Fusarium takes toll on seed


Yields cut by nearly half | Concerns rise over spread of disease through cleaned pedigreed seed

Fusarium graminearum took a huge bite out of pedigreed seed supplies in 2012, particularly in Saskatchewan where some seed growers harvested unusually small crops that were heavily infected with the disease.

Fusarium cut grain yields by as much as 50 percent in some parts of the province, and the proportion of fusarium damaged kernels (FDK) in certified wheat and barley crops was unusually high, leading to additional cleanout losses of 30 percent or more.

The disease’s prevalence is raising concerns about whether it is being spread via pedigreed seed that contains traces of fusarium graminearum, even after the seed has been cleaned and conditioned. Graminearum is the most aggressive and costly of the fusarium species.

The yield losses caused by fusarium will almost certainly result in regional shortages of certified wheat and barley seed, said Bruce Carriere, manager of Discovery Seed Labs.

“There’s going to be a seed shortage, big time,” Carriere said. “There are some growers that have nothing to sell.”

Fusarium losses in Saskatchewan varied from region to region and were largely influenced by local weather conditions.

Seeding date was also an important factor in determining overall infection rates.

Some crops planted in early to mid-May were heavily infected while others planted later experienced minor losses.

Overall, there were numerous hotspots where infections rates reached record levels and where fusarium graminearum was evident on more than 50 percent of harvested kernels.

Joe Rennick, a certified seed grower from Milestone, Sask., south of Regina, said certified seed crops on his farm produced variable yields, depending on when they were seeded.

In some instances, wheat crops that looked like they would produce 50 or 60 bushels per acre yielded in the mid 20s.

“In the crops that were affected, it really hit the yield hard,” said Rennick.

He said certified wheat crops that were hardest hit produced yields of 22 to 28 bu. per acre, a disappointing outcome considering the density of the stands.

Clean-out losses on that material could cut production by another 20 to 30 percent, pushing the total marketable yield of conditioned certified seed as low 15 to 20 bu. per acre.

The prevalence of fusarium in certified seed crops is prompting discussions about whether the pedigreed seed industry should establish fusarium thresholds on certified seed supplies.

Most fusarium damaged kernels can be cleaned out of pedigreed seed using a gravity table, but there is no guarantee that the remaining seeds do not carry traces of fusarium graminearum.

Commercial grain growers who buy certified seed are responsible for asking whether the seed has been tested for fusarium graminearum and whether fusarium damaged kernels were prevalent in pre-conditioned seed lots.

Growers who plant farm-saved seed should check seed for traces of the disease.

In Alberta, fusarium graminearum was declared a pest under the province’s Agricultural Pest Act in 1999.

The declaration, when combined with Alberta’s fusarium management plan, means there is a zero-tolerance threshold on pedigreed seed that contains detectable traces of fusarium graminearum.

In other words, it is illegal for any Alberta farmer to buy, sell, distribute or grow seed that is contaminated with the fungus.

The increasing prevalence of the disease in Western Canada has the Alberta government and some Alberta seed growers questioning whether the zero-tolerance policy for seed-borne fusarium graminearum should be revisited.

Fusarium has already been detected in cereal crops produced in southern Alberta in 2010 and 2011.

The disease has also been confirmed in the Peace River district.

As well, unusually wet weather in Alberta last year is expected to encourage the disease’s spread.

Gayah Sieusahai, chair of the province’s fusarium action committee, said plant pathologists are reviewing the province’s fusarium management plan.

Support for a zero-tolerance policy on seed-borne fusarium may be waning in Alberta, especially given that the disease has already been detected in the province.

As well, Sieusahai said it is difficult to ensure that all certified seed transported across the Saskatchewan-Alberta border is fusarium-free.

To complicate matters, plots of breeder seed planted at Agriculture Canada’s seed increase unit near Indian Head, Sask., were also heavily infected in 2012.

That has prompted concerns that breeder seed from Agriculture Canada’s newest and most promising cereal varieties may contain traces of fusarium graminearum, even after the seed has been cleaned and conditioned.

If that is the case, breeder seed from Agriculture Canada’s Indian Head facility would be prohibited from entering Alberta’s pedigreed seed system unless existing terms of the province’s fusarium management plan are amended.

Officials at Indian Head will be examining conditioned seed lots in early 2013 to determine if heat treatment procedures were effective in eliminating seed-borne traces of fusarium graminearum.

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