Plant Diseases/Sickly Rhaphiolepis shrubs?
QUESTION: I am on a landscape committee for my community. No one can figure out what is wrong with these Rhaphiolepis shrubs. They look terrible and I believe they are supposed to be the "PInk Lady" version. I live in Valencia, CA and our soil here has a high clay content. Do you have any recommendations and or advice on what to do to get these shrubs looking healthy and bloomimg???
ANSWER: Dear Susan, I am happy to say that although I am only seeing these Indian hawthorn from a distance, I can be pretty certain that what you have is a bad case of Cercospora fungus. I have seen this many times. This is a very common disease for these plants, and what you have probably observed is first a small brown/black spot on the leaves, which quickly gets bigger, sometimes with a golden "halo" around the spots. Then the leaf will fall off and the remaining leaves will get infected. It doesn't take too long for the branches to get pretty bare from this. You will need to spray with a strong fungicide. I wish I could tell you that an organic would work for this, but unfortunately, you just won't get effective control with one. I would go for one containing the active ingredient Proprioconozole or Chlorothalonil. These are probably the best for this, but you can use anything that is recommended for Cercospora or leaf spot on Indian hawthorn or ornamental shrubs. The label will indicate that this is what it is for. You can go to a feed store or garden center and ask a knowledgeable salesperson (not all of them are) what products they recommend. You will need to spray thoroughly about every week for at least 4 weeks. Spray with a pump up sprayer until the leaves are completely dripping with fungicide solution. In addition, before each spraying you will need to thoroughly clean up all the fallen leaves under and around the bushes. Be sure to bag and throw them out, never compost. Wash your hands after cleaning up dead leaves and before spraying. This fungus is most easily spread by fungal spores splashing back onto the plants after rain and watering. You might also want to lay down a fresh layer of cypress mulch (good for disease resistance and just about the best mulch anyway) after you remove the bad leaves. It sounds like a lot of work, and it is, but you will be happy with the results. New leaves should begin to grow back fairly quickly after spraying. I hope this information helps, but be sure to write back if you have any questions. I apologize for the delay in getting back to you. Good luck, Melissa
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QUESTION: Wow Melissa! You are the BEST. I'm attaching a close up pic of the shrubs from our community entrance so you can see these as well. This is from from our main entrance to our community and the same pattern is starting to occur over there. It is weird the color they are changing to also. It almost looks reddish and yellowish. Is that the fungus. I verified and they are the Clara variety. Our landscaper is spraying them today.
ANSWER: Dear Susan, Thanks so much for the compliment. I think all my questioners are the best because they have caused me to look up a lot of different subjects on plants from all over the world, and I have learned so much in the process. The picture is definitely of an Indian Hawthorne in distress. I did forget to mention that there is also Entomosporium as well as fire blight and several other diseases that can affect these plants. However, fire blight which is known to all members of the rose family of which Indian Hawthorne is one, presents as branches just turning black as if a torch had been lit under them, so I knew it couldn't be that one. And Entomosporium is treated the same way as Cercospora. Interestingly Clara should be more disease resistant, but I have found that that doesn't always hold true. Prune them if you need to, keep very on top of removing all the fallen leaves and branches, and keep up the spraying. Pull out any plants that you need to. The landscape should look much improved soon. Here is an interesting fun fact. On Indian Hawthorne leaves, if the leaves are flat, (as in Clara), the flowers are white; if they are curled, the flowers are pink. Please feel free to write anytime. In the last 3 or 4 years (I forget how long) I have not taken a break, although occasionally I have taken up to 4 days to respond. Melissa
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QUESTION: Thanks Melissa. Yeah, I figured what you meant when I went to a nursery to look strong fungicides and I noticed it referred to Entomosporium. My landscaper is getting back to me on what brand of fungicide they are using. I will make sure it contains Proprioconozole or Chlorothalonil. Why would Clara be more disease resistant? Which site do you use to look up diseases on plants and how to treat them?
Dear Susan, I'm not sure why Clara is more disease resistant, but some varieties of most plants will be more or less disease resistant than other varieties. It's just a genetic thing, and it's not something which can be controlled yet. It just happens that some plants will become sicker easier. For example, I don't know why but yellow roses are more susceptible to black spot than the other colors. Some yellow roses are more resistant than others, but on the whole, the yellow roses get it faster and worse. It's just something that you plan around. It is interesting that you ask me where I get my information. Many times I've studied the problem for so long, and so frequently that I just know. For example the leaf spot on Indian Hawthornes I see all the time. For the most part, I will try to find information from sites that are listed as .org, .gov, or .edu. I like extension service sites (run by the counties), and occasionally, if I'm not sure where to start, I might check into Wikipedia for a quick overview, and that sometimes helps direct me. Usually what I will put the subject I want to search into the browser and see where it takes me. Once in a while I will do that and find that the top search locations are my own answers. It's kind of a hit and miss method. Sometimes I search something, and when I read the listing, I find so much fault with it, that I know that site will be unreliable. For the most part, I became a Texas Certified Master Gardener 29 years ago, back when the program was very new. I have been a plant geek ever since, and I read plant books a lot. I am always learning. Sometimes you just have to know what information needs to be synthesized with what other information. If you have no clue, then you can often end up with advice that is extremely unhelpful, and often just wrong. I've looked at other allexpert answers and sometimes they seem very helpful, and other times they are very error ridden. Most of it is just having a lot of practice, having seen so many plants up close, and spending a lot of time outside watching. But the best way to learn as much as possible would be to check out the Master Gardener program (best money I EVER spent), and the .org, .gov, and .edu sites. Thanks for writing, and feel free to ask questions any time. By the way, here is a fun fact that I learned from having too much time on my hands. To check for spider mites, put a white sheet of paper under the suspect leaves and rap them sharply. You may see some debris fall onto the paper. Now watch this paper closely. If you see anything moving, then you have spider mites. Now if you take an ink pen and draw a circle around the spider mite, then the mite will be unable to cross the line for several minutes. If you draw an ink line almost around the mite, and leave an opening, the mite will wander around until it finds the opening, and then leave that way. THE BIG QUESTION is how much time did I have to have on my hands to find that out? Enjoy. Melissa