Potato growers and store managers have been urged to keep a close eye on stored crops for the first signs of dormancy break. Even those who applied an in-field sprout-suppressant may need to consider applying their first Gro-Stop (chlorpropham) application soon.

With the quality and maturity of the crop coming into store being very variable, those growers who have used Fazor (maleic hydrazide) will be glad they did, says Dow AgroSciences' John Sellars. "Fazor offers a bit of leeway during the loading and curing period. It may be just the extra security growers need this year."

Applied to the crop before lifting, Fazor helps to suppress sprouting during the early stages of crop storage. It takes the pressure off the first CIPC treatment, says Luxan UK managing director Malcolm Nursey (photo), but should not be seen as a substitute.

"With the mixed bag coming into store this year, growers will be thankful for the flexibility Fazor offers to the start of their CIPC regime. But the effects of the treatment may soon be wearing off. Even treated crops may need as many as two CIPC applications before Christmas," he notes.

Mr Nursey advises that growers follow Luxan's Gro-Stop low-dose programme using only 20 ml product per tonne at each application(1). This would start with Gro-Stop HN or Gro-Stop Fog. Up to three applications of Luxan's new formulation, Gro-Stop 100, can be applied as required in the New Year until stores are unloaded.

Vigilance and best practice will ensure growers get the most out of their CIPC applications and that stored potatoes are kept in top condition. "Growers and storekeepers should monitor crops daily during temperature pull-down. You should also check temperature is even throughout the store," says Mr Nursey.

This is even more important this year because many crops have been harvested in wet conditions. "Where potatoes are particularly muddy, the CIPC particles will stick to the dirt and sprouts may grow quite happily underneath. The damage to quality will have been done before the sprouts come in contact with the chemical."

This is also the time to prepare the store for fogging operations. "Make sure it is as leak-tight as possible. Fans and cooling equipment must be regularly serviced and in good running order."

The first CIPC application should be made before the eyes-open stage, Mr Nursey points out. "Tubers must also be perfectly dry and any nicks and cuts healed over."

To help ensure an even spread of active ingredient throughout the store, he advises storekeepers keep fans running during the fogging operation. This keeps temperature and humidity even throughout the store, which helps distribute the product more evenly.

"But you must ensure your CIPC has a non-flammable formulation," cautions Mr Nursey. "This is one of the key advantages of using Gro-Stop."

Gentle air circulation also reduces the chances of sedimentation, he points out, where chemical condenses on the roof of the store and can drip down on to the stock below. If this happens the top layer of tubers can receive a high concentration, which may result in residue issues or even crop damage.