Effect of Grass on Trees 



but in addition to those mentioned there, the presence 

 of substances detrimental to plant growth, either in 

 the soil or in the air, have to be dealt with, and in 

 a few instances in the cultivation of garden plants 

 we have cases where plants actually come into 

 competition with one another quite apart from 

 overcrowding through too close planting. We 

 may deal with these first. 



One of the most frequent checks imposed upon 

 trees is the presence of grass about their trunks. 

 It is especially seen when young fruit trees are 

 planted in grass, is most marked when the grass 

 completely covers the ground, but is stiU seen when 

 several feet are kept clear around them. Experi- 

 ments seem to show that it is through no direct 

 interference with water, air, or earth-salt supply 

 that the marked check to growth is caused, but 

 rather to the production of some substance dele- 

 terious to the trees by the grass, or the decay of the 

 remains of the grass, roots, etc. The remedy is to 

 remove the grass, and the result of this treatment 

 is, so long as the poisonous effect has not been in 

 operation too long, rapid. 



A second competitive effect is often seen in water 

 where water-lilies and other aquatic flowering plants 

 are often damaged by being smothered with the 

 thready green masses of " flannel weed," which grow 

 with extraordinary rapidity. This flannel weed will 

 grow in any exposed piece of water, but is readily 



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