Published on 07/31/03

Too much rain makes popular landscape tree sick

By Sharon Omahen & April Reese
University of Georgia

When homeowners call University of Georgia plant pathologists for help with diseased Leyland cypress trees, they usually aren't happy with the advice.

The state's recent deluge of rain is taking a toll on one of the most popular landscape trees around. Leyland cypress are being hit hard by disease as a result of too much water.

There's no cure

"Once a Leyland cypress becomes diseased with root rots, there is nothing you can spray to cure it," said Mila Pearce, an integrated pest management specialist with the UGA College of Agricultural and Environmental Sciences.

Pearce works closely with UGA Extension Service county agents to identify submitted disease samples and make recommendations to homeowners.

Due to Georgia's unusually soggy summer, she has been answering a lot of calls about Leyland cypress trees.

"Leylands don't like wet feet, so they don't like wet weather," Pearce said. "And with all of the rain we've had this year, the conditions are right for needle blights and vascular diseases as well."

Preventative measures

There are some things you can do to prevent diseases from taking over your trees.

"You can prune the branches to try to get air flowing through the trees," she said.

Pearce also suggests cutting away diseased sections of the tree.

"If you see a diseased spot, cut six inches below where you see the symptom and discard that piece," she said. "After all, it is better to sacrifice a branch than loose the whole tree."

If the disease has reached the tree's trunk, Pearce says, it's just a matter of time before the entire tree is lost.

Fungicides can be used as a preventative measure on healthy trees.

Pearce recommends using Mancozeb, Cleary's 3336 or a Bordeaux Mixture spray. Just follow the directions on the container.

"If your neighbors' Leylands are doing poorly and are diseased, get ready," she said. "With all of the rain we've been having, it (disease) can easily cross the street."

A healthy plant begins on day one

Consumers can help keep their Leyland cypress trees healthy from day one, says Alfredo Martinez, UGA Extension plant pathologist.

"Leyland cypresses are marketed as a relative low-maintenance landscaping trees," Martinez said. "But consumers should not confuse low-maintenance with no-maintenance."

All trees need to be cared for, whether you are applying fertilizer, watering correctly or planting properly, he said.

Martinez recommends planting Leyland cypress trees at least eight feet apart, measuring from the center of the tree. The trees should also be planted in an area that provides good drainage.

When planting, make the hole big enough and loosen the dirt, especially if you are planting in clay soil.

"You should dig a $5 hole for a $1 plant," Martinez recommends. "In other words, dig a hole at least three times the size of the plant's root ball and refill the area with loose soil to help the roots and tree get established."

Cypress trees have shallow root systems and Georgia clay doesn't drain fast enough to keep them dry, Martinez said.

"Too much rain can drain out nutrients such as nitrogen, phosphorus and potassium into the soil and also leaves the roots in a puddle of water," he said. "This causes the tree to be stressed and makes it prone to root rot disease."

With the amount of rain our state has had over the past month, Martinez says he has seen Leyland cypress trees turning yellow and dying in a matter of weeks. He has also seen Leyland cypress trees actually tilt from their original planting spot and expose their roots atop the soil in flooded sites.

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.