3^6 THE FRUIT GROWER'S GUIDE. 



very disastrous, even when its growth is arrested or destroyed, the epidermal tissues 

 being so impaired by the attack as not to recover, the parts are blackened, and growth 

 ceases, affected berries often splitting, and the crop is more or less ruined. 



The cause of Oidium is its reproductive bodies falling on and finding suitable posi- 

 tions on vine leaves, shoots, and fruit, with certain atmospheric conditions favourable to 

 its development. Cold, damp, low situations, and a stagnant atmosphere indoors aid 

 infestation. But both outdoors and indoors it spreads rapidly in a moist, warm 

 atmosphere. It is greatly checked outdoors by rain, and indoors by dry air. Plenty of 

 air, so as to secure thoroughly solidified growths and thick leaves, is the best preventive 

 of Oidium. Dry soil should also be avoided, for vines that are dry at the roots are 

 prone to fungoid attacks. 



Mildew should be attacked directly small mealy spots appear on the leaves, shoots, 

 or fruit. Sulphur is the general remedy. It is applied in three ways, namely, dusting, 

 in liquid, and as fumes. 1, Dust flowers of sulphur all over the vines, choosing the early 

 morning or late evening for the operation, and the sulphur will rest on the fungal 

 patches and destroy the Oi'dium. In the course of a few days not less than two, 

 nor exceeding seven the sulphur should be washed off by forcible syringings with 

 clear rain-water. This is imperative, because the grapes are not otherwise fit for table, 

 and there ought not to be any trace of sulphur on the berries when they change colour 

 for ripening. In some cases it is necessary to repeat the application, but when taken in 

 time first dressings are usually efficacious. 2, Bisulphide of calcium, prepared and 

 applied in the way advised in Yol. I., page 248, effectually extirpates mildew. The 

 danger of staining the fruit is a serious objection to the employment of liquid compo- 

 sitions, especially those containing soapy matter, and they are best avoided. 3, Highly 

 heat the hot-water pipes in the afternoon while the ventilators are open, wipe a wet rag 

 along a couple of yards of piping at a time, and dust with flowers of sulphur from a 

 piece of muslin while the pipes are wet. A thin coat of sulphur on the top side of 

 the pipes is sufficient. In the evening, after the sun heat is mostly gone, and the pipes 

 have been made as hot as possible without causing the water to boil, the house should 

 be closed, when the fumes from the sulphur will fill it, and in an hour (two, if a large 

 house) every particle of mildew will be destroyed. The heat in the pipes should then 

 fall to that ordinarily required, and in forty-eight hours the sulphur should be removed 

 from them. Some slight portions, however, may remain, and will act as a preventive 

 of further attacks. The suL^w may be mixed with skim-milk, and applied with a brush 



