THE GREEN-HOUSE. 



177 



green-houses carelessly managed. Common spiders 

 are chiefly injurious to plants by soiling them with 

 their webs, as their nests, unlike those of the red 

 spider, are not made on the leaves, but in the angles 

 of the walls, and wood- work of the house. They 

 are useful in catching flies to a certain extent, but 

 form a remedy much more offensive than the disease. 

 They are effectually subdued by the free use of water 

 from the syringe or engine. 



There are few diseases to which green-house plants 

 are subject as such. The principal is the mildew; 

 and occasionally the honeydew, rust, and consump- 

 tion make their appearance. 



The mildew appears in the form of a mealy pow- 

 der (supposed to be a small fungus) on the tops of 

 the shoots of heaths, geraniums, and some other 

 plants. A specific in general use is flower of sul- 

 phur thus applied : — Get a vessel sufliciently large to 

 immerse the plants infected, one at a time, and fill it 

 with clear water. Then provide a pound or more of 

 sulphur, according to the number and size of the 

 plants, and have ready an old powder-puff or a large 

 dusting-brush. Then take up the plant and hold it 

 in an inverted position, with the hand placed on the 

 surface of the pot, so as to prevent the mould or ball 

 from falling out : in this manner' plunge the plant 

 into the water ; and while it is wet, holding it in the 

 same position, let an assistant dust on the sulphur 

 with the puff or brush in such a manner that every 

 part of the plant, including both sides of the leaves, 



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