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Ornamental Diseases

(November 2012)

QuestionI have a fungus of some sorts growing all over my zinnias.  I'm not sure what it is or what to do about it. I figured that because Zinnia season is over with I may as well just let them die but I do not know if this white spotty fungus or mold disease will spread to other parts of the garden or come back next year with a vengeance. What do you suggest?


AnswerZinnias are often plagued by powdery mildew.  The best thing you can do is to clean up the garden, disposing of all the plant remains. You should also remove the underlying mulch so you can start the season off clean.  Pay attention next summer, and control if needed if it begins early in the season. Many of the new varieties of zinnias are resistant to powdery mildew.

(April 2012)

QuestionOur family moved into a new house in January.  We have a tree in our landscaping near the house, and I'm not sure what it is.  The parts that are blooming and leafed out look healthy and pretty.  However, there are several branches with nothing on them.  I'm not sure if I should go ahead and cut those branches out now, or if I should wait until after it's done blooming.  If I cut them all out, there may not be much left.  Also, do you know what could have caused this?  There doesn't seem to be any fungus or pest on it anywhere that I can see.


AnswerThe tree in question is a flowering cherry.  They are one of the most beautiful spring flowering trees, but not the longest lived in our area.  The trees are susceptible to a host of insects and diseases, with borers being quite common.  The fact that your house was for sale probably during last summer, could also have played a factor. If it wasn’t watered as well as it could have been, that would have stressed it even more.  I would go ahead and cut out all the dead wood, enjoy what few blooms it has and then shape those branches to see if you can restructure the tree.  Once it is bad as yours is, probably an easier alternative would be to plant another tree nearby and remove this one eventually.

(January 2012)

QuestionI have several beautiful Leyland cypress trees in my front yard that have done well for years, but this year I noticed one of them has a problem in the top. Something is causing it to look like it is dying. I was wondering if you could tell me what it is and if anything can be done before it is too late.


AnswerDid you water it the past two summers? We are going to have a lot of damaged plants—trees in particular after the past two horribly, hot and dry summers. Die-back from the tips, could be indicative of drought damage. If you are losing sporadic branches, this could be twig canker, a common disease they suffer from, but it usually doesn't attack just the top of the tree. If you can, take a sample of the plant and some photos to your local county extension office for diagnosis


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