|My Arizona Ash, a young tree, planted in late May, has developed brown edges on its leaves. I have a drip system, so it receives water everyday in our over 100 degree heat. It is in direct sun, planted in mostly clay. Am I overwatering? Does it need to be fed already, so soon after planting?|
|Often times with drip systems, they are not timed to run long enough to provide a slow, deep watering. When leaves brown around the edges, the problem is often salt burn. This is common in our area with low rainfall, alkaline soil and water high in salts. Browning usually occurs on the old leaves first. This excess salt accumulates in the leaf edges, where it kills the tissue and the leaf dries out and turns brown. It's important to water deeply, slowly and usually infrequently. With a young tree, you should water once a week, and make sure the water penetrates 2-3 feet deep. Use a pointed stick or piece of metal to push in the soil. It will move easily through moist soil and stop at dry soil. At least once a month, water deeply enough to "leach" or push salts well below the root zone. Frequent, light "sprinklings" or short time spans with drip irrigation, allow salts to accumulate in the top layers of soil, where the roots are, which is bad news.
Similar symptoms occur when too much fertilizer has been applied. It's generally not advisable to fertilize landscape plants in our summer heat. Plant roots often "burn." I hope this information helps!