As the crisp air of autumn settles over Iowa and the trees begin their colorful transformation, gardeners are turning their attention to one of the most important, and often overlooked tasks of the season: fall cleanup. Iowa State University Extension and Outreach experts advise that neglecting the garden now can promote more disease problems next spring.
During this time of year, plants that are affected by pathogens often display unsightly foliage. “If infected plant debris is left to linger through the winter, gardens become an overwintering site for disease-causing pathogens like fungal spores,” said Aaron Steil, consumer horticulture extension specialist with ISU Extension and Outreach. “Problems like powdery mildews, rose black spot and tomato early blight can overwinter in dead and decaying leaves and stems, poised to infect plants again with spring and summer rains.”
Chelsea Harbach, plant disease diagnostician with the Plant and Insect Diagnostic Clinic at Iowa State University, emphasizes that fall is not merely a time to tidy up; it’s a strategic moment to break the cycle of infection. Removing diseased plant material, cutting back perennials and disposing of diseased fallen leaves are essential steps in reducing the reservoir of pathogens.
“A clean garden in the fall is your best insurance for a healthy start in spring,” she said.
In some areas of the garden, a thorough cleanup is best. “Many vegetables have a wide range of serious disease issues. Removing plant debris, fallen produce and cleaning support structures like tomato cages is a great start to a healthier garden next spring,” said Steil. He also suggests gardeners consider planting a cover crop or putting down a layer of mulch over winter once plant material is removed to help reduce weeds and soil erosion.
A clean slate may not be necessary in other garden areas. Steil notes that many gardeners want to leave behind stems and leaves from perennials, trees and shrubs to provide overwintering material for native insects and food for animals and birds. In perennial beds, be selective about what gets cleaned and removed. “Hollyhocks covered in rust and leaves from lilacs covered in powdery mildew can be removed, while healthy plant material can stay to help with overwintering,” he said. Any diseased materials should be discarded properly. Do not add this material to home compost piles, as most do not get warm enough to kill disease-causing pathogens.
“Beyond disease prevention, fall cleanup offers a moment of reflection,” Harbach added. “It’s a chance to assess what thrived and what struggled, plan crop rotations and consider planting disease-resistant varieties next year.”
PHOTO: Girl cleaning autumn leaves from the garden lawn and playing with her cute dog. (iStock │ #1289197439 – Sladic)
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