^SECTfClDES, FUNGiCIDES AND WEEDKILLERS E.BOURCART. D.Sc 3Il]e §. ^- ?itU lltbraro ^ortl] Carolina <^tatc Colkge Cx.7 (5 A Date Due F8&2^ Wari2'32 \M I- My '401 9De'40G /3 00^.1 tMay^i DECl 9^994^ SB 9 51 .G7 INSECTICIDES, FUNGICIDES, AND WEEDKILLERS INSECTICIDES, FUNGICIDES AND WEEDKILLERS A PRACTICAL MANUAL ON THE DISEASES OF PLANTS AND THEIR REMEDIES, FOR THE USE OF MANUFACTURING CHEMISTS, AGRICULTURISTS, ARBORICULTURISTS AND HORTICULTURISTS E. BOURCART, D.Sc. TRANSLATED FROM THE FRENCH, REVISED AND ADAPTED TO BRITISH STANDARDS AND PRACTICE BY DONALD GRANT WITH EIGHTY-THREE TABLES AND TWELVE ILLUSTRATIONS LONDON SCOTT, GREENWOOD & SON 8 BROADWAY, LUDGATE, E.G. 1913 [The sole rights of translation into English remain with Scott, Greenwood 6f Son] NEW YORK D. VAN NOSTRAND COMPANY EIGHT WARREN STREET PRINTED IN GREAT BRITAIN eVTHE ASEflOEEN UNIVERSITY fSaW Lt».. AI&Re£EM. N, a. state uonea^ AUTHOR'S PREFACE. Evert year the diseases of plants become more numerous, their economic importance increases, and the number of those in- terested becomes greater; more numerous by the means of communication estabhshed between different countries, and by more frequent commercial intercourse ; more important and more dangerous because they prevent the heavy yields of dif- ferent crops which should be obtained from the high farming with which the prosperity of our farmers is so closely associated ; the number of those interested increases because gardening for pleasure, ornamental horticulture, extends daily more and more amongst all classes of society. It therefore becomes indispens- able that the farmer, the gardener, and the amateur flower grower should possess a treatise in which they can easily find the cause of the diseases which dishearten them, and at the same time an efficient remedy capable of circumscribing them and of preventing their return. So as to render this treatise complete in itself it was deemed necessary to pass in review the numerous experiments made up to now to suppress and prevent plant diseases. The author has striven from the aggregate of the results reported to frame certain scientific rules which appear to deter- mine the success of certain classical methods and to explain certain notorious failures, rules which may serve as a useful guide to future experiment and aid in the discovery of new pro- ducts of greater efficiency than those now at our disposal. The preventive and combative treatment of the diseases of plants requires a profound knowledge of the parasite as well as the product used as a remedy. Success depends on the judicious choice of the remedy utilized and the manner in which it is applied. The plan of this book is therefore conceived in such a way VI AUTHOR S PEEFACE. as to enable the less initiated to find with the greatest ease the information which they require when they desire to treat a diseased plant. The author has annexed to the book a glossary of the prin- cipal diseases of plants and the parasites which occasion them. The descriptions given therein afford the requisite information as to the different states of evolution of the parasites whilst they are vulnerable, because such knowledge is indispensable to form a decision as regards the periods at which it may be desirable to apply the effective remedies preventively and curatively. In the index, after the name of the cultivated plant, there- follows a list of the diseases from which it may suffer. It suf- fices to turn to the glossary when the reader does not know the cause of any disease, and the name of the disease being identi- fied to find in the index the page where its treatment is de- scribed. The author's object will be attained if this book serves as a guide to those who have sought most often in vain a means of restoring health to plants which form the object of their care or- the joy of their leisure. E. BOURCAKT. Paris, 1911. TRANSLATOE'S PREFACE. Dr. Bourcart has done his work so well that the translator- would fail in his duty if he did not insist on one point on which the author is silent, viz., the enormous value of the great number of tried recipes — recipes which have passed the ordeal of a capable and wise censorship — embodied in this treatise tO' every one interested, whether farmer, gardener, forester or last but possibly not least the manufacturing chemist. But the reader will soon discover for himself that this is not the only featm-e which renders the book unique of its kind. DONALD GRANT. London, November, 1912. TABLE OF CONTENTS. INTRODUCTION. PAGE Relative and absolute diseases 1 Etiology 1 Physical causes of disease - - 1 Chemical causes of disease 2 Parasitic causes of disease ---------- 2 Symbiosis -------------3 Antagonistic symbiosis .-..-.-.-. 3.4 Mutualistic symbiosis ----------- 3-4 Therapeutics 6 Surgical treatment 6 Vegetable surgery 6 Methods of destroying parasites by the naked hand 7 Picking and catching - - - - 7 Traps and baits ------------7 Chemical treatment ..---------8 Curative treatment ..-_.--.---. 8 Anti-crj^ptogamic substances or fungicides 8 Examination of curative agents -------- ^ 8 Action of chemical products on parasites ------- 8 Action of chemical products on plants -------- 9 Liquid products 9 Gaseous products 9 Indispensable properties of the chemical agents 10 Methods of using chemical products in treating the diseases of plants - - 11 Underground treatment 11' Aerial or above-ground treatment by gases 11 Clochage ------------- 12 Scalding or treatment by boiling water 12 Use of chemical agents in the form of powder 12 Use of chemical agents in the liquid form ------- 12 External treatment .-.-------- 13 Internal treatment ..--.------ 14 Prophylaxy ------------- 15 Therapeutic prophylaxy ---------- 15 Preventive surgical treatments --------- 15 Preventive treatment by means of chemical agents 16 Preventive summer treatment --------- 17 Hygienic prophylaxy ---------- - 17 Growth stimulants 18 Nutrition 18 Exhaustion of the soil ----------- 19 Choice of species 20 Meteorological influences - 20 United efforts to exterminate injurious insects, fungi, and weeds - - - 21-22 Vm TABLE OF CONTENTS. CHAPTER I. Wateu, Hot and Cold — Submersion of Field, Forest, and Vineyard — Scalding — Hydrogen Peroxide. PAGE 1. Water, H^O 23-24 Use 23 Cold Water. Submersion of fields and meadows 24 Submersion of forests 24 Anti-phylloxeric submersion 25 Submersion in actual practice .-.--.-. 26 A. Winter submersion --------- 27 B. Submersion during the active period of the vine - - . - 27-30 Spraying 30 Hot Water. Resistance of insects to heat 31 Resistance of seed to heat 31 Resistance of fungi to heat - -------- 31 Action of dry and moist heat on seeds and spores ----- 31 Uko of hot water --------... 32 Hot-water steeping of seed-corn to kill disease spores - - - - 32-36 Immersion of seed against insects, phylloxera ----- 36 Hot-water spraying against cochylis, etc. 37-40 2. Hydrogen Peroxide, HoCj 40 Preparation ------------ 40 Properties 40 Use . - - - 40 CHAPTER II. Hydrogen Sdlphidk — Sulphur. 3. Hydrogen Sulphide (sulphuretted hydrogen, HjS) 41-2 Preparation 41 Properties -----....... 41 Action on plants ----------- 41 Action on insects - - - 41 Use - 42 4. Sulphur, S. Preparation - - 42-4 Use 44 How does sulphur act ?--.-----.- 44 How should sulphur be applied ? 46 The regulator sulphur bellows (illustrated) 47 The torpedo sulphur distributor 47 Use against bacteria (potato scab, etc.) .------- 47 Use against fungi (rusts and mildews) 48-50 Drawbacks to sulphuring --.----.. 50 Use of sulphur against insects 52 Use against acari - - - - .53 CHAPTER III. Carbon Bisulphide, CS.j. 5. Cauuon Disulphide, CS.j 54 Preparation 54 Properties ----.--..--- 54 Action of carbon disulphide on plants 55 TABLE OF CONTENTS. IX PAGE ActioQ of carbon dieulphide on insects 56 Action on fungi - - - 57 Influence on fertility of soil 57.9 Use - - - - - 59-77 History 59 Vaselinated sulphide ---------- 61-2 Instruments for applying carbon disulphide ------ 62 Pal-gastine 62 Avant-pal - - 62 Pal-excelsior ..--.-.---- 62-3 Sulphurators 63 Disinfection in closed spaces 63 Destruction of aerial parasites 64 Use against cryptogamic diseases 64 Use against eel-worms ---------- 65 Use against insects ....------ 65-71 Underground disinfection --------- 71 Extermination treatment -..------ 71 Cropping treatment 72 Use of pure carbon disulphide - - - - - ' - - - 72 Use of carbon disulphide dissolved in water 74 Insecticide irrigations 75 CHAPTER IV. SxTLPHUKOUs Acid — Sulphuric Acid (Oil of Vitriol) — Chlorine — Hydrochloric Acid — Nitric Acid. 6.. Sulphurous Acid, SOj 78 Properties ------------ 78 Action on plants ----------- 78-80 Action on fungi ------ -----80 Action on insects ----------- 80 Use in diseases treated by SO2 in the open air 80 Use in closed spaces - - 80 7. Sulphuric Acid, H2SO4. Natural occurrence 88 Properties 83 Action on plants 83 Action on fungi 83-8 Use as pickle for seed-corn - 83-6 Use as weedkiller ----------- 85 Use against insects and eel-worms - 88 Use against wasps - ■ - - - - - - - - - - 88 8. Chlorine, CU. Preparation ------------ 88 Use against dry rot .-.-.----- 88 9. Hydrochloric Acid, HCl. Preparation ------------ 88 Use - - - - 88 Action of chlorine and hydrochloric acid on plants 89 10. Nitric Acid, HNO3. Preparation ------------90 Properties 90 Action on plants - 90 Use 90 Use against fungi 90 Use against insects - - 90-1 TABLE OF CONTENTS. CHAPTER V. Phosphorus — Phosphobetted Hydrogen — Abseniuretted Hydrogen — Arsenious Sulphide — Arsenious Acid — White Arsenic — Arsenic Acid — Boric Acid. PAGE 11. Phosphorus, P. 92 Preparation 92 Properties 92 Use 92 12. Phospiioketted Hydrogen, PH^. Preparation 93 Properties ----........ 93 Use - 93 13. Abseniuretted Hydrogen, AsHj. Preparation 9,S Properties - - . 93 Use 93 14. Arsenious Sulphide, AsjSg. Use 94 15. Arsenious Acid, ASjOj. Manufacture ------..-.-. 94 Properties 94 Use - - - 94 Use against insects 95 Use against rodents - -' 96 16. Arsenic Acid, AsoOj. Preparation - - 97 Properties - - - - 97 Use 97 Use as pickle for seed-corn 97 17. Boric Acid, BoOg. Preparation - - 97 Properties - - - 97 Use - - - - 97 CHAPTER VI. Ammonia — Ammonium Sulphide — Ammonium Sulphocyanide — Ammonium Suli'hate — Ammonium Carbonate — Sodium Hyposulphite — Sodium Sulphate — St)Dn-M Chloride (Common Salt) — Sodium Nitrate (Chili Saltpetre) — Aksenite or Soda — Borax — Sodium Carbonate. 18. Ammonia, NH., 98 Preparation 98 Properties -.--......-. 98 Use 98.9 19. Ammonium Sulphide (NH4)2S. Preparation - - - " 99 Properties 99 Use - - - 99-100 20. Ammonium Sulphocyanide, NH4CNS. Preparation 100 Properties 100 Use 100 21. Ammonium Sulphate (NHj)oS04. Manufacture - - - " - - - - 100 Properties ............ 100 Use 100-1 22. Ammonium Carbonate (NH4)2C03. Manufacture 101 Properties 101 Use - , ... ...... 101 TABLE OF CONTENTS. XI PAGE '23. Sodium Hyposulphite, NaaSgO.SHoO. Preparation - - - - 102 Troperties - - - 102 Action on plants 102 Action on fungi 102 Crouzel's anti-cryptogamic - 103 24. Sodium Sulphate, Na2S04. Occurrence ..-...------ 103 Prepaiation ------------ 103 Properties 103 Use - - - - - 103 Use as pickle for seed-corn -.------- 103 25. Sodium Chloride (common salt), NaCl. Occurrence ...--------- 104 Properties 104 Role as manure 105 Use as weedkiller - 106 Use to destroy moss 106 Use against potato diseases 106 Use against insects ....------ 106 Use to preserve green fodder during winter ------ 107 26. NiTEATE OF Soda, NaNOj. Occurrence . . - - - 107 Properties - - - - . 108 Action on plants ...-------- 108 Action on fungi - 108 Action on insects ------ ....- 108 Use as weedkiller .---------- 108 27. Arsenite of Soda, NaAs»0,. Use - - - -' " 10& Use as pickle for seed-corn - 10& Use in preparations to kill locusts . . - - - . - 10& 28. Borax, Na.BjOv. Occurrence -.---------- 109 Preparation ------------ 109 Properties ..---------- 109 Use - - - 110 29. Carbonate of Soda, NaoCOj. Preparation -.---------- 110 Properties ..--.------- 110 Action on plants - - - - ------- 110 Action on fungi 110 Action on insects - HO Use 110-11 CHAPTER Vn. Potassium Hydroxide (Caustic Potash) — Potassium Sulphides (Liver of Sulphur) — Potassium Chloride (Muriate of Potash) — Potassium Nitrate — Potassium Sulphocarbonate — Potassium Xanthogenate — Potassium Cyanide (Prussic Acid) — Potassium Sulphocyanide. 30. Caustic Potash, KHO - 112 Properties 112 Use 112 31. Potassium Sulphides, KoS to KjSj. Liver of sulphur 113 Properties - - ----- - . - - 113 Use - - - 113 Use against bacteria 114 Use against fungi - 114 Xll TABLE OF CONTENTS, PAGE Steepinij; of seed-corn -..-.-.... 114 Sprajin^' -wMh dilute solutionB 115-6 Use against insects - - 116-7 32. Potassium CnLORiDE (muriate of potash), KCl ; Potassium Sulphate, K0SO4. Natural occurrence - - - - - - - - - - 117 Properties 118 Action on plants 118 Use - 118-120 Use as weedkiller 118 Use as pickle for seed-corn 119 Use agaiust dodder 119 Use against meadow horsetail 119 Use against insects 120 33. Nitrate of Potash, KNO3. Occurrence 120 Preparation 120 Properties ---......... 120 Action on plants -----.-..-- 120 Action on fungi 120 Action on spores 121 Use against insects - - * - - - - - - - - 121 34. Cakbonate of Potash, K2CO3. Preparation 121 Properties 121 Action on plants 121 Action on fungi 122 Action on insects ----------- 122 35. Potassium Sulphocarbonate, K2CS3H2O. Preparation 123 Properties 123 Action on plants - - 123 Action on fungi ----------- 124 Action on insects 124 Use 126-9 Disinfection of vines and graft-bearers by - 129 36. Xanthogenate of Potassium, CjHbOCSSK. Definition 129 Preparation - 129 Properties 129 Use 129 37. Potassium Cyanide, KCN. Preparation ------ ------ 130 Properties 130 Rapid toxic action 131 Action on plants 131 Trials on healthy vines 131 Trials as a weedkiller - - 132 Action on fungi ----------- 132 Action on insects - - 132 Use 133 Cyaniding of trees 133 Use against insects - - - - - - - - - -134 Fumigating vines ----.