. [Bulletins on forest pathology : from Bulletin , Washington, , 1913-1925]. Trees; Plant diseases. 20 BULLETIN 1186, U. S. DEPARTMENT OE AGRICULTURE. the blister-rust menace several of the nurseries of Belgium and France specializing in conifers for exportation discontinued the growing of black currants, since this species caused the most damage to pine. In other nurseries where the currants are of major im- portance the cultivation of five-leaved pines has been abandoned. The nursery beds shown in Figure 11 are in one of the largest of the French forest nurseries, situated near O
. [Bulletins on forest pathology : from Bulletin , Washington, , 1913-1925]. Trees; Plant diseases. 20 BULLETIN 1186, U. S. DEPARTMENT OE AGRICULTURE. the blister-rust menace several of the nurseries of Belgium and France specializing in conifers for exportation discontinued the growing of black currants, since this species caused the most damage to pine. In other nurseries where the currants are of major im- portance the cultivation of five-leaved pines has been abandoned. The nursery beds shown in Figure 11 are in one of the largest of the French forest nurseries, situated near Orleans. These were started since the war and contain Austrian and Scotch pines, but no Ameri- can five-needle pines, the growing of which was discontinued. BRITISH ISLES. British foresters declare the rust to be altogether too prevalent, but have made no efforts to control it. The fungus has raised more interest and concern among fruit growers than it has among the foresters, because the former feared a decrease in their black-cur- rant crop, entailing financial Fig. 10.—A 17-year-old white-pine plantation near Epinal in the French Vosges. Blister rust has attacked 52 per cent of the trees. This entire plantation is ex- posed to further infection from black-currant bushes growing 600 feet distant. It is doubtful whether merchantable timber will ever be obtained from it. Trials made at Oxford, England, to check the rust by spraying Eibes proved quite unsuccessful (#, p. 24). Eeference to the spray- ing of young pines with a fungicide is made in the Quarterly Jour- nal of Forestry (5), with a statement that in a Belgian nursery seed- lings sprayed with a 1 per cent solution of potassium permanganate had been effectively protected. Chemically treating diseased parts of stem or limb may retard the development of the disease, but results thus far obtained are rather uncertain. Silvicultural methods will never control the fungus as long as Ribes bushes are permitted to grow
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