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ceases. Helnlcke In New York has shown that while some root growth may take 

 place during the dormant season, the amount Is relatively small compared to that 

 made several weeks preceding leaf fall. 



Boynton in New York found that the oxygen and carbon dioxide levels In the 

 soil affected feeder root formation. When the oxygen level of the soil was 

 reduced somewhat below 15 per cent and the percentage of carbon dioxide increased 

 about the same araountj the rate of new root fozmatlon decreased. 



Root systems of apple trees show large differences on different soils. 

 Rooting Is shallower and tree growth poorer on poorly drained soils. 



Cultural practices can affect root distribution. Probably most striking in 

 this aspect is that of mulch. Conditions under mulch appear to be very favorable 

 for root growth and generally a thick mat of roots can be found near the soil 

 surface under the mulch and extending into the mulch. 



Velhmeyer and Hendrickson in California have found that withholding irriga- 

 tion does not force trees to send roots deeper into the soil. Light irrigation 

 does not encourage shallow rooting, and irrigation of one side of the tree only 

 will not result in confining the roots to that side. 



---William J. Lord 

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