Book Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ...develops during the winter. When old diseased leaves fall to the ground in the autumn, carrying the fungus with them, the fungus does not die but lives over winter in the dead and decaying leaf-tissues. Here spores are formed in sacs (asci) produced in small shieldor spherical-shaped bodies called perithecia. These ascospores are discharged from the asci and pile up in whitish masses in the opened perithecia. They are mature by the time the leaf-buds have begun to expand in the spring, and are carried to the newly developing foliage by the wind, where, under proper conditions of temperature and moisture, they germinate and produce infection. Within eighteen days after infection by ascospores a crop of summer spores will develop. Control.--Two methods should be employed in the control of black-spot: (a) sanitation, and (b) application of fungicides. Best results will be obtained where the two methods supplement each other. (a) Sanitation. Since the fungus lives over winter on fallen leaves, where spores are produced which serve as a source of infection in the spring, it follows that these old leaves should be carefully collected and burned, either late in the fall or early in the spring before the buds expand. This refers especially to outdoor roses, as it is probable that winter spores are not formed under glass. However, it is advisable to keep the benches free from old leaves affected with black-spot, for they bear the summer spores and thus serve as sources of infection. (b) Application of fungicides. Sanitation alone will fail in the control of black-spot, and must be supplemented by the application of fungicides. Present recommendations call for the use of liquid fungicides. It is held that any of the standard copper compounds will...