Damage on White Fir (Abies concolor)

(Question)

Hello,
I work at a Garden Centre in Mississauga and received this sample of a White Fir from a customer who has a pair of these Firs on her property. One is fine and the other (about 40′ away) is rapidly dropping needles. They have been in the ground for 5 years and are about 15′ high. The brownness of the one was first noticed in Feb of this year. I voted that it was wind burn. My customer suggested girdling, but is there any disease you know of attacking Firs in the GTA? I don’t believe it is Needle Cast as I don’t see any black spore bodies on the needles. The new buds on the end are still resinous (not dry).

 

(Answer)

White firs prefer full sun to light shade with moist well drained soils and are heat and drought tolerant.

If the growing conditions of the two trees, which are the same age and size as each other, is virtually the same in terms of soil type and cultural practices used, then wind exposure is very likely the difference.

If the tree not dropping its needles has some protection, whereas the other does not, then wind burn is certainly possible – especially during this past particularly brutal winter. As no spots, streaks or cankers are noted, needle cast is not likely and usually affects Douglas fir, not White fir.

Unless strips of bark are missing – not noted – girdling (ring barking) seems unlikely, as well.

Botrytis blight (gray mold) causes new growth to be dry and brown on White fir and likes moist conditions with poor air circulation. Trees planted too closely together and/or with poor drainage are more likely to have blight, but as no mold is noted on this tree, it doesn’t seem to be the cause either.

 

 

For further information concerning evergreens in general and the winterburn problem, please see:

www.nurserymen.com/care-instructions/winterburn.html