Intense summer heat is wreaking havoc on many trees

Published: Monday, Aug. 13 2012 8:00 a.m. MDT

Additional conditions that cause leaf scorch include poor water penetration into the soil. This problem is worse on hillsides or slopes. Salt in the soil or water causes chemical drought. Certain herbicides also cause leaf burn on the plants.

Avoid the temptation to drown the plants. Overwatering causes leaf scorch because the water displaces the oxygen in the soil and can rot the tiny feeder roots that absorb the water.

Without feeder roots, the plant cannot take up water.

Iron chlorosis is very prevalent this year and contributes to leaf scorch in susceptible trees. Silver maples, flowering pears and other trees have bright yellow leaves with green veins.

These are highly susceptible to scorching, and they sometimes develop black spots. These are more likely to show additional problems because the leaves are already stressed.

Salts from roads or other sources cause burned edges on the leaf. Herbicides may burn the leaves or interfere with the normal growth of the plant. When this happens, the plant does not take up sufficient water and shows burned symptoms.

Diseases and insects, including aphids, scale and others, rob trees of needed moisture. Borers prevent translocation of water up the tree. Fungi, including phytophthora, verticillium and other wilt diseases cause trees to scorch.

Check susceptible trees and give them a deep watering every two or three weeks. Let the water dribble around the base of the tree until it penetrates one or two feet into the soil. Normal lawn watering is shallow and does not supply the deep soil moisture most trees need.

Larry A. Sagers is a horticulture specialist for the Utah State University Extension Service at Thanksgiving Point.

Garden tips

Garden Talks in the Park are complimentary garden talks at Brigham Young Historic Park on the southeast corner of State Street and North Temple. "Roses, Everybody's Favorites, The Skinny on Keeping Them Fat and Happy!" is the topic on Aug. 15 at 7:30 p.m. No tickets are required, and all ages are welcome.

Thanksgiving Point is offering a basic landscape design course on Aug. 14, 21, and 28, 10 a.m.-noon or 6-8 p.m. The class includes a consultation on your plan by a USU Extension Service master gardener. Cost is $40. For more information, or to register, call 801-768-4971 or log on to www.thanksgivingpoint.org.

Thanksgiving Point is also offering a class on "Spectacular Spring Flower Bed Designs," Aug. 14, 21, and 28, 2-4:30 p.m. Cost is $43. For more information or to register, call 801-768-4971 or log on to www.thanksgivingpoint.org.

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