How can fruit and vegetable farmers prepare for El Niño?

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

The current El Niño is likely to be the strongest we've seen in our lifetimes. How can we prepare for it?

El Niño events typically get stronger through the fall and peak in the winter and often result in a warmer cold season in Minnesota. For context, the warmest winter on record in MN (2023-2024) happened during a relatively moderate El Niño. A stronger event means that we expect some stretches of notably warmer winter weather.

Although warmer conditions could mean less snow cover, it’s possible we won't actually see a drier winter, just precipitation in the form of rain; snow may not linger as long. If we look back to the last El Nino in 2023-2024, the winter was dry, but the following spring was very wet, meaning that we didn’t see lasting impacts of dry conditions in the following growing season. According to Kenny Blumenfeld, MN DNR climatologist, strong El Niño events can result in “active” weather in the following spring or summer, with six of the last seven major strong and very strong El Niño events being followed by frequent severe weather activity and/or flooding.

Although El Niño events weight the dice for these conditions to occur, don’t plan on every week this winter being warm or snow-free. Variability will still occur, but the following tips below are good practices to keep in mind for milder winters this year and beyond. 

What can you do with this information?

• Use cover crops and mulch strategically: Manage your soil for precipitation swings and fluctuating snow cover. Using cover crops or mulches will be especially important for preventing erosion. Straw mulch can be used to insulate non-woody perennial crops like June-bearing strawberries.
• Pay more attention to tracking pests next year: Pests can overwinter, or emerge earlier in the season after mild winters (especially if there is a lack of extreme cold temps). Spend some time this winter making sure you have proactive integrated pest management plans to roll out early in the season. For fruit growers, keep track of growing degree days and use software like Cornell's Network for Environmental and Weather Applications (NEWA) to determine when to set traps out for pests like codling moth in apples.
• Carefully plan your planting schedule: Using succession planting, or finding other ways to be flexible in your planting schedules may help if spring weather is severe.
• Be wary of planting early next year: Every year we see farmers planting early when the weather is unseasonably warm in March and April, yet most years we still get a hard frost in May. It's great to take advantage of early warm weather with crops that can handle a later freeze (Brassicas, spinach, lettuce, etc.), but don't assume that your heat loving crops will survive if they are planted early.
• Watch for early bud break in fruit crops: With a warm winter, woody fruit crops that require a certain number of chilling hours (hours of temperatures between 30-45F) may end up with less consistent bud break, while warm periods that occur after chilling has completed can lead to early bud break. To learn more about spring frost protection strategies, you can check out the article, "Escaping spring frost in the Upper Midwest," to find out if there are any feasible ways to prepare on your farm.
• Prevent rabbit and vole damage: With less snow cover, tree trunks and lower branches can become more susceptible to girdling from rabbits and voles. Using tree guards that make contact with the soil can be especially helpful to prevent damage.
• Prune for cold snaps: Woody fruit crops develop cold hardiness to make it through our harsh winters. The amount of insulation they have is not steady throughout the winter and can go down when temperatures warm up, which can make them more susceptible to freeze damage if a cold snap happens after a warm period. While there isn't much we can do to influence this, those who grow grapes can use the new Cold Hardiness Risk Assessment tool to track potential damage from cold events during the winter. When more damage has happened, it's helpful to leave more bud on each vine during pruning to make up for potential damage.
• Continue irrigating fruit crops before dormancy: While we don't know what precipitation will look like over the winter, most of the state is currently experiencing drought. Drought stressed trees will generally have a harder time surviving a potentially tough winter. As long as the drought continues, keep watering your trees and shrubs. And, if you grow June-bearing strawberries, remember that they set their fruiting buds for next year during late-summer to early fall depending on the region. Irrigate them to ensure a healthy crop next year.