The practice of selling agrochemicals in twin packs is being questioned by both agronomists and farmers this year, after high disease pressure has meant spray programmes need constant adjustment.

Twin packs are universally disliked by those using them in the field, but it seems as though they’re here to stay.

Issues and delays with getting new products registered with the Chemical Regulations Division (CRD), as well as the number of active ingredients being revoked, means manufacturers have turned to twin packs as the best way of distributing new chemistry and meeting demand.

As a result, twin packs or co-packs, rather than co-formulated products, have become the default way of getting new active ingredients onto the market in a more realistic timescale, with the new product being matched with a suitable partner and sold in one “handy” box.

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While they have long been a feature in the distributor trade, independent agronomists have tended to prefer recommending the right combination of products to deal with the specific situation and get the best deal for their clients.

This is being made more difficult and more complicated by twin packs, they note, with pack sizes, foils and packaging also coming under fire.

What’s the problem?

Common gripes are that twin packs are confusing, create extra work, don’t fit with ordering and stock control systems, result in agrochemicals being delivered that people don’t want, and, in certain circumstances, compromise spray decision-making.

The problems have become more evident in the difficult 2024 growing season, with agronomists pointing out that putting a half-rate azole partner in with a strong septoria active is not going to help, either with septoria control or the all-important resistance management.

In an extreme pressure season, additional or different chemistry has been required and the ratios in the supplied products have sometimes been wrong, they stress.

Nor do the twin packs give the best value for money. “They can come at a cost which is higher than it should be, with different quantities arriving in cans and boxes,” says one commentator.

“In a year like this, when we’ve needed robust mixes, it has added to complexity and reduced flexibility.”

Similarly, with rust being such an issue, rust-active materials have been required – but not necessarily the one the manufacturer opted to put in the pack ahead of the growing season, when marketing decisions had to be made.

“Again, the best results come from having the right product at the right rate.”

At a time when farms are battling to keep a lid on costs and reduce input use, being forced to buy a product when there’s a cheaper generic option available also rankles, while smaller farms are often disadvantaged by the pack sizes.

It’s not restricted to fungicides: getting a herbicide active ingredient that no longer works on the farm as a partner product is another annoyance.

“They’ve been an added complication over the last few years,” says Sussex-based independent agronomist Tod Hunnisett. “We sometimes end up getting a partner product that we neither want nor need, rather than the most appropriate choice.”

In his mind, there’s a danger that the products that are surplus to requirements end up getting used anyway, which is not a direction that the industry should be taking.

“There were instances last autumn where we couldn’t buy one herbicide without getting another,” he adds.

“All it does is put agronomists off using them. Given a choice, I will always go for the one not in a twin pack.”

What are the advantages?

It can be more cost-effective if the boxes are split and the components mixed and matched – despite that course of action not being what the manufacturer intended.

While that’s the best way of getting the optimum value and performance for the situation in the field, it distorts the market. Certain products have been cheaper to buy in a box than if bought on their own.

Opportunities can be created, and savvy buyers have been quick to take advantage of certain deals.

“They don’t have to be put in the same tank,” says another agronomist. “So occasionally they will represent very good value and are split for use on different crops. To take advantage of this, you do forfeit simplicity.” 

However, once split, there can be issues with returning products. They tend to come in hectare packs, rather than being sold by volume, which is another grumble as it may put smaller farms at a disadvantage.

Is there an alternative?

Yes, say independent agronomists. Give us the actives as straights.

Agronomists are trained professionals who can be trusted to use products with their stewardship in mind. As independent South West agronomist Steve Harrison points out: “That will allow us to mix the two best materials and do a good job.”

He stresses that the diminishing armoury means the number of chemical groups is restricted, so it’s more important than ever that the right partner product is used.

“There are compelling agronomic reasons for letting us decide what to put in the tank and whether a two-way or a three-way mix is required, for example.”