Getting pre-harvest management of OSR crops right is essential for minimising harvest losses, which is not just money down the drain, but creates volunteer problems for years to come.

Losses can be high, and while nothing can stop freak hailstorms wreaking havoc with pods close to harvest, Hutchinsons technical manager Dick Neal says there are still ways to mitigate harvest losses. 

“Choosing varieties with in-built shatter resistance is a starting point,” he says. “But also look at varieties with good disease resistance profiles.”

See also: Tips to achieve successful long-term grain storage

He points out that turnip yellows virus, verticillium wilt and light leaf spot can stress the plant or if desiccation is too early, pods can split and open, leading to premature seed losses.

Pests 

Pest infestations such as mealy cabbage aphid, which directly feed on the plant, can remove moisture from it, stressing it and causing pods to split.

“They tend to go for plants already suffering from a disease or areas where, for example, spray treatments have overlapped or there is compaction stress.”

Less use of pyrethroids to treat cabbage stem flea beetle in autumn, due to resistance issues, may be leading to mealy cabbage aphid being more prevalent in summer, Mr Neal says.

“We’re not taking them out like we used to, which isn’t necessarily a bad thing if populations of the early-autumn predator profile that feed on them grow.”

Pod sealant

Growers should also consider using a pod sealant, he advises.

“Zip-Pod is a polymer that can be applied to the pod, making it more resilient to serious weather conditions such as thunderstorms, hail and high winds.

“It is also a precaution against pods splitting open on the combine table.”

Desiccation can also predispose OSR crops to pod shatter, so growers should consider whether it is necessary, says Mr Neale.

“There is only one choice from a chemical point of view and that is glyphosate. Growers used to grow large areas of OSR and used glyphosate to manage the harvest window. Now areas tend to be lower.”

He believes using glyphosate can only be justified if there is uneven crop ripening.

“Lots of this year’s crops are quite even so will come to harvest at an even rate. There is no reason why we can’t let OSR come to harvest under its own steam.

“If you don’t put glyphosate on, the crop will mature more slowly and losses will be lower, as the pods will be more resilient to shatter.”

It will also save the cost of glyphosate, which is higher this season.

Pod sealant timing

Many growers apply pod sealant at the same time as glyphosate, however, they should be applied separately, says Mr Neale.

“Ideally, you should apply Zip-Pod earlier than glyphosate, when pods are still pliable.”

Even for varieties with pod shatter resistance, it is still worth applying a pod sealant, he says.

“I’ve seen too many crops after a thunderstorm where growers have ended up with a 4t crop on the deck. It is heartbreaking and not worth the risk. It is a belt-and-braces approach.”

There are differences in pod sealants, he says.

“Some are sold as anti-shatter when they are more of an adjuvant. You get what you pay for. They are easier to use these days, but remember to wash out the sprayer as they are a glue.”