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17 crop disease prevention strategies

Fungicides are key, but there are many other parts to an effective long-term strategy

As you can tell by the fact that this article includes 17, yes 17, strategies for crop diseases prevention, there are no quick fixes. Crop disease prevention is going to be an ongoing struggle.

1. Use multiple strategies: Understand that multiple strategies are the way to go. There isn’t one big hammer, rather lots of little hammers with lots of little effects. Using multiple strategies like those laid out in any standard info sheet will help you avoid a complete shipwreck.

2. Add diversity: Pulling diversity into the system is key. Don’t repeat patterns year after year! Whether it’s the rotation you follow, the varieties you grow, or the fungicide you apply, you’ve got to change it up.

3. Do things differently: Every move you make to change things up will make our current resistant varieties and our current fungicide last longer. Saskatchewan Agriculture’s plant disease specialist, Faye Dokken-Bouchard says the best way to help plants keep their resistance is to use Integrated Pest Management (IPM) and rotations.

4. Share information: Learn from other producers, both positive and negative. Pulse growers have led the way in managing diseases and applying fungicides. In Manitoba and Ontario, fusarium head blight (FHB) is now a given. Producers in Europe cope with much wetter weather than we do and have been using fungicides for years. Australian producers and their experiences with blackleg in canola also contain a valuable lesson for us.

5. Use longer rotations: One year between crops is not enough time for infested residue to decompose. In dry periods, Sabine Banniza, pulse specialist with the Crop Development Centre at the University of Saskatchewan, believes, you can get away with it. “But in the wet periods, when conditions are right, you will get hammered.” Crop rotation is really important especially for diseases that are host-specific. Farmers need to rotate away from that particular crop.

6. Calculate your long-term economic benefits: Banniza believes that producers who stick to very good rotations may be missing out a bit but they are ensuring the long-term sustainability of their fields. We also need long-term studies on the economic impact of longer rotations, says Turkington. In the short term, the farmer will gain because canola’s paying $10 to $14 per bushel. But canola also tends to be input intensive. Inserting pulses into the rotation will lower input costs for cereals, especially because the producer will also be able to rely on resistance. “If we spread those costs and benefits over a five to 10 year frame, what do we get?”

7. Do the best you can: If you’re not going to change your rotation, then do the best thing you can. Gardner knows that longer rotations are not an easy sell: “I could talk rotation every day.” But if you aren’t in a position to change your rotation, what are the other ways that you can introduce diversity into your system?

8. Rotate crop types, not just crops: Longer rotations aren’t completely problem-free because some diseases are not crop specific. For instance, sclerotinia crosses over between lentil, peas, soybeans and canola.

9. Try new crops: Kelly Turkington, Agriculture and Agri-Food research scientist, says, “humans gravitate towards what’s familiar.” For Prairie farmers, it’s cereals and canola. Turkington advocates employing whatever method of tech transfer available — demo plots, extension agronomists, crop centres to expand producers’ capacity to grow unfamiliar crops. Marketing support for these crops is as important as agronomic support.

10. Use resistant varieties: But, not the same one every year. You need to keep changing what you do or any pathogen will adapt. Jay Schultz, a farmer near Standard, Alberta, mixes up his seed source. For instance he alternates between planting Roundup Ready canola and Liberty canola. By doing this, you will help the scientists and plant breeders keep ahead of the game. They are constantly searching for new and better sources for resistance and then trying to incorporate them into our new varieties.

11. Use fungicides as part of a larger plan: If fungicide is your sole approach to managing a disease with a tight rotation, Turkington warns, depending on how frequently you use it, you could be selecting for a non-susceptible fungus. Brulé-Babel worries that though fungicides in Manitoba have been effective to date, we run the risk of overusing them. “The better the fungicide works, the more we select.” There are different formulations but there aren’t a lot of different modes of actions. For the most effective use of fungicide, Gardner urges farmers to take care of all the cultural things they can “at the front end” including choosing resistant varieties and using seed treatments.

12. Know your fungicides well: Especially, know their active ingredients and how they work. Gardner observes that in Europe, farmers don’t even use product names when they talk, but rather they refer to active ingredients. Some fungicides work on single sites of selection and others work on multiple sites. The single site fungicides give you just one kick at the can. Over time disease will figure it out more quickly.

13. Rotate between fungicide groups: Gardener says, “You want to mix things up.” If you repeatedly use the same fungicide, you select for resistant pathogens. This is especially important in the same year: if you spray fungicide at flag-leaf, switch groups if you are going to spray again later in the same year. (Using a seed treatment with the same active ingredients as a foliar application later in the same season is not an issue.)

14. Use the right fungicides, with good timing and good application technology and good coverage: Many farmers are penciling in fungicide application and budgeting for it but they still must be conscious about when and how to use them and how to get the best return on investment. They cannot be recreational or cosmetic. If the risk factors are low, don’t spray! Schultz notes that pre-buying fungicide in the winter is not good agronomic practice, since you don’t know what the conditions will be — you may not need them.

15. Scout, then scout again: You must check and see what’s in the field at the right time and then figure out what you’re going to do if a disease issue is apparent. There is a small window to apply fungicide, for instance, for FHB prevention. You have to catch it.

16. Watch the weather: If you spot symptoms of FHB, you’re too late. What you need to be doing is watching the weather at the time of flowering. “There are no curative applications,” says Jay Schultz. “You only have preventative. You only have one shot.” Manitoba and Ontario have an FHB forecast. With data collection, Brulé-Babel believes that forecasts could be established for other diseases too. Shultz keeps a close eye on the weather forecast and stays up-to-date on disease issues through websites like the one run by the Alberta Canola Producers. He also relies on Twitter. “It’s basically coffee shop talk for all of Western Canada.”

17. Accept the inevitable: There is no simple recipe. Coping with disease issues is ongoing and complex. Success is only achieved through lots of smaller actions. Brulé-Babel, acknowledges that though “Resistant genes can make things better, we may have to combine multiple strategies and, in the end, live with some FHB.”

About the author

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Patty Milligan is a freelance writer based at Bon Accord, Alta.

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