Seridium Canker on Leyland Cyprus
31 Mar
Why Are My Leyland Cypresses Dying?

Leyland Cyprus trees are a cold hearty, fast growers. They can tower to about 60 to 80 feet and make for a good screening tree.

Many builders use them to gain fast growth for new homes. Unfortunately, they are usually planted too close to anything else. They need a 15-foot diameter for best growth results, or they will be smothered or not have enough space for optimal growth.     

When choosing an area to plant Leyland’s, consider the tree in full canopy growth so that there is approximately 15 feet of diameter for good soil-organic material and far away enough from other trees and impervious surfaces such as driveways, asphalt and concrete.

The tree needs about 6 hours of full sun per day. As the tree grows in height, the lower branches become shielded from the direct sun and the lower branches begin to thin out and dieback. This generally occurs at about the 15-year age mark. This is not a sign of the tree dying, rather a concentration of growth where the sun is most prevalent.

The first year you may see 6 inches of growth and the second, about 2 feet. After that, expect as much as 3-5 feet annually.

  1. Routine Dieback. This in-itself is not a factor of the tree dying. Many trees shed parts of their inner branches sometimes due to not enough sun or water or proper nutrients. If certain corrections are made, then the tree may recover. If the tree is infected by a fungi or bacteria, this could cause dieback. The tree needles brown out from the inside of the branch outward.

  2. Needle blight. There may be too much water or moisture, possibly from overwatering or too much mulch packed around the tree or up to the trunk. Again, with proper corrections, the tree should survive. Too much of this for too long of a period of time could possibly compromise the tree and die.

  3. Mulch should be no deeper than 3 inches thick and remain about 12 inches from the base of the trunk. Mulch piled up on the tree trunk is improper and can cause damage by pathogens, stem-feeding rodents and insects and stem-girdling roots.

  4. Soil Compaction can cause a lack of oxygen to the roots and too much soil can cause smothering of roots to absorb water. The drip line is the outer band of canopy in which the majority of water and the decomposing organic layer of soil that feed the tree.

  5. Animal Damage. Deer may be rubbing their antlers on the trees. Possibly consider fencing around the tree(s).

  6. Insects. Bag worms or spider mites may be on the tree. The larvae of a moth suck the chlorophyll out of the needles which is used to photosynthesis. Spider mites live in their webs nestled in between the branches and they also suck the chlorophyll.

  7. Seiridium Canker. This is a fungal disease that attacks the branch tips and will brown the tips out as they die. If you can reach the infected area, take a pair of clean, sharp shears and cut just behind the dead area and throw the diseased cuttings into a trash bag. This is a fungi that can kill the tree.

    Be sure to clean the shears before cutting any other branches so as not to infect anything else when cutting.

  8. Botryosphaeria Canker.This is also a fungal disease that attacks the trunk of the Leyland and eventually kills the tree.
Botryosphaeria Canker on Leyland Cyprus
Botryosphaeria Canker