Importance of control of volunteer potatoes
- Control of volunteer potatoes is important to reduce the risks of pests and diseases and to maintain purity of the next potato crop at that site.
- Failure to control volunteer potatoes can maintain populations of potato cyst nematodes between potato crops.
- Frost: a minimum of 50 accumulated hours of frost (below -2 ºC) is required to kill a potato tuber. In the U.K. these temperatures very rarely occur at soil depths of more than 10 cm; tubers below this horizon are therefore unlikely to be killed. Ploughing following a potato crop increases the proportion of potatoes in the deeper soil horizons. Cultivation during frost helps frosting of the tubers.
- Mechanical damage to the tuber: damaged tubers are more susceptible to fungal or bacterial attack.
- Crop competition: competitive crops, especially those sown in the autumn after potatoes, restrict growth of volunteer potatoes and reduce the production of progeny tubers.
Integrated control of volunteer potatoes
- Apply maleic hydrazide to the growing potato crop where protocols permit this (check protocols).
- Ensure efficient harvesting and use of crushing rollers if appropriate.
- Use cultivation to expose tubers to frost, where preparation for the following crop allows this.
- Spring cropping allows greater opportunities to cultivate during frost periods
- Grow competitive autumn sown crops.
- Use spring or summer application of appropriate herbicides in following crops, with application of salt in sugar beet crops.
- Apply glyphosate prior to harvest of cereals or other combining crops.
- Apply glyphosate or amitrole in stubbles, where volunteer potatoes have re-grown.
- Steps 3 to 8 should be repeated in successive crops, as appropriate.
Use of maleic hydrazide in the growing potato crop
- Check whether the application is permitted by the market protocol.
- Apply to actively growing foliage when smallest tubers required for market are not less than 25 mm long. This will usually be 3 – 5 weeks prior to haulm destruction. The haulm should still be green.
- Apply in a high water volume, according to the manufacturer’s recommendations.
- Do not apply to seed crops or to first early potatoes.
- Use this link for more information on application and efficacy of maleic hydrazide.
Use of salt in sugar beet crops
- Sodium chloride (common salt) may be used for control of polygonums and volunteer potatoes in sugar beet. The following suggestions are made.
- Apply between 3 true leaves of crop and end of July.
- Use in a programme where earlier sprays have failed to control large plants.
- For greatest efficacy obtain good spray cover in hot, humid weather.
- A saturated solution should contain 0.1 % w/w non-ionic wetter and be applied at 1000 litres ha-1.
- Salt acts by contact scorch and has no direct influence on daughter tubers.
Production of berries by potato plants
- Cultivars vary in the potential to produce berries.
- Production of berries in a potato crop or on volunteer potatoes allows production of true potato seed.
- True potato seed may remain viable in soil for 10 years.
- True potato seed can thus contribute to the population of volunteer potatoes.
- Production of berries on volunteer potatoes within a vining pea crop is a particular problem, due to contamination of the pea sample with berries.
Suppression of berry production
- Experiments have been performed to assess the efficacy of herbicides in suppressing potato berry production.
- Application of MCPA or MCPB during early to full bud production of potatoes suppressed berry formation.
- There was little effect of these treatments on production of the potato haulm or tubers.
- MCPA was tested on peas at the same time as the potatoes, with no detrimental effects on yield of the peas but there are no products currently registered for application in pea crops.
Notes on volunteer potato control
Potato berries 2000 (Principles of berry formation and suppression)
Control of volunteer potatoes 1998 (Principles of volunteer control, including use of maleic hydrazide and use of salt)
Chemicals for volunteer control 1998 (Now out of date)