PREVENTIVE AND COMBATIVE MEASURES. 65 



l^ (4) Ifemoval and destruction of dead parts of plants carrying 

 sporocarps or other hibernating stages of any fungus. 



II. Methods for combating fungi by removal of diseased 

 plants or plant-organs. 



(1) Eemoval of the parts of a host-plant harbouring fungi. 

 ^^„A2) Removal of the whole or part of a complementary host 



of a heteroecious fungus, for the purpose of saving the other 

 host or hosts. 



III. The avoidance or removal of conditions which favour 

 infection. 



' (1) Preventive measures against wound infection ; antiseptic 

 and aseptic wound-treatment. 



(2) Avoidance of localities favourable to disease. 



(3) Avoidance of the massing together of plants of the same 

 ^ species and like age ; rotation of crops on the same cultivated 



area. 



(4) Avoidance of neighbourhood of those plants which are 

 hosts of the same heteroecious fungus. 



IV. Selection and cultivation of varieties and species of 

 cultivated plants least liable to the attacks of parasites. 



I. Extermination and removal of the parasitic fungi alone. 



(1) That the seed be clean and free from the spores of 

 ])arasitic fungi, is a most essential condition. The purity of 

 seed is investigated in seed-control stations,^ where special 

 attention is paid to purity of seeds {e.g. clover, from its 

 liability to contain seeds of the parasitic Dodder), and to their 

 freedom from spores of smut or other fungi. 



As a preventive against smut, especially those forms due 

 to species of Ustilagineae, sterilization of the seed is adopted,- 

 This is chiefly carried out by the use of " steeps," which kill 

 the smut-spores adherent to the seed. The composition of the 

 steep-liquid, and the duration of immersion are the points to be 

 attended to, and for these various recipes are extant. Recently 



^State-aided stations of this kind are fairly numerous in Germany, France, 

 and other continental countries, also in America. It is thus somewhat remark- 

 able that in Britain this important work receives no state recognition, but is 

 left in the hands of more or less experienced analysts, or others. (Edit.) 



-Swingle, W. F. "Grain-smuts and their prevention." Yearbook of 

 U.S. De.pt. of Agriculturt, 1894. A very useful summary. (Edit.) 



E 



