Attending spring demonstrations growers have been finding out how variety Harper can optimise disease control
Attending oilseed rape spring demonstrations growers have been finding out how RL variety Harper can optimise disease control and getting some pointers to tackle the challenge of establishing crops without neonicotinoid seed treatments. Growing a variety that is top-rated for phoma stem canker resistance allows autumn and spring fungicide timings to focus on light leaf spot, potentially saving a spray and easing management, growers heard at the recent Bayer CropScience demonstration at R&R Farms, Scothern, Lincolnshire.
Only three varieties on the HGCA (E&W) Recommended List are rated 8 or more for stem canker resistance and Bayers new addition to the list, Harper, leads the pack with a 9, points out the company. Bayer commercial technical manager, Darren Adkins explained that with Harper the 10 per cent phoma leaf spotting threshold was rarely breached. It means growers can delay their first Proline (prothioconazole) spray until first signs of light leaf spot infection usually in November and deploy the appropriate dose of 0.46 litres/ha.
With dual low resistance varieties growers are forced into an earlier 0.32 litres/ha spray for phoma and generally need to put a second on four to six weeks later. With Harper this can, in most seasons, be avoided and the later timed light leaf spot spray should see the crop safely through to spring. Typically this spray would also conveniently coincide with the timing for black-grass control, he added.
Bayers seeds development manager, Carol Norris (above) said Harper had the highest gross output of varieties with robust stem canker resistance ratings on the RL. Its gross output of 103 per cent is 2 per cent higher than Quartz and 4 per cent ahead of DK ExPower. Harper had also proved its standing ability under severe pressure in the 2012 season and last year demonstrated its vigour in both the autumn and spring, she added.
Neonic challenge Moving on to the challenge of establishing next years crops, seed treatments campaign manager Peter Stacey said that doing this without neonicotinoid seed treatments would be a massive experiment for growers. Oilseed rape has never been grown in the UK without insecticidal seed protection. Before the second-generation neonicotinoid insecticides such as Modesto (clothianidin + beta-cyfluthrin), growers had Chinook (imidacloprid + beta-cyfluthrin) and before that Lindane (gamma-HCH). The very first crops were grown with this and it provided decent control of cabbage stem flea beetle, if not aphids. This autumn the trick will be to get crops out of the ground uniformly and reach the 24 true leaves stage as quickly as possible to minimise early cabbage stem flea beetle attack. Considerations in achieving this will be variety, drilling date, establishment method and seed rates, Mr Stacey advised. Showing growers round the plots he pointed out the difference in establishment between varieties with good early vigour, such as Harper, and those which were slower out of the blocks. He suggested: Think about drilling date and make it a priority task. Establishment method might also become more important. To get uniform emergence disc and drill may be better than dropping seed behind a subsoiler leg. Seed prates may need to be increased a little as well if currently at the lower end of the spectrum ie 3040 seeds/m2, but doubling rates will not be the way to go. Use of starter fertilisers should also become standard. One hope on the horizon for growers is that an insecticidal seed treatment based on methiocarb and currently used as standard in France may become available here. Bayer is developing a formulation for UK approval and the experimental plots established with it at Lincoln looked as good as the Modesto treated ones, says Bayer. Not surprisingly, the untreated plots were very patchy but the use of two pyrethroid sprays had made some improvement. Mr Stacey said that in trials the experimental treatments performance had ranged from 6070 per cent of Modestos control of cabbage stem flea beetle damage. Bayer hopes for approval in time for autumn 2015 drillings