-3- 



WHAT IS A VIRU S? 



Recently, at a meeting of strawberry growers, strawberry viruses were under 

 discussion. There was a request for a good layman's definition of a virus. 



In the U.S.D.A. Yearbook of Agriculture for 1953 the following appears: 



"Virus. An infectious agent too small to be seen with a compound microscope'. 



This Is adequate if one is not interested in technicalities. If one is 

 interested in a more precise definition, the same paragraph continues: 



"It is not yet settled whether virv^ses are living organisms, because they 

 have characteristics of both the living and nonliving worlds. The definition that 

 is generally accepted is that they are large, high-molecular-weight protein 

 bodies capable of multiplying and acting like organisms when they are in living 

 tissue." 



— J. S. Bailey 



I I I I I I I I I I I I I I I I 



WHY MOW GRASS IN THE ORCHARDS? 



In an article published in the American Fruit Grower, Dr. John R. Magness 

 stated that on a hot summer day with low humidity a vigorous 20 to 25 year old 

 apple tree with a large leaf area will use up to 125 gallons of water a day. 

 Under average conditions, however, a large apple tree in our eastern orchards 

 will use about &0 to 70 gallons per day. Using the later figures, an acre of 

 20 to 25 year old apple trees planted 40' x 40* will use approximately 1600 to 

 1900 gallons of water a day during the summer months. With these figures in 

 mind, what can a grower do to conserve soil moisture? 



A study conducted at the University of New Hampshire Experiment Station 

 showed that the soil moisture loses at 12 inches and 30 inches depth were reduced 

 considerably by mowing the grass in the orchard and letting it lie. 



Soil moisture studies made in Michigan orchards (Quarterly Bulletin, Michigan 

 Agr. Exp. Sta., Nov., 1956) showed that permanent sod covers vary considerably 

 in the depth to which they deplete soil moisture. "Kentucky bluegrass, timothy, 

 redtop, and Chewing' s fescue grass sods depleted soil moisture the least; they 

 satisfied their needs primarily from the upper 24 inches of soil. These four 

 grasses were similar in both amount and depth of depletion. 



The legume sods, white dutch clover, Ladino clover and alfalfa, depleted 

 soil moisture seriously to the lowest measured depth of 40 inches. White dutch 

 clover used somewhat less moisture than Ladino and alfalfa. Ladino clover and 

 alfalfa used moisture about equally to a depth of 40 inches. Quackgrass water 

 usage was intermediate between the grasses and legumes . 



