I think most people have seen leaf scorch. The edge of the leaf is brown or black, and often this discoloration continues between veins. The veins themselves are usually the last to be affected. Now is the time of year we usually see scorch because new growth is succulent and has not yet developed a thickened cuticle to protect it from drying factors. Scorch is a noninfectious, environmental condition that occurs each year when water cannot be translocated to the foliage as rapidly as it is lost. The causes vary and might include root injury, root rot, poor soil conditions, strong winds, transplant shock, flooding, and drought. Often injury is worse on the south and west sides of the plants where foliage is more exposed to wind and sun. Badly affected leaves drop from the tree, but most scorched leaves hang on and become tattered and torn as the wind whips the scorched areas. The possibilities are explained more completely in RPD no. 620, “Leaf Scorch of Woody Plants.”

Scorch does not kill a tree. To assess the tree’s ability to refoliate, look for live buds on the twigs. A bud is alive if it is green and fresh inside. Pick off a few buds and look at their bases to make this observation. Also try scraping the newest twig growth with your thumbnail. If the wood is green and fresh, then it has a good chance of producing more leaves. If there are no live buds and internal wood tissue is dead, then a more serious problem has affected your tree. Trees scorched due to weather stress just need a little extra TLC. Water them in periods of low rainfall, and consider a fall application of a balanced fertilizer.

Leaf tatters is a condition that occurs when the scorched tissue is whipped about in the wind. It looks much worse than scorch, but the actual effect on the plant is the same. Another condition is dubbed spring leaf tatters. It too is harmless. Sometimes you see holes and splits in the otherwise normal foliage. The missing leaf tissue seems to have a similar pattern on both sides of the main vein. This is not insect feeding (unless you actually see them feeding), and it is not scorch. This condition results from cold injury when the buds were first developing. Even a slight injury at this critical stage in the leaf development would be greatly magnified as the leaf expands. Such injury usually is fairly symmetrical on both sides of the leaf. Insect injury never shows this symmetry. Treat spring leaf tatters as you would scorch.