove early volunteer growth by tillage.
- Select a competitive crop (i.e. barley) to follow potatoes, or a crop with a high potential for volunteer potato control (i.e. corn, Round-up Ready crops). Increase crop competitiveness with adequate fertility and higher seeding rates.
- Apply an appropriate in-crop herbicide treatment.
- Feeding from Colorado potato beetle, in combination with early herbicide treatment, may be enough to limit the impact of volunteer potatoes in cereal crops.
- Apply an appropriate pre-harvest herbicide if many volunteers are present, as certain pre-harvest herbicides can limit daughter tuber production and viability.