-.---- 134 Disinfection of vines 136 38. Potassium Sulphocyanide, KCNS. Preparation 136 Properties .---.-..---- 136 Action on plants 136 Trials as a weedkiller I3(j Trials on healthy vines in pot 137 Action on fungi -.-.--.--.- 137 Action on insects 137 TABLE OF CONTENTS. CHAPTEE VIII. Babium Chlokide — Baeium Sulphate — Babium Carbonate — Barium Sulphocar- BONATE — Calcium Oxide (Quicklime) — Calcium Sulphide — Calcium Chloride — Calcium Chloro-hypochlorite (Bleaching Powder) — Calcium Sulphate — (Gypsum Plaster of Paris) — Calcium Sulphite — Calcium Carbide — Calcium Phosphide — Calcium Arsenite. PAGE 39. Barium Chloride, BaClg 138 Preparation - 138 Properties 138 Action of plants 138 Action of insects 138 Use against plant diseases 138 Use against insects 138-9 Use against rodents 139 40. Barium Sulphate, BaS04. Use 139 41. Barium Carbonate, BaCOg. Preparation 139 Properties 139 Use against rodents - 139 42. Barium Sulphocarbonate, BaCSg. Preparation ------------ 139 Properties 139 Use 139 43. Calcium Oxide (Quicklime), CaO. Occurrence 139 Preparation - - - 140 Properties . - - 140 Use as manure - - 140 Action on plants 141 Use against fungi 142 Use against gummosis of stone fruit trees 143 Use against nematodes - - - - 143 Use against insects ......--.- 144 Liming of trees - - - - - - - - - - - 145 Use against mammals ---------- 148 Use against late frosts ---------- 148 44. Calcium Monosulphide. Preparation 148 Properties 148 Action on plants 149 Action on fungi 149 Action on insects 149 Uses 149 Use as weedkiller - - • - 150 Use against fungi ----------- 150 Use against insects 151 45. Calcium Chloride, CaClj. Preparation 152 Properties - 153 Use 153 Use as weedkiller 153 46. Chloride of Lime (bleaching powder), CaCljO. Preparation 153 Properties . . . - 153 Use 153 Use as weedkiller ----------- 153 Use against insects ....-----. 153-4 47. Sulphate of Lime (gypsum), CaSO^. Occurrence ..----- 154 XIV TABLE OP CONTENTS, PAGE Properties lo4 Action on insects .... 154 Use as a manure 154-6 Use against late frosts 156 Use against fnngi 156 Use against insects .......... 156-7 Use against snails and slugs 157 Use against rodents 157 47a. Stlphite of Lime, CaS032H20. Preparation 157 (Pi-sulphite of lime 157) Use 157 Use against vine rot 157 Use in dairies 157 Use in breweries 157 48. Calcium Carbide, CaC^. Preparation 157 Properties 157 Use 157 49. Calcium Phosphide, CagP.j. Preparation .--.-..-.... 157 Use 158 50. Arsenite of Lime, Ca.iASaOg. Preparation 158 Properties ............ 158 Use 158 CHAPTEE IX. Maonesium Chloride — Magnesium Sulphate (Epsom Salts) — Magnesium Bisul- phite— Magnesium Silicate (Talc Soapstone) — Alum — Aluminium Silicate (China Clay) — Zinc Sulphide — Zinc Chloride — Zinc Sulphate — Zinc Borate — Zinc Silicate — Zinc Ferrocyanide — Zinc Sulphocarbolate — Cadmium Sulphate. 51. Magnesium Chloride, MgClg 159 Occurrence - - 159 Preparation -----....... 159 Properties 159 Action on plants 159 Trials as a weedkiller 160-1 Trials as a pickle for seed-corn ........ 16I Use as weedkiller -..----..-. 161 Use against charlock in corn crops 161 Use in pine nurseries against yellow leaf of pine 161 52. Magnesium Sulphate (Epsom salts), MgS047H20. Preparation ------- 161 Properties - 161 Use 161 Use to disinfect beet seed 161-2 53. Magnesium Bisulphite, MgH2(S03)2. Preparation 162 Use 162 54. Silicates of Magnesia. Occurrence 162 Use 162 55. Alum, A1o:-3(S04)KoS04, 24H.,0. Preparation 163 Properties - . . 163 Action en plants 163 Action on fimgi 163 TABLE OF CONTENTS. XV PAliE Action on inBects - 163 Use - - 163 56. Silicate of Alumina (china clay). Occurrence ------------ 164 Properties 164 Use - 164 Use against insects 164 Use against rabbits 164 57. Zinc Sulphide, ZnS. Preparation ------------ 164 Properties -----.-..--■- 164 Use 164 58. Zinc Chloride, ZnClg. Preparation ------------ 165 Properties ------------ 165 Action on fungi ----------- 165 Trial as pickle for seed-corn 165 59. Zinc Sulphate, ZnS047H20 (wiiite copperas, white vitriol). Preparation 165 Properties 165 Action on plants 165 Stimulating action of minimum doses 165-6 Action on cryptogamic parasites 166 Use 166 60. BoBATE OF Zinc, ZiiBfi^. Preparation 166 Use as bouillie for oats and wheat 166-7 Use against fungi - 167 61. Silicate of Zinc 167 62. Zinc Ferrocyanide 167 63. Sulphocarbolate of Zinc (zinc sulpho-phenate) ----- 167 64. CAD.MIUM Sulphate, CdS044H20. Preparation - - - " - - - - 167 Properties 167 Use 167 CHAPTER X. Iron Peroxide — Iron Bouillies — Iron Sulphide — Iron Chloride — Green Vitriol — Ferric Sulphate — Potassium Ferroctanide — Prussian Blue — Borate of Iron. 65. Ferric Hydrate, Fe2(H0)g. 168 Preparation ------------ 168 Bouillies 168 Properties --------.... igg Action on plants ----------- 168 Pellegrini's bouillie ---------- 169 Aderhold's bouillie 169 Sorauer's bouillie ----------- 169 Failure of ferric bouillies 169 Mixed cupric and ferric bouillies 169 66. Sulphide of Iron (ferrous sulphide), FeS2. Preparation -" 169-70 Properties ------------ 170 Use - 170 67. Iron Chloride, Fe2Cle5H30. Preparation ------------ 170 Properties 170 Use 170 Use as pickle for seed-corn --------- 170 Use against chlorosis - - . - ------ 170 XVI TABLE OF CONTENTS. PAl.E 68. Sulphate of Iron (green vitriol), FeS047HjO. Manufacture 171 Properties ..--.-.-.. . . 171 Action on plants - . . . 171-4 Action on fuu;,'i 174 Comparative action of blue and green vitr'ol on spores - - . . 174-5 Action on insects 175 Use 175 Use against chlorosis 175 Use as a weedkiller 176 Destruction of moss 177-8 On meadows and lawns 177-8 On trees 178 On roofs 178 Destruction of dodder 178 Use against plant diseases 178-9 Application of green vitriol to the soil 179 Use on aerial part of plant - - - 180-1 (n) As spray ISO (6) As a coating - 180-1 Use as an injection in the trunk 181 Use against cryptogamic diseases of plants 182 Use against potato scab 182 Use against potato disease 182 Use as a pickle for seed-corn 183-4, 18-5 Use against grape rot .-.-----. 185-6 Use against insects - 186-7 69. Febbic Sulphate, Fe2(S04)3. Preparation ------------ 187 Properties - - - 187 Use - - 187 70. Ferrocyanide of Potassium, K4FeCy6. Preparation 187 Use 187 Action on plants 188 71. Prussian Blue (ferric ferrocyanide), FeyCy^g. Discovery 188 Preparation 188 Use 188 Trial as pickle for seed-corn 188 Trial as spray for growing oats and summer wheat and pear-trees - - 188 72. Bobate of Iron, FeB407. Preparation 188 Properties 188 Use - 188 Formula for bouillie 188 Trial of such against leaf spots of pear-tree and chestnut-tree - - 188 CHAPTER XI. Potassium Bichromate (Bichrome) — Chbome Alum— Potassium Pebmanganate — Manganese Sulphate — Nickel Sulphate — Cobalt Sulphate. ( Tii. Potassium Bichromate, KjCrjO, 189 \ 74. Chrome Alum, K2S04Cr2(S04)324H20 189 Preparation ------------ 189 Properties 189 Action of chrome salts on plants 189 Action on parasitic fungi 189 TABLE OF CONTENTS. XVll PAGE Trial as pickle for seed-corn -------- 189-90 Action on uredospores - - - - 189-90 Use against fungi ----------- 190 Use against insects 190 75. Permanganate of Potash, KMnO^. Preparation ------------ 190 Properties ----------- - 190 Action on fungi - - . 190, 191, 192 Use as pickle for seed-corn --------- 190 Use as a disinfectant - . . 190 Disinfection of trees 192 Use against conifer disease 192 76. Manganese Sulphate, MnS0^5H20. Preparation ------------ 192 Properties .--...------ 192 Stimulating action of minute doses of manganese salts on plants - - 192-3 Use against fungi ----------- 193 77. Nickel Sulphate, NiSO,7H20. Preparation ------------ 193 Properties ------------ 193 Stimulating action of minimum doses on plants ----- 193 Action on parasitic fungi --------- 193 Use against fungi ----------- 193 Use against grey rot of the vine 194 78. Cobalt Sulphate, C0SO47H2O. Stimulating action of minimum doses on plants ----- 194 Action on parasitic fungi ...---.-- 194 CHAPTER XII. Red Lead— Lead Arseniate — Lead Arsenite — Lead Carbonate (White Lead) — Lead Acetate (Sugar of Lead)— Silver Nitrate (Lunak Caustic) — Silver Chloride. 79. Red Lead, PbgO^ 195 Preparation - - 195 Properties 195 Use 195 Use to protect seed-corn against birds 19'5 Use to preserve pine and spruce fir seeds from birds . . . . 195 80. Arseniate of Lead, PbgASjOg. Preparation ------------ 195 Properties - - - ......... 195 Action on plants ----------- 195 Action on insects ----------- 195 " Disparin," composition of -------- - 196 Use against insects -........- 196 Bouillies 196 81. Lead Arsenite, PbAs.^Of,. Preparation ------------ 197 Properties 197 82. Lead Carbonate. Use 197 83. Lead Acetate, PblC.^HgOa)^ 3H2O. Preparation 197 Properties 197 Action of lead salts on plants 197 Action on parasitic fungi 197 Trial as pickle for seed-corn 197 Bouillie with milk of lime 197 XVm TABLE OF CONTENTS. PAGE 84. NiTUATE OF SlLVEU, AgNOj. Treparation 197 Properties 198 Action on plants . . - - 198 Action on fungi 198 Action on spores 198 Use 198 65. Silver Chloride, AgCl. Preparation 198 Properties 198 Use 198 "Puknos," composition of -.--..--- 198 Use against cryptogamic diseases in general 198 CHAPTER XIII. Copper Sulphide — Copper Nitrate — Copper Chloride — Copper Sulphite — Copper Sulphate (Blue Vitriol). 86. Copper Sulphide, CuS. Preparation - - - - 199 Properties 199 Use 199-200 Use as bouillies - - - - 199-200 Guillon's formula 200 87. Copper Nitrate, Cu(N03)„3H20. Preparation ------------ 200 Properties 200 Use - - 200 Use as a pickle for seed-corn 200 Use as weedkiller .......... 200 88. Copper Chloride, CuCl22HoO. Preparation ------------ 200 Properties 200 Use - - -200-1 Use as a pickle for seed-corn 200-1 Recipes for bouillies 201 89. Copper Sulphite, CuSO^. Preparation of bouillie 201 Properties -.--.-.----- 201 Action on plants ..--.------ 201 Action on fungi 201 90. Sulphate of Copper (blue vitriol, blue copperas), CuSO^SHoO. Preparation ------------ 201 Properties ----------- 201-2 Toxic effect of copper salts on human subjects 202 Verdigris woikers immune to anjemia 202 Distribution of insecticidal and anti-cryptogamic copper between wine, lees, etc. (table) 203 Action on plants 203-7 Action on algffi and saprophytic fungi 207-8 Action on parasitic fungi . - - 208-11 Use as pickle for seed-corn 208-11, 217-24 Action on insects ---------- 210-11 Use as a weedkiller -....----- 211 Use to destroy dodder ---------- 211 Use against mosses and lichens -------- 211 Use against cryptogamic diseases of plants .... - 211-13 Use of mixtures containing blue vitriol 214-15 TABLE OF CONTENTS. Composition of proprietary mixtures in powder for making bonillies, or to spread with a bellows in a dry state :- "Poudre Coignet" 2I6 "Sulfatine" -----...... 2I6 " Kupferschwefelkalk " 216 Bouillie bordolaise in a single powder ...... 2I6 " Skavinsky's powder "----..... 2I6 " Skavinsky's sulphur ''----..... 2I6 " Kupfer Klebekalkmehl "---..... 2I6 " Kupferzuckerkalkpulver" ---..... 2I6 " Cuprocalcit " 216 " Cupreina " - 216 " Oceidine " 216 216-7 216 Composition of powders to be diluted with water and used exclusively bouillies -----..... " Parasiticine " -----.... " Antimildioidium " - - 216 " Poudre Crochepeyre " ------... 2I6 " Gelatinous cupric hydrocarbonat'; " ---... 2I6 "Bouillie d'Azur " ----..... 2I6 " Poudre Eclair " - - - . 216 '• Fostitebriihe " ------.... 2I6 " Krystallazurin "-----..... 217 " Kupferpreparat Gmund " - - 217 "Kupfer soda" -----..... 217 Use against root rot of vine ----..... 224 Use against black rot of grapes -----... 224 Use against beet diseases -----.-.. 225 Use against worms and snails 225-6 CHAPTER XIV. Copper Hydrate — Bouillie Boudelaise — Bouillie Bourguignonne. 91. Copper Hydrate 227 Preparation of normal bouillie bordelaise 227 Specifications for raw material -----... 227 1. Blue vitriol 227 2. Milk of lime -----.... 227-8 Properties of copper hydrate - 228 Properties of bouillie bordelaise ----.... 228 Tests to which it should respond - . 228 Action of cupric hydrate on plants 229-32 Stimulating action of infinitesimal doses of copper - - - 231-2 Action on fresh-water algae . 232 Action on fungi ----....... 232 Action OL bouillie bordelaise ---...... 232-3 Use of bouillie bordelaise ---..... 233-60 History of bouillie bordelaise - - 233 Practical spraying (illustrated) 234-7 Use against mosses and lichens --...... 237 Use against bacterian diseases of plants 237 Use against parasitic myxomycetes ....... 237 Use against parasitic fungi 237-8 Use against potato disease 238 Treating the tubers 238 Treatment of the stems - - - 238 Effect of treatment on weight and] starch-content of crop, and per- centage of diseased potatoes ....... 239 XX TABLE OF CONTENTS. I'AGE Cost of treatment - - 240 Time for spraying '240 Experimental data --------- 239-41 Use against vine diseases -------- 242-3 Use against beet diseases ..--.--.- 243 Use against lettuce disease 244 Use against mildew of the onion 244 Use against cucumber disease -------- 2^4 Spraying against smut, bunt, and rust of cereals - - . - 245-(i Use against juniper disease --------- 246 Use against leaf curl of the peach ...-.- 24f)-7 Use against oidium of the vine ------- 248-50 Use against black rot of grapes --..-.- 2o0-3 Experimental data ....--.. 250-3 Use against leal spot diseases - - 254-5 Use against apple scab - - - 255-7 Use against pear scab 255-7 Use against leaf scald of pear and quince-tree 257 Use against various fungi -------- 258-9 Use against insects -.----..- 259-60 Carbolated, etc., bouillies --------- 260 CHAPTER XV. Eau Celeste — Copper Phosphate — Copper Borate — Copper Ferrocyanide. 