Seasonal factors, plus lower standing power scores in some spring barley varieties, were to blame in 2017, but experts insist there’s no reason for a repeat.
“Lodging is largely preventable,” says Dr Pete Berry, ADAS head of crop physiology.
“There are two main types, with stem lodging above ground and root lodging at ground level.”
Root lodging occurs earlier, soon after flowering, when anchorage strength of roots is less than the leverage exerted by plants. Stem lodging happens towards harvest, when stem strength is overwhelmed by shoot leverage.
Do not confuse stem or root lodging with brackling and necking, he notes.
“Brackling, which happens in the top-third of the stem, is a form of stem lodging, while necking is when ears drop off. Unfortunately, there’s no way of stopping the latter.”
Whatever the type, the earlier lodging occurs, the more yield is lost.
Early sowing, high seed rates or applying more nitrogen can increase lodging risk. Well-established winter crops with bigger canopies coming out of winter are at particular danger, Dr Berry says.
“Look at canopy size just before GS 30. A Green Area Index (GAI) of 1, which represents around 50% ground cover, should be okay. Typically crops have a GAI of 1-1.5 at this stage.”
If ground cover is up to 65-75% with GAI of 2 or more, consider remedial action.
“As a rule of thumb, each unit increase in GAI reduces varietal lodging resistance score by two points.”
Over-large canopies in winter or spring barley can be corrected with PGRs, nitrogen timing, or both. He suggests starting by reducing early nitrogen.
“It’s a delicate balance, as there must be enough to not restrict yield potential, so take account of how much is in the soil.”
With PGRs, a common mistake is to rely on chlormequat to address lodging, he warns. “It will reduce risk a bit, but you need other actives at the start of stem extension.”
A late PGR active at mid-stem extension may also be necessary. “The greatest shortening comes from this later application.”
Dr Berry believes more growers should use two sprays. Problems last year were partly due to dry weather preventing many growers making the second application, for fear of stressing crops.
“Should the weather be similar, the best action is to reduce PGR rate rather than cut it out altogether.”
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