Good results were obtained only when a high pressure was maintained in spraying. There was a clearly observable difference between plots sprayed with low pressure and those sprayed with a pressure of more than 175 pounds. For large orchards a power sprayer is desirable; for small orchards a barrel sprayer with an air-pressure tank attached is large enough. Such an outfit can be bought for $35 or $40 and can do good work.
The cost of spraying three times should not exceed fifteen cents a tree. The results from spraying orchards which contain a great deal of brown rot and have never before been sprayed will probably not be so good the first year as in better kept orchards, but by spraying regularly each season the disease can be well controlled.
Mr. Cashman: Please state what you mean by 3-4-50 there.
Mr. Stakman: 3-4-50 Bordeaux mixture means three pounds of bluestone or copper sulphate, four pounds of lime, and fifty gallons of water. The copper sulphate should be dissolved in twenty-five gallons of water, the best way being to put it into a sack and hang the sack in the water. The lime should be slaked and then enough water added to make twenty-five gallons of milk of lime. Here is where the important part of making up the spray comes in. Two people should work together and pour the milk of lime and the bluestone solution together so that the streams mix in pouring. It is very important that the mixing be thorough and the mixture should be used fresh.
The President: Do you add any Paris green at any time or arsenate of lead?
Mr. Stakman: Always add arsenate of lead two times, when the buds are swelling and when the plums are the size of green peas.
The President: How much?
Mr. Stakman: I would rather leave that to Professor Ruggles. We used from 2-1/2 to 3 pounds and Mr. Ruggles, I think, found 2-1/2 pounds was enough.
The President: That is, 2-1/2 pounds to 50 gallons of water with the other ingredients?
Mr. Stakman: Yes.