136 Report of the Botanist of thb 



ground; also, that air currents affect the distribution of the 

 dews; that is, dews are not evaporated as rapidly on the wind- 

 ward side of a hill. Although the base of this field is as high as 

 any of the fields of the Oneida Community' Limited yet the land 

 adjoining it on the northeast is low and moist. All these condi- 

 tions indicated that dews might have had more to do with the 

 fostering of the rust than had any other condition, such as culti- 

 vation, fertilization, soil conditions and varietal differences, 

 which man could furnish. Taking the conditions as they were, 

 it appeared that dews had been the principal fostering agent in 

 the fields of the Oneida Community Limited, the only exception 

 being in the case of the new field of Barr's Mammoth. This field, 

 as stated, is about fifty feet above the stream and nearly level. 

 In addition it is open to wind currents from all directions. 



The supposition that fogs and dews have more to do with the 

 varying conditions found regarding the rusting of asparagus 

 fields applies in all cases on Long Island. It is a common occur- 

 rence to have a week or ten days during each month of the fall 

 on which the sun is not seen until 10 a. m. The low grounds 

 always get the larger portion of these fogs. 



Although Messrs. Stone and Smith do not state whether the 

 fields examined by them were on high or low ground, they give 

 the post office address of each locality. A study of the contour 

 map of the State of Massachusetts shows that four of these 

 localities are less than one hundred feet above sea level ; that is, 

 they are in sections which are reached by sea fogs, while a fifth 

 locality is in the valley of the Connecticut River. From what 

 has been observed regarding conditions in this State it would 

 seem as if the factor of fogs and dews might play an important 

 part in the conditions found in the State of Massachusetts. 



SPRAYING. 



From the fact that all the true rusts which attack plants are 

 internal parasites, that is, they grow and develop within the plant 

 and do not show themselves on the surface of the plant until 

 mature enough to form their spores, writers on plant diseases 



