that a fungicide will cure a plant of a disease. It can only pre- 

 vent the. spread of the pest by destroying the spores actually 



nt on the exposed parts of the plant; the fungus inside the 

 plant cannot be killed unless the tissues containing it share the 

 same fate. The fungicide that is applied must therefore be of 

 such a nature that it is injurious to the parasite and at the same 

 time innocuous to the plants under treatment. 



In spite of considerable investigation on the subject, no uni- 

 versal fungicide, which can be used as a panacea for all fungus 

 diseases, has been evolved. vSome diseases are, however, more 

 easily controlled by certain sprays which in the case of other dis- 

 eases are nothing like so effective. 



Of all the known fungicides, not more than two are uni- 

 versally adopted at the present time. These include Bordeaux 

 mixture and Lime-sulphur solutions. Bordeaux mixture would, 

 no doubt, be much more popular than it is. were it not for the 

 labour involved in making it up, and from the fact that to be 

 effective it must be freshly prepared each time. Apart from its 

 fungicidal value, Bordeaux mixture has certain advantages which 

 should be borne in mind by the planter. For instance, experi- 

 ments have shown that potatoes treated with Bordeaux mixture 

 give a far heavier yield than the untreated ones, even if no dis- 

 ease appears in either portion of the crop. On the other hand, 

 the action of Bordeaux mixture has been shown in the case of 

 certain varieties of potatoes to delay the ripening of the crop in 

 some instances by about three weeks. 



Its action on plant foliage varies considerably. Apple and 

 peach are very liable to injury from strengths which normally do 

 no damage to most other foliage. 



The spray should not only be used in the spring or summer 

 months when some particular disease is expected or has already 

 made its appearance, but orchard trees should be thoroughly 

 washed over when the trees are dormant during the winter. In 

 the case of many important orchard pests, this winter spraying 

 is far more effective than three or four sprayings in the summer. 



For the winter spraying of dormant trees, the formula 

 usually recommended is : 



Copper sulphate 5 Ibs. 



Quicklime 5 Ibs. 



Water 45 gallons. 



A good formula for the spraying of such crops as potatoes, 

 tomatoes, apple, pear and mangoes, is: 



Copper sulphate 4 Ibs. 



( Juicklime 4 Ibs. 



AYater 50 gallons. 



