DISEASES AND OTHER ENEMIES. 307 



Ions of water. Slake four pounds of lime in five gallons 

 of water. When cool, strain the lin e water into the 

 copper solution and add thirty gallons of water, making 

 forty-fiye gallons of the mixture. If desirable to poison 

 insects at the same time, four ounces of Paris green or 

 London purple may be added to this amount of the mix- 

 ture. The ammoniacal copper carbonate solution, also 

 diluted to half the original strength, is made by adding 

 to five ounces of copper carbonate enough water to make 

 a thick paste. On this pour three pints of strong aqua 

 ammonia, or enough to dissolve the paste. Add forty- 

 five gallons of water. Paris green should not be used 

 with this. To make the potassium sulphide solution, 

 dissolve one ounce of potassium sulphide in two gallons 

 of water. For larger quantities of any of the solutions 

 use the same proportions. The treatment of insects by 

 pyrethrum or insect powder, and by arsenites, and the 

 remedies for other pests, are given throughout this vol- 

 ume, in the descriptions of the plants they attack. 



For the remedial treatment of tubers and bulbs 

 affected with injurious fungi, the successful researches 

 on the Potato-scab fungus, by Prof. H. L. Bolley, of 

 the North Dakota Experiment Station, are very sugges- 

 tive. He succeeded in killing the fungus spores and 

 raised a crop of healthy tubers, by treating the washed 

 seed tubers to a ninety minutes' immersion in a weak 

 solution, one part in one thousandth, of corrosive subli- 

 mate or mercuric bichloride. Two ounces of this deadly 

 poison, finely pulverized by the pharmacist, were dis- 

 solved in two gallons of hot water for twelve hours, in a 

 vessel not made of metal, and then diluted with thirteen 

 more gallons of cold water. The cleaned and washed 

 tubers were then soaked in this solution for one hour 

 and a half. Caution should be used, as the solution is 

 poisonous. The best preventive of all plant diseases is a 

 vigorous growth, brought about by healthful conditions 

 of fertility, moisture and sunlight. 



