Lodging risk to cereal crops is likely to be higher than normal this season and growers must assess the threat now and plan what action to take, say experts.

Many winter crops were sown earlier than normal into good seedbeds and, combined with autumn temperatures 2-3C above average, some crops are showing “profuse tillering” and almost double the number of shoots normally expected, says ADAS’s Peter Berry.

“Greater tillering with shoots closer together means thinner, weaker stems and increased stem lodging risk.”

Growers should also be aware of the risk of root lodging (due to poor root anchorage), which could be higher as dense plants do not have sufficient room to develop a large root “plate”, he adds.

“It’s very important to recognise these two types of lodging.

Root ball lodging in particular, occurs early on, which can be most damaging to yields.”

Higher soil nitrogen following relatively low winter rainfall (and less leaching) could also increase stem lodging risk, he adds.

Growers should start assessing the risk to any variety by looking at its lodging resistance score on the HGCA Recommended List.

Adjustments can then be made for individual crops, depending on the Soil Nitrogen Supply Index, sowing date and plant establishment.

Taking an example of Einstein (HGCA rated seven for lodging), sown after oilseed rape (SNS 3) on 20 September, with an average establishment of 175 plants/sq m, this equates to adjusted root and stem lodging scores of 7.25 and 5.5 respectively.

This score can be used to identify remedial action against root and stem lodging.

Syngenta’s Jason Tatnell warns growers that even resistant varieties (rated 8 or 9) can lodge.

He suggests the yield and quality benefits from PGRs outweigh their cost and they act as a valuable insurance policy, particularly in high-risk seasons.

Syngenta trials in 2004 (the last bad lodging year) found Einstein treated with 0.2 litres/ha Moddus (trinexapac-ethyl) + 1.25 litres/ha chlormequat yielded 0.6-0.7t/ha yield more than the untreated control, when applied at GS31-32, he notes.

While single PGR applications can increase lodging resistance scores by 0.5-1.5 points, sequential treatments have an additive effect, he notes.

Combining a gibberellic acid inhibitor with an ethylene producer is an effective way of reducing the length of lower, middle and upper internodes, he says.

paul.spackmand@rbi.co.uk