Monday, August 4, 2014

Leyland Cypress Part 3

This article is the third in a series about Leyland Cypress. If you have missed any of the other articles and are interested, please go to and look under the Horticulture Hotline tab.

Phytophthora root rot is a disease that attacks the root system of plants and ruins the roots where they cannot absorb water and nutrients; therefore, killing the tree. If you had a very high dollar tree and you wanted to spend a lot of time and money, you could possibly save a tree from Phytophthora; however, it would be cheaper and easier to replace the Leyland Cypress with a plant that is not susceptible to this disease.

Phytophthora is a disease that does well in wet, poorly drained soils. Most plants like well drained soils. If you are going to replant, treating the area with a product labeled for Phytophthora, correcting the drainage and increasing the good fungi in the soil that will compete with Phytophthora (good organics) would be a good idea.

The canker diseases and Phytophthora are the killers. The needle blight just leaves you with an ugly tree – dead from the bottom up. I have a friend with a Christmas Tree Farm that is constantly battling these diseases. If the diseases were not enough, insects and mites love these trees as well.

Mites are what I encounter the most. Mites seem to like hot, dry weather. Mites are very small, but with a “beat sheet” you can find them. A Leyland Cypress has layered limbs so it makes this very easy (you can do this with any plant – I started using this method a long time ago while working with cotton). Just place a white sheet of paper between the layers of limbs and slam the limb above the sheet down onto the sheet. If you have mites, you will see these very small creatures running around on the paper.

I like using neem oil, horticultural oil or insecticidal soap to control them because they will also help control scale, another pest that attacks Leyland Cypress.

Bagworms also attack Leyland Cypress. They are easy to see and you can pull them off by hand. Bt, a bacteria insecticide, works great if you catch them while they are young.

After writing about Leyland Cypress issues for three weeks, I would consider another tree if I was planting a new tree. Many hollies would have similar form and not near the issues.

Bt also works great on mosquito larvae. With all this rain, I’m seeing a lot of fungus and mosquitoes.

Always read, understand and follow product label. The product label is a Federal Law.