A Bacterial Disease of Stone Fruits 431 



poison to fifty gallons of the mixture. The first application was made 

 about seven days after the petals had fallen, and the three others followed 

 at intervals of four weeks. On August 8 only a few spots were observed 

 en (he leaves, and the twigs were apparently free from cankers, but fifteen 

 per cent of the fruit was infected. The foliage on the check trees was 

 badly injured, and fifteen per cent of the leaves had fallen. Many of 

 the twigs were badly cankered. Sixty-three per cent of the fruit was 

 infected, and most of this was worthless. 



Apparently the arsenate of lead improved the effectiveness of the self- 

 boiled lime-sulfur solution. It is quite probable, however, that the 

 beneficial results obtained from the addition of arsenate of lead are due 

 rather to the control of insects which serve as agents of dissemination than 

 to the improvement of the mixture as a fungicide. Laboratory tests show 

 that arsenate of lead used at the rate of two and one-half pounds to fifty 

 gallons of water has very little influence on the growth of this organism. 



From these and other experiments, it is evident that bordeaux mixture 

 will control the disease. But the foliage of the trees, especially in the case 

 of peach and nectarine, is extremely sensitive to the action of copper, 

 and in some cases the trees are defoliated even when the copper is used 

 at the rate of one-half pound of copper sulfate to nine pounds of lime and 

 fifty gallons of water. Self-boiled lime-sulfur alone is much less effective, 

 and in all the writer's experiments it failed to control the disease; but 

 when two pounds of arsenate of lead were added to fifty gallons of the 

 mixture it became much more effective. 



Cultivation 

 A tract of about two hundred acres of new land at Koshkonong, Missouri, 

 was set in 1906 with two-years-old Elberta peach trees which were more or 

 less infected with the organism. Strips about four feet wide were plowed 

 across the field and trees were set on the plowed land. The orchard was 

 fairly well cultivated during the first three years. The organism gradually 

 spread from the diseased to the healthy trees, and at the end of the third 

 year every tree in the entire tract was more or less infected. Many of 

 the trees were stunted and some of them finally died. Their death, 

 however, could not be attributed directly to the work of this organism, 

 but was apparently due to a combination of winter injury of the roots, 

 premature defoliation due to the work of the bacteria, and, finally, the 



