Fresh growth vulnerable after frost
Beware of fresh growth in cereal crops – it could be more prone to crop damage, an agronomist has warned.
Any leaves that haven’t had a chance to lay down a thick waxy layer are more likely to suffer crop damage, says independent agronomist, Sean Sparling, meaning a night-time frost can turn a little yellowing into scorching. And with current weather bringing on rapid new growth during relatively high day-time temperatures, followed by freezing night conditions, the potential for crop damage following herbicide application is very real.
"Frosts break down the lipids that are the building blocks of the waxy coating which protects the epidermis of the leaf. These lipids are weaker in new growth anyway," explains Mr Sparling. "Extreme diurnal fluctuations are a cause for concern.
"The crop puts on luscious green growth during the warm day, and doesn’t get the chance to harden up by the time it is plunged into freezing conditions at night.
"Crops will harden up given the time," he says. "For example, a warm day and night in between the first and second frost will allow plants to lay down additional layers to compensate for the damage done during the first frost. The absolute worst-case scenario is spraying the day after the first frost, when there is another frost forecast.
"This year the early-sown crops are most at risk, because of the rapid growth earlier in the season. Later-sown crops have grown more slowly, building up the waxy layer gradually.
"Growers that are rightly pushing on with Atlantis WG (iodosulfuron + mesosulfuron) applications need to just keep an eye on the diurnal temperature fluctuations, as well as all the other factors. This is even more important where they are planning to tank-mix or stack to tackle the most stubborn of weeds.
"Often it is the adjuvants and safeners, rather than the active substances, which cause the issue. Stacking or tank-mixing will add to the problem.
"As a rule of thumb, if a fluctuation of more than 10oC is forecast then I would hold back a day or two until there are more consistent day and night temperatures," he advises.
