Fungicides not always an answer in alfalfa

Spraying could make sense when conditions are right for fungal disease

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Farmers must weigh many factors before applying fungicides to alfalfa, said Christine O’Reilly, forage and grazing specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs.

Why it matters: Farmers have found that there have been advantages to using fungicides in corn and with approved options, are now looking at alfalfa.

O’Reilly says the increased talk about using fungicides in alfalfa is probably due to an increase in grower awareness about the available tools to manage diseases. But, she said, fungicide won’t solve all of growers’ forage problems.

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“Looking at your whole production, I’m sure that increase in yield (from the fungicides) is part of it. But, the day you harvest your crop isn’t exactly the amount you have by the time you go to feed it, depending on how you store it.”

Storage is the first place to look for improved alfalfa volume that is fed to cows.

“Some (fungicides) can have that bit of boost effect, but you have to wait through to see what else is going on. If their bunk management is excellent maybe (fungicides) is the next step to get a little bit more forage yield.”

Fertilizer and proper variety selection also play important roles in increasing forage quality and yield.

O’Reilly says excellent marketing from a recent fungicide approved on alfalfa has attracted attention. However, the broader conversation relating to getting more yield out of alfalfa is the result of several years of poorer hay yield. Hay has gone up in price as fewer people grow it and weather has made harvest challenging. The first cut in 2020, however, was excellent.

“We’ve had a few years where inventories have been a little tight. Just an awareness of ‘I need to do something else to make sure I have enough feed’ is on producers’ minds.”

Although there is little research completed on using fungicides on alfalfa, O’Reilly says a study from the University of Wisconsin suggests that fungicides pay for themselves on alfalfa less than half the time.

“We do know what conditions are more likely to help make it pay for itself. If growing conditions favour fungal disease development, such as wet and warm, that’s a good chance that it’s going to be worthwhile applying a fungicide.”

Also, if producers are planting a variety that is not resistant to a disease, that’s an issue, and more likely a possibility that the fungicide will boost quality and yield.

If the hay crop has a higher yield potential, or a longer cutting interval such as 35 days or more, then it’s more likely the fungicide will have a better return on investment.

“If you have three or four of these factors happening at once, particularly when weather conditions favour disease development, when those things are happening, that’s when you’re most likely to get a good return on investing in using a fungicide,” says O’Reilly.

“Fungicides are one piece of a highly productive forage system. It’s not an easy answer, but the big thing is looking at the whole picture and saying ‘does this tool really fit with how that farm is producing forage’ and what they need to do to get the yield and quality that they want.”

About the author

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Jennifer Glenney

Jennifer is a farm reporter who lives in Cayuga, Ontario.

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