Leylands gradually dying
live in the country and have planted Cypress Leylands around the
house boundary for wind protection. I keep them clipped to about
8 feet high and the majority are healthy, but there is the odd one
dying. The foliage on one branch gradually dies then over time it
spreads, killing the whole tree. I hope you can advise what the
main threat to cypresses in New Zealand is the fungal disease cypress
canker. The fungus attacks the cambial layer of trees, affecting
twigs, branches and whole stems. If the main trunk is infected,
the whole tree can die. Symptoms include cracking, dark patches
on the wood, sunken patches, resin bleeding and death of the foliage.
Often one branch will die, sometimes followed by the entire tree.
Macrocarpa (Cupressus macrocarpa) and Leyland cypress (C.
leylandii) are quite susceptible, while Mexican cypress (C.
lusitanica) has some resistance. Outbreaks of disease come and
go, and vary in severity.
Canker damage can be
minimised by making sure that trees are well-sited and spaced, and
are generally healthy. Weak trees are much more susceptible to attack,
and should be removed as a preventative measure. Avoid high levels
of nitrogen in the soil and avoid over pruning as the canker seems
to enter through pruning cuts. When pruning off infected branches,
remember to clean equipment between trees. Remove severely infected
trees. Fungicides can help where tree size and numbers make this
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH