2 A MANUAL OF WEEDS 
of the first class, Burdock and Wild Carrot of the second, and Fielc 
Sorrel and Canada Thistle of the third. Some plants that rounc 
their life-cycle in a year are known as “winter annuals”’; the seeds 
that have matured during the summer germinating in the fall, mak. 
ing a certain growth before the closing in of winter, and completing 
their development in the next summer. To this class belong the 
hated Penny Cress, or Frenchweed, the Corn Cockle, and the Fielc 
Gromwell or Wheat-thief. Obviously, the best time to compas: 
their destruction is in the spring, before they can develop fruiting 
stems. Spring plowing or harrowing is of course in order, but it i 
with such plants as these that the newer method of killing with < 
chemical spray, or herbicide, is most successful, particularly wher 
they appear in grain fields. The grains are resistant to injury fron 
the spray, for, being “‘ center growers,” they make a swift recovery 
from the slight harm received on outside sheath-leaves, while thi 
tender, outspread foliage of the weed seedlings is often totally 
destroyed. 
For biennials, also, the one sure means of destruction is preventior 
of seeding. Where plowing out is impracticable, frequent cuttin; 
must be practiced, in the first season spudding out or cutting of 
the rosettes, or crown leaves, and in the second season mowin; 
off the flowering stems before the formation of seed. 
Perennial weeds are by far the hardest to fight, sometimes requir 
ing the cultivation of special hoed crops in order to insure thei: 
complete eradication. The plowing and harrowing given to ordi 
nary field crops often only stimulate the growth of these perniciou: 
plants by breaking or cutting the long-lived underground stems anc 
inducing them to send up new shoots. It should be rememberec 
that their food reserves are in fleshy or woody roots, undergrount 
stems, bulbs, or tubers, and that the growth above ground neve 
seems to exhaust these hidden stores of nourishment. However 
there is a time when they are most vulnerable to attack, and it i 
just at that stage of growth when flowering stems are nearing ful 
size, but before the formation of seed. They should then be plowe: 
down, or, if too tall for that, first mowed and then plowed under 
Any and every plant, even the sturdiest tree, must die if kept de 
prived of leaves during the growing season; for it is in these gree! 
laboratories that the food gathered from soil and air is so change: 
