. The more important fruit tree diseases of Ontario [microform]. Fruit; Pulvérisation et poudrage en agriculture; Spraying and dusting in agriculture; Fruits; Exploitations agricoles. so Symptoms. This disease is confined to the leaves, on which are seen small, â omewhat angular spots, usually with grey centres and brownish or purplish brown borders; but sometimea the whole spot is dark in colour, with no distinct grey cen- tral area. In the centre of the spots as they mature, small black specks, the fiuit- ing bodies (pycnidia) of the fungus, appear. The size of the spots appear to vary â wi
. The more important fruit tree diseases of Ontario [microform]. Fruit; Pulvérisation et poudrage en agriculture; Spraying and dusting in agriculture; Fruits; Exploitations agricoles. so Symptoms. This disease is confined to the leaves, on which are seen small, â omewhat angular spots, usually with grey centres and brownish or purplish brown borders; but sometimea the whole spot is dark in colour, with no distinct grey cen- tral area. In the centre of the spots as they mature, small black specks, the fiuit- ing bodies (pycnidia) of the fungus, appear. The size of the spots appear to vary â with the variety and the season. When the disease is severe the spots may be so numerous as to injure the leaves markedly. Life Hittory. The tiny black specks or fruiting oodies (pycnidia) are filled with minute, slender, thread-like spores, which are discharged from a small open- ing at the tip of the fruiting body (pycnidium). They are scattered through the orchard by wind and rain, and serve to spread the Leaf Spot during the summer months. Moisture is essential for the germination of these spores and for the. Leaf Blight of quince. (V. B. Stewart.) penetration of the leaf by the germ-tube. Hence it is that the Leaf Spot is always most prevalent in a wet season. The fungus lives over the winter in the fallen leaves. In these another form of spores (ascospores) are developed in a special kind of fruiting body (peritheeium). These arc discharged in the spring o' the year and some of them are blown by the wind to the newly developed leaves on which in a short time they produce the characteristic spots and the first generation of summer fruiting boditJ (pycnidia). Preventioii. The sprayings which are given for Scab appear to control com- pletely Leaf Spot. To control it on nursery stock spraying with Bordeaux mixture or with commercial lime-sulphur 1 gallon to 40 gallons of water is recommended. The first application should be made just as soon as the trees come into full leaf
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