Focus on Mildew

Article taken from the Farm Contractor & Large Scale Farmer

Applying co-formulation protectant fungicides at T0 is the key this year to keeping cereal crops clean of disease and can prevent having to deal with specific diseases later in the season when workload pressure is at its most intense.

Mildew is an emotive disease says Agrovista agronomist Tim Harrison.  It is not a usually major yield robber and so it has not always been given the respect or attention that it deserves.  However, leaving it until later in the season can have a knock on effect in respect of controlling other more damaging diseases such as septoria, fusarium and rust.

“Gone are the days where growers can take a wait and see attitude with mildew,” he says.  “You have to be in there early to protect new leaf.  If mildew gets up onto new leaf and it goes from the flag leaf to the ear it’s impossible to eradicate.

“Nobody wants surprises later in the season but mildew is one of those diseases that can appear throughout the season,” he says.  “This season looks like it could be big for mildew as there are forward and lush crops already showing signs of overwintered mildew on lower leaves.  Light land farms and those that have an historical manganese deficiency are going to be more at risk.”

Mr Harrison urges growers to be extra vigilant for mildew from now on.  While the disease does not always have a massive impact on yield it can weaken the plant, making it more susceptible to other diseases, such as fusarium.

The key this year is to keep on top of mildew and stop it from taking hold.  The disease is already in crops.

We recommend applying at T0 the co-formulation protectant fungicide Fielder® (proquinazid + chlorothalonil) at 1 l/ha plus Centaur at 150ml/ha to protect cereal crops against mildew, septoria and rust,” he says.  “If mildew is present in the crop at the T1 timing then the weather will dictate if the disease is going to explode.  A T0 application will help to get on top of the disease now.  Older mildewicides such as Corbel are only curative so offer no longevity.

“The proquinazid takes care of mildew while the multi-site active chlorothalonil provides early protection against septoria,” says Mr Harrison.  “Some septoria actives which are not multi-site are now showing levels of resistance to the disease.”

He explains that overwintered cereal crops on which mildew has been detected should be fine provided there is no delay applying a protectant at T0.  The theory being that the older infected leaves will die off anyway rendering them harmless.  But the risk is that the spores migrate up the stem and onto new leaves and this is where the problem starts.  Keeping new leaves clean of disease is paramount.

He adds that the physiological benefits of proquinazid are well known and are relative to its competitors, but the likes of metrafenone (Flexity) and others are now showing signs of resistance.

“Applying Fielder® at T0 will protect any new growth from mildew as well as from septoria and rust, but even in the absence of disease the extra greening and associated yield increase far outweighs the initial cost of the chemical.”

Protect from mildew.  Grow yield

Mildew tends to be a disease that is ever-present and flares up periodically leaving growers chasing it throughout the season.  Unless, of course, they’ve had the foresight to apply Talius® early in the season.

Talius® acts on mildew in a range of ways leading to very effective long term protection from mildew – including plant growth produced after application.  One of these modes of action is to induce the host plants own resistance mechanisms.  It is perhaps because of this and the excellent mildew control that Talius® added to a base programme has, on average, shown a yield response worth 3x the cost of the product.  Results have shown that higher rates of product protect for longer and ultimately generate higher yields so growers must take caution when considering rate reductions.

With the majority of varieties planted in 2013/14 having a HGCA mildew resistance rating of 6 or less, and lots of mildew already seen in crops growers need to consider whether they wish to risk chasing mildew this year or apply Talius® at the T0 / T1 timing.

Copyright © 2014 Dupont.  The Dupont oval logo, DuPontᵀᴹ, The miracles of scienceᵀᴹ, Talius® and Fielder® are registered trademarks or trademarks of E.I. du Pont de Nemours and Company or its affiliates.  Talius® contains proquinazid.  Fielder® contains chlorothalonil and proquinazid.  Flexity contains metrafenone, Corbel contains fenpropimorph and cyclhexanone, Centaur contains cyprocorazole.  All rights reserved.  All manufacturers trademarks are duly acknowledged.


01 April 2014

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