92. Eau Celeste - 261-268 Preparation - - - - - - - 261 Audoynaud's recipe - - - - - - - . - - 261 Bellot des Minieres' recipe -------- 261 Schweizer's cupro-ammoniacal liquor (cellulose solvent) - - - 261 Ammoniacal solutions of copper carbonate 261 Mohr's recipe -----...-- 262 Properties of eau celeste ----...-- 262 Spraying vines, experimental results -.--.-. 263 Eau celeste dissolves cellulose ----...- 263 Solvent eau celeste mixture for silk ---...- 263 Comparative action of blue vitriol and eau celeste on plants and fungi - 264 Use of to combat cryptogamio disease in full evolution - - - - 265 Use against potato and various other fungoid diseases - - - 265-7 Spraying growing wheat with eau celeste ------ 266 Galloway's eau celeste recipes -------- 267 93. Phosphate of Copper, CUHPO4. Preparation ------------ 268 Properties 268 Uses 268 Use against leaf scald of pear-tree - - ' 268 Use on growing grain crops --------- 268 Diminished yield of same --------- 268 94. Borate or Copper, CuB^O-. Preparation 268 Uses 268 Use against leaf scald of pear 268 Fairchild's bouillie for same 268-9 Increased yield of grain by spraying with borate of copper bouillies - 269 95. Ferrocyanide of Copper. Preparation 269 Uses ----- 269 Galloway's bouillies, recipes 269 Results obtained on growing grain by use of same 269 TABLE OF CONTENTS. XXI CHAPTER XVI. Copper Aceto-Ausenite (Emerald Green, Paris Green), Copper Arsenite (Scheele's Green) — Copper Silicate — Copper Carbonate — Bouillie Borde- laise Celeste — Verdigris Copper Acetate — Various Bouillies. page 9(1. Aceto-Arsenite of Copper --.-.-... 270 Definition ------- 270 Manufacture ------------ 270 Properties (action on plants) --------- 270 Freshly prepared bouillies versus bouillies from commercial green in powder 270 Behaviolir of arsenic in soil ^ ------- - 270 Tlie aeeto-arsenite free from sodium arsenite innocuous to plants - - 270 Whitehead's harmless doses, recipes for : — Apple-trees - - - 271 Pear-trees - . . - - 271 Gooseberry bushes ---------- 271 Plum-trees 271 Currant bushes - 271 Action on insects - - - - - - - - - - - 271 Uses ------ 271 Methods of use - - - . - - 271 1. In dry state 271 2. As bouillies - - - 271 Precautions in use - . . . 272 Arsenic not absorbed by plant 272 French law interdicts arsenious acid' and compounds - . - - 272 Time of spraying ----------- 272 Spraying with arsenites during fertilisation kills bees, etc. - - - 272 Spraying with arsenites suitable for rainy countries . - - - 272 Profit incidental to use of arsenites - 272-3 Use against apple scab and potato disease ------ 273 Use against insects, apple weevil, cotton weevil, etc. - - - 273-6 Treatment by powders ---------- 274 Recipe for same ----------- 274 Treatment with bouillies - - .-.---. 274 Use of same inte?- alia against : — Colorado beetle, etc. - - - - - - - - - 274 Codlin mo'h, etc. ----- - - - - 275 Evesham moth, etc. - - 276 Acari - - - - - 276 97. Copper Arsenite, CujAs^Og. Preparation (Gaillot's recipe) - . 276 Properties - - - 276 Use - - - 277 98. Copper Silicate, CuSiO... Preparation - - "- - - 277 Properties - 277 Use - - - - - 277 99. Carbonate of Copper, CuCO:j. Preparation, formula for 277 Tests for normal product 277 Properties 277 Neutral bouillie 277 Various manufacturing hints and instructions . . - . . 278 Uses - - - 278-9 Use to disinfect purchased onions and tubers ------ 279 100. Bouillie Boudelaisk Celeste. Preparation ------------ 279 Formula - - - - - - 279 Xxil TABLE OF CONTENTS. PAGE Action on fruit trees - 279 Good qualities of 271) 101. Basic Acetate of Copper (Veruiguip). Definition 27it Prepiiriition 279 Pro])t'rties (action on plants) --------- 280 Analogies between various copper bouillies ------ 280 Ferret's bouillie 281-4 Use of verdif^ris against various cryptogamic diseases - - . . 281 Results by spraying growing corn (Galloway) ------ 281 Viala and Paeottet's bouillie (recipe fori --.-.. 281 Galloway's experiments on vines -------- 281 102. Copper Acetate Cu(C,H30„)2H„0. Preparation •■ 281 Properties (action on plants) 282 Uses - - 282 102fl Perket's Bouillie Cupric Saccharate in Part. Preparation (formula recipe) --------- 282 Properties 282-3 Action 283 Ratio of sugar to blue vitriol 283 Function of sugar - - 283 An ideal bouillie 283 Possible direct assimilation of saccharate of copper - . - - 283 Galloway's recipe ----------- 284 Bee-keeper's complaints unfounded ------- 284 Use - - - - - 284 Deterioration of present product 284 1026. Various Bouillies. Use of binders - - 285 Action of binders on organoleptic properties of wine - - - - 285 103. Albuminous Bouillie ---------- 285 104. Lactocupric Bouillie (Crouzel's). Preparation 285 Formula for 285 105. Bouillie Bordelaise Modifi^e. A skim-milk bouillie 286 Use against poppy rust ---------- 286 Galloway's recipe ----------- 286 106. Soapy Bouillies. Soap as a binder in bouillies 286 Oil as a binder in bouillies --------- 286 Copper soaps -.--.--.--- 286 Swingle's recipe ---.----..- 286 Galloway's recipe ----------- 286 Soapy eau celeste 286 American recipe for same 286 Comparative adherence of soapv bouillies tested against various other bouillies- - - - " - 287 Deterioration on storing ----...- 287-8 Condeminal's linseed-oil bouillie -------- 288 Addition of petroleum to render bouillie insecticidal as well as anti- cryptogaraic - - - 288 Stable bouillie, recipe for -------- - 288 Zacharewitsch's bouillie recipe 288 Results from same - - 288 Copper soap (in ether, etc.), use of on wounds made by woolly aphis - 288 Insolubility of such coating in water 288 107. Resinous (Cupric Rosinate) Bouillie. Perraud's recipe ----------- 288 Precautions in making - - - - ....-- 288 Olive oil and turps bouillie - - 288 TABLE OF CONTENTS. XXlll CHAPTER XVII. Mercuric Chloride (Corrosive Sublimate) — Tin Crystals. PAGE 108. Mercuric Chloride (corrosive sublimate), HgCl, - . - . 289 Preparation ------------ 289 Properties - - 289 Action on plants 289 Action as weedkiller - - . 289 Stimulating action of infinitesimal dose 289 Pickling of seed - - . . 289-90 Comparative dose of sublimate, green vitriol, and blue vitriol to kill spores - . - . 290 Action on insects - . . 291 Uses 291 Use against lichens - - 291 Use against potato scab - - . . 29L Use against beet jaundice - - - . 291 Use against vine mildew - . . 291 Use against black rot of grapes 291 Use as pickle for seed-corn ----■--..- 291 Disinfection of flower seeds --------- 291 Use against insects ---------- 291 Use against ants ----------- 291 Use against rodents .-.----.-. 291 109. Tin Crystals, SnClg. Preparation - - - 293 Properties ----- --..... 293 Use - - - - 293. CHAPTER XVIII. Derivatives of Carbon (Carbon Compounds). Products Derived from the' Fatty Series : Petroleum (Burning Oil) — Petroleum Sprays — Petroleum Oil Emulsions — Petroleum Soap Emulsions — Petroleum Spirit — Vaseline — Acetylene. 110. Petroleum - - - - 295 Occurrence ------ 295 Commercial products . - - - - 295 1. Petroleum ether ---.---.. 295 2. Light oils - - ■ - - 295 3. Petroleum oil ----- - . . - - 295 4. Heavy petroleum oils ----.-.. 295 5. Crude paraffin wax scale -------- 295 Petroleum oil, burning oil 295 Action on plants ------ 295 Action on insects - - - - 295 Use in pure state ------ 295 Sprays ------------- 295 Directions (specifications) for spraying 295 Time tor spraying - - . . 296 Action on pear and apple-trees ------.. 296 Use against insects - - - . . 296 To be used against San Jose louse ------ 296-8 Petroleum emulsions 298-301 Preparation and formulae 298-301 Sand emulsion .-.-...-... 29& Xxiv TABLE OF CONTENTS. PACK Water emulsion - - 298 Salt-water emulsion - - 299 Example 299 Ingredients of several emulsions --..--.. 299 Ingredients of four stable emulsions 300 Fish-oil emulsion r 300 Milk emulsion 300 Insecticide and metallic salt emulsion 300-1 Use of petroleum emulsions against : — Fungi 301 Coleoptera 301 Hymcnoptera .......... 302 Lepidoptera ----------- 303 Hemiptera - - - - 304 Homoptera - - - - - - - - - - - 304 Woolly aphis - 305 Coccides ---.--.--.. 306 Diptera - 306 Acari ..----..---. 307 111. Petroleum Spirit. Preparation - - - - ,307 Action on plants - - - - 307 Action on insects ----------- 307 Use - - - 307 Petroleum spirit emulsions --------- 307 Formula, recipe for - 307 Use against insects 307-8 112. Vaseline. Action on plants ----------- 308 Action on insects - - - - 308 Uses - - - - 308 Ward's recipe for vaseline emulsion ------- 3O8 Use against insects 308 113. Acetylene, C.^Ho. Preparation - - - - 308-9 Properties 309 Action on plants 309 Action on fungi ..--.-.---- 309 Action on insects ----------- 309 Uses - - . - 309 Use against fungoid diseases 309 Destruction of insects by 310 CHAPTER XIX, Carbon Compounds (continued) — Chloroform — Carbonic Oxide — Methyl Alcohol — Ethyl Alcohol — Amylic Alcohol — Glycerine (Tki-Hydkic Alcohol) — Ether — Mercaptan — Formic Aldehyde — Acetic Acid — Oxalic Acid. 114. Chloroform, CHCL - . - - 311 Preparation - 311 Properties 311 Action on plants 311 Trials to disinfect seed-corn against formol and ammonia - - - 311 Stimulating action of small doses .------- 311 Mrs. Latham's experiments ----.---- 311 Johanssen's experiments .-.-.---- 311 Blooming by - . - . - 311 Action of vapour on spores --------- 312 TABLE OF CONTENTS. XXV PAGE Tests, comparative, on seed-corn -------- 312 Action on insects ----------- 312 Uses 312 114a. Carbonic Oxide, CO. Preparation - ■ - 312 Properties - 312 Action on red corpuscles - ■ ------- 312 Uses - - - 312 Alcohols - - 312-15 115. Methyl Alcohol, CH..pH. Preparation 313 Properties ----- 313 Use in admixture ----------- 313 German recipes ----------- 313 Another recipe 313 116. Ethyl Alcohol, C.^HjOH. Preparation - - - - 318 Properties 313 Action on plants ----------- 313 Use against insects ---------- 313 Disinfection of Hower seed --------- 313 117. Amyl Alcohol, CgHnOH. Preparation ------------ 314 Properties - 314 Action on plants 314 Action on insects " - - 314 Uses 314 Proprietary insecticides into which amyl alcohol enters with their ingredi- ents : — " Nessler's," " Aphidin," " Antivermin," " Amylocarbol," Fichet's composi- tion of " Nessler's " 314 Composition of "Knadolin" - - - 314 Composition of mixed amyl alcohol insecticides ----- 315 Another recipe - 315 118. Glycerine, CH,0HCH0HCH„0H. Preparation 315 Use - 315 II80. Ether, C.H, . 0 . C.Hj. Preparation - 315 Properties - . . - - 315 Action on plants 315 Uses 315-6 Stimulating action of small doses on plants similar to chloroform - - 315 Audebert's recipe for ethereal insecticide (bordelaise insecticide) - - 316 119. Mercaptan, C.HgSH. Preparation - . - - 316 Properties 316 Mouillefert's experiments against phylloxera 316 120. Formic Aldehyde (formaline, formol). Manufacture by Trillat's process - - - 316 Commercial solutions ---------- 316 Formol pastilles ----------- 316 Properties of formic aldehyde - - : 316 Action on plants - - 316 Trials as pickle for seed-corn ------- 317-19 Tabulation of results 317-19, 320, 322 Action of formol on fungi --------- 318 Action of formol on insects --------- 319 Uses 323 Use against potato scab -------- 319-23 Use against grey rot of vine - - ------- 320 Use against other fungoid diseases ------- 320 XXVI TABLE OF CONTENTS. PAGK Practical disinfection of seecl-eorn 323 121. Acetic Acid, CH.,C0H0. Preparation - " 323 Properties 323 Action on funt,'i and their spores .-----.. 323 Uses - - - 324 Use as pickle for seed-corn 324 Use against gum of stone fruit trees 324 122. Oxalic Acid, COOH . COOH. Properties -------..... 324 Action on fungi -.-.---.... 324 Uses 324 Uses against canker of pear-tree - - 324 CHAPTER XX. Carbon Compounds {contimied) — Oils and Fats — Soaps — Hard Soap — Soft Soap — Whale Oil Soap — Fish Oil Soap 323-333 123. Natural Oils and Fats (Glycerides) ------- 325 PiOperties -....- 325 Colza oil - - - - 325 Poppy oil " - - - - 32& Olive oil ----- 325 Linseed oil ----------- - 325 Whale oil ------------ 325 Action on plants - . - - 325 Action on insects - - - 825 Uses - - - - 325-7 Uses against insects 325-7 124. Soaps. Preparation - 327-8 Solubility of soaps ---.---... 327 1. Hard soaps ----- 327 Marseilles soap 327 Soap boiling - - - - 327 2. Soft soaps - - 328 {a) Whale oil soaps --------- 328 (b) Fish oil soaps - - - 328 (c) Black soap (green soap) 328 Insecticide preparations ---.--... 328 Composition of (recipe, for) a few insecticides - . . . 328-9 Action of soap on plants - 329 Action on insects - - - 329 Action of Mart^eilles soap - - . 329 Action of hsh oil soap - . - - - - - - - - - 329 Action of whale oil soap --------- 329 Uses - - - - 329-33 Use against cryptogamic diseases - - - - - ' - - - 329 Use against insects --------- 329-33 Halsted and Keisey's recipe --------- 329 Marlatt's recipes ----------- 329 Targioni's recipes 330 Ducloux recipe 331 Lowe's recipe - . 331 Taschenberg's recipe ---------- 331 Delacroix recipe ----------- 331 Muhlberg's recipe ----------- 331 Nessler's recipe 332 TABLE OF CONTENTS. XXVll CHAPTER XXI. Carbon Compounds [continued) — Products of the Aromatic Series : Benzol — Coal Tar — Wood Tar— Naphthalene, PAGE 125. Benzene, CgH^ 334-7 Preparation ----- 337 126. Tar - 337 1. Coal tar - - - - - - - - - - - 337 2. Wood tar - 337 Action of tar on plants ---------- 337 Action of tar on insects ---------- 338 Uses ------------ 338-43 " Rubinia," composition of - - - - 338 Tetard's recipe - - . - 338 Howard's recipe ----------- 338 Balbiani's ointment, recipe - - - - 338 Rathay's bouillie ------ 338 Use as weedkiller --.-..---- 338 Use against fungi -------- . . - 338 Use on insects ..---.---- 339-43 De Quercio's recipes --------- 342-3 Use against rabbits and mice -------- 343 Use against birds ------ 343 Use against birds, Howard's recipe ..-.