272 GARDEN FOES. 



a safe preventive. Strict attention, too, should be paid 

 to ventilation, never allowing cold currents of air to come 

 in direct contact with the foliage, especially of roses. In 

 the event of mildew appearing, dust the affected foliage 

 with flowers of sulphur, and after moistening the hot- 

 water pipes dust these with sulphur also. Instead of the 

 sulphur the following recipe may be used: Boil lib. of 

 sulphur and lib. of quicklime in five pints of water for 

 ten minutes in an earthenware pot; keep well stirred. 

 When cool, strain off and add one part of this to a hun- 

 dred parts of water, and apply it to the infested plants 

 by means of vaporiser or a diffuser. A solution of sulphide 

 of potassium, prepared by dissolving one ounce of the 

 latter in a quart of hot water, then adding the liquor to 

 two and a-half gallons of water, is also an excellent pre- 

 ventive or cure for mildew. Apply by means of a sprayer 

 or a syringe to both sides of the leaves. In applying the 

 solution avoid allowing it to touch any painted surface, as 

 it will damage the paint. If a syringe be used see that 

 the solution is ejected with as fine a spray as possible. 

 Painting the hot-water pipes with a solution of hot lime 

 and sulphur — a quarter of a pound of each to three gal- 

 lons of water — will also help to eradicate mildew. 



Orang^e Mould. — The leaves of oranges and other 

 evergreen greenhouse plants are sometimes covered with 

 patches of dark mould. This is the work of various minute 

 fungi, which develop on the honey-dew deposit formed on 

 the surface of the leaves by various insects. If the mould 

 is allowed to remain long on the leaves it seals up the 

 stomata, or breathing pores, and causes the leaves to 

 become sickly. 



Kemedies. — The foliage of the plants should be fre- 

 quently sponged, so as to remove the honey-dew deposit. 

 Insects also should not be allowed to infest the plants. 



Orchid Diseases. — A few diseases attack orchids. 

 First of all, there is the Leaf Spot (Leptothyrium perni- 

 ciosum), which forms brownish spots on the leaves The 



