WHA T IS A WEED ? 3 



and assimilated as to become available for the making of new plant 

 substance. Without leaf-growth the roots must die. 



General principles 



1. Allow no weeds to ripen seeds. 



2. Kill while in the seedling stage if possible, for then the weeds 

 die most easily and in the greatest numbers. 



3. Induce autumn germination of the seeds of annuals by sur- 

 face cultivation of fields after harvest. Many weeds are thus 

 winter-killed before seeds can be produced. Following spring cul- 

 tivation will rid the ground of a second crop of seedlings and leave 

 the soil comparatively free of this class of plants. 



4. Never plow under weeds bearing mature seeds. Burn them. 

 For seeds of many weeds, particularly of some of the most trouble- 

 some annuals, have great vitality and may lie dormant in the soil 

 for long periods, to germinate when brought to the surface by future 

 cultivation. It is an old saying that "One year's seeding means 

 seven years' weeding," but it may be much more than that. Mrs. 

 Thaxter wrote that in her Island Garden she destroyed seedlings 

 of Common Dodder every season for twenty years after the first 

 seeding. Professor Deal's experiments demonstrated that the 

 seeds of Charlock and Purslane will germinate after lying for thirty 

 years in the soil, and it is said that the seeds of the Indian Mallow 

 or Butterprint Weed have survived for more than fifty years, 

 dormant but ready. 



5. Thoroughly compost all stable manures that are known to 

 contain the seeds of noxious weeds. Some few hard-coated seeds 

 there may be which are able to survive the heat and ferment of the 

 compost heap. Concerning this, the Iowa State Experiment 

 Station, under the direction of Professor L. H. Pammel, has carried 

 out a series of valuable experiments. Collections of various weed- 

 seeds were made and placed in gauze bags in the heart of fermenting 

 compost heaps for periods varying from five weeks to six months. 

 The result proved that almost all seeds so treated were thoroughly 

 rotted and their vitality was destroyed. The process is a costly one, 

 in that the fermentation which kills the life-germs in the seeds also 

 deprives the manure of some of its most useful properties, par- 

 ticularly of nitrogen, its most valuable constituent. But to sow 