--- 343 127. Naphthalene, C^„Hy. Preparation 343 Properties - - - 344 Balbiani'^ ointment, recipe - - - 344 Action on plants - - - - 344 Action on seed germination 344 Action on insects ----------- 344 Uses ----- 344-7 Naphthalenized sawdust --------- 346 Pradel's naphthalene mixture -------- 346 Taschenberg's mixture ---------- 346 Mixtures to kill woolly aphis --------- 347 Guozdenovic's mixture ----- 347 A German mixture against phylloxera ------- 347 Guozdenovic's mixture against cochineals 347 CHAPTER XXII. Carbon Compounds (c nitinued) — Terpenes — Oleo Resins — Galipot — Turpentine — Rosins — Rosin Soaps — Rosin Emulsions — Metallic Rosinates — Copper Rosin- ate — Camphor. Terpenes - 348 128. Turpentine ------ 348-52 Action on plants - - - - ------- 348. Action on insects ---------- 348-9 Recipe for grafting wax --------- 349 Uses - 348-9 Mouillefert's experiments against phylloxera ------ 349 Use to drive off moles ---------- 349 129. Pine and Spruce Resin [? Rosin]. Uses - 349 Use in soap emulsions ----- 34c> XXviil TABLE OF CONTENTS. PAGE Use in coatings and bird-limes 349 Use in cupric bouillie as binders 34!» Rosin soiip emulsions 349 Numerous recipes 350 Action on plants - 3o0 Action on insects - - 350 Uses . . - - 350 Bird-limes and coating compositions .-..-.. 351 Numerous recipes for coating compositions ------ 351 Use of coating compositions --------- 351 Use of bird-limes as tar rings -------- 351 Clarac's composition against woolly aphis .-..-- 352 Rosin bouillie in which rosin is used as binder ----- 352 130. Cami'Hou, C,nHifiO. Natural occurrence ----.-..-. 352 Sublimation ------------ 352 Refining 352 Properties - 352 Uses - 352 Use against insects 352 Use to protect corn-seed, etc., against mice ------ 352 CHAPTER XXIII. Carbon Compounds [continued] — Nitrobenzene — Carbolic Acid — Picric Acid — Cresol — " Sapocarbol " — Creosote — " Creolines " — " Lysol "—Potassium Dinitro-Cresyl.vte — Thymol — /3-Naphthol — Methyl Violet. 131. Nitrobenzene, C,;HgNO,, - 353-4 Preparation ------------ 353 Action on insects ----------- 353 Action on plants •"553 Uses - - - - 353-4 Papasogli's recipe - 353 Use against insects -..-----. 353-4 Knadolin 354 Composition of same ---------- 354 132. Carbolic Acid, CgHgOH. Preparation 355 Properties 355 Action on plants - - - - - - - - • - - - 355 Action on fungi ----------- 355 Action on insects ----------- 355 Use as weedkiller - - - . 355 Use against bacterian, etc., diseases .-..-- 355-6 Use as steep for beet seed 355-6 Experiments in disinfecting beet seed 356 Method of disinfection 356 Use against insects --------- 356-8 133. Trinitrophenol or Picric Acid. Preparation ------------ 358 Properties ------------ 358 Use as pickle for seed-corn --------- 358 Action on insects 358 /OH 134. Cresol or Cresylol, C^Ha XCHs Preparation - - - - 359 Properties - - - 359 TABLE OF CONTENTS. XXIX PAGE Commercial preparations containing cresylol 359 Sapocarbols ------------ 359 Lysols - - 359 Creolines - - 359 Solveol - - ■ - - - - - - - - - - 359 Araylocarbol ..----.---- 359 Thymocresol -...---.--- 359 135. " Sapoca_rbol." Preparation ------------ 359 Properties 359 Composition .---...... 359-60 Action on plants ----------- 360 Action on plant lice - - - - - 360 136. "Creolines." Artmann's creoline - . . - - 361 Properties ------------ 361 Action on plants - - - - 361 Action on plant lice - ... - 36I Uses - 361-2 Disinfection of seed potatoes - - 361 Use against insects - . . . 362 Recipes for mixtures which gave good results against cochylis - - 362 137. Creosote (wood tar). Preparation .--------- - - 362 Properties ----...---.- 362 Uses - - - - - 362-3 Use against insects - - 863 American recipe for gipsy moth ---...-- 363 Mouillefert's experiments on vines ....... 363 138. " Lysols." Preparation --------...-- 363 Properties ------------ 364 Action on plants ----------- 364 Action of solutions of various strengths on organs of different plants - 364 Action on fungi ....--...-. 364 Action on plant lice ..--...- - . 365 Use against fungi -------.-- 365-6 Coating fruit trees in winter against insects 366-7 Use against insects -...-.--- 366-7 139. Potassium Dinitro-Cresylate. Properties .-..-,.----.- 367 Action on plants .---.--..-- 368 Action on insects -..----.--. 368 Action on mice and rats ......... 368 140. Thymol. Preparation --.-----.--- 368 Properties 368 Use - . . 368-9 141. ^-Naphthol, C10H7OH. Preparation -.---------- 369 Properties --.------..- 369 -\ction on plants -.--.------ 369 Action on fungi --...-..... 369 Recipes for naphthol mixtures 369 Naphtholate of soda .-.....--- 369 Naphtholate of lime 369 Naphtholate of copper - - - 369 Naphtholate of iron 369 Use against fungi 369-70 142. Methyl Violet or Pyoctanine. Preparation 370 Properties 370 Use 370 XXX TABLE OF CONTENTS. CHAPTER XXIV. Carbon Compounds {co7itinned) — Tobacco (Nicotinic Tobacco Juice) — Quassia — Hellebore — Pybethra — Delphinium (Larkspur) — Strychnine — Nux Vomica — Walnut Leaves — Glue— Cutch — Aloes. paop 143. Tobacco 371-5 llecipeB for tobacco insecticides (7) 371-2 Properties 372 Action on plants . - - 372 Action on insects ----------- 372 Uses 372-5 Fumigation 372 Use in open air --------- - 372-3 Spraying with tobacco juice 373 Use against insects --------- 372-5 Nessler's tobacco insecticide 371-4 Sajo's recipe 374-5 Sajo and Czerhati's recipe 374 Ahlisch's recipe - - 374 Mohr's recipe - . - 375 Guozdenovic's recipe 375 Noel's method ----------- 375 Sirodot's method 375 144. Quassia Amara Insecticides with quassia basis ------- 375-6 Numerous recipes ---------- 375-6 Properties 376 Action on plants ----------- 376 Klein's solution - - 376 Action on insects - - 376 Uses - - - . . . 376-7 Mouillefert's experiments on vines . . - - - . . 377 A German quassia mixture against phylloxera 377 Recipe against Phytoptus Ribis 377 145. Helleboke RoiiT. Preparation of liquid insecticides . - 377 Several recipes --.-.---.-- 377 Uses - - . 377 Against insects .-.-.----.- 377 Against sparrows 377 Against rodents 377 146. Pyretuba. Preparation of pyrethra powder 378 Preparation of pyrethra extracts -------- 378 Soap extract (recipe) -.-..----- 378 Alcoholic extract (recipe) 378 Alcoholic and ammoniacal extract (recipes) ------ 378 Composition of pyrethra insecticides (recipe) ------ 378 Cupric insecticide bouillie (recipe) 379 Alcoholic and carbon disulphidc extract (recipe) ----- 379 Pyrethra petroleum emulsion 379 Properties of pyrethra - - 379 Action on plants - - - 379 Action on insects 379 Uses 379-81 Use against insects 379-81 14'i Strychnine. Source ------------- 381 Uses ----- 381 Use against insects -..---.-.- 381 TABLE OF CONTENTS. XXXI PAGE Use against sparrows - 381 Use against rodents 382 148. Delphinium (larkspur). Preparation, properties, and use -------- 382 149. Glue. Use - - - - • . - . - 382 Use against insects . - 382 150. CUTCH. Use against oidium . - - 382 151. Rose Laurel. Uses ----- 382 Use of infusion against insects -------- 382 152. Aloes. Source 382 Properties - - 382 Use in human medicine . - 382 Use as addition to bouillie bordelaise 382 Glossary - - - - . • - - - - - - - - 383-406 Index - - .. - 407-431 LIST OF TABLES. A. Tahi.es Showing Effect of Water, Hot and Cold, and of Hydrogen Peroxide. PAGE 35 Table I. — Showing the effect of the systematic immersion of vineyards on the volume of wine produced ....--... 26 Table 11. — Showing the daily loss of water by absorption by the soil during immersion ------------ 27 Table IH. — Showing the increase (1) in the area of submersion, (2) in the insecticidal treatment of French vineyards, 1880-1890 - - - - 30 Table IV^. — Showing the temperature at which the spores of different varieties of U.stilago are killed 32 Table V. — Showing the effect of steeping seed-barley in hot water on the germinative capacity - - - - 34 Table VI. — Result of steeping seed-wheat in hot water for different lengths of time - 34 Table VII. — Effect of steeping seed-oats on germinative capacity - - - 35 Table VIII. — Effect of steeping seed-rye in hot water on germinative caps city ----- Table IX. — Inactivity of hydrogen peroxide on Puccinia uredospores - - 40 B. Tables Showing Use and Effect of Sulphur and of Sulphdkic Acid, Chlorine, Hydrochloric Acid, and Arsenious AaD. Table X. — Proportions of sulphur and lime used in mixtures against anthrac- nose at different stages of treatment 52 Table XI.— Effect of steeping seed- wheat for different lengths of time in solu- tions of dilute sulphuric acid, oil of vitriol, of various strengths on its germination capacity per cent 84 Table XII. — Showing the action of dilute sulphuric acid of 0-5 per cent on the spores of oats and wheat ..-----.- 85 Table XIII. — Showing the strength of dilute sulphuric acid required to kill the old and young spores of Ustilago of barley, oats, and wheat respec- tively, and the circumambient temperature ------ 85 Table XIV. — Showing the action of different doses of sulfarine (Kieserite; con- taining 15 per cent of sulphuric acid on the potato disease - - - 87 Table XV. — Showing the effect on the chlorine content of forest timber in proximity to a hydrochloric acid works 89 Table XVI. — Showing sensitiveness of leaves of various fruit trees to solutions of arsenious acid of various strengths ------- 04 C. Tables Showing the effect of Nitrate of Soda, Muriate of Potash, Potassium Cyanide, and Magnesium Chloride. Table XVII. — Showing the effect of a 30 per cent solution A and of a 15 per cent solution B of nitrate of soda on different plants - . - - 108 Table XVIII. — Showing the action of a 30 per cent solution and a 15 per cent solution of potassium chloride (muriate of potash) on farm crops - - 118 Table XIX. — Showing the amount of potassium cyanide, water, and sulphuric acid to use in cyaniding trees of different height and diameter - - 133 Table XX. — Showing the effect of 30 per cent and 15 per cent solutions of magnesium chloride on plants 161 xxxii LIST OP TABLES. XXXlll D. Tables Kelating to Green Vitriol and Chrome Salts. PAGE Table XXI. — Showing the number of pounds of green vitriol which wheat, rye, barley, and oats can bear per 100 lb. of soil ----- 174 Table XXII. — Showing the comparative strength of solutions of blue and green vitriol respectively required to kill spores of Phytophthora, Perono- spora, Ustilago, and Puccinia - - 175 Table XXIII. — Showing the results of the experiments of De Dombasle on the disinfection by green vitriol of seed-corn artificially infected for the purpose 183 Table XXIV. — Showing the toxic dose of chrome salts in a nutritive solution 189 E. Tables Relating to Blue Vitriol and to Copper Salts. Table XXV. — Showing the distribution of insecticidal and anti-cryptogamic copper between wine, marc, lees, etc. ------- 203 Table XXVI. — Showing the effect of solutions of blue vitriol of various strengths on spores of Phytophthora, Peronospora, Ustilago, Puccinia, and Cliviceps ----------- 2IO Table XXVII. — Showing the effect of steeping seeJ-corn in solutions of blue vitriol of different strengths for different periods of time - - - 217 Table XXVIII. — Showing the effect on height of plant of steeping seed in solutions of blue vitriol of various strengths 217 Table XXIX. — Showing effect on germination of steeping injured seed-corn in water and in solutions of blue vitriol 218 Table XXX. — Showing effect on germination of seed-barley of steeping in solutions of blue vitriol of various strengths ------ 221 Table XXXI. — Showing delay in germination by Kuhn's treatment - - 221 Table XXXII. — Showing effect of blue vitriol steep on crop of barley - - 221 Table XXXIII. — Showing sensitiveness of seed-oats to blue vitriol steep - 222 Table XXXIV. — Showing delay in germination by blue vitriol steep of seed- oats (Kuhn's method) ---------- 222 Table XXXV. — Effect of blue vitriol treatment of seed-oats on the crop - - 222 Table XXXVI. — Showing reduction in germinative capacity by delay in sowing after steeping seed-corn in blue vitriol 223 F. Tables Relating to Bodillie Bordelaise. Table XXXVII. — Effect of 2 per cent bouillie bordelaise in preventing potato scab 237 Table XXXVIII. — -Showing effect of bouillie bordelaise of various strengths on weight and starch content of potato crop and on the percentage of diseased potatoes 239 Table XXXIX. — Showing beneficial effect of repeated spraying with copper bouillies on potatoes ---------- 239 Table XL. — Showing effect of bouillie bordelaise on potato disease - - 239 T.ABLE XLI.— Showing eff'ect of first spraying on the weight of the crop of Magnum Bonum potatoes --------- 240 Table XLII. — Showing number, weight, and size of large and small potatoes before the appearance of the disease on treated and untreated plots - 241 Table XLIII. — Showing number, weight, and size of large and small potatoes after the appearance of the disease - - - - - - - 241 Table XLIV. — Showing the effect of various copper preparations on the bulk of the potato crop and the number of diseased potatoes - - - 241 Table XLV. — Showing composition of moistenable sulphur - - - - 249 Table XLVI. — Showing the composition, volume per acre, time of treatment, order of sequence of bouillies bordelaises used in the prevention of black rot of the vine 2-51 Table XLVII. — Showing order, time of spraying, and strength and composi- tion of bouillie bordelaise in treatment of black rot of vine - - - 2.51 Table XLVIII. — Showing results of repeated spraying of vines with solutions of blue vitriol of various strengths 2.53 C XXXIV LIST OF TABLES. PACE Tahlk XlilX.— Showing the offect of spraying with bouillie bordelivise on the percentage of diseased pears --------- 250 Table L. — Showing the effect of repeated spraying with bouillie bordelaise on the percentage of diseased pear-tree leaves 257 G. TABLES Relatint. to Eau Celeste, Cupno-ALncMiNous Bouillies, AND 10 Corrosive Sublimate. Table LL — Showing the effect of spraying vines with eau celeste on the density of the wort, the weight of the wort per kilogramme of grapes, the sugar content per litre of the wort, and the weight of the grapes - - 263 Table LIL — Composition of Galloway's eau celeste 267 Table LIIL— Showing the percentage of sound grapes on untreated vines and on vines treated by eau celeste made by two different fornuiliE - - 267 Table LIV.