A SECOND OHIO WEED MANUAL. 



ni 



Fig. 16. Sorrel. The cut 

 shows creeping- parts. 

 (After Vasey.) 



soils also occur in portions of Lucas, Henry, and Fulton counties, on the old 

 lake beaches south of Lake Erie, and elsewhere in limited areas. The drift 

 clays cover much of the northern portion of the gen- 

 eral district before outlined. On suitable lands the 

 sorrel crowds out feeble growths of other crops. 



Seeds small, brown, triangular, about 1-20 inch 

 long, almost as broad as long; when thoroughly 

 cleaned, smooth and shining, more commonly invested 

 by a dull brown, adherent covering. Very frequent 

 in clover seeds of all sorts and sometimes in other 

 seeds. Especially difficult to separate from seeds of 

 Alsike clover, samples of which have been received 

 that were found to contain thirteen percent, of sorrel 

 seed. 



In dealing with sorrel we cannot hope to eradicate 

 it, at most but to control and subdue it. It is an 

 index of soil character. How far in Ohio it may 

 indicate an acid soil I am unable to state, although 

 the two conditions are associated. In Rhode Island, 1 

 it has been found that treating the soil with lime 

 largely controls the sorrel. 



Enough has been done in Ohio, including work on the Station farm in 

 recent years, 2 to justify the conclusion that sorrel is controlled through liming, 

 fertilizing or manuring the land to smother it by the increased growth of other 

 crops, especially clover and grasses. After liming, if the fertility of the soil is 

 sufficiently increased the growth of forage plants will smother the sorrel, and 

 infested tracts or fields can be successfuly dealt with only by improving them. 

 Lime used on such lands in Ohio, corrects any acid condition and may serve 

 further useful purposes. Climate will influence results, the maximum good may 

 be looked for in seasons favorable to a good stand of clover and grasses. 



79=80 Knotweed (A) Polygonum aviculare L. and Polygonum ereclum L. 

 These weeds are very abundant in yards and by waysides where the ground has 

 been trodden. The first named species is much smaller, the leaves less than an 

 inch in length, while the second or erect knotweed, grows one to two feet high 

 and has leaves one or two inches or more long. These are attacked by a species 

 of mildew, Erysiphe communis (Wallr. ), which also attacks certain cultivated 

 plants. Ustilago ulriculosa (Nees) Tul., a smut, is also reported upon knotweed. 

 Seeds rather small, dull black, 1-8 in. long, triangular, apparently not abun- 

 dant. The knotweed may be prevented by substituting cement walks and paved 

 ways for trodden paths. 



81 Pennsylvania Smartweed (A) Polygonum Pennsylvanicum L. This 

 is a much larger growing sort than the preceding ones, being from two to four 

 feet in height and sometimes even higher. The flowers are often bright rose 

 color, with gland-tipped hairs on the stem (peduncle) below the flower cluster. 

 The heads of this smartweed are often affected with a smut Ustilago utticulosa 

 (Nees), which converts them into a mass of violet spores, thus destroying the 

 seeds. The leaves are frequently spotted by a leaf spot fungus, Scptoriapolyg- 

 onorum Desm., and also attacked by a rust, Puccinia polygoni Pers. 



Seeds rather large, lenticular (lens-shaped), 1-8 in. long by 1-12 in. wide, 



dark and shining. Frequent in clover seed since this plant ripens its seeds at 



the time of cutting clover for seed. Destroy the plants before the seeds are 



formed. The seeds follow closely the opening of the first blossoms, commonly 



maturing from August to October. 



iReport "Rhode Island Experiment Station, 1895: 193-199; also 1894. 

 2Bulletin Ohio Agricultural Experiment Station, 159; 1905. 



