Oilseed Rape Lodging Could Be Affecting 35% of UK Crop

The impact of lodging in oilseed rape could be dramatically underestimated in the UK according to a new report undertaken by ADAS for BASF. The report is based on a comprehensive field survey which found that, on average, 35% of the crops surveyed were lodged, but because it occurred in the centre of fields, on many farms it could go unnoticed until harvest.

“If the lodged area of 35% were representative of the whole of the country, it is estimated that it could have reduced the 2012 national average yield by between 0.25 and 0.61 t/ha*,” explains BASF’s Will Reyer. “The financial losses resulting would have equated to between £88/ha and £214/ha - a total loss to the industry between £56 million and £137 million.” ADAS’ report carried out by Dr Charlotte White and Dr Sarah Clarke identified that lodging losses result from the collapsed canopy’s reduced ability to intercept light coupled with difficulties in general crop management and harvest. “Physically the losses are a consequence of low seed set, poor seed fill plus pod shatter,” Mr Reyer adds.

A previous review of available published data found that yield losses depends on when lodging starts and its severity as shown in the graphs below. “Lodging at flowering will reduce seed set and seed weight whilst if it occurs at early pod fill it is the most damaging for yield loss - averaging 52% when the crop is 70º to the ground.”

BASF Agronomy manager Clare Tucker advises that assessment of Green Area Index (GAI) should be routine for all crops every year if lodging risk is to be reduced and yield to be maximised. This tool has been proven to provide consistent advice on the effective use of metconazole across many contrasting years. Growers and advisors should have absolute confidence in its ability to gauge the beneficial use of Sunorg Pro (metconazole) in rape.

Growers and advisors should ideally use the GAI tool from March onwards and, if the GAI of the crop is greater than 0.8, an application of up to 0.8 l/ha of Sunorg Pro to the crop will be economically justified. I’d recommend that applications should be from about mid-stem extension through to yellow-bud – in layman’s terms - once the crop is visibly growing. The mid-stem extension application of metconazole in March is the most effective timing for shorten the crop and reduce lodging risk. However strong active growth is more important than actual growth stage so it is better to delay if it is too cold or dry.

The GAI tool should also be used into April at about yellow-bud. At this timing Sunorg Pro will maximise canopy effects and seeds/sq m for yield; it will also reduce lodging risk and contribute to Sclerotinia control. The April application has been the most common in recent years, in part due to the need to wait for sustained active growing conditions before application.

* Based on an average yield of 3.5 t/ha