- Author: Jan Rhoades
I don't know about you and your gardening practices, but I just can't bear to give up on a seemingly “lost case” plant. In fact, I will go to just about any length to save it and nurse it back to health. For example, last summer I ordered live tomato plants from a reputable supplier – and yet, one came broken and wizened up and looking like compost. So I soaked its roots and planted it in lovely soil and put a sun shade over it. True to its name, “Legend”, it slowly came back and, of course, became one of my best producers. That kind of success only encourages me.
All that said, here is a story of survival that might be helpful. I have an apple tree in my backyard, not just any apple tree mind you, it is a Cripps Pink, also known as a Pink Lady. I love these apples and was excited to plant a tree that might provide me with some delicious fruit. However, not knowing the pitfalls of planting certain varieties of fruit trees in this region, I came to find out that it is a delicate type and falls victim to many pests and problems, not the least of which is the dreaded fire blight. So, a couple of years ago, when I saw the wilting, black, shriveled leaves, I was, at first, in denial,and then in emergency mode.
Right away, I blamed myself and set about studying up on this problem. I was determined to find out what I was doing wrong and make it right. And, ultimately, save that tree!
It turns out the Fire Blight is a bacterial infection caused by the bacterium Erwinia amylovora, and is a common destructive disease of pome fruit trees (think apples and pears) and related plants. Pear and quince are extremely susceptible. Apple, crabapple, and Pyracantha also are frequently damaged.
The bacteria enter the plant through previous injury, much like a bacteria enters a scratch and causes an infection. In spring, branch and trunk symptoms can appear as soon as trees begin active growth. The first sign is a watery, light tan ooze that exudes from cankers on branches, twigs, or trunks. The ooze turns dark after exposure to air, leaving streaks on branches or trunks. Pollinators and other insects that come in contact with the ooze can carry the bacteria to blossoms on trees they are pollinating. The kicker is, most oozing cankers are small and inconspicuous so infections might not be noticed until later in spring when flowers, shoots, and/or young fruit shrivel and blacken. Infected blossoms wilt and turn black on pear trees and brown on apple trees. Fire blight infections might be localized, affecting only the flowers or flower clusters, or they might extend into the twigs and branches, causing small shoots to wilt forming a crook at the end of each infected shoot. The name “fire blight” comes from the dead, blackened leaves and fruit that cling to branches throughout the season, giving the tree a scorched appearance. Infections can extend into limbs, trunks, or root systems and can kill highly susceptible hosts.
Fire blight development is influenced primarily by seasonal weather. The perfect storm, so to speak, comes in Spring when temperatures of 75° to 85°F are accompanied by intermittent rain or hail, and conditions are ideal for disease development. Rapidly growing trees are especially vulnerable, so typical springtime gardening practices, such as fertilization and heavy pruning, which promote such growth, should be avoided. Also, trees shouldn't be heavily irrigated during bloom.
Affected trees need to be monitored regularly, and infected branches must be pruned out and destroyed. Pruning cuts should be made at least 8-12 inches below the visible infection. Sterilizing pruning shears with alcohol or household bleach between each cut is always recommended. Good control of insects with piercing and sucking mouth parts (aphids, leafhoppers, pear psylla) can help slow the spread of blight infections,too.
So, the rest of the story – once burned, twice shy. I have become a better student of varieties of fruit trees and plants, and have done my best to make selections that are suited to this region and climate, and that are resistant to pests and problems that might plague our area. Most pear tree varieties, including Asian pears , are very susceptible to fire blight. Varieties of ornamental pear trees that are less susceptible to fire blight are Bradford, Capitol, and Red Spire; Aristocrat is highly susceptible. Among the more susceptible apple varieties are Fuji, Gala, Golden Delicious, Granny Smith, Gravenstein, Jonathan, Mutsu, Pink Lady, and Yellow Newtown.
Imagine my dismay when my 5 year old Seckel Pear – just full of developing fruit, began showing those tell tale symptoms of, you guessed it, fire blight. Hey, it is supposed to be very resistant!!! Oh well – no denial this time, just emergency surgery and daily vigilance. So far, my quick response has paid off. The tree is looking quite healthy, even though it has gone through quite a bit of emergency surgery. I will continue to monitor and treat, and, I think we are out of the woods for now. What gives me hope (and just a touch of pride) is my Pink Lady Apple – the one that had fire blight last year. This season it is full and healthy, and has set fruit. I know that fire blight can overwinter and that my trees might not make it, but for now I keep a close eye on them and make it a daily practice to tell both trees how much I love them – can't hurt!