Crreenhouse Troubles. 307 



GREENHOUSE PESTS. 



FUNGI INFESTING PLANTS. 



There is such an enormous variety of plants grown under 

 glass that each cannot here be treated individually. Nor is this 

 necessary, for a few general directions may be made to cover 

 almost all cases. Fungi as a rule prefer a warm, moist atmos- 

 phere for their growth, and this is generally found in a green- 

 house, as it is essential to the proper development of many 

 plants. But the general opinion of gardeners is that even when 

 such conditions exist, mildews need not necessarily appear. It 

 is said that extremes of temperature, of humidity, and draughts 

 of air are conducive to disease, and common practice tends 

 strongly to support the notion. Such conditions shoiild there- 

 fore be avoided as far as possible. 



Some of the surface fungi found on plants grown under glass, 

 especially in houses improperly ventilated, are destroyed by 

 spraying the foliage with clear water or with some prepared 

 insecticide or fungicide, soapy mixtures being most commonly 

 employed. Fungi which cannot be disposed of in this manner 

 are reduced by removing diseased parts of the host-plant and 

 destroying them. This tends to prevent new infections, and it 

 is a process which well repays the outlay of time and labor. 



Sulphur is probably the most valuable preventive of the fun- 

 gous diseases which attack greenhouse plants. It may be used 

 in various ways. An early method of making applications, and 

 one still employed, is to dust the plants with the dry powder. 

 This is effective in destroying several surface mildews. A prep- 

 aration of sulphur formerly very generally employed is in 

 liquid form. It is the Eau Orison of the French, and is very 

 valuable in the treatment of diseases which may be controlled 

 by the powder. But the most efficient method of using sulphur 

 is to place it in a warm situation so that it will rapidly give off 

 its fumes, and still not take fire. It may be mixed with equal 

 parts of lime or some similar powder, and then by the aid of 

 water, oil, or other liquid, it is wet until a thin paste is formed. 

 This is then smeared upon the heating surfaces of the house. 

 Or the sulphur may be evaporated in a sand bath over an oil 

 stove, but in such cases extreme care must be exercised that 



