Pests and Diseases: Fire Blight

After a week talking about our Lunatic Tour at Polyface Farms, it’s time to get back to gardening. While I believe that we can learn a lot about gardening from Polyface Farms, I know that you have questions about the plants that you are growing in your backyard. If you have Bradford Pears in your yard, you may be experiencing symptoms that look like this:

fire blight

This picture shows the classic case of fire blight. Fire blight is a bacterial disease that affects Bradford pear trees as well as fruit-producing pears. Its victims can also include apples, crabapples, Pyracantha and hawthornes. Fire blight gets its name from the damage that it causes: it looks like someone has gone around and set the tips of your plants on fire. The leaves turn brown and then black and the affected areas can reach a foot or more from the terminal growth tips. This damage causes a classic shepherd’s hook appearance. Fire blight can also affect the blossoms and they end up turning brown prematurely and dying. Let’s take a closer look at the life cycle of fire blight in order to understand it better.

The bacteria that causes fire blight causes cankers that generally set up shop on the trunks of the trees. These cankers weep and ooze and allow for the bacteria to be transmitted from tree to tree by insects as well as wind driven rain. Sooty mold is often seen growing near the cankers due to their sweet exudate. With the mild winter and wet spring that the Mid-Atlantic Gardening region is experiencing, fire blight infections are a common experience in a landscape still dominated by Bradford Pears. It’s one more reason to remove Bradford Pears from your landscape…or at least vow not to plant anymore.

So what can you do if your trees are infected? If the outbreak is relatively minor, you can prune out the infected branches, ensuring that you remove an additional 8″-12″ of stem below the apparent infection. Dispose of these branches in a landfill or burn them if your local conditions permit it. You can also spray your trees with a bactericide every 7-10 days from bloom time through the spring rainy season but who wants to go through all of that trouble?

The old saying that “an ounce of prevention is worth a pound of cure” certainly applies here. There are many, many varieties of apples, pears and crabapples that are resistant to fire blight. While that doesn’t mean that these varieties will never get fire blight, it does mean that they stand a fighting chance without a lot of fussing over them by you. Resistant apple varieties include Honeycrisp, Jonagold and Winesap. Resistant pear varieties include Honeysweet, Magness and Moonglow. If crabapples are more your style, consider planting Candied Apple, Louisa or Prairie Fire. Consult your local extension agent for other varieties that work well in your gardening area.

If you have experience with combating fire blight in your landscape, please leave me a comment below or e-mail me at If you enjoy being part of the Mid-Atlantic Gardening community, join our e-mail list, become a fan on Facebook and follow me at Twitter. Happy gardening!


Mulch Volcanoes…Oh the Horror of Them All

November 13, 2011

Since when did the Mid-Atlantic region consist of volcanoes? Perhaps many, many moons ago it did (or maybe not at all…I wasn’t a geology major). The volcanoes I’m speaking of are man-made and they appear every year when people are mulching their trees…that’s right, the mulch volcano. The picture below shows a typical sight in the Mid-Atlantic region: a Bradford Pear with a mulch volcano…in my opinion, they both need to go, but that’s a different story for a different day.

While they don’t spew forth lava, they do speak volumes about a belief among well-meaning gardeners that if the landscaper down the road is doing something, they should too. I need to insert a disclaimer here: while there are certainly folks in the landscaping industry that follow proper horticultural techniques, there appear to be far more that just do what the next guy is doing.

Not too many years ago, it was hard to convince landscapers to apply mulch at all. It was a hard sell to them and they couldn’t believe that people would be willing to pay them to put down mulch in their landscape beds. But then the dollar signs began to appear to them, much like they do in a cartoon. “Do you mean that people will pay me by the yard to put mulch around their plants? And they want it done twice per year? SOLD!” And so the mulch volcano was born.

A mulch volcano consists of a mountain (or volcano) of mulch that is applied around the base of a tree. It is usually piled up at least two feet high on the trunk of the stem. Unfortunately, after most people are finished, they sit back and think “wow…that tree is really happy now!” And there are some people who think that the mulch volcano will help keep the tree warm. Now if you are one of those people, don’t fret. It’s easy to believe such things when you are surrounded by them. Look around at the landscapes in any commercial setting; I’ll bet you that 9 out of 10 trees have mulch volcanoes. Now look in the woods and tell me what you see…no mulch volcanoes for sure!


I can’t blame money-hungry landscapers entirely for the epidemic of mulch volcanoes; laziness is a factor too. You’re probably thinking “laziness? It’s a lot of hard work to haul in all of that mulch for the volcanoes”. And you are right; it is a lot of hard work. But it’s far easier to mulch the tree than to plant it correctly. You see, most of the trees that are mulched like a volcano were never fully planted in the ground. A shallow area for the root ball to sit in was excavated but that was it…the top of the root ball is usually well above-grade (and that may not be a bad thing but we’ll discuss that in a later post). Mulch is added as a disguise to cover up the nonsense and the next tree is “installed”. I’ll bet you dollars to doughnuts that if we took away the volcano in the picture below, you’d find that the tree hadn’t been planted at all…in fact if you look closely, you can see that there is bare soil under the layer of mulch. That’s either soil from the original rootball or soil from where the “hole” was dug. Either way, this tree is suffering from a severe case of “mulch volcano”.

So what can you do to fix the problem?

First, look at the trees in your yard…are there volcanoes that are ready to erupt? If so, pull back the mulch to a depth of 3″ or so and instead of mulching up, mulch out. Take the mulch and spread it out as far as you can stand it…the more mulched area there is, the less the tree has to complete with grass for water and nutrients. Congratulate yourself for unburying a tree that was otherwise suffocating under all of that mulch. Once the celebration is over, take a look at your neighbors’ yard, the common areas in your subdivision, your church, where you work or your local park. Chances are that there are mulch volcanoes there too. Let people know that you’ve been knocking down volcanoes all over your city and they can do it too!

I’d love to see some pictures of the mulch volcanoes that you’ve encountered. Send them to and we’ll start a photo gallery…a wall of shame if you will.

November 13, 2011Permalink Leave a comment