— Showing the eft"ect of disinfecting haricot bean seed with eau celeste - - 267 Table LV.— Showing the effect of spraying bramble bushes with eau celeste - 208 Table LVI. — Composition of cupro-albuminous bouillies - . - - 286 Table LVIL— Showing the dose of green and blue vitriol and corrosive sub- limate required to prevent the germination of the spores of different parasitic fungi - 290 Table LVIII. — Showing the respective doses of corrosive sublimate re- quired to prevent the germination of spores of the various species of Ustilago 290 H. Tables Relating to Petroleum Emulsions, Nessler's Insecticides, etc. Table LIX. — Showing ingredients of several petroleum emulsions - - 299 Table LX. — Ingredients of four stable petroleum emulsions - - - - 300 Table LXI. — Showing the disinfectant capacity of anti-cryptogamic vapours - 312 Table LXII. — Showing the composition of Nessler's insecticides - - - 814 I. Tables Relating to Use of Formol (Formaline). Table LXIII. — Showing effect of steeping seed-oats on formol solution on germination 315 Table LXIV. — Showing effect of steeping seed-oats in formol solutions on germination ..---------- 317 Table LXV. — Showing effect of twenty minutes' steeping in formol solutions of various strengths on the germinative capacity of seed-corn. Water = 94-5 per cent - - . - 317 Table LXVI.— Showing effect of duration of steep in formol solutions on germinative faculty of seed-corn -------- 318 Table LXVII. — Showing effect on oat crop of steeping the seed-oats in solu- tions of formol of different strength and for ten minutes up to one hour - 319 Table LXVIII. — ^Showing the results of growing oats from undisinfected seed and from seed disinfected by 2 per cent bouillie bordelaise, and from seed disinfected by 0-2 per cent and 0 3 per cent solutions of formaline - 321 Table LXIX. — Showing the effect of solutions of formaline corrosive sublim- ate, oil of vitriol, and blue vitriol on the germinative capacity of millet seed and the spores of Ustilago crameri 322 Table LXX. — Showing the effect of certain disinfecting fluids on the crop pro- duced from the rusty seed-corn which floats on the fluid - - - 322 Table LXXI. — Showing the action of formol and lime and mixtures thereof on onion rust .----.----- 323 J. Tables Relating to Use of Preparations made from Coal-Tar Products. Table LXXII. — Showing action of naphthalene on germinative capacity of cotton seed ----------- - 344 Table LXXIII. — Showing the comparative amount of active ingredients in various brands of " sapocarbols " and "lysols" ----- 360 LIST OF TABLES, XXXV PAGE Table LXXIV. — Action of "sapocarbol" on plants 360 Table LXXV. — Action of "sapocarbol" on plant lice 360 Table LXXVL — Showing action of Artmann's " creolin " on plants - - 361 Table LXXVII. — Action of Artmann's "creolin" on plant lice - - - 361 Table LXXVIII. — Showing composition of "creolin" mixtures which give good results against plant lice .--..--- 362 Tablk LXXIX. — Showing the action of "lysol" solutions of various strengths on the organs of different plants -------- 364 Table LXXX. — Showing the action of " lysol" solutions of various strengths on plant lice ------------ 365 K. Tables Relating to Use of Tobacco, Quassia, and Pyrethra Preparations. Table LXXXL — Action of tobacco juice on crioceris of cereals - - - 373 Table LXXXII. — Showing the action of Klein's quassia solution on the organs of various plants . - . 376 Table LXXXIIL — Showing the composition of pyrethra insecticides - - 378 INTEODUCTION. Relative and Absolute Diseases. — Plants, like man and animals, in virtue of their living cellular constitution, are liable to disturb- ances of their physiological equilibrium, that is, to diseases. The diseases of plants are quite as well defined as those of animals, and a certain analogy exists between them, so also with the inducing causes. We again find amongst these causes the same physical, chemical, or para- sitic elements. These causes generally co-operate to produce disease ; but one cause is always preponderant and serves as a basis for clas- sification. Plant diseases are divided into (a) relative and [b) absolute diseases. Eelative diseases are a return to the natural wild state of the plants artificially selected and profoundly modified by man, and so it is that Brussels sprouts, turnip cabbage, and the difterent species of cauliflower are derived from a species of cabbage to which a disease Parenchymatosis has been imparled artificially by over-nitrogenous feeding systematically pursued for several generations. The tend- ency of these plants to form large fleshy buttons, in the form of a cabbage-head, or excrescence of the stem, is not at all inherent in the species, and it is not unusual in dry seasons to observe a leturn of these plants to the primitive condition. This degeneration is regarded as a relative disease. It is the same with fruit trees ; we skilfully maintain by pruning the morbid condition which forces them to pro- duce an exaggerated amount of fruit so as to accomplish in this way the end which we assigned to them. Their return to the natural state is regarded as a degeneration or a relative disease. Absolute diseases result, on the other hand, from more or less profound alteration,, general or local, of the organs of the plant ; from a more or less ex- tensive and complete alteration of the cellular tissue. It is to absolute diseases alone that the etiological observations which are about to be examined apply. Etiology. — Etiology is that part of pathology which is con- cerned with the research of the origin of diseases, and examines the causes which induce them. The latter are divided into effective causes (those which actually cause the disease) and adjuvant (helping, predisposing) causes (those which place the plant organism in such a condition that the efl'ective causes can act). In practice, these causes are confused and linked together in such a way that an adjuvant cause in a given disease may become an effective cause in another disease. It has been seen that the etiological factors of disease may be divided into (1) physical, (2) chemical, and (3) parasitic. (i) Physical Causes. — These depend on climate and season. Heat, cold, drought, and humidity, more or less sun-light, are factors 1 2 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. which greatly influence plant growth. They cause deadly plant diseases when all favourable conditions do not work together. Here, as in the animal kingdona, the great law of selection intervenes. Only plants able to live in the existing climatic conditions will subsist, the others suffer, fall ill, and disappear. There are few remedies for climatic causes. (2) Chemical Causes. — These relate, especially, to the chemical composition of the soil, from which the plant draws the elements required for life and growth. These may exist too abundantly, or not in sufficient amount. Ee terms those diseases due to an excessive amount of nutritive elements sthenic diseases, and those due to an in- sufficient amount asthenic diseases. These physical and chemical causes favour the hatching of parasitic diseases. Plants weakened by these causes can exert little or no cellular resistance to being overrun by parasites, which find in them a medium favourable to their growth and development, for however unfavourable these conditions may be to the development of the plant, they are, precisely, those which favour the evolution and multiplication of parasites. (3) Parasitic Causes. — The evolution of all parasites, animal or vegetable, should be well known, as they are neither injurious nor destructive to the same extent in different phases of that evolution. Each parasite has a very characteristic evolution, more or less long, always the same for the same species. (1) Animal Parasites.- — These belong to the most diverse classes, but insects especially occasion the most frequent and perceptible damage. The insect originates in the egg. The insect which it contains passes through very different con- ditions, until after a greater or less length of time it becomes perfect, that is, capable of laying eggs to ensure its reproduction. The sequence of these intermediate conditions is called metamorphosis, and the different forms, larvae, caterpillai'S, grubs, chrysales, etc. It is especially in the larva form that the insect is most injurious, because it sometimes remains several years in that condition. That form represents in every instance the longest period in the life of the insect. A sound knowledge of these metamorphoses, of the periods at which they take place, and the spots where they occur will render the struggle against insects at the moment of their evolution — when they are the most sensitive to insecticides and when they cannot withstand their energetic action — comparatively easy. (2) Vegetable Parasites. — These include fungi and certain phanerogams. Fungi have also an evolution, differing greatly with the species, and often very complex. Their method of reproduction, the time and place where the spores are produced as well as the plants on which these spores can germinate, should be known. The elements of reproduction of fungi are spores (name given to seeds of fungi). These spores develop when climatic conditions permitting their evolution are realized. The mycelium (this is the name given to the new-born parasite) can then expand, either in the interior or on the exterior of the plant. In both cases it lives at the expense of the cellular tissue, and in so doing pro- duces characteristic diseases. Organs of reproduction are formed on the mycelium, from which spores that spread the disease are de- INTEODUCTION. 3 tached. The spores produced differ wi h the season and locality of the plant. They are differentiated into (1 summer spores, very delicate, which generally produce a mycelium forthwith, and (2) winter spores, very hardy, which do not develop until after a winter passed as such. No general rule can be given as to the evolution of fungi. It differs as much from one species to another as in that of insects. Species exist of very complex forms, the evolution of which obliges them to pass each cycle on very different species of plants. The suppression of one of these plants in the district may lead to an instantaneous and complete stoppage of the disease. These fungi are not all equally injuri- ous. The following classiiication, based on their action on plants, has been adopted : (a) Absolute jmrasites, {b) Wound or weakness j^arasites, and (c) Facultative i^arasites. {a) The first, the most dangerous, are capable of attacking healthy plants, {b) The second can only attack the plant if its physiological condition is abnormal, i.e. attacked by disease, if its vital energy be diminished by climatic conditions ; or if hail, or frost, grub, or other cause, has made an opening in the epi- dermis, enabling them to penetrate into the interior, (c) The third are the fungi formerly termed saprophytic fungi as opposed to parasitic fungi. Whilst the latter draw their nutriment from the living cell, the former live on inanimate organic matter. It has been ascertained, nevertheless, from the profound study of cryptogamic diseases that saprophytic fungi may, in most instances, become dangerous parasites if, through special circumstances, the plant cell may happen to con- tain elements sought after by one of these fungi. Thus the penicillium glaucum, the well-known green mould, which usually grows on an in- animate medium, is attracted during the ripening of fruit by the sugar contained in the latter, and penetrating therein causes them to rot. (3) Microbe Parasites. — In the case of a microbe parasite it is especially necessary to know what factors induce its development, which is closely connected with the composition of the cellular substance, the tem- perature, and the moisture. Plants, however, suffer less from these than animals, because the reactions of vegetable plasma are acid, which are less favourable to their evolution than an alkaline medium. However, the daily discovery of parasitic microbes helps to throw light on some of the morbid phenomena of plants, and microbes appear to play a most important role in plant pathology. The antagonism between animate beings, as much animal as vege- table, which live in the same medium does not give rise solely to very weak, morbid conditions, but also to relations between beings of very different species, which are advantageous to the two antagonists. These associations are termed symbioses. De Bary, generalizing the term symbiosis, distinguished (1) Mutualistic symbiosis or advan- tageous co-operation of the two associates, and (2) Antagonistic symbiosis, where the one lives at the expense of the other. Vuillemin, on the other hand, calls the first association symbiosis and the second antibiosis. I. Mutualistic Symbiosis. — Many cases of evident symbiosis occur between phanerogams and cryptogams, between cryptogams and microbes, and between phanerogams and microbes. Amongst these sym- 4 INSECTICIDES, FUNGICIDES, AND WEED KILLEES. biotic associations the lichens must be regarded as the most typical and the most perfect example. It is the most complete association known, where the elements, fungus, and alga are so closely associated that henceforth it is impossible for them to live apart. The most interesting cases are those of evident symbiosis between certain fungi and trees such as