The Hope pioneer., 1922-10-12
(By o. II. Stevens, Botanist, North
Dakota Agricultural College.)

(By o. II. Stevens, Botanist, North
Dakota Agricultural College.)
The history of agriculture shows us
that weeds have always been an i'm
portant factor in the growth Of crops.
Present conditions indicate that such
lack Of diversified farming and of in
tensive cultivation has contributed to
the prevalence of weeds.
How Weeds Are Harmful.
The plants most commonly referred
to as weeds are those which interfere
with cultivated crops. For the most
part, such weeds have been introduced
from the older countries where they
have been weeds since time immemOr
ial. They affect crops by: (D using
moisture and food materials needed by
by the crop plants; (2) crowding and
shading, preventing growth Of seed
lings or reducing the light needed by
the crop plants; (3) harborng insect
and disease pests. supplying additional
food for their growth and spread; (4)
increasing labor by adding to the bulk
Of straw and grain, and by the clean
ing necessary for seed.
Weeds also detract from the value
of the land. A few contain virulent
poisons affecting man or animals, while
others are irritating or annoying on
account of prickly leaves or seeds,
pollen producing hay fever, and the
pDcs. oQ 1,,lt Il
fields, some are troublesome in pas
lures, some in lawns, and others are
coarse unsightly plants of roadsides,
and parks.
Habits Of Growth.
A general knowledge of habits of
growth is necessary for effective con-
troll There are two chief groups.
Annals reproduce by seeds only. The
seed germinates, the plant flowers,
ripens seed and dies within the year
The roots or rootstocks of perennials
live many years, producing each year
new stems (hardy any weeds have
perennial stems as do the trees and
shrubs). Many of them produce new
plants by the growing Of the roots OF
rootstocks. They also reproduce by
4 seeds.
A few weeds are biennial, Towering
the second year and dying. Winter
ANNALS are similar to biennials, but
germniate late in summer and flower
quite early the next season. Biennials
are of comparatively small Importance
but winter ANIMALS are very important
Most of the mustards may act in thi:
way.
Perennials are Of different types
Some perennials like dock and dande
lion, have thick roots with larg.
crowns which produce new leaves yea
after year, but do not divide to form
rev plants to any extent. Others lilz,
quackgrass and sow thistle develop
long horizontal shoots which extent
many feet in a single season causing
rapid increase in the ground occupied
Such growths are either rootstock
or true roots. In case of quack gras
they are rootstocks (rhizomes, under
ground stems) which show their sten
nature by being composed Of jointe
sections. Buds are formed at tn
joints, and scales, reduced form 0
leaves, are usually present. In cas-
of SOW thistle such growths are tru
roots, having an irregular non-jointe
body with buds at any place. There /
much confusion Of these terms in wee
.. books and bulletins but for practica
purposes it makes little difference. Bot
the rootstocks and running roots serv
the same purpose They cause dis
tribution Of the plant by their natura
growth, and establish new plants whe
pieces are carried to different parts Q
| the field by cultivating machinery.
Weeds of similar habits are not a
alike. Important as are the genera
habits of reproduction, the nature c
; the particular kind Of weed may b
even more SO. Some are more tens
" cious of life, grow more vigOrousl.
;, and tend to re-estahlish themselve
! readily when partially uprooted. We
! tern wheat grass has the same mnnne
of growth as quackgruss, but it is nj
. SO persistent.
Weeds are reproduced and scattere
by seeds and by other parts of til
plant-chiefly by roots and rootstocl
us lust described Seeds are the con
II mon method, and they are scattered L
) four general agents: (D water, &
x wind, CD animals and (D man. III
Il water of drainage bitches and that I