What you need to know about fire blight

Fire blight, a bacterial disease that makes fruit trees look scorched by fire, is a growing threat to Iowa's orchards and home gardens. Suzanne Slack, a fruit specialist at Iowa State University, explains that the disease spreads rapidly—up to two inches per day—through wind, rain, and insects, and can kill young trees in a single season. The real danger lies in its stealth: symptoms often appear only after the bacteria has already moved deep into the tree. Once infected, trees require aggressive pruning at least six to eight inches below visible damage, though recent research shows sterilizing tools between cuts offers minimal benefit due to the bacteria's ability to survive in tiny numbers. The disease thrives in warm, wet springs, and 2024 was a particularly bad year across Iowa—so bad that infected trees were being sold at box stores. While resistant rootstocks exist, resistant fruit varieties are rare because the most disease-resistant apples and pears are often unpalatable. Prevention is key: copper sprays during bloom can help, but timing is critical. For homeowners, vigilance is essential—checking trees weekly during spring bloom can mean the difference between saving a tree and losing it. The episode also covers related horticultural concerns, from transplant shock in newly planted maples to the challenges of growing citrus indoors and the limited success of releasing beneficial insects like lacewings in open gardens.