Best cure is prevention when it comes to crop diseases

By Tim Kalinowski

Alberta Agriculture and Forestry crop specialist Mark Cutts says the old adage an ounce of prevention is better than a pound of cure applies very well when it comes to crop diseases this year.
“Everybody can learn something by being out in their fields, and it’s a good practice to get into,” says Cutts. “And it’s something which is being done more often by more producers and their consultants.”
While frequent field inspections can help in some instances to allow farmers to take quicker action when it comes to diseases in their crops, says Cutts, there is also an element of timing and luck involved.
“Last year, for example, in canola sclerotinia was certainly a disease found in a number of fields,” explains Cutts. “It’s an interesting one because you have to actually spray a fungicide for that one before you actually see the disease present. You are spraying based on the indicators. So if you had a field nearby with it the previous year, there is still certainly a chance for picking up that disease. And it can’t be managed strictly by rotation. It’s one of those diseases where if the spores are out at the right time, and a susceptible crop is there, with the right weather that disease can have an impact on any field.”
If you decide to spray for it, says Cutts, there is a little bit of guesswork involved even then.
“You have a window of application, typically at 20-50 per cent flowering on the canola plant, if you can hit that window it can certainly help with managing the disease.”
While sclerotinia is certainly a major disease problem in some fields, at least there are some spraying and treatment options. With other diseases like Aphanomyces, your options are much more limited.
“Aphanomyces is becoming more of a significant factor over the last number of years, and it tends to do well in poorly draining soils,” confirms Cutts. “Unfortunately, there is not a lot of control options at this time. It’s disease, if you do have it, taking a break from growing susceptible crops is really the best option.”
There is exactly one seed treatment option on the market, but it isn’t what farmers would call a silver bullet by any means.
“There is one seed treatment call Intego Solo that has been registered for suppression on Aphanomyces, but that’s only for early season suppression. So it’s not going to be the home-run a producer is looking for at this point in time,” Cutts says.
Crop rotation may be key to eliminating the risk of Aphanomyces, but with clubroot there is no security except proper disinfection of farm machines when moving between fields.
“If you are not currently infected with clubroot, your main objective there would be to make sure your equipment, or your contractor’s equipment, is clean when moving from field to field. Prevention is the main goal with this disease,” confirms Cutts.
Cutts says there is also a costly option to buy some clubroot resistant varieties of seed, but that only makes financial sense if you are at immediate risk of infection.
“If you are not currently infected, but live in an area where you know clubroot is close by, using resistant varieties is another agronomic option to pursue. The ideas is if you can prevent the disease from taking hold by keeping the spore numbers at low levels, you can manage that disease to a certain extent.”
Cutts says in all cases direct observation of fields early and often in the growing season can mean the difference between a costly loss later in the year or a cheaper fix early on.
“I think it is something which allows you to get a good feel for your crop, and allows you to make decisions about whether you do or do not need to control some of these diseases in the crop.”