I have a row of Leyland Cypress trees here in the suburbs of Seattle. This year after a very wet and cool spring I noticed that some needles on most of the trees in the row have started turning yellow and brown. In addition there are sections on the trunk where sap is oozing out. Please see the pictures at the bottom of the post for an illustration. As an additional data point I went through the row of trees earlier in the year and pruned them with a shearer - could this have caused any disease to enter the tree?

Is this a disease affecting the trees? If so should I be worried and can I do anything to get rid of it? Thanks in advance!

Tree bleeding sap:

A closeup of a sap filled blister on the branch:

Picture of the needles on a tree:

no conifer.. holds it needles forever.. most shedding them within 1 to 3 years ... interior needles are the oldest.. and are the ones shed.. on schedule..

the fact that all your pix.. refer to the oldest needles.. attached to the trunk.. are proof ...

it is when the youngest needles.. the growth tips.. lets call them.. start browning.. that you have trouble..

all that said.. these plants have a multitude of problems... of which i have no experience .... because they really dont like MI.... lol ...

but bboy is in the center of it all.. and if he says.. normal interior leaf shedding.. then ....what he said..

ken

===>> exactly ...

you were afraid it was personal .. lol.. to your tree ... and that MIGHT be an issue..

but when i have a problem.. the first thing i do.. is start scoping the neighborhood.. to see if it isnt some general problems.. which means one of 2 things

1-- its normal.. as this case

2-- its not normal.. but its a general plague.. and there is little you can do anyway.. since you cant treat all the trees int eh area ...

this plant will still have problems over the years.. learn about them now.. so you will be prepared .. emotionally.. when real problems start..

ken

"Seiridium Canker

Seiridium canker, caused by Seiridium unicorne, is probably the most damaging disease on Leyland cypress. Plants of all sizes and ages are affected. Cankers may form on stems, branches and in branch axils causing twig, branch or, at least on smaller plants, stem dieback. Cankers appear as sunken, dark brown or purplish patches on the bark, often accompanied by extensive resin flow. It should be noted that resin exudation often occurs from the branches and stems of otherwise healthy plants of Leyland cypress thus resin flow by itself is not a diagnostic characteristic for Seiridium canker. Scattered twigs or branches killed by the fungus turn bright reddish brown, and are in striking contrast to the dark green healthy foliage. Fruiting bodies of the fungus appear on the bark surface of the cankers as small circular black dots barely visible to the naked eye. Spores of the fungus are spread to other parts of an infected tree, or from tree to tree by water splash from rain or irrigation. The fungus also can be spread from tree to tree on pruning tools. Long distance spread appears to be through the transport of infected cuttings or plants.

Currently there are no chemical control measures recommended for the disease in the landscape or nursery. Avoiding water stress and tree wounding may reduce infection. Infected branches or twigs should be pruned and destroyed as soon as symptoms are noted. Prune at least one inch below the canker, and sterilize the pruning tools between cuts by dipping them in rubbing alcohol or in a solution of 1 part chlorine bleach to 9 parts water. Tools should be cleaned and oiled after using bleach to prevent rusting. Severely affected plants should be removed and destroyed."