460 Identification and Eradication of Weeds, [sept., 



THE IDENTIFICATION AND ERADICATION OF 

 SOME COMMON WEEDS. 

 II * 



Harold C. Long, B.Sc. (Edin.). 



With Drawings from Nature by Bertha Reid. 



In the present article three weeds of the order Cruciferae will 

 be dealt with ; all of them are annuals, and two of them (Char- 

 lock and Runch) are among the worst weed pests of the 

 farm. 



Charlock. 



Charlock (Sinapis arvensis, L., or Brassica Sinapis, Visiani, 

 or Brassica Sinapistrum, Boiss.) is commonly known to farmers 

 under such names as Kedlock, Skallock, Karlock, Yellows, 

 Yellow Weed, or Wild Mustard. Taking Great Britain as a 

 whole, it is probably the most troublesome of all annual weeds 

 of arable land, and in twenty-nine returns from practical 

 agriculturists throughout England, Scotland, and Wales, as 

 to the six worst weeds of arable land, Charlock and Runch, 

 taken together, occupied a position which was second only 

 to various species of couch or twitch. So serious is the damage 

 that this weed may cause that, in 1900, the Board of Agricul- 

 ture issued a leaflet dealing with its destruction, f From this 

 leaflet the following quotation may be given : — 



"In corn crops its growth is often so rank as seriously to 

 reduce the yield of grain. In root and bean crops the weed 

 can be more easily dealt with ; but here also it often proves 

 very injurious, and especially so when the conditions of the 

 weather, or scarcity of labour, prevent its timely eradication. 

 As a rule, it is not conspicuous amongst rotation grasses or 

 clover, and it is practically absent from permanent grass land. 



"The injury induced by charlock is partly direct and partly 

 indirect. It competes" with crops for light and air; that is to 

 say, it overgrows more or less completely, and smothers, other 

 plants with which it is associated. It also robs crops of a part 

 of their nutriment, and prevents their deriving full benefit 

 from the moisture of the soil. But in other ways — though 

 more indirectly — this weed may be the cause of much loss. 

 The turnip "fly," for instance, would be unable to exist in 



* The first article appeared in the Journal for July, 1911, p. 2S8, and dealt with 

 Corn Buttercup, Common Fumitory and Spurrey. 

 t Leaflet No. 63 {Destruction of Charlock). 



