Industry optimism but OSR challenges remain Following some difficult seasons, there appears to be more optimism among OSR growers. However, key yield-driving messages still need to be understood. Dominic Kilburn reports from a BASF briefing. While the growing of oilseed rape continues to provide a challenge for many growers in the UK in terms of achieving increased yields while dealing with pressure from pests and disease – initial results from a recent survey by crop protection company BASF shows that most growers are feeling more positive about the crop than in recent seasons. That’s according to BASF OSR campaign manager, Jane Kitchen (right), who unveiled initial results from the ‘OSR State of the Nation’ survey, part of the company’s Real Results OSR Profitability initiative, and a way of better understanding some of the challenges faced by growers. Ms Kitchen said that there was no doubt that growing OSR was a challenge; flea beetle, phoma and slug pressure were just some of the factors that often made it a “headache crop”. However, with 600,000ha currently in the ground, this was a positive increase in area compared with recent seasons, she suggested. “In addition, the survey highlights that most growers felt there was less pressure from CSFB this season than in previous years, and crop failure was down too, so there is definitely some positivity,” she added. According to Ms Kitchen, 304 farmers and 58 agronomists took part in the survey over the winter.
Headline results Thinking ahead to next season, 61 per cent of respondents stated that their intended OSR area would remain the same as this current season, 23 per cent planned for a slight increase and 14 per cent planned a decrease in area. Just 2 per cent planned to grow no OSR at all for the 2018/2019 season. “Not surprisingly, 73 per cent of growers experienced CSFB pressure in the past three years – anything from mild to severe – but encouragingly the feeling was that
there was less pressure now than in 2017 and 2016.” The survey also suggested that while 42 per cent of growers questioned have suffered from crop failure over the past three years, the overall crop failure percentage had reduced for harvest 2018 (4 per cent of crops failed) compared with 2017 (8 per cent) and 2016 (7 per cent). When considering approaches to try and minimise the risk of CSFB, 65 per cent of those surveyed said they had improved seedbeds; 53 per cent increased seed rates and 47 per cent used hybrids. “Some growers will invest in hybrids to try and get their crops away as early as possible, and some opt for increased seed rates, however, when asked, growers thought that drilling early (40 per cent) and improved seedbeds, something that we would advocate, were thought to be the most effective methods of mitigating CSFB risk,” commented Ms Kitchen. Full results of the survey can be found at: www.basfrealresults. co.uk.
Components of yield With one of the survey questions highlighting a lack of industry understanding of yield drivers for OSR compared with wheat, ADAS head of crop physiology (and one of the OSR Profitability panel of experts), Dr Pete Berry (left) outlined some of the key components for realising the crop’s yield potential. He said that OSR yield potential was created by the number of seeds that are set, which was determined by photosynthesis during the two to three weeks after flowering. “An open canopy at the end of flowering is critical to maximise the number of seeds that are set,” explained Dr Berry. “But once the seeds are set they need to be filled and crop leaves should be kept green for as long as possible into seed filling,” he said, adding that, often, because low
plant population crops let more light in, they stay greener for longer and reach their yield potential. With a target GAI of between 3–4 by flowering, Dr Berry highlighted 2009 ADAS trials which demonstrated that an application of PGR Caryx (mepiquat + metconazole) at a crop threshold of 0.8 GAI and above, delivered a positive yield response from the crop. “PGRs reduce the height and apical dominance of the plant, and reduce the number of flowers produced on the terminal raceme, resulting in less light reflection and an increase in the amount of light transmitted below,” said Dr Berry. “This allows more light to penetrate the leaves and stems beneath the flowers which are photosynthesising. The reduction of apical dominance stimulated more lower primary and secondary branches which more than compensated for fewer flowers on the terminal receme. “This is one of the mechanisms whereby a PGR can increase crop yield even in the absence of lodging,” he added. Dr Berry also stressed that growers shouldn’t underestimate yield losses from crop lodging, or leaning.
Aerial surveys of 3,000ha in 2012 and 2014 highlighted an average of 31 per cent of the crop area lodged – an estimated national cost of £120m if crops were lodged flat at flowering, or £45m loss if lodged at 45 degrees during seed filling. ADAS research over several seasons also showed that yield losses (up to 50 per cent) occurred at any time from early flowering to mid-seed fill if crops lodged flat, while significant yield loss could also be expected at 45 degree lodging or even leaning at just 20–25 degrees lodging during the same period. Dr Berry said that in trials, every 5cm reduction in crop height reduced the percentage area lodged by 10 per cent. “Lodging was reduced by spring applications of PGR before the green bud up to early-flowering stage and this demonstrated that you don’t need a big reduction in height from a PGR application to reduce the lodging risk.” As well as canopy and lodging management, Dr Berry concluded that trials with spring applications of PGR active metconazole (2004–2008) had increased crop root length density, facilitating additional water uptake and, in a dry year, was estimated to provide an additional yield of between 0.22–0.34t/ha. ■
Forward OSR crops will need careful management Oilseed rape crops across the UK are generally leafier than usual and many will require timely growth regulation to deliver optimum yields this season. The need for treatment can be assessed by measuring the green area index (GAI) of a crop just before stem extension, typically in late February, says BASF business development manager, Clare Tucker (right). “GAI is the ratio of green leaf to soil, and its value prior to stem extension is an important predictor of canopy size at flowering and consequent lodging risk. “This year we have seen many more leafy crops going into the winter due to good drilling conditions, earlier drilling, the open autumn and less flea beetle damage than we saw in the previous two seasons. “These crops tend to form overly thick canopies at flowering, which limits light penetration and seed production, and will be more likely to lodge.” BASF has updated its mobile OSR GAI app to help growers accurately measure crops and optimise plant growth regulation programmes. “GAI is measured by taking a photo from directly above the crop, covering about 1m2 using the white bars as measuring aids. The app will then calculate the GAI score automatically,” says Mrs Tucker. The GAI measure provides the economic threshold for Caryx (mepiquat + metconazole) use, she continues. Crops with a GAI above 0.8 should be sprayed with 0.7–1-litre/ha of Caryx any time between the start of stem extension (typically from mid-March onwards) to yellow bud. Where GAI exceeds 2 the rate should be raised to 1–1.4-litres/ha.
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Published on Mar 1, 2018