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Need for Broad-Spectrum Fungicides in Brassicas – The Vegetable Grower – Andy Richardson

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Andy RichardsonBrassica growers know only too well that they must produce vegetables free from pests and disease in order to satisfy the ever-demanding retail sector. They need to grow great quality brassicas with good shelf appeal and with no visual blemishes.

According to ADAS Crop Notes, recent warm weather interspersed with rain showers has encouraged the development of leaf diseases such as ring spot light leaf spot and Alternaria. Ring spot has been cited as the main disease affecting brassicas with reported incidence of this in kale in the east.

Ring spot and Phoma are reported on purple sprouting broccoli and Brussels sprouts. In sprouts, light leaf spot affects quality and appearance of the buttons and its presence can lead to  crop rejection.

The main brassica diseases are ring spot (Mycosphaerella brassicola), light leaf spot (Pyrenopeziza brassicae), white blister (Albugo candida), Botrytis, Dark leaf spot (Alternaria), Powdery mildew and Sclerotinia. All these diseases spoil the visual appearance of the crop as well as significantly eroding yield.

"Light leaf spot is the same pathogen as the one that attacks oilseed rape and it requires long periods of leaf wetness for infection. Consequently, it is an increasing issue the further north you go. In conjunction with this, resistance to tebuconazole is also widespread in northern England and Scotland. Similarly Sclerotinia has been increasing as rape moves into vegetable brassica growing areas, says Andy Richardson of the Allium and Brassica Agronomy Centre in Kirton, Lincolnshire "We are seeing more Sclerotinia in kale and cabbage, i.e. the longer season crops over the last 5 years or so"

"Signum (pyraclostrobin and boscalid) is effective on Light leaf spot and Sclerotinia and we have been recommending its use as the foundation of a brassica disease programme, for many years with great success says Rob Storer of BASF. "We must not overlook other diseases of brassicas, just because we are so familiar with Light leaf spot in rape.”

The fungicide Signum is a robust basis to a fungicide programme in brassicas. "It controls a wide spectrum of diseases - Sclerotinia, Alternaria and Powdery mildew plus useful control of white blister, ring spot and Light leaf spot- and it can be recommended in a wide range of vegetable crops including Brussels sprouts, cabbage, cauliflower and broccoli/calabrese on its label plus baby leaf  production, kohl rabi, Chinese cabbage, chard, spinach, choi sum, collards, kale, pak choi, tat soi, oriental cabbage and salsify, all as EAMUs," says Rob.

Andy says "Signum has been round tor many years now and has become part of the furniture. It has an impressive crop list, either as label or EAMU recommendations which is useful."

Signum is a protectant fungicide and should be applied at 1 kg/ha early in the programme before the first signs of disease. This is followed by other fungicides with different modes of action 3 or 4 weeks later as part of a proactive resistance strategy.

In Brussels sprouts the first of three fungicides is usually applied in July, the second the end of August and the third October to December. Signum has a harvest interval of 14 days and a maximum number of 3 kgs/ha can be made in brassicas. "SDHI fungicides (as in boscalid) can form no more than 50% of the spray programme," reminds Andy.

Signum also has full label recommendations for carrots, combining and vining peas, field beans, outdoor and protected lettuce, outdoor and protected strawberries, blackcurrants, raspberries, blackberries, red currants, white currants, plums - an impressive list. If you add all the other EAMU's  such as asparagus, parsnips, poppies, leeks, protected herbs, hops, bulb onions, garlic, shallots, leeks, salad onions, potatoes, aubergine, pumpkins and celeriac.

"Signum is an essential input that needs to be in the spray chemical shed at the start of most seasons. It has so many opportunities to be used on so many crops.

When vegetables are on the supermarkets’ shelves, they must look of the highest quality with no blemishes or spots. Growers need to invest in their inputs to assure of this high-quality food," says Rob Storer.

BASF are committed to supporting specialty growers and launched a new fungicide, Perseus last year. Perseus contains two highly effective fungicides; fluxapyroxad (Xemium) and difenconazole. Fluxapyroxad is a SDHI fungicide with broad spectrum activity and difenconazole is a well-known triazole fungicide with excellent selectivity in specialty crops.

Perseus has activity on Powdery mildew Alternaria (Light and Dark leaf spot), Mycosphaerella (ringspot) and Sclerotinia, so most key diseases in vegetables and it has label recommendations for lettuce, potatoes, carrots, broccoli, cabbage, cauliflowers and Brussels sprouts.

The combination of two complementary active ingredients in Perseus means excellent efficacy as well as inbuilt resistance management, leading to good yield, quality and profitability. Its rapid uptake and mobility means excellent efficacy, local systemicity and rainfastness, maximising the spray window. Its long lasting protectant activity means robust field performance so Perseus can be relied upon as a key part of the spray programme during long seasons.

Combining Signum and Perseus can be used in a planned programme, although as they both contain an SDHI they must not exceed more than half of the programme.

This season BASF are giving brassica growers the chance of winning a Brinno TLC200 time lapse camera. To enter, Brassica growers are invited to go to: https://www.agricentre.basf.co.uk/Signum and fill in the form.