A SECOND OHIO WEED MANUAL. 



329 



141 Black Mustard(A) *Btassica nigra (L.) Koch. Black mustard is a tall, 

 prickly plant, growing- in waste places and fields. It is often confused with 

 the next, from which it is distinguished chiefly by the pods. The pods of black 

 mustard are four-angled, smooth, oblong, 1-2 inch or more long, contracting 

 suddenly to a slender, conical style 1-8 inch long, while those in charlock are 

 knotted and usually contracted to a stout two-edged beak, commonly containing 

 a single seed in the beak. 



Seeds black to dark brown, commonly spherical or ellipsoidal, 1-20 inch 

 long, slightly granular-roughened. Frequent in seeds of clover and grasses, 

 also in forage, but apparently less common than the next; dealt with in the 

 same manner as charlock. 



142 ' Charlock, Wild Mustard(A) *£rassica arvensis (L.) B. S. P. This is 



the commonest and worst pest among the Bras- 

 sicas, occurring in Ohio; it is the plant mostly 

 called wild mustard. It is distinguished from 

 the others by its long knotted pod, with its 

 stout, two-edged beak, Fig. 25. It is among 

 the very worst weeds known to Ohio farmers, 

 especially in the northern half of the state, 

 where oat growing is largely practiced. It 

 comes up and grows with the oats, remaining 

 in them when threshed, or having seeds already 

 ripened when mown for hay. With other Bras- 

 sicas, charlock harbors the club-root fungus, 

 Plasmodiophora Br-assiccz Wor. 



Seeds spherical, 1-16 inch in diameter, 

 larger than those of black mustard. Very 

 common in hay, in seed oats, and in clover seed; 

 retaining their vitality for a long time when 

 buried in the soil. The measures here recom- 

 mended will apply to black and spreading 

 mustard as well. The oat crop seems to be one 

 particularly favorable to the propagation of these two mustards. Infested 

 land may be rendered comparatively free from them by surface burning and 

 continuous cultivation in hoed crops or by spraying. Where a limited quantity 

 is to be dealt with, hand pulling from the grain, is to be recommended. 



Spraying to destroy charlock and other mustards is a recent practice 

 which originated in France and became known in America in 1898. Experi- 

 ments in the United States and Canada have fully confirmed the European 

 results as to safe destruction of these weeds by the spray, 1 - 2 - 3 in crops of cereals. 

 The method is to use a solution of either copper sulfate (blue vitriol) or iron 

 sulfate (copperas) as a spray; of the copper sulfate 2, 1% or 3 percent solution, 

 (8, 10, or 12 lbs. in 50 gallons), applying 40 to 50 gallons to the acre upon the 

 fields of grain containing mustard plants in dry weather either cloudy or 

 bright and sunny. The most effective results are obtained before the mustard 

 comes into bloom. While the cereals, such as corn, oats and wheat, may show 

 slight apparent injur\- at the time, the injured plants appear to recover and 

 the mustard is killed or prevented from seeding. Showers soon after spraying 

 may require repetition of spray. 



This will kill or injure practically all plants of the mustard family if 

 applied on the foliage. To be especially recommended in wheat and oats on 

 this weed. Of the iron sulfate solution, 15 to 20 percent solution (60 to 80 lbs. 

 in 50 gallons) may be employed as the chemical is cheaper though less active. 



iBolley, H. L. Proc. Soc. Prom. kg. Science, 1899: 107-109. 



2Stone, J. L. Bulletin Cornell Experiment Station, 216: 107-110: 1904. 



sShutt, F. T. Rep. Canada Exp. Farms, 1899: 194-196. 



Charlock. 



[After Vasey.) 



