Answer: When leaves brown around the edges, the problem is often salt burn. This is common in areas 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 trees, 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 the summer. Plant roots often "burn." I'd start by making sure the tree is watered properly and if problems continue, then apply nitogen or chelated iron, depending on the symptoms. Fertilize in late winter/early spring just before new growth starts.
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