A SECOND OHIO WEED MANUAL. 



22: 



fields, horse-radish to kill out of cultivated ground, winter-cress in grass lands, 

 arid charlock and black mustard almost universal in his seed oats, even in his 

 bran used for feed, the farmer's mustard problem does not require any exaggera- 

 tion. Spraying with 2 to 3 percent solution of copper sulfate (8 to 10 lbs. to 50 

 gallons) or 15 to 20 percent solution of iron sulfate, applied as given under 

 charlock, is an efficient remedy in grain fields. 



For those sorts growing and seeding throughout the winter, like shepherd's- 

 purse and penny-cress, some winter green manuring such as rye or crimson 

 clover seems valuable, while for all, the utmost scrutiny of seeds and the 

 greatest care in plant and seed destruction are indispensable. If more objection 

 were needed it is found in the harbors afforded insects, especially plant lice, 

 by many species of the family. 



133 Field Peppergrass (A) *Lepidinm campestre (L.) R. Brown. This 

 field pest, Fig. 23, has become introduced into Ohio within the last twenty 

 years. It is now quite general along Lake Erie and 

 locally throughout the whole state. It is especially 

 fitted to take care of itself in permanent grass lands and 

 almost equally difficult to destroy in cultivated grounds. 

 Field peppergrass may be distinguished from all the 

 other similar plants by its downy appearance and 

 clasping leaves and by the spoon-shaped seed pods. 

 The flowers are white and inconspicuous. 



Seeds dark brown, rather large, oblong ovoid, taper- 

 ing at one end, 1-12 inch long, half as wide, rough and 

 dull, shown in Fig. 23 d. Becoming frequent in grass 

 and clover seeds and in hay. Like most winter annuals 

 the field peppergrass matures seed early in the season, 

 beginning in May. He who would destroy it must, 

 \\ fir/ therefore, soon be about it. Mowing will do little good, 



so that hand digging or cultivation are the methods 

 available. 

 ^{A/t^nlwejT' 134 Roadside Peppergrass (A) *Lepidinm ruderale 



L. This is also called narrow-leaved peppergrass and differs from both the 

 others in the divided leaves. It may, in time, become general, though as yet 

 only locally introduced. It is to be dealt with as the others. 



135 Peppergrass, Tonguegrass (A) Lepidium Virginicum L. This native 

 peppergrass is Smooth, with leaves tapering to the base and slightly cut on 

 the border, pods round with notch at the top. Common everywhere in fields 

 and gardens. Peppergrass is attacked by Cystopus candidus (P. ) L<§v. and by 

 Peronospora parasitica (P.) Tub, both of which also attack cultivated crucifers. 

 With shepherd's-purse it also harbors the melon louse. 



Seeds light brown, flattened, egg-shaped with a very distinct narrow bor- 

 der, 1-16 inch long, half as wide. Very frequent in clover seed and in grass 

 seeds and hay. Chiefly separable from clover seed by the use of proper care in 

 screening. This and the preceding weeds, as well as shepherd's-purse, are 

 peculiarly trying in enriched clover fields. Often the clover seems crowded 

 out or perhaps a lack of stand opens the way for the mustards, since after the 

 hay, these spring up to contaminate the seed crop. With peppergrass and the 

 others we must not only destroy th . plants but the reserve store of seeds in the 

 soil. In bad cases of mustards generally there seems no better method of deal- 

 ing with them than two or more years of successive cultivation in some well 

 tilled, preferably, a hoed crop. In such cases frequent cultivation will induce 

 germination of the seeds in the soil as well as destroy any plants that may begin 

 growth. The measures indicated are drastic but it is well to repeat that half- 

 way measures will not rid lands of mustards. 



Pig. 23. 



