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My Pears.....My Pears.......
What is happening to my Pears???
Do the Branches on your
Ornamental Pear trees
Look Like
THIS?
Then they "could be" suffering from a disease called Fireblight. Fireblight can affect over 130 plant species including edible and ornamental pears, apples, crabapples, hawthorn, mountain ash, cotoneaster and pyracantha; not to mention raspberry and thornless blackberry.
The bacteria that causes this disease ( Erwinia amylovora....say that one twice...) can actually be living on the plant surface and in cankers ( old diseased areas ) formed during the previous year.
Then with the rise in spring temperatures together with the usual and/or unusual amounts of wet weather it begins to oooooze out of the cankers. Then the rain splashing from leaf to leaf and tree to tree together with the help of wind and our friendly insects manages to get the bacterium to the pretty little blossoms which then causes "blossom blight". Or it can arrive on tender new shoots and leaves that may have been previously injured by insects, wind, hail etc.....or even from pruning. Once infected, these new, young shoots turn brown or black as though they have been burned or scortched in a fire. Hence the name "Fireblight". These blackend new shoots will usually curl at the tip and take on an appearance of a "shepard's crook".
 | | "shepard's crook" |
Now, having said all this, here is the problem "this year".
Due to our extremely "early" spring warm up all of these trees bloomed out earlier than normal. Then ( and most people don't remember this ) we had 3 back to back nights of freezing weather....26, 27 and 32 degrees. We all know what those kinds of temperatures can do to blossoms and tender new growth. And it did! And.....after a couple of weeks and our then extreme heat, many of these new shoots have taken on the "appearance" of Fireblight. I recently was involved in such a case with a good friend and customer. Due to the above mentioned it could not be absolutely determined if the "shepard's crook" appearance displayed on his Aristocrat Pears was Fireblight or freeze / frost damage. Pictures were forwarded to the lab at Purdue University for their opinion. Their response: Suspect Fireblight but would need a sample for microscopic inspection to determine with certainty that it was Fireblight. Samples were then sent and the final determination by Purdue was that the suspected Fireblight was actually "freeze damage".
The point of all this is that even the great minds at Purdue can be fooled by Mother Nature. So, if your trees have the appearance of Fireblight "this year".....Don't Panic! Send a sample off to Purdue and have it checked under the microscope. It may just be freeze damage! You can click on this link for a "submission form" to send with your sample.click here. Cost by the way is $11.00.
However, if you actually do have Fireblight attacking your trees
you may want to do the following to help manage the problem.
1. Avoid fertilizing with high nitrogen fertilizers ( that's the first number on the bag such as 24-3-6 ...24 being the nitrogen) as this will stimulate rapid new growth and branching.
2. Prune out the damaged shoots but wait until we are done with the wet weather. Preferably do this in summer. Make your cuts a minimum of 12" below any visibly infected area on the branch. And do NOT cut into any branch "collar". You can also wait until late winter to prune out the damage but be sure to mark the infected branches with string or something now as you may not be able to find them once the tree loses its leaves.
Extremely Important: Dissinfect your cutting tools between each new cut you make or you are likely to unknowingly spread the disease. Disinfect with a diluted solution of 20% alcohol or bleach to 80% water. If you use the bleach though make sure you clean and oil your tools afterwards to prevent rust.
3. There are "chemical controls" that can be used but we are past that time of application for this year. These control measures are most likely to help at bloom time when temperatures are 60 - 75 degrees. If you plan on spraying you will need to use a copper-based fungicide or a bactericide called Streptomycin.
Signs of Fireblight can be more or less prevalent each year depending on the amount of ground moisture, sustained temps in the 60's and 70's and the amount of spring rainfall. These conditions, taken together, all provide for rapid succulent and susceptable new growth. So bottom line is: When these conditions all come together in the spring.....Be Vigilant!
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