Fagus (beech), Corylus (hazel), Castanea (chestnut), and several species of Conifercz. In this symbiosis, known as Mycorhiza, the mycelium of the fungus invades the roots of the tree, and, whilst borrownng the necessary elements of life from the tissues of the plant, cedes to it the nutritive elements favourable to its growth. Other symbioses of great importance to agriculture exist between certain cultivated plants and certain microbes. We have, on the one hand, the Bacteriorhiza of Hiltner and Stromer, in which bacteria, whilst drawing their nutriment from the cells of the root epidermis of Beta (beet) and Pisum (pea), without injuring the latter pre- vent injurious fungi, such as Phoma and others, from invading and destroying these plants. Again, microbes and Leguminosce are as- sociated together : Bhizobium leguniinosarum (Frank) and Bacillus radicola (Beijerinck). These bacteria live on the excrescences, the characteristic nodosities which they produce on the roots of the LeguminoscB. If they draw the necessary elements of life from the cellular tissue of the root, they as a matter of compensation cede to the nursing plant nitrogen of the air in an assimilable form. These symbioses are favourable to the development of the plant, and the rupture of this association necessarily creates a less prosperous state, more akin to a grave pathological condition ; the more complete the symbiosis the more the health of the plant depends on the nutritive elemeats with which these associates are capable of supplying it. In the disinfection of the soil by chemical agents it sometimes happens that by destroying noxious parasites, the mutualistic parasites are des- troyed at the same time, and that in curing one disease another is created. Pure cultures of these useful bacteria, or of the mycelium of mutualistic fungi, must, therefore, be spread on the fields some time after disinfection. Pare cultures of these bacteria are on the market, under the name of " Nitragine," etc. The very contradictory results obtained on the large scale by the use of pure bacteria arise from the fact that these should be appUed, not upon any soil, but on a soil dis- infected by carbon disulphide. The soil is like a wort, and there is a great analogy between selected leavens (yeasts) and soil bacteria. The selected leavens cannot yield a result except on wort previously freed — -by sterilization, by means of heat — from any other leaven which would hinder their development. In the same way, the soil which it is desired to sow with mutualistic bacteria should be freed, by previous disinfection, from the elements which can, by their presence, oppose the normal evolution of these useful bacteria. Each plant possesses its own bacteria, and in each particular case requires the aid of a pure, selected, and well-defined culture of microbes. 2. Antagonistic Symbiosis. — The most common result of the an- tagonism between auimated beings is the parasitic disease — general or local — to which the plant, badly equipped, or in bad condition to resist INTRODUCTION. 5 the attack of its enemies, succumbs. The number of plant parasites is immense, and they are found in all classes of animated beings (phane- rogams, cryptogams, bacteria) as well as animals (worms, insects, acari) living at the expense of the plant. They all become more dangerous, the one more than the other, in so far as they find the medium favourable to their development and extraordinary multiphcation — a medium of constant and invariable composition, and climatic conditions lying be- tween narrov7 limits, to which are intimately linked the growth and reproduction of each organism. Between enemies the struggle is con- stant. The reaction of the plant against the parasites which threaten it, its cellular activity, which opposes to them its layers of bark which creates deposits of tannin, of acids in the cells, layers of wax on the epidermis, prevent it from succumbing. There is no disease until the reactive forces of the plant become powerless to prevent the develop- ment of parasites, until the disposition of the subject, and special and exceptional conditions, facilitate their evolution, increasing their viru- lence and their number. There is, however, disease when the parasitic antagonists imported from a foreign country (as was the case with certain insects imported from America, and as is seen in America as regards insects of European origin) are deprived of their natural parasites capable of hindering their abnormal multiplication. Great invasions of parasites must be regarded, in fact, as accidents, for nature has attached to each ravager one or more parasites which live at its expense, just as it itself lives at the expense of the plant. These parasites obey the same laws as the ravagers, multiply with the same rapidity as the latter, and by diminishing their number is the check which nature opposes to the abnormal multiplication of the species. Moreover, sudden changes of temperature at the time of the casting of the skin of the larvae of the insects — then very delicate — frosts, heavy rain, free electricity', appear to be some of the causes which hinder the development of too great a number of parasites. In nature these causes prevent epidemics, which would be very rare if man did not, by his methods of culture, create specially favourable conditions for the evolution and multiplication of parasites. Formerly, this state of affairs was remedied by the bare fallow ; to-day, rotations are preferred ; to- morrow, the annual disinfection of the soil by means of carbon disul- phide, that of the underground and aerial (above ground) part of plants by insecticides and anticryptogams will definitely abolish a condition which necessarily results from our methods of cropping. We must re- place by new processes the action of stable equilibrium which is mani- fested in nature and which we have suppressed. It will be seen, however, that the complete destruction of parasites is not indispensable, but even injurious, and that disinfection should only re-establish equilibrium, a modus vivendi between the plant and its parasites. It is necessary, in fact, to avoid diminishing in the plant the reactive force of the cells, so that these may always be armed 'and active, and able at any moment to sustain the struggle against parasites. This equilibrating disinfection is only reahzed, up to now, in the treatment of the vine against Phylloxera and cryptogamic parasites by the annual treatment (a) of the soil by weak applications of carbon disulphide, of dissolved sulpho- 6 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. carbonate, and (b) the aerial or above-ground parts of plants by sulphuring, multiple spra3'ing with weak cupric bouillies, washing of the stock with ferrous sulphate (green vitriol), and by scalding or hot water treatment. The number of plant diseases daily increases, as now we do not solely cultivate native plants, but more and more foreign species imported into the country. The deportation of the latter places them in new conditions against which nature has not armed them ; and in the country of their exile they are defenceless against parasites. But these plants import parasites which find a favourable medium for their evolution in the plants of our country, against which the latter are not armed. Thus it is that very severe diseases have appeared in our crops, and that America has been dowered with parasites, harmless with us, but formidable enemies in that new country. Therapeutics. — Therapeutics is that part of medicine which treats of curative agents and studies the manner of using them in the treat- ment of disease. Vegetable therapentics is based on physiological data on the knowledge of the physico-chemical properties of curative agents, on their action (1) on the plants to be treated, (2) on the factors which cause the disease. It will therefore be necessary to indicate in the case of each chemical product used in the treatment of plant diseases (1) The process of manufacture of the chemical product. (2) Its physico-chemical properties, a knowledge of which facilitates the preparation of therapeutic specialities and makes known their mode of action. (3) Its use in human medicine, (4) Its action on the plants treated. (5) Its action on the parasites to be overcome, or on the factors injurious to plants. Curative treatment is surgical when the effective causes are suppressed without the aid of chemical products, and chemical when recourse is had to the aid of chemical products. The use of the one does not exclude the use of the other, and the two utilized simultaneously may produce a better effect. Surgical Treatment.— Surgery, or operatory medicine, is the part of medicine which comprises the intervention of the naked hand or the hand armed ^oith mstruments. The intervention of the hand armed with instruments has given rise to vegetable surgery, the inter- vention of the naked hand to the metJwds of destructivn of 'parasites — picking, collecting, trapping, baiting. Vegetable Surgery. — Vegetable surgery has many analogies with animal surgery. An organ deeply attacked or capable of being regarded as a seat of infection should be removed in either case. That is so much the more easy in the case of a plant, as the latter is a being whose growth, by budding, is indefinite, and that the organs removed are replaced by equivalent organs in a comparatively short time. The researches of Eeaumur, Ratzeburg, Eobert, Count Jaubert, and Knight have shown how vitality may be restored to a sickly tree. The best known process, called " phloioplasty," consists in removing in a partial or general way the old bark from the trunk and large branches of a diseased tree as far as the liber. The dressing of the wounds, which ought to be kept as clean as those of man, is done thus : If the disease be so deep seated as to necessitate exposing the INTRODUCTION. 7 wood, a protective coating, after cleaning, is spread on the surface of the wood, which preserves the wound from contact with the air, but if there be a living piece of bark (parenchyma, cortical fibres, or liber), whether in the heart of the wood or on its edges, it must be respected and protected by some folds of the suberose layer. In this latter case, the application of a coat of tar would be fatal, especially if used hot. The artificial wound method is practised to restore health to a tree whose bark is invaded by scolytus. Longitudinal incisions are made on the parts attacked, penetrating the cortical layers only as far as the liber. In serious cases, a narrow band is removed from the suberose layers. This superficial incision induces a flow of sap, leads to the formation of new tissue, and stops the transversal progress of the larvae of the scolytus. If the tree has been invaded in all parts by scolytes, the great part or even the whole of the circumference of the tree is decorticated but so as not 'to wound living tissue. When the strips are removed, hems are formed ; when the tree is completely decorticated, a network of cortical fibres is seen to form on the sur- face, the diameter of the tree grows, and a new bark is formed. Surgical interventions of this kind, although rarely employed, may be useful when chemical treatment has no effect. Methods of Destroying Parasites by the Naked Hand.— When a parasite is of appreciable size, and especially when it forms visible and accessible colonies, its suppression by catching gives immediate results. On a large scale the parasites may be induced to localize themselves in spots where their destruction is easy. According to circumstances the methods used are (1) Picking or catching, (2) Traps or baits. Picking and Catching. — Coleopterous insects (cockchafers), grubs of butterflies, especially when they live in colonies, the agglomeration of eggs of certain Bombyx (Ocneria) are picked. This picking is gener- ally done by hand. However, when it is desired to pick small insects rapidly, tinned iron funnels with a wide mouth are used, above which the infected organs of the plants are shaken. The neck of the funnel is connected with a cloth sack into which the parasites fall (altise of vine). The gathering of insects on farm land is also accomplished by aid of poultry. For this purpose there are portable hen-houses, which are drawn into the middle of the fields. The poultry wandering about at will soon free the plants and the soil from all their parasitic insects. It is a very cheap, useful and ready method.! Traps and Baits. — To facilitate the collection of insects and their larvae artificial shelters fixed on the plants have been tried. The trunks of trees in autumn have been girdled half-way up with un- dulating cardboard bands of about four inches wide or with bands of straw. All the insects which hibernate as perfect insects take refuge there. All that has to be done is to remove and burn the refuges. This process is of frequent use in Germany to destroy the vermin of fruit trees. 1 Translator's iV^oi!e,— Neither British farmers nor British gardeneis take kindly to poultry, and both would regard the cure as worse than the disease. 8 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. Traps fulfil the same purpose as shelters, they draw the insects to a certain point and render them more accessible to destruction. When a polyphagous (omnivorous) insect has a marked predilection for a plant," trap-plants are sown between the lines of the crop. The insects prefer to seek the trap-plant, on which it is easy to collect them or destroy them by energetic chemical means, destroying both the insects and the trap-plant at the same time. The larvae which ravage the plants in the soil may be destroyed by analogous methods. Fleshy roots or tubers are buried in the soil between the rows of the cultivated plant which are removed when the parasites have chosen a domicile there. Nematodes and grey worms, which are polyphagous but have a marked predilection for certain tubers, are destroyed in this way.'