April 16, 2015

16/04/2015: Maintain fungicide use to protect yields

In stark contrast to spring 2014 growers across the country are reporting crops to be generally clean of disease. This will undoubtedly come as welcome news, but as increasing temperatures raise the risk of disease, what are the implications for fungicide strategies?

“It has so far been a kind season; crops are clean and in good shape, but the evidence of our trials suggest it still pays to get your protection in first,” says KWS product development manager John Miles.

The lower pressure start to spring coupled with lower commodity prices has prompted some growers to consider cutting back on fungicide use in a bid to reduce costs. While perhaps an understandable reaction Mr Miles warns that disease is no respecter of the commercial pressures facing growers.
    

http://www.agricentre.basf.co.uk/agroportal/uk/en/startpage.html


“We all realise pressure will soon begin to intensify. There is a desire to save on inputs, but if growers plan to change their strategy on the back of current conditions they need to be aware of the implications should the situation deteriorate.

“The results of long-term trials demonstrate that even in low pressure years, there is a clear payback to be had from following a comprehensive fungicide programme.”

Mr Miles was speaking at a recent agronomy briefing held in conjunction with BASF and Prime Agriculture to consider how learnings in plant disease resistance could be used to inform fungicide programmes. Although not a replacement for fungicide applications, he said resistance ratings could be used to determine the order in which crops were to be treated, but with the caveat that this is highly dependent on drilling date and disease pressure.

“2014 presented ideal conditions to investigate the contribution disease scores make to combatting Septoria tritici. In a typical year, measuring the differences between a variety with a Septoria score of 4 and one with 6 is quite difficult and often masked by other diseases such as rusts. Less than four or more than 6 is, in contrast, quite easy, but most varieties fall in to the first category so it is important to know how these will react to pressure,” he said.
  
Perhaps not surprisingly the crops receiving more robust programmes performed better, but the difference in programmes was stark.

“Visually, there was little difference between crops, but those that received a second SDHI and a higher rate of chlorothalonil were able to better utilise the applied nitrogen. As a result we observed an average yield increase of more than 0.75 tonnes/hectare (t/ha) for a regime applying 280kg N/ha.”

His observations were supported by BASF regional sales manager Steve Dennis who explained that the yield differential between treated and untreated crops in trials was greater than the long-term average.

“There is always a strong response to fungicides, but the margin narrows as you move to those with better disease ratings. For example, Gallant, with a Septoria rating of 4, showed a 5.0t/ha response to fungicides in our trials while Cougar, with a rating of 7, gave a response of 3.3t/ha.”

“The average response across 30 varieties in 2014 was 4.39t/ha. At a wheat price of £110/t that is an extra UK£483/ha in output. At a fungicide cost of UK£114/ha that is a MOIC of UK£369/ha, equivalent to 4:1 return. Across 200ha that is an extra UK£73,860 so there is a compelling argument for not skimping on control.”

If viewed in isolation however, response to fungicides as a single measure could be considered misleading.  


“It is important to look at output. Varieties with lower resistance ratings tend to show the greatest response, but not all yield to the same level.”

This is partly explained by 'linkage drag' said KWS’s John Miles. 

    
https://www.kws-uk.com/
John Miles with KWS Magnifico hybrid rye in background
“No one truly understands how Septoria resistance works though we are learning all the time, but we have observed lower yields in plants demonstrating higher levels of resistance. Overcoming this ‘linkage drag’ is the subject of research at the highest level,” he said.

According to Steve Dennis, the analysis does not provide a basis for dropping those varieties with relatively poor scores, but rather supports the case for managing them accordingly to meet potential.

“On average margin increases by 22 percent so there is a benefit from choosing a cleaner variety, but varieties with recognised high yield potential will always respond. Horatio and KWS Kielder, for example have Septoria ratings of 4 and 5 respectively, but yielded close to Revelation and Skyfall, both of which have a score of 6,” said Steve Dennis.

For Prime Agriculture agronomist Philip Simons, disease ratings are coming to be seen as an increasingly useful management tool among his clients.

“There is certainly a desire among growers to adopt varieties with better resistance. About a quarter of the Prime portfolio is down to varieties with a rating of 4.

“It fits with wider economic and environmental pressures. There is a desire to make the most of the plant’s natural resistance to disease, buy some time when conditions make application difficult and prolong the life of the plant protection products we have,” he said.

But equally there was recognition that rates needed to be maintained and the best products used. 


“You can’t afford to skimp on programmes. Responses will follow, but rate, interval and product choice are important to maximising that response,” he added.
 

Visit the BASF website HERE

Visit the KWS website HERE.  

Visit the Prime Agriculture website HERE.
 


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