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Leyland cypress can succumb to disease
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Leyland cypress has become one of the more popular trees for homeowners and landscapers to use over the past few years.

It is a great buffer from noise, dust from a road or screening from a neighbor. Because of the popularity of this tree, it has been planted in areas where it does fairly well, but in time tends to struggle.

One major flaw about Leylands is the shallow nature of the roots. In times of drought, this tree will stress and that leads to problems with disease.

In Georgia, Seiridium canker is probably the most important and destructive disease on Leyland cypress in the landscape. Plants of all sizes and ages can be affected by the disease.

One of the most noticeable symptoms of Seiridium canker is yellowing or browning of the foliage on one or more branches. The discoloration is most likely to appear in early spring, but can happen at any time.

When you take a closer look, the disease can be traced back to numerous thin, elongated cankers on stems and branches. These cankers cause twig and branch dieback.

Most of the cankers are slightly sunken, with raised margins, and they may be discolored dark brown to purple. Cracked bark in infected areas is often accompanied by extensive resin. The inner bark beneath oozing sites is discolored reddish to brown.

Another major disease that is commonly found on Leyland is Bot canker. Bot canker symptoms resemble those caused by Seiridium canker.

Bright, rust-colored branches and yellowing or browning of shoots or branches are the first observed symptoms. Closer inspection reveals the presence of sunken, girdling cankers at the base of the dead shoot or branch. These cankers rarely girdle the trunk, but they will kill branches that may be encompassed by the canker as it grows.

Canker surfaces may be cracked and have a darker color than the surrounding healthy bark. The discoloration often extends several inches below the canker. Little or no resin oozing is produced on the infected areas.

Control of both of these diseases has more to do with how well the tree is planted than any chemical control.

Due to the composition of many of Georgia's soils, establish new plantings of Leyland cypress in tilled and well-drained areas. It is better suited for sites that are well drained and fertile.

Till areas 3-4 times the diameter of the root ball, and amend soils as needed. Perform a soil fertility test, and adjust soils with lime and fertilizer as recommended. Set the tree at or just above the soil level. Avoid environmental and cultural stresses that predispose the plants to infection.

To minimize water loss and water competition, mulch an area several feet beyond the lowest limbs.

Removal of diseased twigs and branches helps prevent disease spread. Remove and destroy pruned material and disinfect pruning tools. Remove extensively damaged trees.

Leylands are a great tree, but there are plenty of alternatives. Arborvitae and Thuja "Green Giant" are two alternatives you can use if you have to replant a space where Leylands were planted.

Michael Wheeler is the Hall County extension coordinator. Phone: 770-531-6988. Fax: 770-531-3994. Email wheelerm@uga.edu.

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