^ Lantern-traps are used to destroy winged nocturnal para- sites, butterflies, and coleoptera. They form luminous fires which attract the moths at night. Acetylene lamps fitted with a reflector and surrounded with a plate coated with birdlime retains the nocturnal visitors. This process is used in viticulture in which it helps to lessen the Pyralis and the Cochylis. Therapeutical surgery is there- fore chiefly used to combat animal parasites. Chemical Treatment. — Cryptogamic diseases require chemical ti'eatment, for it is a case of overcoming organisms so infinitely little that the eye can often only see them with difficulty. Curative Treatment. — The chemical treatment consists in placing the parasites in contact with substances which have an injurious effect on them. Insecticides are used to kill insects ; ayiticryptogamics or fungicides to combat parasitic fungi. To get the best results from the use of chemical reagents, it is desirable to know the properties of the curative agents and the right method of using them. Examination of Curative Agents. — The chemical products utilized in the struggle against parasites ought to respond to the following different requirements : (1) To destroy the pal-asite or. arrest its evolution. (2) To be more poisonous to the parasite than to the plant. (3) To preserve their poisonous properties for a certain time and to adhere sufficiently to the organ of the plant. (4) To enter into inti- mate contact with the parasites or their elements of propagation. Action of Chemical Products on Parasites. — Most of the chemical agents employed against parasites act chemically on their vital substance. The most active are in general those which form inei^t derivatives with it, which precipitate the albumen or which modify the plasma ; such are corrosive sublimate, formol, copper salts, phenols, etc. They thus arrest, temporarily or definitely, the evolution of parasites or their elements of propagation. In the case of bacteria the phenomena of intoxication may be more easily observed. It is then observed that their evolution and reproduction are arrested by the formation of an inert layer around them. It suffices often by prolonged washing of these bacteria with appropriate liquids to re- move the immobilizing layer and to allow them to resume under normal Translator's Note. — As many as 150 wire-worms have been trapped by rape cake, etc., 2-3 inches underground close to one hop hill by Whitehead. INTRODUCTION. 9 conditions the sequence of their uninterrupted evolution. The chemical agents do not therefore necessarily kill the parasites and their organs of propagation ; often they only paralyse for a certain time the normal evolution of the parasite. The more the therapeutic agent is capable of insolubilizing albumen, or of modifying the substances constituting the cells, the more active it is. Wuthrick (" Zeitschrift fiir Planzen krankeiten de Sorauer," 1892, p. 81) examined the comparative action of various substances on the different spores of fungi. His researches, in which mention is made of the relation which exists between the molecular weight of the chemical products and their action on parasites, leave no room for doubt on the subject of the sinirilarity of the action of various chemical products on the vital substances of parasites. Other poisonous chemical products act on parasites, some in virtue of their properties as solvents of organic matter, such as the caustic alkalies, alkaline soaps in aqueous or alcoholic solution, and certain acids, others by their dehydrating action exerted chiefly on the medium on which the parasite lives. No parasite living in an aqueous medium can develop except when the amount of water contained therein does not descend below a minimum. A disease may be stopped if the conditions of existence of a parasite be modified in this direction. Other chemical products are asphyxiants : impalpable powders, and oils and fats ; they obstruct the respiratory passages. Action of Chemical Products on Plants. — The chemical pro- ducts used to combat plant diseases have all, to a certain extent unless insoluble, an injurious action on plants. The plant is gener- ally less sensitive to chemical agents than the spores of fungi, and more sensitive than insects, their larvae, and their eggs. Liquids Spread on the Surface of Plants may penetrate therein by endosmosis, whilst gases and vapours do not appear to be, or are with difficulty, absorbed by the plant. It follows that the treatment of plant diseases may be preferably done — 1. By iiroducts under the form of gas or vapour. 2. At a time ivhen the organs lohich ])ermit endosmosis no longer exist, and luhen the cellular activity of the plant is reduced to a mini- mum, that is to say, in lointer. At that time of the year chemical agents of any degree of concen- tration may be used without injuring the plant, whilst in summer infinite precautions must be taken not to destroy the organs of the infected plant at the same time as the parasites. Treatment by gas 13 very efficient, and is becoming more common every day, whether it be the treatment of the part of the plant above ground (aerial), or of that underground, the roots being infected as frequently as the stems by parasites injurious to their normal evolution. With this end in view injections of carbon disulphide, petroleum, benzene are made into the soil, and by enclosing (clochage) the part above ground, an atmosphere may be created charged with sulphurous acid, carbon disulphide, prussic acid, nicotine, etc. When solutions or emulsions of the chemical agents are to be used in spring and in summer, the sensitive- 10 INSECTICIDES, FUNGICIDES, AND WEED KILLEES. ness of the plant towards these ingredients must be known. Each plant possesses its own particular sensitiveness towards substances poisonous to parasites, and it is desirable to use these substances, in each instance in an appropriate degree of concentration. AA'hen the sensitiveness of the plant is gi'eater than that of the parasite, there is reason to abstain from the use of such substances, or it is then necessary to follow the spraying by washing with pure water, only giving them the time required to act on the parasite. This latter precaution allows the use of strong doses of toxic substances, doses w^hich would kill the plants if the w^ashing did not intervene to prevent prolonged contact. Indispensable Properties of the Chemical Agents. — The chemical agents should be of such a nature as to guarantee reaching the parasites. Certain insects and their larvae are covered with hair and down, or even with a coat of wax, which prevents aqueous solu- tions from reaching them. The insecticides which should be employed in such cases are alcoholic, ethereal, or oily solutions, soaps and caustic alkalies having a solvent action on the organs of protection, and capable of moistening them, so as to let the toxic sub- stances penetrate as far as the sensitive organs of the insect. The treatment should often be curative and preservative, and it is then necessary that the substances used should persist for the longest time possible on the surface of the plant. This problem would be easily realized if rain did not remove in a short time the deposit of substances created by spraying. Attempts have been made to protect plants from the effects of the natural washing by the use of substances of poor solubility in water, and with a perfect adherence to the organs of the surface treated. The agents only slightly soluble in water spread on the surface of the plant, m the form of bouillies, form deposits which the rain cannot remove owing to their own adherence, or to an adherence acquired artificially, by the incorporation of gluey substances, insoluble in water (silicate of soda, saccharates, soaps, gelatine, rosin). But cai-e must be taken not to use too insoluble substances and in too great quantity, for there is a risk of covering the whole of the respiratory surface of the leaves wath a layer rendering the exchange of gases impossible, which, if it does not cause asphyxia, produces at least an annoying disturbance in the growth (evolution). The insoluble, or the only slightly soluble products are, in general, of greater service than the soluble products. In addition to their less injurious action on the plant, they persist longer on the surface of the vulnerable organs and their action is of longer duration. The insoluble products are intended to poison insects through the stomach. A slight layer of arseniate of lead, or of arsenite of copper (Paris green), 1 on the leaves penetrates into the stomach at the same time as the leaf and kills the insect. In the case of cryptogamic parasites, slightly soluble substances are used, which in contact with the dew causes it to become toxic, owing to the traces of poison which it has dissolved, and to kill the spores, which require its aid for their evolution. Briefly, it is necessary in each particular case to choose 1 Note by Tra7islator. — Arsenite of copper is not Paris green but Scheele's green. Paris green is our emerald green, the aceto-arsenite of copper. INTRODUCTION. 11 the appropriate remedy and to use it with discretion. It is the most difficult side of vegetable therapeutics. The therapeutic store contains a great number of products the action of which is analogous. Those which can be usefully employed can be reduced to a small number. The most interesting are carbon disulphide, bouillie bordelaise,^ lime, sulphur, sulphate of iron, sulphuric acid, emerald green, soap-emulsions of petroleum and alcohol, tar, prussic acid, tobacco, and nitrobenzene. The greater number of the chemical products which have been the subject of experiment against the diseases of plants are, nevertheless, dealt with in this treatise, and deductions drawn from the aggregate of the results obtained by the experimenters. The results which have been published are so very different, and the opinions expressed so contradictory, that the author has been obliged to control the facts by personal experiment before expressing aa opinion. Laboratory experiments do not always permit of the conclusion that their results will be confirmed in actual practice ; parasites have natural means of protection which are awanting in the laboratory, but which enable them in a natural state to escape very often from the deadly action of the agents used. Experiments, therefore, to which most weight is attached are those made in practice. According to their mode of action and their nature, chemical agents are used and applied in very different ways. Methods of Using Chemical Products in Treating the Diseases of Plants. — Insecticides and anticryptogams are used in three forms : (1) As gas. (2) As powder. (3) In the state of solution or suspension in a liquid vehicle. Use of Chemical Agents in State of Gas. — Gases are used in closed spaces under a cloche'-'- or in the soil. For this pur- pose there is utilized either liquids which evaporate at the ordinary temperature or solid products which disengage gas by heat, combus- tion, or chemical decomposition. In any case it is necessary that the gas mix perfectly with air and reach all the corners of the area to be disinfected. In closed spaces that is comparatively easy, in the soil it is more difficult to realize. Underground Treatment. — Injections of volatile liquids are made in the soil at suitable depths by means of an instrument called the pai injector (fig. 5, p. 63), when by sprinkling the soil with water the gas which is disengaged is enclosed. When such treatment is carried out with the necessary care, so as to avoid the contact of the liquid sub- stance with the roots of the plant it yields perfect results. But diffi- culties are encountered due to the nature of the soil. If it be easy to disengage toxic gases in a friable soil it becomes difficult to spread the gases uniformly in a compact wet soil. Gases circulate with difficulty through certain soils, and are not retained long enough in others. Water creates an impenetrable barrier to the circulation of gases. 1 The translator has retained the original French term throughout. The usual English rendering of the term as " Bordeaux mixture " being, in his opinion, a poor rendering. All bouillies are perforce mixtures, but only a few mixtures are bouillies. - Note by Translator. — A bell- or dome-shaped glass vessel familiar to those who dab le in the French style of gardening recently resurrected in Great Britain but well l^nown to London market gardeners at least 150 years ago who even in those early days used them by the hundred. 