Plant Growth Regulation - South East Farmer

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Based in Kent, Hutchinson agronomist David Shepard considers growth regulation for the cereal crop this spring.

Preventing crop lodging is a key objective as lodging can result in poor grain quality, lower yields, delayed harvest, increased drying costs and grain losses at harvest. He reports that most first winter wheats drilled before mid-October in Kent are looking strong and healthy and have between five and seven tillers. Second wheats and later drilled first wheats however are looking a little hungry and David says it won't be long before nitrogen is recommended, to tiller them up a bit. There has been little rain in the last month, so some rain in late January and into February wouldn't be unwelcome.

Normally he recommends a two spray growth regulator programme in cereals, with the first application at TO (Growth Stage 30) and the second application at T1 (G Stage 31 to 32). The first growth regulator, which would normally consist of a mix of trinexapac-ethyl and chlormequat, aims to get rid of apical dominance and get the roots down into the soil. If it is particularly cold at TO he prefers to use prohexadione-calcium containing growth regulators as they tend to be better under colder conditions. The T1 PGR applications help thicken cell walls and strengthen the crop so it stands up better. The second spray aims at strengthening the stem by shortening the internodes and would again be chlormequat and trinexapac-ethyl. The priority is to keep the crop standing well.

David reports that in the past few years there has been more emphasis on choosing a cereal variety with intrinsic good standing power such as KWS Bassett. He says that on some farms he is recommending increased seed rates in order to compete with black-grass, but he is mindful that this increases lodging risk and will also mean more comprehensive growth regulation.

In exceptional years a third PGR may be applied at Growth Stage 33-37, but he would not rely on this to keep the crop standing. It is more important to get it right first time earlier on, he says.