200 IOWA DEPARTMENT OF AGRICULTURE 
ized and then planted to corn it has less weeds than a field that has been 
in small grain or in corn the previous season. During the interval dur- 
ing which the meadow has been in pasture many of the weed seeds have 
been destroyed. If the meadow is then sowed with corn the second year 
it can be planted with small grain but the grain should only be sown on 
a comparatively clean field. If the oats have been removed it would 
be a good thing to allow the field to be used one year more for a grain 
crop and then it can be sown with clover and brought into a timothy 
meadow gradually; in this case a large number of the ordinary annual 
weeds will be exterminated. 
Treatment for Annual Weeds. The most important point in connection 
with annual weeds is to prevent the formation of seeds. Cultivation of a 
field should be thorough at all times. The best time to kill these annual 
weeds is when they are young. The roots of all seedling plants are 
readily killed when exposed for a short time to the sun. A field or 
garden should be plowed, then brought into a good state of tilth by using 
the harrow. When planted with small grain or any other crop, a little 
jnore work in the spring may mean the saving of much labor later. All 
of the annual weeds mentioned in the list of most troublesome weeds 
should be treated in this way. It may be more difficult to destroy the 
older plants of Purslane but the young seedlings are readily destroyed 
with a solution of iron sulphate or copper sulphate. 
Treatment for Biennial Weeds. The biennial weeds are not nearly so 
numerous in kind as the annual or perennial and are much more readily 
destroyed than the latter. The Bull Thistle and Burdock, and other bi- 
ennial weeds of this character are readily destroyed by cutting the plants 
off a few inches below the surface of the ground. A small spade will cut 
the plants off readily. In cutting, of course, it is essential to cut the 
root below the buds. The Bull Thistle produces a mat of leaves and 
when this is cut off just below the surface of the ground, the Bull 
Thistle will cause no more trouble. 
Treatment for Perennial Weeds. It is difficult to suggest any one line 
of treatment for perennial weeds but in general one must take into ac- 
count the habits of the plant. For instance, Quack Grass must be treated 
very differently than Canada Thistle or Milkweed. In many cases the 
summer fallow or frequent and shallow cultivation can be resorted to 
and will be found very effective. For instance, a field containing Canada 
Thistle and Morning Glory should be plowed in the spring, disced and 
harrowed and the process repeated at least once a week. In some cases 
perennial weeds may be held in check by sowing thickly to some legum- 
inous crop like clover, millet, or sorghum and buckwheat and rape. 
Quack Grass. Quack Grass can be killed, I am certain from our ex- 
periments. A good plan is to sow thickly with some crop like millet, 
sorghum, buckwheat or clover. When the crop is removed plow deeply. 
The roots of Quack Grass are all near the surface of the ground, very few 
are beyond a depth of four inches. We found that few roots can push 
through the soil beyond six inches. None of the roots were able to push 
through a soil when covered twelve inches. Where Quack Grass is 
abundant the soil should never be planted with corn because the cultivator 
