Varietal susceptibility to lodging is a key factor to consider with PGR applications this spring.

Whilst the Recommended List gives an overall rating for lodging, growers and agronomists can now use InSpire online PGR calculator to integrate variety specific susceptibility to root and/or stem lodging, in different seasons and individual agronomic situations.

Syngenta Field Technical Manager, James Southgate, reported that understanding specific varieties’ strengths and weaknesses for root or stem lodging can prove invaluable in tailoring PGR requirements.

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He cited the example of the wheat variety Grafton, where the description of a short, stronger-strawed variety would indicate low risk of lodging. However, the Harper Adams University studies by Dr Mitch Crook had identified the variety typically does not score well for root anchorage.

“Using that information in InSpire, the in-field implication is that Grafton, for example, will benefit more from an emphasis on Moddus application at T0, to encourage greater root development,” advocated Mr Southgate.

“In contrast, the variety Revelation is far better at developing good root anchorage, but has a weak centre of gravity and more susceptible to stem lodging,” he added. “Whilst both varieties have similar Recommended List scores for lodging risk, InSpire can differentiate and devise the most appropriate options in specific situations.”

Examples of how InSpire would tailor recommendations to specifc scenarios include: 

Dr Mitch Crook, lodging specialist at Harper Adams University in Shropshire, pointed out that different varieties have different root architectures that can be instrumental in their anchorage in the soil, and susceptibility to the most widespread issue of root lodging in wheat crops.

His unique profiling of individual varieties provides a key indicator as to how they will perform in the field, and how they can be better managed with PGR use and other agronomy decisions.

"The basal rigid coronal root structures that hold plants in place are established early in the crop’s development – typically before GS39" – highlighted Dr Crook,"so any factors to influence their growth need to be instigated early in the season".

Coronal root development could be adversely affected by soil conditions, particularly a wet winter where roots have been waterlogged for a period - which could be the case this season. Heavy soil structure or compacted pans can also restrict this essential root growth.

ADAS analysis has shown today’s wheat varieties typically produce smaller and weaker rooting systems, which makes them inherently more susceptible to root lodging, compared to older varieties.

Dr Crook also warned that root lodging risk is highly influenced by soil type, structure and conditions. Wet soils provide less stability for roots, so clay soils that rapidly wet up after rain are especially vulnerable – particularly if rooting has been restricted through the season. Light fluffy soils, however, offer little support for root anchorage that can result in widespread lodging.

Root lodging can be further compounded by windy conditions, especially late in the season when crops are at their heaviest and exert the greatest leverage.

Furthermore, different varieties also have specific characteristics that can make them more or less susceptible to stem lodging – where the plant’s stem is physically unable to support the weight of ears and folds over. Varieties with extended length between nodes are most vulnerable – but will also be influenced by season, planting density, ear size, agronomy and PGR use.

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Harper Adams trials by Dr Crook has identified that some varieties have inherently stronger stem walls that are better at supporting higher yield heavy ears, however growers agronomy decisions and PGR timing can again influence the seasonal performance.

"The specific characteristics of different varieties will directly influence how they perform over the course of the season in individual situations – and how tailoring PGR application timing and rates can have the greatest influence to keep crops standing". 

Dr Crook’s studies have shown that wheat crops are generally more liable to succumb to root lodging, whilst barley varieties are more susceptible to stem lodging, compared to wheat.