ACANTHOSTIGMA 221 



Perithecia immersed in the matrix; asci elongato-clavate, 

 apex thickened, 65 X 75 X 12-14 /*; spores narrowly elliptical, 

 ends rather acute, hyaline, for a long time i-septate, finally 

 3-septate, 16-22 x 5 /*. 



So far as I am aware no preventive methods have been 

 tried. Probably Bordeaux mixture would save healthy 

 leaves and shoots from being infected. Certainly all fallen 

 leaves and twigs that are diseased should be swept up and 

 burned. 



Sphaerulina intermix ta (Sacc.) occurs on living stems of 

 bramble and wild rose, and may, possibly, pass on to culti- 

 vated forms. 



Perithecia gregarious, minute, under the epidermis, 80- 

 100 p. diam. ; asci clavate, apex thickened, 45-55x12-14 /x, 

 8 - spored. Spores elongate - clavate, 3-4-septate, hyaline, 

 16-18x6-8 p. 



Sphaerulina myriadea (Sacc.) Perithecia crowded, form- 

 ing vague patches on fallen leaves of oak and beech, 90-100 p 

 diam. Asci subfusoid, 8-spored. Spores elongated, both 

 ends rather acute, 3-septate, hyaline, 30-35X2-3 p. 



ACANTHOSTIGMA (DE NOT.) 



Perithecia free, globose, fragile, hairy, papillate; asci 

 8-spored; spores elongate-fusoid, i-5-septate, hyaline. 



Silver fir leaf disease (Acanthostigma parasiticum, Sacc. 

 Trichosphaeria parasitica, Hartig) is abundant in fir 

 woods, attacking more especially the silver fir, less frequently 

 the spruce. The mycelium is white at first, then yellowish- 

 brown, and covers the under surface of the leaves. The 

 leaves are first killed but do not fall, being fixed to the 

 branch by cobweb-like mycelium. At a later stage the 

 branches are also killed. In crowded woods the fungus 

 passes quickly from tree to tree, and does a considerable 

 amount of injury. 



Perithecia minute, mouth distinct, upper portion with rigid, 

 spreading bristles ; asci 8-spored ; spores elongate-fusoid, 

 smoky-grey, 2-3-septate, 15-20 /x long. Most abundant in 

 damp localities and where the trees are crowded. In dry, 

 airy districts the fungus does but little harm. 



Hartig, Alkg. Forst. u Jagd. Zeit., Jan. 1884. 

 Prillieux, Malad. des Plantes Agric., 2, p. 208 (1897). 



