Cocklebiir. 5 



fact that the burs of cocklebur contain two seeds, while those of the 

 burdock contam more than two. Also burdock burs do not possess 

 the pair of hooked beaks usually found on the cocklebur. 



DAMAGE. 



Aside from its general unsightliness on the farm and the severe 

 damage done to crops such as corn, cockleburs also occasionally kill 

 svrme and young cattle. Although fatal results are generally at- 

 tributed to poisoning, there is little evidence to substantiate this 

 theory. The harmful effects are largely due to the mechanical action 

 of the spiny burs, which are injurious in several ways. These burs 

 may (1) irritate the walls of the stomach, causing inflammation and 

 sometimes death; (2) lodge in the throat and thus choke the animal; 

 or (3) clog the intestinal tract, frequently with fatal results. 



Overeating the young and succulent plants may cause bloating, 

 which is similar in nature to bloating caused by succulent clovei:, 

 corn, etc. The hairy leaves are also said to cause severe itching. 



Serious loss is occasioned by the burs becoming tangled in the wool 

 of sheep and in the hair of Angora goats. The presence of the burs 

 causes the heavy dockage of wool, a fact which makes cocklebur one 

 of the greatest enemies of woolgrowers. . 



USES. 



Lately, a method of extracting oil from cocklebur seed has been 

 developed, producing a valuable oil useful for paints and varnishes 

 and as human food. The resultmg cake is utilized for feed and fer- 

 tilizer in the same manner as cottonseed oil cake. The burs are also 

 used in the manufactiu-e of advertising novelties, a practice which 

 should be discouraged, since it tends to spread the pest. 



ERADICATION. 



Methods of eradicating cockleburs should aim to prevent seed pro- 

 duction and to destroy the seeds alread}" contained in the soil. With 

 any method of eradication the fact should be remembered that one of 

 the two seeds contained in the bur normally sprouts during the first 

 season, while the other germinates the following season. During wet 

 seasons the two seeds may germinate together, suggesting that such 

 a time is particularly favorable for eradicating the plant. 



Since cockleburs are annuals, they must eventually disappear if the 

 production of seed is not permitted, although the delayed germination 

 of one seed will continue the weed for an additional year, and bmied 

 burs may contain seeds viable for several years. 



If cocklebur-infested land is to be planted in corn, it should be 

 plowed early in the spring and then harrowed at least t^^ice before 

 planting, in order to induce the germination of cocklebur seeds and 

 to destroy any cocklebur seedluigs which ma}^ have developed. 



