Brenchley 1920 Weeds of the Farmland.Pdf
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IflHiDS )F RM LAND :HI ,' /\ v' WEEDS OF FARM LAND Fio. 31. RED BARTSIA (Bartsia odotttites), parasitic on Wheat. WEEDS OF FARM LAND BY WINIFRED E. BRENCHLEY, D.Sc, F.L.S. FELLOW OF UNIVERSITY COLLEGF., LONDON BOTANIST, ROTHAMSTED EXPERIMENTAL STATION WITH ILLUSTRATIONS LONGMANS, GREEN AND CO. 39 PATERNOSTER ROW, LONDON FOURTH AVENUE & 30TH STREET, NEW YORK BOMBAY, CALCUTTA, AND MADRAS 1920 PREFACE. EVERYONE who cultivates the soil, whether on the farm or garden, is perforce interested in weeds, for their absence or presence amongst the crops has much to do in' determining the relative success or failure of the undertaking. A very great deal has been written on the subject, but the information is widely scattered throughout the literature of agriculture and botany. In this country, at least, very few efforts have hitherto been made to gather up and correlate this varied know- ledge, thus rendering it accessible to those most inter- ested. Furthermore, it is only of recent years that definite attempts have been made to work out the quanti- tative and qualitative relations between weeds, the soils on which they grow and the crops with which they are associated. In this respect the conclusions so far drawn can only be regarded as tentative, subject to modification and revision as more data become available. It has seemed justifiable, therefore, to attempt to set forth the present position of affairs, in order that future attacks on the weed problem may be more co-ordinated, and that valuable time and labour may be utilised to the best advantage. The original investigations embodied in the follow- ing pages owe much to the cordial assistance afforded by the many landowners and farmers whose land has been utilised for the purpose. It is impossible to record each individually, but my special thanks are due to Pro- fessor T. B. Wood, Mr. Spencer Pickering, Mr. E. S. Beaven, Mr. E. E. Stokes, and Mr. J. H. Burton, all vi PREFACE of whom facilitated the work by giving me introductions throughout the districts with which they were best ac- quainted. Miss M. B. Lee and Miss V. G. Jackson have rendered valuable assistance with the proof sheets, and, above all, I am specially indebted to Dr. E. J. Russell for his constant advice and criticism throughout the pre- paration of the book. W. E. B. ROTHAMSTED, June, 1920. CONTENTS. PAGE CHAPTER I. INTRODUCTION i CHAPTER II. DISTRIBUTION OF WEEDS - - - 10 CHAPTER III. PREVENTION AND ERADICATION OF WEEDS - 43 CHAPTER IV. VITALITY OF WEED SEEDS 72 CHAPTER V. HABITS OF WEEDS ------- 84 CHAPTER VI. PARASITIC WEEDS " -92 CHAPTER VII. POISONOUS AND INJURIOUS WEEDS 103 CHAPTER VIII. ARABLE WEEDS. ASSOCIATION WITH SOILS. I. GENERAL - - - 117 CHAPTER IX. ARABLE WEEDS. ASSOCIATION WITH SOILS. II. SPECIAL - - - 121 vii viii CONTENTS PAGE CHAPTER X. ARABLE WEEDS. ASSOCIATION WITH CROPS 159 CHAPTER XI. GRASSLAND WEEDS 175 CHAPTER XII. USES OF WEEDS 187 CHAPTER XIII. POPULAR AND LOCAL NAMES OF WEEDS .... 206 LIST OF ILLUSTRATIONS. FIG. - 31. RBD BARTSIA (Bartsia odontites), parasitic on Wheat Frontispiece PAGE 1. BLACK BENT (Alopecurus agrestis) - - - - - - - 8 2. FAT HEN (Chenopodium album) 13 3. ORACHE (Atriplex patula) 14 - - - - 4. SPIKELET OF FRUITS OF WILD OAT (Avena fatua) 16 KNOTGRASS 5. (Polygonum aviculare) -------19 6. FRUIT OF NARROW-LEAVED VETCH (Vicia angustifolia) 21 - 7. A. WINGED SEED OF YELLOW RATTLE (Rhinanthus crista-galli) 22 B. WINGED SEED OF SPURRY (Spergula arvensis) 22 C. WINGED FRUIT OF HOGWEED (Heracleum sphondylium) - - 22 D. WINGED FRUIT OF BROAD-LEAVED DOCK (Rumex obtusifolius) - 22 8. PLUMED FRUITS A. Coltsfoot (Tussilago farfara) ------- 24 B. Creeping Thistle (Cirsium arvense) 24 C. Hawkbit (Leontodon hispidus) 24. D. Dandelion (Taraxacum vulgar-e) ---.-. 24 E. Groundsel (Senecio vulgaris) - - - - 24 F. Goatsbeard (Tragapogon pratensis) 24 - - 9. PLUMED SEEDS OF WILLOW-HERB (Epilobium sp.) 25 10. HOOKED FRUITS A. Agrimony (Agrimonia eupatoria) 26 B. Wild Carrot (Daucus carota) 26 C. Goosegrass (Galium aparine) -------26 D. Corn Buttercup (Ranunculus arvensis) 26 11. CORN BUTTERCUP (Ranunculus arvensis) 27 12. SHEPHERD'S NEEDLE (Scandix pecttn) 28 13. BINDWEED (Convolvulus arvensis) 29 14. CREEPING THISTLE (Cirsium arvense) 30 15. HORSETAIL (Equisetum arvense) 31 16. COUCH-GRASS (Agropyron repens) 32 17. CORN SOWTHISTLE (Sonchus arvensis) 33 18. COLTSFOOT (Tussilago farfara) 34 19. WOODWAX (Genista tinctoria) 35 20. SORREL (Rumex acetosa) ---....