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Moist mulch leads to fungus epidemic

QUESTION: “I just laid several inches of fresh, high-end dirt, an inch of shredded hardwood mulch and planted 150 bare root vinca (periwinkle) under a large pear tree in the front yard. With all the rain, I’m now faced with mushrooms everywhere and the beginnings of a fungal epidemic.

“There are several small patches of white fungus growing on the mulch. The drainage is relatively good, but the several inches of new soil are still very loose and so the moisture stays put longer. That, plus the incessant rain and high humidity seem to make for a great medium for these problems. Is the vinca safe or should I try to take protective measure of some kind?” – John B.

ANSWER: This should not hurt the vinca but moisture is creating the environment for the fungus. You might want to make a solution with Captan to spray the area. Captan is a fungicide available under various other names such as Agrox, Captal, Phytocape, Sorene, etc. Captan has a low toxicity for humans, although it can cause skin and eye irritation. It is practically non-toxic to birds and bees when used as directed, but is highly toxic to fish, so keep it away from your pond. Additionally, if you stir the soil once a week this will help to eliminate the problem.

If you’d like to learn more about Captan before you use it, you can find a lot of information posted by the Extension Toxicology Network at http://extoxnet.orst.edu/pips/captan.htm and you can click on a direct link to that site when you find this column under the Plant Man heading at my Web site www.landsteward.org

Here’s a question that my wife Cheryl answered for a reader:

QUESTION: “About this time each year, the upper leaves of our Burning Bush begin to drop off. What is the cause? Does the plant need to be sprayed with something?”– John & Jan Davis

ANSWER: Early defoliation can be caused by several things. The spider mites are a big enemy of the burning bush. Hot/dry summers can escalate this situation. Here is a link to an extension office site on dealing with spider mites on burning bush. http://extension.missouri.edu/extensioninfonet/article.asp?id=1760

Too much sun during the hot part of summer can pose a problem. The plants like the sun, but during the heat of summer, they could use a shady break during the day. Burning bush grow best in moist soil, so make sure the plants are getting enough water to keep their moisture level up.

A few days ago, we received the following e-mail: Cheryl, thanks for your prompt and informative reply on our problem with the Burning Bush. Yes, we found that we did have spider mites and have taken steps to get rid of them. Thanks again, John & Jan

QUESTION: “I have a young dogwood tree that I believe got an overspray of MSMA on it this spring when I treated my lawn. It got some dark spots on the lower leaves and a few of them eventually fell off. I thought that would be the end of it, but it seems to be getting worse as the summer progresses. The dark spots are appearing on higher leaves and my entire tree seems to be doing badly. I know it did not get reinfected, because I did not treat my lawn again. Could it be something else, and just coincidentally happened shortly after I treated my lawn? If so, what can I do? If not, will my tree be OK after the winter passes? Do you know of anything I can do to reverse the effects of this on my tree?” -- Dwight

ANSWER: MSMA is a product to designed to kill crabgrass. If the damage was caused by the MSMA, there is little you can do except wait it out. One thing comes to mind is to feed it a root stimulator in order to give it some help and maybe a plant food (not fertilizer) that will give it a boost.

The Plant Man is here to help. Send questions about trees, shrubs and landscaping to [email protected] For resources and additional information, or to subscribe to Steve’s free e-mailed newsletter, go to www.landsteward.org