Signs Of Fire Blight On Fruit Trees And How To Get Rid Of It

When we first moved into our home, there was a spindly pear tree. It was dormant when we bought our house, but as the tree started producing new growth in late spring, there was clearly a problem. Instead of healthy young stems, our newly acquired pear tree looked like it was being scorched by extreme heat. Indeed, that's where the name "fire blight" comes from, and it's the easiest way to tell your tree is infected.

Fire blight spreads quickly, and most often infects apples, pears, and quince, but you may also notice this damage on other susceptible ornamental and edible plants. Members of the rose family are prone to succumb to this problem, so it's a disease that could also be lurking in your rose garden. Fire blight, caused by bacteria, is dispersed in a few ways. Unfortunately, it spreads easily through water, including rain and irrigation, as well as pollinators. As House Digest's Garden editor and in-house Master Gardener, I can offer a few tips to help you identify this problem and hopefully save your trees. The first step to success is pruning off affected wood at the earliest signs of fire blight.

Spotting the signs of this disease early is the key to keeping fire blight from spreading — not only through the infected tree, but to nearby plants. These bacteria spread most efficiently when the days get warm and humid. So, as daytime temperatures reach around 75 degrees Fahrenheit, start looking for brown or black leaves, stems, and blooms.

Before warm weather arrives, the bacteria that cause fire blight overwinter in cankers, but during the early stage of disease, you may not notice them. These cankers may appear on any part of the tree. When the weather warms, they break open, releasing the bacteria. At this point, the pathogen enters a damaged part of the tree, including the trunk, stems, and even leaves. The more systemic the infection, the larger and more gruesome those cankers can get. Of course, that also makes the infected parts easier to identify.

Because the bacteria are so small, they don't need a large opening to infect a fruit tree. Small knicks in plant tissue offer an entry point. So, bent stems, sliced leaves, and even tiny holes created by pests offer an opportunity for fire blight to take over. If a pollinator picks up the pathogens from the bloom of one plant, and deposits them on another, they can easily be carried by wind or water into one of these injuries — thus the infection begins and spreads.

Young fruit trees are the most susceptible to severe fire blight damage. While you're pruning your apple trees in late winter or early spring, watch for cankers and remove any damaged stems. Pruning at this time, while the bacteria are still enclosed, gets rid of those nasty cankers before they can open to spread the pathogens. If you're seeing large cankers or severely infected growth, remove the branch at least 8 inches below where the damage starts. If you suspect the tree might be infected, sterilize your pruning shears between each cut and burn or throw away all cuttings. While there are no products that can cure a tree of fire blight, a copper-based treatment, like Bonide Captain Jack Fungicide, may help control the disease.

To give your fruit trees the best chance, give them the soil conditions they need to flourish. This means providing enough fertilizer, but not too much, as excessive nitrogen can weaken new growth and make it more susceptible to disease. If fire blight has been a problem in your yard, but you want more fruit trees, you can find resistant varieties, like Liberty and McIntosh apples. The Shinko Asian pear is also highly resistant to this disease. I have grown Liberty and Asian pears after my fire blight infection, and they have proven to be quite resilient. After several years, I've seen no sights of this disease, but be sure to choose the best resistant species for your location.