July 30, 2020 8:00 PM

2020 Vision for brassica disease alerts

Brassica growers can stay ahead of damaging diseases more effectively this season with Brassica Alert, and see how to make the best of Syngenta’s exciting new fungicide technology. The 2020 season’s first risk forecasts are now live to download on the Brassica Alert page.

Brassica Alert spore monitoring on sites north and south of Boston in Lincolnshire gives a good representative picture of seasonal risks for ringspot and, white blister, according to Allium & Brassica Centre agronomist, Simon Jackson.

Now, spore detection technology contained within the traps gives an instant feedback of spore presence and, crucially, a quantitative assessment of the intensity of spore numbers that signifies risk levels.

“Being able to issue forecasts of disease risks within hours of trap inspection will help to target application timing more effectively, before disease impacts on plant health and crop quality,” he advised. “It’s particularly important with the increasing unpredictability of weather conditions.”

With ringspot, for example, he reports growers typically have five days from the point of infection, before disease break out into damaging physical symptoms – it’s the vital time to make best use of fungicide activity to keep leaves clean.   

Furthermore, with the increasing pressure from light leaf spot (LLS) on brassica crops in Lincolnshire and southern counties, Simon believes growers are going to need to be smarter with decision support systems for product selection and timing.

Last year’s Syngenta fungicide trials in Lincolnshire suffered most severely from intense LLS pressure, along with typical seasonal ringspot and alternaria infection.

Results in Brussels sprout trials showed Amistar Top gave significant reduction in both the numbers of buttons infected and the severity of the multiple disease pressures. The four spray programme at Bicker, for example, reduced button infection by 64%, with an 80% reduction in severity in another Swineshead trial.

The trials also saw new Syngenta fungicide technology providing significant advances in increased disease control over and above existing current standards – either when used alone or in programmes with Amistar Top.

The development fungicide, alone and in combinations, consistently gave the best results for disease control, with up to 90% reduction in infection and severity of LLS and other diseases, along with noticeably extra greening of healthy crops.

Register now to receive weekly Brassica Alert risk texts through the season

Brassica Alert also provides risk forecasts of key pests, along with the AHDB Pest Bulletin published on the Syngenta website. Growers are advised to avoid soil drench options at planting that could restrict use of Minecto One for emerging pest problems later in the season.

Syngenta Technical Manager, Dr Max Newbert, recalled the quality of mid-season Brussels sprout production was impacted by high numbers of beetles, with feeding damage to the buttons. “The availability of Minecto One targeted at chewing pests provided effective incidental control.”    

Dr Newbert highlighted it has also been shown to control aphids in the growing crop, which could limit spread of damaging viruses and quality losses. “That’s important for any longer season brassicas, and particularly essential in storage cabbage – to prevent heavy losses from turnip yellows virus.”

To protect against resistance, he pointed out that where cyantraniliprole has been used at planting, growers are not permitted to use Minecto One in any crop in the field for the rest of the season.

“That could seriously limit growers’ options, given increasing issues of resistance and reduction of available insecticides,” he warned. “Using spinosad for the early control of cabbage root fly and thrips, opens up the opportunity to use Minecto One later in the season.”   

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