78 



Fig. 30. 

 Canada Thistle, ok Creeping Thistle. 

 Carduus arvensis, (L. & Robs). 

 This weed was originally introduced from Europe, and hence in- 

 correctly named Canada Thistle. It is a hardy perennial, with 

 numerous underground stems which bear a large number of shoots. 

 (See Fig. 29, illustrating two of these shoots). It grows to a height 

 of 1 to 3 feet. The leaves are narrow and long, deeply indented into 

 very prickly, lobed segments. The leaf has a crimped appearance, 

 and at the base slightly clasps the stem. The under suiface of the 

 leaf is woolly, the upper surface less so. It produces numerous heads 

 containing flowers, which are ^ to f inches across and of a lilac-purple 

 color. The flower is smaller than that of other thistles. The seed is 

 grey, oblong, and about 1-8 in. long, with slight longitudinal mark- 

 ings. Attached to the top is a conspicuous tuft of long hairs (the 

 pappus) (Fig. 80, a). The seed is carried long distances by the wind. 

 An average plant produces 3,500 se"'ds. 

 Time of flowering, June- August. 

 Time of seeding, July- September. 

 Dispersal — chiefly by the wind. 



Great care should be taken to prevent Canada Thistle from seeding. 

 Eradicition. The Canada Thistle can be eradicated in several 

 ways, if thorough work is done at the right time : 



1st. By careful and persistent spudding, done in such a way as 

 to prevent the plant from developing top above the ground. 

 2nd. By early after-harvest cultivation of stubble ground. 

 3rd. By the frequent introduction of hoed crops into the rotation. 

 4th. By seeding much with clover, taking one or two crops of 

 hay, plowing the clover sod shallow early after harvest, and cultivat- 

 ing frequently throughout the fall. 

 5th. By summer- fallowing. 



Assuming that all land should be plowed in the fall, we may out- 

 line briefly one or two methods of destroying thistles : 



(1) In stubble ground for spring crop. Gang-plow shallow and 

 harrow early after harvest (immediately after the crop is oft") ; and as 

 soon as seeds have had time to sprout or thistles begin to appear, 

 cultivate thoroughly with a broad-share cultivator, the points or 

 shares overlapping far enough to cut all plants ; and harrow again, to 

 pull up and expose the plants that have been cut. Repeat the culti- 

 vation at intervals throughout the fall, and plow in the usual way, 

 or, if possible, rib up with a double mould-board plow just before the 

 frost. This systematic cultivation from harvest till winter, will check 

 thistles and other weeds very much, and when followed by a hoed 

 crop (mangels, corn, turnips, carrots, beans or rape), properly cultivat- 

 ed, it will not only clean the land, but put it into good shape for a 

 crop of grain (oats, barley, etc.,) the next spring, which crop should be 

 seeded with red clover. 



