Forward growth has put winter wheat and barley crops at high risk of lodging this season, an independent ADAS expert is warning, with possible weaknesses in stems and roots.

According to Peter Berry, senior research consultant at ADAS High Mowthorpe in Yorkshire, a combination of early drilling and the mild autumn means many wheat and barley crops have been left with much bigger canopies than usual for this time of year.

This has been compounded where high seed rates were used, he says, after many growers found that crops drilled early at higher seed rates last season produced the best yields.

Additionally, where crops were lower yielding last year, because of the drought, he says residual soil nitrogen carry-over is likely to have been high, also exacerbating this season’s growth.

“The high density of tillers present in crops is important because it leads to weak stems which are lodging-prone,” Dr Berry explains.

“Dense crops also have a built-in shade avoidance mechanism, where they put resources into shoot growth rather than root growth, to escape from shade. This results in weaker root anchorage in the soil.”

Although cold weather could still slow crop growth down, Dr Berry believes that, in terms of lodging risk, the damage has already been done. “It would have to be a very prolonged cold spell to change things.”

In response, he urges growers to look at three courses of action to alleviate lodging pressures – rolling crops to consolidate soils, using plant growth regulator (PGR) programmes and adjusting the timing and dose of nitrogen fertilisers to rein back the number of tillers.

“Crops need 500 ears a square metre to achieve yield potential. Most crops have at least that, so can afford to lose a few tillers. Most farmers look at applying nitrogen in early March, but if you’ve got a big canopy you may look at incorporating this into the main dressing at growth stage 30-31.

“Rolling crops before GS30 increases anchorage because it strengthens the soil around roots.”

To reduce lodging risks using PGRs, Dr Berry says a programme based on two applications around early stem extension and a later application at growth stage 37 is best employed. “With Moddus + chlormequat at early stem extension, we know you get a bigger effect if you split the application at growth stage 30 and 31.”

Syngenta lodging expert Jason Tatnell agrees growers must take account of high lodging risks this year and echoes the use of a programme approach to PGR use.

“As well as shortening crop height, Moddus has been shown to improve rooting and strengthen stem bases in wheat,” says Mr Tatnell. “So it tackles all the key causes of lodging.

“Early season, our lodging management guidance for targeting both roots and stems in winter wheat and winter barley is to apply Moddus at up to growth stage 30, followed by Moddus + chlormequat at growth stage 31-32.

“When assessing a variety’s lodging risks, identify its standing power on the Recommended List, but also be aware of both stem base and root lodging. Remember, even a variety with high standing power will lodge if pushed hard enough. By targeting all the causes of lodging, it improves your chance of keeping it standing. Later on, a follow-up PGR at growth stage 37 may use different chemistry,” he adds.