Stress-free crops key to getting most out of maleic hydrazide

Now-widespread use means a lot has been learned about getting the most out of it as a sprout suppressant as well as for reducing volunteers between potato crops.

Healthy canopy

For independent Shropshire-based agronomist Graeme Ditty, one of the most important lessons has been applying Crown MH to healthy, stress-free crops.

Almost all his processing crops are treated when destined for medium to long-term storage, with varieties known to have relatively short dormancy a priority.

“You really need a healthy crop to apply to with tubers at the marketable size, which for us is 25mm or above. We’ve also encouraged growers to put it on with 400-litres/ha of water as standard, which helps,” explains Graeme.

Weather conditions at application are vital, with cool temperatures and high relative humidity, in addition to the higher water rate, extending the time it takes for the spray solution to dry on the leaf, improving uptake of the active substance.

A key message is that crops must be treated 3–5 weeks before desiccation.

Good communication

Frontier advisor Ben Naylor, who oversees potato crops across Shropshire and into Herefordshire, says the window is a good guide, but crop and environmental conditions must be right too.

He has also found that these factors and good communication between himself and clients have achieved great results with products like Crown MH in recent seasons.

“We’ve worked hard on getting across the reasons why we need a healthy crop, a higher water volume and cool and humid conditions. It’s more than just writing a recommendation,” he explains.

If there is any uncertainty about when to apply, he adds that a quick conversation over the phone leads to the best decision, whether that’s applying slightly earlier than planned, or a week later.

“Don’t let it become too prescriptive and worry about where you are with desiccation date. If the crop is stressed, you’re better off waiting for things to improve,” adds Ben.

Liquid formulation

Both agronomists have seen preference for the liquid formulation Crown MH growing over recent seasons with the product supplied in 600 litre IBCs that are transferred to the sprayer via the Fastran closed transfer system.

 Graeme says with the application rate at 11-litres/ha and many potato growers having large self-propelled sprayers to fill and significant areas to cover quickly, the advantages for operational efficiencies by using the liquid are clear.

It also contains an anti-foam formulation, which means sprayer operators are not slowed down by excessive foaming that is often experienced when ripping and tipping bags of granular product into the tank.

“They can pull up to the IBC system, meter out the exact quantity of product and move on, so it makes the job a lot easier,” he explains.

Satellite fill-ups

For smaller areas the flexibility of 20-litre cans of Crown MH has been retained.

With many potato growers, particularly in the west of the country, having individual or small groups of rented fields to treat, sprayers need to fill up away from the main yard.

“Sometimes from a logistical point of view, it’s easier for someone to drop off a few 20-litre cans at the filling point than a 600-litre IBC, which will require a forklift to move it around,” Ben explains.

Following good application and uptake, Ben has seen good results in store, helping to reduce the need for any in-store treatments, which on a per tonne basis are more costly than an application of MH.

He’s also seen far fewer volunteers across rotations where potatoes are grown since the product has become a routine part of potato
crop protection programmes.

This helps reduce potential sources of disease inoculum, including late blight and virus, and reduces multiplication of soil-borne pests like potato cyst nematode (PCN). “Maleic hydrazide is very much a part of growing stored potatoes now,” concludes Ben.

Read more arable news.