Test your strength for variety lodging risk

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Varietal susceptibility to lodging is a key factor to consider with PGR applications this spring. But whilst the Recommended List gives a useful overall rating for lodging, the InSpire online PGR calculator now enables growers and agronomists to assess more detailed variety specific information on susceptibility to root and/or stem lodging, in conjunction with individual agronomic situations the seasonal pressures.

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.

InSpire is a new PGR decision support tool from Syngenta designed to tailor treatment timing and options to best meet individual in-field situations.

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 will benefit more from an emphasis on Moddus application at T0, to encourage greater root development,” advocated Mr Southgate. “That could be particularly relevant this season, where wet weather has further affected root development.

“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.”

InSpire combines specific variety profiling research with other factors that influence PGR use – such as sowing date, soil type, weather conditions and yield potential – to give an instant recommendation on what to apply and when.

Cambridgeshire Farm Roxburghshire Farm Wiltshire Farm Field
Scenario 1: Sandy, clay loam soil; late drilled (22 October) with Grafton at high seed rate to shade out black-grass. Average establishment with GAI at 0.9 at GS30. Scenario 1: Loamy sand field. Reflection (good resistance to lodging with medium anchorage and stem strength) drilled 28 November, with resulting reduced growth and GAI of 0.3 at GS30 Scenario 1: Chalk soil; very late drilled (3 November) with Grafton (very low ranked anchorage and low stem strength). Average establishment with GAI at 0.9 at GS30.
T0 Moddus @ 0.2 l/ha T0 Moddus @ 0.15 l/ha T0 Moddus @ 0.2 l/ha
T1 Moddus @ 0.1 l/ha + CCC 750 @ 1.0 l/ha T1 Moddus @ 0.2 l/ha + CCC 750 @ 1.0 l/ha T1 Moddus @ 0.1 l/ha + CCC 750 @ 1.0 l/ha
Scenario 2: Same conditions and objectives, but drilled at the end of October and with poorer autumn establishment – resulting in a GAI of 0.4 an GS30. Scenario 2: Reflection in same loamy sand soil; drilled on 20 September in good conditions, with fair establishment to give a GAI of 0.7 at GS30 Scenario 2: Chalk soil growing Shabras (medium stem strength and anchorage, sown earlier (1 October), with vigorous growth from early sowing, giving GAI of 1.9 at GS30.
T0 Moddus @ 0.15 l/ha T0 Moddus @ 0.15 l/ha T0 Moddus @ 0.15 l/ha
T1 No Moddus; CCC 750 @ 1.0 l/ha T1 Moddus @ 0.1 l/ha + CCC 750 @ 1.0 l/ha T1 Moddus @ 0.15 l/ha + CCC 750 @ 1.0 l/ha


Harper Adams research

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.

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.

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.

The timing of Moddus PGR application in the spring can influence plant physiological development to minimise the risk of lodging, according to James Southgate of Syngenta.

“Earlier application, at the T0 timing, has been shown to promote greater root development, with benefits for anchorage as well as nutrient and moisture uptake; it can also instigate plants to develop thicker stem walls to reduce breakage,” he advised.

“Application at the conventional T1 timing has a greater influence on crop height, to reduce leverage and the overall risk of lodging.”

Using InSpire growers and agronomists can develop a specific plan for individual varieties and fields to identify where Moddus is most likely to deliver an economic return, and optimise timing for an overall PGR programme to keep crops standing. To try out InSpire now visit: http://www.syngenta.co.uk/PGR-decision-tool


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