WHAT 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 Beal’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. Pammedl, 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 
