Leyland Cypress is a fast growing columnar evergreen tree most often used for screening. Once established, it can grow three to four feet in a year. Its ultimate height is 60 – 70 feet with a spread of 8 to 10 feet. It is critical to be aware of the tree’s requirements so that it will grow to maturity. Leylands require full sun and adequate drainage, and should be planted 8 to 10 feet apart for good air circulation. The majority of nutrient absorbing roots exist in the upper 12 to 16 inches of the soil. Large trees require a minimum of 200 to 400 square feet of rooting area.
The tree has a thin bark which splits easily when temperatures are high and the soil is dry. Cold injury caused in winter when temperatures are less than thirty degrees at night followed by a daytime temperature in the sixties also cause the bark to split. Leylands are susceptible to several fungal problems which invade the tree at these cracks, wounds and natural openings.
|Fungus||Seididium unicorne||Botryosphaeria dothidea|
|Vector||Wind, Water from rain & irrigation distribute spores.||Wind, Water from rain & irrigation distribute spores.|
|Entrance to tree||Wound, cracks, lenticles (natural openings)||Wound, cracks, lenticles (natural openings)|
|Prime Season||Early Spring||Spring and Summer|
|Symptoms – Initial||Small black dots barely visible to naked eye,||Spore causes canker which discolors cambium tissue.|
|Symptoms – Primary||Sap oozing from entry point. Sunken reddish, dark brown purplish cankers form on stems, branches, branch axils. Cambium layer red/brown color.||Bright, rust colored branches and yellowing or browning of shoots and branches. Diseased needles do not fall off. Little or no sap ooze.|
|Symptoms – Within one year||Dieback of foliage above canker. Needles will fall off.||Sunken, girdling canker at base of dead shoot or branch.||Symptoms – Year(s) Later||Much of tree dead.||Large cankers on trunk. Tree dying.|
|Controls – Chemical||None once infection takes place.||None once infection takes place.|
|￼Controls – Pruning||Prune 6 inches below canker. Disinfect tools after each cut.||Prune 6 inches below canker. Disinfect tools after each cut.|
|Prevention||Keep properly irrigated during periods of drought.||Keep properly irrigated during periods of drought.|
|Prevention||Avoid injury during planting or working around Leylands.||Avoid injury during planting or working around Leylands.|
|Prevention||Ensure sufficient air circulation and sunlight.||Ensure sufficient air circulation and sunlight.|
|Prevention||Destroy infected and pruned materials.||Destroy infected and pruned materials.|
|Prevention||Mulch several feet beyond lowest limbs.||Mulch several feet beyond lowest limbs.|