Q. Two of my Indian hawthorn bushes developed unhealthy looking brown spots on their leaves. It started on the southernmost of the two bushes and then the second was affected. These are in the middle of a row of bushes planted along the sidewalk when the house was built in 1986. None of the bushes get a great deal of direct sunlight, but bushes on both ends of the row, with conditions about the same as for these, are looking all right. Can you tell me what is wrong with these two bushes and how to fix it?
A. From the picture this looks like a soil related issue. The soil around the plant looks like it is fairly rocky and I am guessing unimproved over the years.
I think you'll see a big response by taking a bag of decent compost and spreading it under the plants one or 2 inches thick and watering and in. The other thing you might try is replacing any rock mulch under the plants with wood chips that will slowly decompose and improve the soil.
If you put the compost down now and water it in, you should see some improvement in the plant when it continues growing in the spring. The second thing you could try doing is spraying the foliage with liquid good quality fertilizer.
Miracle Gro or Peters would be a good choice. Use one or 2 teaspoons of liquid detergent in a gallon of fertilizer spray to help it penetrate the leaf surfaces. I would try spraying the foliage during the winter. If it's in a warm spot, you may see a response before next spring. Otherwise you'll have to wait until growth resumes early next year.