630 USEFUL FUNGICIDES 



as a matter of considerable importance in horticulture and agri- 

 culture. 



Good cultivation a preventive of disease. The remarks ap- 

 plied in the case of insect pests with regard to the importance of 

 maintaining a vigorous condition of the plants or crops grown, 

 are equally applicable in the case of fungus diseases, for plants in 

 vigorous growth are often capable of combating the parasitic 

 effects of a disease, while those of a weaker constitution succumb 

 to it. Therefore, good cultivation, as secured by proper draining, 

 manuring, careful priming, etc., should be considered an effective 

 measure towards the suppression of a fungus disease. 



Importation of plants from infected areas. This has often re- 

 sulted in the introduction of new diseases, and many countries 

 have now formulated laws to prevent such an occurrence. The 

 importation or transference of seeds or plants from countries or 

 localities affected with fungus diseases should, therefore, be 

 allowed only where quarantine measures for disinfection are 

 adopted. 



USEFUL FUNGICIDES 



Bordeaux Mixture. This is one of the most useful and 

 effective fungicides for application to plants attacked with mildew 

 or other fungus disease. There are various formulas for making 

 it, all of somewhat varying degrees of strength. The following 

 proportions represent a standard formula and may be recom- 

 mended for general use in the tropics : Copper sulphate ( 98 per 

 cent.) 5 Ib. ; lime (freshly burnt) 5 Ib. ; acid water to make up to 

 50 gallons. Dissolve the copper sulphate in a small quantity of 

 water, using a wooden tub for the purpose, slake the lime to a 

 paste, mix it with the remaining water and pour into the copper 

 solution. Treacle is sometimes added to render the mixture more 

 adhesive. When being applied, the mixture should be kept 

 thoroughly stirred. 



Sulphur. This is used for the destruction of mildews, whose 

 mycelium is superficial and forms a whitish down on the surface 

 of living leaves, fruit, etc. It is applied as a powder in the 

 familiar form known as " flowers of sulphur," preferably when 

 the affected leaves are damp. Various appliances are in use for 

 blowing the powder on to the leaves, such as sulphur-sprayer, 

 sulphur-bellows, etc. Quicklime is sometimes added to the 

 sulphur, but it should not exceed one third of the whole. 



