Linospora Leaf Blotch, Linospora tetraspora

Fig. 383 Black stromata on diseased leaf.	Fig. 384 Brown blotches with feathery margins caused by linospora leaf blotch.

Distribution:  North Vancouver Island, Fraser River, and Mid-Coast of B.C. 

TREE SPECIES ATTACKED:  Black cottonwood, balsam poplar, and hybrid poplars are attacked.

WHAT TO LOOK FOR: Large, irregular-shaped, brownish-grey blotches on leaves with feathery margins. Blotches with light brown centres and black rectangular spots (stromata).

SIGNS & SYMPTOMS: Large, irregular-shaped, brownish-grey blotches appear along leaf veins. The margins of the blotches look feathery in appearance. The blotch centres later turn light brown with black, rectangular spots (0.5 mm). Entire leaves are often affected.

DAMAGE: Native cottonwood in coastal plantations can be severely defoliated. In hybrid poplars, the lower canopy is most frequently attacked. Localized epidemics can cause significant economic losses in intensively managed broadleaf stands. Plantations in the Fraser River delta have had low to moderate foliar damage.

SIMILAR DAMAGE: Early stages of leaf damage may be confused with Septoria populicola and Marssonina spp. A closer examination of the leaf blotch will identify the characteristic feathery margins, which distinguish Linospora tetraspora from the above foliar diseases.

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BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated March 04, 2002