272 The Spraying of Plants. 



solution of copper carbonate may be substituted, although it is 

 perhaps not so efficient. The plants should at all times be pro- 

 tected in this manner. 



Rust (Uromyces caryophyllinus, Schr.). Desertion. This 

 European disease was first noted in this country about the year 

 1891. It has been rapidly dissemina- 

 ted here by means of the stock sent 

 out by propagators, and now it can 

 be found in the house of nearly every 

 extensive carnation grower. The 

 first external appearance of the dis- 

 ease (Fig. 49) is the formation of 

 gray, blister-like elevations on the 

 leaves and stems, these being- of 

 various sizes and shapes. As the 

 fungus develops, these parts rupture 

 and a large amount of a reddish- 

 brown powder is forced through the 

 broken epidermis. This powder con- 

 sists of spores which are capable of 

 reproducing the parasite in other 

 localities. Later another kind of 

 spore is matured from the affected 

 part, this being of service to carry 

 i the fungus through conditions which 

 prove fatal to the body of the para- 

 site and also to the spores first pro- 

 duced. 



Treatment. A plant that has be- 

 come infested with the rust fungus 

 cannot be cured ; the only remedy is 

 to cut out the affected parts and de- 



FIO. 50. - Spot" of carnation, stroy them. The spread of the dis- 

 ease may, however, be checked by 



the proper use of fungicides. The disease appeared in the 

 Cornell forcing houses during the winter of 1894-95, and was 

 practically controlled by thorough applications of the Bordeaux 

 mixture. Copper chloride appeared to be equally effective. 

 Soap was used with the mixture in order to make the liquid 

 adhere better. This, however, did not prove entirely satisfac- 



