Question
QUESTION: Hi,
We used to have 10 poplar trees in the backyard right in front of the fence, but now only 8 left.
Since this Spring, the trees are turning brown and die one after another.
First, the trunk fades out to be orange.
Then, the leaves turn brown.
Finally, the whole tree turns brown and die.
No leaf is falling, though.
We've cut 2 dead trees out, but the same thing happened to the 3rd tree.(not necessarilly the right next one)
What can be the problem?

ANSWER: Hi there. Sounds like a canker disease.
Cytospora canker is caused by the fungus Cytospora chrysosperma (the sexual stage is Valsa sordida). Poplars, aspens, and willows are the most commonly affected trees.
Cytospora canker is confined to weakened trees. The fungus enters the tree through a wounded or weakened twig and kills the twig back to a larger branch or the trunk. Brownish, circular-to-oval cankers with sunken bark are formed in the smooth bark of branches and trunks. The diseased area gradually enlarges, and frequently stems are girdled and killed. When the older trunk or large branches are attacked, the inner bark blackens and gives off a disagreeable odor. Severely attacked trees 3 to 6 inches in diameter die in 2 or 3 years.
The fungus produces small fruiting bodies in the diseased bark. Spores are splashed by rain or carried by wind, birds, or insects to other trees.
You can goggle(although I like Ask.com) cankers and find a lot of info. Hope this helps,Bill

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dying poplar   QUESTION: Thank you so much for your prompt answer.
I'm relieved to know the possible cause.
The trees must have been gradually weakened since we moved in 4 years ago.
With the lack of knowledge of gardening, I searched the internet and found out bordeaux mixture is good to prevent such disease.
But can't find where to buy it while I'm not sure if I could handle this disease myself.(and I don't wanna lose any more trees..)
May I show you a picture of the tree to get your advice for the next step please?

Kim

Answer
Hi. From what I can see in the picture it looks like a large canker in the lower right of the the right side stem. I would also check the watering. It looks like the tree has also reacted to a drought situation. Here is the web address for making your own bordeaux mixture.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7481.html?