WEEDS 159 
Harm Done by Weeds. — It is easy to see that all weeds 
are more or less injurious in fields and gardens. We know 
that when plants stand too close they do not thrive, because 
the available supply of food and moisture is limited and all 
the leaves cannot get sunlight. When weeds compete in 
this way with cultivated plants, they take their full share 
of all the good things and will thrive better than the other 
plants because they are more robust. Weeds therefore do 
harm because (1) they help to exhaust the plant food from 
the soil, taking the nourishment that should go to the crops; 
(2) they use up equally valuable moisture; (3) they take 
up room and crowd other plants; and (4) they often tower 
above other plants and rob them of sunlight. For these 
reasons weeds are to be counted among the farmer’s and 
gardener’s enemies and should be studied with the view of 
learning the best method of combating them. That method 
varies with different weeds according to their nature and habit. 
Annuals and How to Kill Them. — In the case of annuals 
the only thing necessary is to prevent the plants from bear- 
ing seeds, not only one year but for a number of years, until 
all the seeds in the soil have germinated and died. This is 
best accomplished by careful plowing and cultivating. We 
must also be on guard against bringing weed seeds upon our 
land from other parts. They may be carried by threshing 
machines or they may be mixed with seeds that we purchase 
for garden and field. The wind also brings many weed seeds 
to our farms, but the author cannot suggest any way to pre- 
vent this. Annuals are confined to cultivated and waste 
places. In grass lands they perish, for there they meet con- 
ditions with which they are not able to cope. If they do 
grow, it is because the sod is poor, and then spreading on 
fertilizer to produce a better growth of grass is the best treat- 
