- Temperatures between 1 and 5 ºC slow the rate of sprout growth but can result in increased concentration of reducing sugars (see processing quality).
- Low temperature control of sprout growth is expensive due to the high cost of refrigeration for large stores.
Pre-harvest foliar applied chemical: maleic hydrazide
- Maleic hydrazide inhibits cell division and sprouting is irreversibly depressed.
- Maleic hydrazide should be applied when tubers are > 25 mm long and to a green, actively growing canopy 3 – 5 weeks prior to desiccation or haulm destruction.
- Apply in a high water volume.
- Check with the manufacturer before making any tank mix with maleic hydrazide (it is suggested to be most effective when applied alone).
- Apply only to second early or maincrop potatoes; do not apply to seed potatoes or first earlies.
- Check whether packers and processors will accept crops treated with maleic hydrazide.
- Maleic hydrazide alone may suppress sprout growth during short term storage but for longer storage periods in-store application of another sprout suppressant may be required.
- Application of maleic hydrazide to the growing potato crop may also result in a significant reduction of volunteers in the following crop. The number of progeny tubers produced by volunteers may also be reduced.
- Use of maleic hydrazide should only be considered as part of an integrated programme for volunteer control – not as the only method of control.
- Uptake of maleic hydrazide can be very variable: it is suggested that application during high temperatures and low relative humidity may be particularly ineffective (more …)
Use this link for recent trials data including maleic hydrazide.
Use this link for background information and volunteer control data.
Sprout suppression and post harvest storage chemicals
- Approval for use of CIPC was withdrawn on 8 January 2020.
- Chlorpropham (CIPC) inhibits mitosis and thus cell division to suppress sprouting during storage.
- CIPC can be absorbed by concrete and wood in stores; it is very persistent and can contaminate subsequent crops.
- Seed tubers must never be stored in a store or boxes where CIPC has been applied.
- Appropriate store cleaning may be required to avoid residues in ware crops stored where CIPC has been applied in the past.
- Continuous exposure to a low concentration of ethylene in the atmosphere can inhibit sprouting (but short exposure to a higher concentration can release dormancy).
- Commercial storage with ethylene is available in the UK and stored products are generally regarded as “residue free” (there is no MRL).
- Control of air quality and careful application are required in processing stores in particular, as ethylene can reduce fry quality.
- Initially ethylene was combined with low temperature storage, although use in processing stores being investigated.
- Efficacy may vary between cultivars.
For more details on application see the manufacturers’ websites, via the Links page.
- The active ingredient, carvone, is a volatile plant oil which controls sprouting by physically damaging sprouts.
- New sprouts can begin to grow in each eye, so repeat application is required.
- Mint oil, e.g. “Biox M” is applied as a thermal fog.
- Potatoes should have a set skin and be largely free from soil / debris.
- Application should not be made until tubers are dry and cured, generally 6-15 days post harvest.
- The first application should be made before sprouting is visible.
- The store should be maintained at a temperature suitable for the end use of the crop, generally 2-10°C (except during application).
- Applications should be made at a minimum interval of 21 days throughout the storage period.
For more details on application see the manufacturer’s website, via the Links page.
Products under development
- These include:
- DMN: 1,4-dimethylnaphthalene
- A volatile chemical naturally emitted by potato tubers.
- Inhibits sprouting.
- Registered in the EU; limited use in the UK in 2021.
- Orange oil
- Mode of action similar to spearmint oil.
- Registered in the EU but not yet in the UK.
- A volatile-oily liquid.
- Used in north America and Israel, not yet registered in EU or UK.
- DMN: 1,4-dimethylnaphthalene
- More information and recent trials data can be found here.
Sprout suppression notes
Sprout suppression 2021 (Influence of dormancy; concentration of maleic hydrazide required; results of PRG maleic hydrazide uptake study)
Application of maleic hydrazide 2020 (Principles of use for volunteer control and sprout suppression; conditions influencing uptake)
Sprout suppression 2020 (Physiology of sprout suppression techniques; trials data on products under development)
Storage 2015 (Includes sprout suppression: introduction to DMN and 3-decen-2-one)
Planting 2014 (Includes influence of storage conditions on dormancy break)
Sprout suppression 2013 (Information on initial suppliers of spearmint oil and ethylene)
Sprout suppression with spearmint oil 2012 (Initial information on physiology and use of mint oil)
Recent research on sprout suppression 2008 (Includes initial information on use of ethylene)
Sprout suppression 1997 (Information on effects of maleic hydrazide is still relevant)