Brown Spot on my Rhododendron?
Question:We bought the house last year (June 28) and the rhododendron was fine (mind you, we didnt do anything to it - it just was "fine" all on its own). Now I've noticed "some" of the leaves are turning brown. (About 20% if the leaves) We live in southern ontario - cold winter. There ia a hedge surrounding one side of it and its up against our house, full sun in the morning with afternoon shade. The previous owner said the soil was "acidic" and also mentioned petemoss. Can anyone help out a beginner?? Thank you SO very much. I love this site!! I really need to know how to care for her on a regular basis.
Answers:
Sounds like you have Rhododendron Leaf Spot, a fungal infection. Check out the links below (especially the first one) and see if it looks like your problem. These pages provide management suggestions for various Rhodie problems.
WSU suggests trying these non-chemical approaches for Rhodie leaf spot before turning to pesticides (my comments added):
- Avoid overhead watering and maintain good air circulation in plantings. (wet leaves encourage fungi growth)
- Clean up and destroy any fallen leaves to prevent spread of infection. (spores are on the old leaves and may re-infect the plant)
- Prevent injury to reduce likelihood of infection. (damaged foliage provides paths for infection)
- Provide proper culture for plants. (healthy plants can resist infections better)
- Prune out and destroy all infected tissues. (spores are on these plant tissues. DO NOT compost, but burn or discard)
UConn states: "As many as ten different leaf spot fungi can be found on rhododendron. Although unsightly, none of them cause serious injury." This may help you feel a little less anxious...
Good luck!
You said the entire leaf turns brown--to me that eliminates a leaf disease. It sounds to me like winter dehydration damage. With plants like rhodys (that keep their leaves all winter) dehydration is a fairly common problem, especially if you get cold winters--which you do. The ground freezes so the roots can't take in any water (because it's solid ice) but the leaves are still exposed to the wind and water evaporates from the leaves. This water cannot be replaced so the leaf gets dehydrated. The damage doesn't show up at the time because in winter the plant's metabolism is so slow. Once temperatures start to moderate the damage begins to show.
You can help prevent this by using an anti-dessicant like Wilt-Pruf in October or November,
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