CHAPTER X 



FUNGICIDES AND THEIR APPLICATION. 



Apart from experiment stations the spraying of plants, whether 

 for insecticidal or fungicidal purposes, has come little into practice 

 in the West Indies, and less for the latter than the former purpose. 

 This can be attributed to the usually unintensive methods 

 of raising crops, to the lack of adaptation of available methods 

 to the needs experienced, to the general unsuitability for spraying 

 operations of the type of labour employed, to the difficulties of 

 maintaining the apparatus, especially rubber parts, in order, 

 and not least to a reluctance to face the trouble and supervision 

 involved. Even the simple operation of dusting cotton for 

 caterpillar attacks is often badly organised and carried out, 

 and the most general use of a fungicide, that of Bordeaux mixture 

 for treating cane cuttings, is made in a routine fashion which is 

 frequently inefficient. Improvement in these matters depends 

 on agricultural education, and on the ability of agricultural 

 officers to demonstrate the advantages to be secured. 



The use of fungicides may be (i) protective against infection, 

 as in the spraying of leaves and fruits, the dipping of sugar-cane 

 cuttings, and the coating of exposed wood ; (2) remedial, as 

 when a fungus growing on the leaves of a plant is directly at- 

 tacked ; (3) disinfectant, when fungi, bacteria, or their spores 

 existing on seeds or other planting material, on a growing plant, 

 or in the soil are destroyed to prevent infection. 



By far the most important function, in the extent of its 

 application, is the protective one, and the most common mis- 

 apprehension regarding fungicides is that spraying designed for 

 this purpose is of value as a remedial treatment, which very 

 frequently is not the case. 



Bordeaux mixture is the standard protective fungicide, 

 but it has little remedial value. For the destruction of a fungus 

 on living organs, which naturally can as a rule only be atten-j.pted 

 when the mycelium is superficial, the sulphur fungicides are 

 in general most effective. For disinfection various poisons are 

 available for different purposes, such as mercuric chloride, 

 formalin and copper sulphate. 



It is necessary to bear in mind that the pint of the United 

 States and Barbados is 16.6 fluid ounces as compared with the 

 20 ounces of Imperial measure, so that to get comparable results 

 in using American formulse with British measures five-sixths 



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