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FHB: a disease of even-numbered years

It seems unlikely that FHB strikes every second year, but the data backs it up

This is an update of a piece about fusarium head blight (FHB) we did about one year ago now. To be honest, much of it is actually “cut and paste” from last year. I’ve never done that before, but it seems appropriate for this situation. We are just adding another year of data. In agronomy we need data from as many years as possible to try to understand how to deal with Mother Nature.

My crop rotation for many years had been wheat, peas, wheat, canola. That is too much wheat and change was needed.

Some history

Until about 2010 FHB was a Manitoba problem. In 2010 my wheat crop had some of that ugly pink/orange colour on the sick-looking part of some heads, and it was like a blow to the head. I could still take you to the exact spot I first observed that dreaded but unmistakable colour. We had heard about folks in Manitoba augering wheat into the bush as the FHB left them with no market. There are also stories about digging holes and burying it, but I have yet to talk to anyone who has done that.

In 2011 there was no big problem in our area so we thought it was a one off. But, in 2012 I had AC Goodeve (midge tolerant) wheat with low FHB resistance and it was really scary. I still managed to sell it as No. 2 for $8.30/bushel. (Anyone remember that price?)

In 2013 most wheat crops in our area were sprayed with fungicide for FHB. But, few needed to — it was a year with very low FHB problems. In 2014 I planted AC Waskada wheat with moderate resistance to FHB and sprayed with expensive fungicide (Prosaro) but I still had FHB. It yielded well and was marketable but it was high time to learn more.

The photos at top and below show my experience in 2014.

But, later in august the FHB was easy to see, although we used a fungicide at the right time.
photo: Les Henry

In 2015 my crop was canola and for 2016 I switched to barley. Barley is affected by FHB but not as bad as wheat, and I managed to get lucky and sell mine for malt.

The FHB literature

A University of Saskatchewan colleague provided a literature review paper on FHB by Marcia McMullen from North Dakota State University.

It was a good piece of work and it answered one burning question: “What are the environmental variables that ‘juice up’ FHB?” About weather and FHB risk they said the best model used “the duration of hours that relative humidity was greater than 90 per cent when temperatures were between 15 and 30 C for the 10 days after anthesis.”

With eight years of continuous data it is clear that the criteria as established by decades of work in the U.S. fits our situation very well.

The table below shows the eight years of data I have compiled based on Environment Canada’s Saskatoon weather records. It shows very clearly that, in this area, FHB is a disease that is bad on even-numbered years. To drive home the point, the number of hours favourable for FHB in 2010, 2012, 2014 and 2016 were 177, 178, 137 and 231. In the odd years in-between, the number of favourable hours were only 18, 60, 89 and 29.

With this history there is no way I wanted to plant wheat in 2018, so I’ve already bought seed to switch to canola. That leaves only two years since I last grew canola but I’ll stretch out the rotation and keep looking for another cereal to replace wheat.

The future?

Even with the decades of work in the U.S. we are still left with Band-Aids to deal with a very big knife cut. New varieties offer moderate resistance at best and fungicides are a Band-Aid. My answer is to use the most expensive fungicide and try to get the best possible timing but all of that does not fix the problem.

Longer rotations are great to talk about but difficult to implement. Perhaps we should be stepping back and looking for entirely new approaches. If high ammonia in the atmosphere is a factor we should at least start to measure what atmospheric ammonia is present. I have found extensive data on atmospheric ammonia in U.S. but nothing in our part of the world.

When I look at areas of FHB, the most serious infection is where the crop is the best — that is, in a high nitrogen environment. Unless plant breeding has a huge breakthrough we must expand our horizon of potential solutions.

About the author

Columnist

J.L.(Les) Henry is a former professor and extension specialist at the University of Saskatchewan. He farms at Dundurn, Sask. He recently finished a second printing of “Henry’s Handbook of Soil and Water,” a book that mixes the basics and practical aspects of soil, fertilizer and farming. Les will cover the shipping and GST for “Grainews” readers. Simply send a cheque for $50 to Henry Perspectives, 143 Tucker Cres., Saskatoon, Sask., S7H 3H7, and he will dispatch a signed book.

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