Only one field so far | Growers are urged to send samples of suspect cases to the Crop Development Centre for testing
TABER, Alta. — A bacterial disease that first found the Alberta spotlight last year is giving an encore performance in corn crops this year, but so far it’s a limited engagement.
Goss’s wilt has been identified in only one cornfield east of Taber, but agronomists and plant pathologists are keeping a close watch on the infectious disease.
Though fairly widespread in Manitoba, Goss’s leaf blight and the more serious Goss’s wilt are new to Alberta corn crops. Last year, six fields were found to be infected with leaf blight and only two showed serious wilt symptoms, said Alberta Agriculture plant pathologist Michael Harding, who works at the Crop Development Centre in Brooks, Alta.
Read Also
Agri-business and farms front and centre for Alberta’s Open Farm Days
Open Farm Days continues to enjoy success in its 14th year running, as Alberta farms and agri-businesses were showcased to increase awareness on how food gets to the dinner plate.
“The traditional range where this pathogen had existed in the past has been expanding over the last few years and so it’s not nearly as big a surprise to us that it showed up again this year,” said Harding.
There is no effective chemical treatment for the disease, which impedes plant’s ability to photosynthesize and in later stages impedes the flow of nutrients in the stalk.
Experiments with bactericides haven’t proven effective.
Prevention is the primary tool, and involves good crop rotation, using resistant varieties and starting out with clean, disease-free seed, said Harding.
“You definitely want to be in the prevention game.”
Even those measures may not prevent infection because the bacterium that causes Goss’s wilt can be easily spread on equipment, in dust, by water splash and even by clothing and human hands.
“That’s true for a lot of the bacterial diseases that we see, but clavibacter (the pathogen behind Goss’s wilt) is kind of notorious for being able to spread plant to plant with just a little bit of contact.”
Lloyd Van Eeden Petersman of Taber Home and Farm Centre showed samples of infected leaves at an Aug. 6 corn school near Taber. He said residue management will be important in controlling the disease should it become more prevalent.
“It’s something we want to be careful with,” he said. “We do need to manage how we move the residue off of the field but also how we move equipment back and forth. Call it field hygiene.”
Turning residue under in the fall may help, said Van Eeden Petersman. But Harding said growers have to weigh the options before getting out their plows.
“That’s not the management practice that I would use as the foundational principle for managing the disease,” said Harding. “It can help, because the bacteria probably isn’t going to survive long in the soil without some host tissue there.
“But there’s lots of other good reasons to not turn residue under. Growers will have to gauge the pros and cons.”
Goss’s leaf blight and wilt can be identified by the appearance of water-soaked leaves with pepper-like brown or black spots and greyish brown lesions.
In the early stages, it can be difficult to identify. That is one reason Harding is seeking as many samples as possible of suspect cases.
“We would really like to get an idea of how frequent it is, and the reason is …we’d like to know if it’s expanding in the province and we’d also like to know if it’s getting worse or if the situation is balancing out.”
If samples test positive, it’s not necessarily indicative of a serious problem, Harding added. Not all cases lead to economic losses. However, identification could indicate needed changes in management.
“It’s too late to do anything about the problems that we’re seeing now, but this is the time to evaluate whether or not the management practices that are being used are effective.”