--36 x LIST OF ILLUSTRATIONS FIG. PAGE 21. BULBOUS BUTTERCUP (Ranunculus bulbosus) - - - - 37 - 22. MOUSE-EAR HAWKWBED (Hitracium pilose I la) 39 23. CREEPING BUTTERCUP (Ranunculus rtpens) 40 24. ONION COUCH (Arrhenatherum avenaceum) ----- 41 25. SEEDLING OF CREEPING THISTLE (Cirsium arvtnse) - - 82 26. DODDER (Cuscuta trifolii), parasitic on Clover 93 27. BROOMRAPE (Orobanche minor), parasitic on Sainfoin. Right. "\ Sainfoin plant not attacked. Left. Sainfoin plant attacked by ! face broomrape, showing the harmful effect on growth - p. 96 - - ' 28. BROOMRAPE (Orobanche minor), parasitic on Lucerne - - 29. YELLOW RATTLE (Rhinanthus major), parasitic on Oats 100 30. SECTION ACROSS BARLEY ROOT PENETRATED BY SUCKER OF YELLOW RATTLE (Rhinanthus major) 101 32. AUTUMN CROCUS (Colchicum auiumnale) 109 33. PURGING FLAX (Linum catharticum) 109 34. CROW GARLIC (Allium vineale) - 113 35. RAMSONS (Allium ursinum) 113 36. SPURRY (Spergula arvensis) - - 142 37. ANNUAL KNAWEL (Scleranthus annuus) 143 38. SHEEP'S SORREL (Rumex acetosella) 144 39. CORN MARIGOLD ..... 1^5 (Chrysanthemum segetum) 40. QUAKER-GRASS (Briza media) 180 41. PLANTS COMMON IN TRODDEN PLACES A. Greater Plantain (Plantago major) - 184 B. Silverweed (Potentilla anserina) ...... 184 C. Rough-stalked Meadow-grass (Poo trivialis) - - - 184 CHAPTER I. INTRODUCTION. IT is impossible to begin to work land under any system of farming without immediately being confronted with the prob- lem of weeds. Weeds are the inevitable corollaries of crops, and much of the science of farming consists in the skilful use of methods by which the weeds are kept in subjection. In the ordinary course of events all vacant land tends to clothe itself with vegetation, and soil that is artificially laid bare during farming operations offers a situation that is most favourable to the ingress of a native plant population. The farmer's crops are more or less alien to the areas on which they are grown, and consequently would havebut little chance against the natural colonists if it were not for the assistance rendered by husbandry methods. Weeds have thus a very great practical and economic importance, and a right know- ledge of their habits and distribution is a valuable asset. Every farmer has a general knowledge of the worst weeds that occur on his land, and usually knows how to deal with them, but comparatively few have that special know- ledge of the individual weeds which is necessary if the more up-to-date and less-known methods of prevention and eradication are to be successfully applied. The farmers of this country are in possession of a vast amount of weed lore, and much information is scattered up and down agri- cultural literature, but hitherto very little attempt has been made to bring together the facts and so to correlate them that they form a complete whole, instead of being merely disjointed scraps of knowledge of local interest and value only. The field of inquiry is so large and the difficulty of obtaining the necessary mass of information so great that it is impossible to present anything like a perfect picture of the weed problem, but the aim of the present book is to sketch a preliminary outline from the facts that are already available, in the hope that at some future date it may be possible, 2 WEEDS OK KAKM LAND in the light of fuller knowledge, to fill in and to correct inaccuracies in the details. Before beginning to discuss the problem in its general bearings it is essential that one should have a clear idea of the meaning of the term weed. The word is used very loosely, and under some circumstances is made to apply to almost any plant in any situation. For our purpose, however, it is essential to narrow the meaning down so that it bears an exact significance. British farm-land is worked on two distinct systems, according as the land is under the plough or laid down to grass. Generally both systems are combined, and a typical English farm consists of grass and arable land in pro- portions which vary according to the locality and to the in- dividual needs of the farmer. The cropping under the two systems is radically different, as on the arable land the crop plants are fugitive and occupy the soil for a comparatively short season before they make way bodily for another crop, whereas on grass-land the plants are permanent, and retain their positions year after year, never being replaced by others unless the sward is ploughed up and a new crop sown. This difference in chopping has so great an influence upon the vegetation that covers the ground that it is necessary to have different definitions for the weeds of arable and grass-lands. On ploughed land a farmer desires only the crop from the seed he intends to sow, and anything else that appears on the field may be regarded as a weed. Consequently, a weed of " arable land may be defined as any plant other than the crop sown ". On grass-land, on the contrary, a varied herbage is desirable, provided that the constituents of the herbage are of good nutritive value. Old pasture is usually clothed with a mixture of grasses, clover, and miscellaneous plants, which vary in proportion and in their value as food for stock whether as green fodder or as hay. Some of the grasses, such as Yorkshire fog, in some districts are almost useless or are positively harmful, whereas some of the miscellaneous plants such as rib-grass, are of high feeding value and in moderation are welcomed in the herbage.