110 PLANT GROWTH 



such a good lawn in many regions during August and Sep- 

 tember when bluegrass lawns are least vigorous that many 

 people make the mistake of not considering it a bad weed. 

 It is objectionable and a serious weed because it injures the 

 better grasses so seriously that a poor lawn usually results 

 for the other ten months. 



The eradication should begin by providing an unfavor- 

 able environment for its growth in June and early July when 

 it germinates. If the grass has been kept growing well by 

 watering heavily at weekly intervals when necessary, it will 

 have a dense top and a deep root system, so that the crab- 

 grass roots will find low nitrogen and moisture in the surface 

 soil and the shoots will be crowded and shaded by the estab- 

 Hshed grass. The crabgrass plants will have roots beginning 

 an inch above the soil level and the leaves will be upright 

 instead of growing prostrate as they do on a thin lawn. They 

 grow slowly under these conditions and can be pulled sur- 

 prisingly easily or cut close to the roots when mowing. This 

 is the easiest time to fight crabgrass where the infection is 

 mild, in fact, when the plants are fully grown, pulling is too 

 difficult. 



Nothing favors crabgrass in the lawn more than summer 

 application of fertilizer and sprinkling lightly every day. 

 The deep rooted grass suffers for water and grows slowly 

 while the new crabgrass seedlings can grow with less compe- 

 tition and have water for their shallow root systems. If the 

 lawn becomes too badly infested to control in July and 

 August, it should be mowed and raked out with an iron rake 

 in the fall and seeded under more favorable conditions, with 

 the ambition to have it in control next summer. Some of the 

 chemical treatments for crabgrass make its eradication easier 

 than to rake out the growing plants. 



Biennial and perennial weeds, such as plantain and 

 dandelion, may persist, but will spread very little. Here 

 again fertilizers, if applied in late fall or very early spring, 



