OBSERVATIONS, COLLEGE PARK, MD. 



13 



They were 



American, and the peaches, Elberta and Mountain Rose, 

 all in good condition and from 5 to 10 years old. 



The following table gives a description of the weather conditions 

 during the experiment: 



Meteorological conditions at College Park, Md. 



OBSERVATIONS. 



The spraying was done on May 11, 1903, and the first observation 

 was made on May 18, no rain having fallen in the meantime. No 

 injurious effect from the sprays could be discovered on any of the 

 trees. The orchard was examined a second time on May 26, a light 

 rain having fallen on May 24. Among the apple trees a small per- 

 centage of the leaves of Nos. 4, 5, and 6 (6, 7, and 8 per cent of arseni- 

 ous oxid, without lime) were very slightly burned, while No. 5 (7 per 

 cent of arsenious oxid, with lime) had an occasional blackened leaf. 

 The remainder showed no injury. 



A number of the pear trees were affected with leaf spot (Septoria 

 pyricola) and the pear leaf blister mite (Phytoptus pyricola) so that a 

 great many leaves were beginning to blacken and wither. 



A small part of the foliage of all the peach trees used in the experi- 

 ment had begun to turn yellow and an occasional leaf showed black 

 spots, but the general effect at this time was so slight that no appre- 

 ciable difference could be said to exist between the several trees. 



The plum trees showed no injurious effect from the spraying, with 

 the exception of No. 5 (7 per cent of arsenious oxid, without lime), on 

 which a few leaves were spotted. 



On June 9, after three more rains, the apple trees had undergone 

 practically no change since the first observation. 



On the pears the disease and mite before mentioned were working 



