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2014 was a bad year for fusarium

Farmers need better data to make good decisions around spraying for fusarium

Fusarium head blight in a wheat head.

Nothing sharpens focus on a production problem like a little skin in the game. My crop rotation on my tiny Blackstrap farm has been wheat, peas, wheat, canola since 1998. It is too much wheat, and for a very scary reason: fusarium head blight (FHB).

FHB was a Manitoba problem, so no big worry for us. Until 2010. That’s when we saw the first sign of the ugly, blank heads and parts of heads with some pink blemishes. It caused not only a yield loss but if there’s too much DON in wheat (DON is short for deoxynivalenol, and also known as vomitoxin), too bad — auger it into the bush. A very scary prospect.

In 2012 I grew Goodeve wheat — midge tolerant but poor for FHB and no fungicide was used. FHB was bad in 2012. Fortunately we squeezed out No. 2 wheat at 15.5 per cent protein and the day it was delivered, the elevator price was $8.30 per bushel so straight to the bank. Oh, for the good old days of eight bucks a bushel.

In 2013 I grew peas (mine were 55 bushels per acre, but some neighbours had 70). Local wheat crops in 2013 had nary a FHB wheat head in sight. Almost all wheat was bumper yield with little or no FHB disease, sprayed or not.

2014 has proven to be a bad year for FHB. I grew Waskada wheat (rated good for FHB). I seeded May 14 — gobs of fertilizer, high seeding rate, good herbicide and a bumper in the making. Easy decision for an old man with cash — shut up and spray. On July 14 the wheat was at precisely the correct stage and sprayed with high end chemical (Prosaro). And still there was some FHB. My problem was thinking the spray was a control for FHB, when it is really meant to reduce severity. I was disappointed to still see some FHB. Some of the blank heads were aster yellows and a few had the stem chewed off by a bug of some sort. So not all blanks were FHB and overall a good crop is nearing harvest.

But many with much more skin in the game and facing declining wheat prices struggled to decide to take on another $20 to $25 per acre cost when it might not be needed. Talk around our fields was “cooler this year than 2012 so we should be okay.” Or some have made the decision to suck it up and spray every acre, every year. Some decided to spray half a field and leave half — a good strategy in the face of uncertainty. Andy Sirski (former Grainews editor) does that with stocks. If the price goes down you are happy you sold half; if the price goes up you are happy you kept half.

It is well known that FHB is weather dependent. Hot and humid weather “gooses” it up to be a big problem. BUT, how hot and how humid and for how long? The critical time is well known — the flowering period.

  • More Grainews: Whether to spray for fusarium: flowering period is key

My point is that we need better information and support to aid in the fungicide spraying decisions.

Manitoba Agriculture produces a FHB risk map on a daily basis through July and I checked the website often. But, what good is that to central Saskatchewan?

Saskatchewan Agriculture information states: “The disease is most likely to thrive when temperatures range from 25 to 30 C and moisture is continuous for 48 hours or more.” “Moisture” is taken to mean rainfall. But, on my farm we had 2.6 inches of rain in July 2013 (no FHB) but only 2.1 inches in 2012 (lots of FHB). In 2014 we had 2.5 inches and lots of FHB. So forget rainfall as a criteria for FHB.

Randy Kutcher, disease specialist in the plant sciences department at the University of Saskatchewan, provided me with a recent and excellent literature review on FHB by Marcia McMullen and others. Marcia is recently retired from North Dakota State University. FHB has been a big problem in several U.S. states for many years. This review is a grand piece of work and answered many of my questions. For keeners, the citation is: “A Unified Effort to Fight an Enemy of Wheat and Barley: Fusarium Head Blight,” by Marcia McMullen, Gary Bergstrom, Erick De Wolf, Ruth Dill-Macky, Don Hershman, Greg Shaner, and Dave Van Sanford. Plant Disease, Dec 2012, Volume 96, Number 12.

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.”

Looking at the data

thumbnail image for chart

Armed with that criteria, I used the hour by hour records for Saskatoon. The results are shown in the table (click here or on the thumbnail image at right). I looked at all of July and took August up to August 20. Some wheat was seeded well into June and flowering could have been well into August. There was an opinion that later seeded wheat was not affected as much — not so this year.

Based on that criteria, the data in the table does show clearly that 2013 was not a FHB year but 2012 was bad. But, with the 2012 experience in mind, many sprayed in 2013 anyway. The only serious FHB day in 2013 was July 6. That day was an all-day rain with 1.6 inches and a temperature around 16 C.

As for 2014, my spray date of July 14 did provide protection for a few bad days. And, some of the bad cases I have seen in later-seeded wheat fit with the many FHB hours in early and mid-August.

The data in the table is based on strict adherence to the rule — that is, relative humidity greater than 90 per cent and temperature between 15 and 30 C. On some days, hours with 89 per cent relative humidity or a temperature of 14.9 C would likely count. It makes sense to me that some sort of sliding scale would provide better criteria. Maybe the Manitoba model already does that.

To get better information we need better weather data. Alberta and Manitoba have a large number of automatically recording weather stations with feeds to be used by models. Saskatchewan is left only with the inadequate Environment Canada stations — too few in number and with ever decreasing resources to keep them operating.

Saskatchewan Agriculture does have a very good network of farmers who report rainfall weekly. That’s good enough for soil moisture mapping but of little use for FHB.

So, as research organizations think about funding for future FHB work the weather piece and information analysis and access should be front and centre.

This article first appeared as, “Fusarium: again… or “still” in the Sept. 30 issue of Grainews

About the author


Les Henry

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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