12 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. The gases produced in the soil should not enter into reaction therewith and be fixed by the substances in the soil. From this point of view carbon disulphide is the best substance. Other substances, such as tar, petrol, benzene, sulphuretted hydrogen, are retained by the capillarity and chemical action of the soil which often energetically opposes their distribution. To avoid failure it is well to give the preference to insecticides in dilute solutions in winter, and to volatile insecticides in summer, when the soil is dry. Aerial (or above ground) Treatment by Gases. — Clochage, or treatment in a closed space, gives the most certain results, and does not exert an unfavourable influence on the development of the plant. Highly poisonous gases may be used against parasites, because they do not generally have a deadly action on the plant, especially when con- tact with the plant is not prolonged beyond measure, which result is obtained by aerating after a predetermined time. Clochage is used to disinfect the vine by sulphurous acid. The stock is covered with a cloche made of a tun (cask) cut through the middle, or with a zinc receiver fitted with two handles. Under the cloche the gas is disengaged by combustion or by chemical decomposi- tion of certain salts : sulphur is burnt, or potassium cyanide is decom- posed by sulphuric acid. The operation is finished in ten minutes. In greenhouses or in closed spaces made around fruit trees or against espaliers with waterproof awning, the operation is performed in the same way. In all cases where disinfection by gas is possible, it ought to be applied as a process sure to disinfect without injuring the plant treated. It is the only process applicable to food warehouses. Treat- ment by gas is always curative. When this treatment is not applicable recourse is had to treatment by boiling water, or solutions of toxic substances, emulsions, or pulverulent products. Scalding or treatment by boiling water finds a very extended use in winter to kill by heat all parasites and their germs lodged along the trunk of a plant. But that is a winter treatment which cannot be applied in summer, the delicate organs of the plant not being able any more than the parasites to support contact with hot water. Use of Chemical Agents in the Form of Powder. — Non- poisonous but asphyxiant powders are used such as they are ; toxic powders are reduced more or less according to the intensity of their insecticidal or sporicidal capacity with flour, talc, chalk, or any other inert matter, finely divided and cheap. The powders are projected on . to the plant by means of bellows called sulphurators (figs. 3 and 4, p. 47). Powders may be projected where liquids cannot penetrate. Liquid treatments are sometimes alternated in the struggle against stubborn diseases with pulverulent treatments of the same composition. Use of Chemical Products in the Liquid Form. — Poisonous substances in a state of solution are used in both the external and internal treatment of plants. In the external treatment the poisonous substance is spread on the plant, whilst in the internal treatment it is introduced into the juice, either by causing it to be absorbed by the roots or by injecting it into the trunk. External treatment is most INTRODUCTION. 13 generally used, and it is from it that the most successful results are to be anticipated. External Treatment : Liquids. — Solutions, bouillies, emulsions are much more used than gase'? and powders owing to their easy use. These preparations are distributed by the spraying machine (figs. 8-12) when the treatment is general, and by the brush when it is local. The efficiency of the treatment by liquids depends to a great extent on the mode of application. The substances should be projected in a finely divided state, best in the form of a mist, because it is less important to accumulate large quantities of substance in a given point than to spread a little everywhere in a uniform manner, above as well as below the leaves, on the twigs and on the trunks. The largest number of points of contact between the spores of the fungi or the insect and the poisonous solution must be secured. The appliances which attain this object are the spraying machines which have reached a high degree of per- fection. The liquid preparations must possess a certain degree of concentration to be active. It is injurious to increase this concentra- tion, and dangerous to diminish it. When a liquid preparation has a poisonous action on the plant, or if it has no adherence, these draw- backs may be obviated by multiplying the treatments with a weaker preparation. It has been found that it is better to diminish the strength of the applications and to increase the number of spray- ings, for it is the abundance of these rather than the strength of the preparation which forms on all the organs, in proportion as they are developed, an extremely thin layer of a toxic substance capable of preventing the development of spores or of poisoning parasites. Experience has proven that periodically spraying at short intervals with weak bouillies yields far better results than a single annual spraying with concentrated bouillie as formerly practised. The single spraying with a 4 per cent copper sulphate bouillie used some years ago has been replaced by three to seven treatments with bouillies prepared with 0'5 per cent of copper sulphate. Although the total amount of copper spread on the surface of the plant be mostly less than formerly, the result is better, because all the surface of the plant remains covered with a very thin pellicle of hydrated oxide of copper of which a trace dissolved in rain water or dew suffices, as has been found, to kill the spores which are germinated. This new process is the more efficient because it especially guarantees against disease all the young organs of the plant, which being more tender and more aqueous, are more easily invaded by parasitic fungi and have there- fore a greater receptivity for cryptogamic diseases. The perfection of the treatment is, therefore, an element as important to secure success as the properties of the product. When anti-cryptogamic substances are used, it is necessary to bear in mind that the external treatment of a plant cannot destroy the mycelium of the fungus which has penetrated into the plant, and its multiple ramifications in the interior of the latter are perfectly protected from all outside spraying. The ex- ternal treatments are intended to destroy the organs that disseminate the disease, the conidiophores and isolated spores, and thus prevent the extension of the disease to other plants. If for any reason the treat- 14 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. ment has been deferred and the disease has assumed a great extension, it is well to remove before spraying the parts of the plant most seriously attacked and to burn them ; that is a surgical complement to the chemical treatment which may be of great service and which must not be neglected if one be anxious to suppress the disease. It is well to say that neglect of one factor may compromise the results of the treatment by liquids and rob the experimental effort of any beneficial result. I Internal Treatment. — From analogy, with the treatment of human diseases, attempts have been made to introduce into the sap of the plant toxic elements, intended to be carried through the plant, and to destroy the mycelium of fungi which have invaded it, or to kill xylophagic insects and those which suck the sap. The experi- ments of Laffitte and Henneguy have shown that a substance dissolved in water, absorbed by the roots, may ascend to the leaves and reach the extremities of the tree if it does not form insoluble compounds with the constituent elements of the sap ; however, the greater number of salts yield with the plasma insoluble derivatives, which prevent their entrainment by the sap towards the part of the plant attacked by the parasites. Numerous experiments have been made in this direction to combat the phylloxera. The method used, it must be confessed with mediocre success, consisted in making a hole in the vine stock from above downwards by a gimlet, and in introducing therein the chemical agents such as calomel, camphor, potassium sulphide. These were the first experiments carried out under very bad conditions, nevertheless carbolic acid, used by Green against lice, prussic acid against bugs, have given appreciable results. The first fortunate results were obtained by Mokretzki with injections of a dilute solution of sulphate of iron, and nutritive elements which he injected into the sap to cure chlorosis. These were crowned with complete success. But they must be executed in such a way that the air cannot penetrate into the wound, and a slight pressure is required to enable the liquid to enter into direct contact with the sap of the plant. However, when Mokretzki tried sulphate of copper under the same conditions, his experiments were a failure. It is possible, however, that oi'ganic salts of copper soluble in the sap may behave as indifferent salts, especially if used in small doses, and produce the satisfactory eifects on the health of the tree given by dilute solutions of sulphate of iron, and by sprinkling the soil with sulphate of copper. Metals are capable of forming organic salts, which no longer precipitate albumen, and, injected into the sap, may behave in quite a different manner from the corresponding inorganic salts. These organic salts have found multiple applications in human therapeutics, and it is to be supposed that their use will extend in the domain of vegetable thera- peutics. The internal treatment discovered by Mokretzki will perforce extend further when it has been determined under what form poisons can be incorporated with the sap, and especially in what degree of concentration they should be used. These remedies will form a powerful instrument against all sucker-lice, and will be capable of arresting the internal evolution of the mycelium of parasitic fungi. INTRODUCTION. 16 But vegetable therapeutics will often yield imperfect results in spite of all the attention brought to bear in the application of appropriate remedies, for it is difficult to dislodge or to destroy in the interior and on the exterior of a plant without injuring it the parasites which develop there, surrounded by the very efficient means of protection which nature has given them ; and if we insist on this axiom, that a plant disease cannot be cured, but that it can only be diminished or its extension prevented, the important role which preventive methods play in the struggle against plant diseases will be understood. Prophylaxy. — Prophylaxy is that part of medicine which deals with the means of guaranteeing against disease and preventing it. Knowing the cause or the causes of the diseases it is possible to protect plants efficiently against them. The knowledge acquired as to the reactions of the organism, and the means by which it naturally arranges to defend itself against disease, have enabled prophylaxy to utilize physiological processes instead of agents destructive to parasites. It is necessary to differentiate between therapeutic prophylaxy and hygienic prophylaxy. The former utilizes therapeutic agents, surgical processes as well as antiseptic insecticides, fungicides. The latter employs dietetics, stimulants of growth, rational feeding, selection of vigorous and hardy species. Medicine in its application to plants is in fact as complicated as when applied to man, and it is not surprising to see it necessary to take at the same time prophylactic and thera- peutic measures in order to have crops free from disease. Therapeutic Prophylaxy. — When the cause of a disease is known, its evolution and that of the parasites which produce it, it is com- paratively easy to find the means of checking it by preventive measures. These treatments may be very often carried out at a time when the plant can bear them with impunity ; in winter when the delicate organs have disappeared and when the sap is at rest. One must never wait until a disease manifests itself, even if the possibility of its appearance is not absolutely certain. Preventive treatments if they are not always capable of removing all the effective and adjuvant causes of disease will minimize them. When the cause is a parasitic one, the object pursued is not to destroy all the parasitic elements, but to reduce them to their normal or natural number increased by our methods of cropping. In these conditions, parasites having always ex- isted and their complete destruction being as chimerical and as useless as a complete disinfection of the air which we breathe, with the object of destroying all microbes, disease is no longer to be feared, because it no longer causes us appreciable injuries. Preventive Surgical Treatments. — Operatory medicine may be of great assistance in the prevention of plant diseases ; in fact the suppression of everything which may transmit a disease from one year to another is often capable of giving radical results — excision of the diseased parts, removal of branches attacked or bearing spores or eggs, washing of the bark of the trunk and branches to suppress refuges formed by mosses and lichens for acari, aphides, and coleoptera. In- tervention by naked hand plays a role not less important, by the eollection and suppression of the old organs of plants, leaves, and 16 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. rotten and wormy fruit on which receptacles containing the spores of fungi serve as refuge to grubs and chrysales and as shelter to masses of insect eggs. The destruction of the parasites and their hiding-places by this simple means causes them to disappear completely after a certain time. Birdlime traps preventing insects and their larvae from reaching points that they might ravage, are likewise useful auxiliaries. The most usual trap is the ring of tar or of birdlime with which the trunk of tx'ees is surrounded. The going and coming of apterous parasites between the leafy portion and the soil being along the trunk, the ring of sticky substance drawn round the trunk is intended to stop these often daily journeys and to retain all these parasites stuck fast. An examination of the habits of parasites demonstrates that almost all are forced to use this road ; some to seek a refuge in the soil for the night, others to ascend nightly from the soil in which they had taken refuge during the day. Thus the grub descends along the trunk to place itself as a chrysalis in the soil, and the butterfly, even when it is not apterous, ascends along the trunk to deposit the eggs which weigh down the female. The grey worm and many moth grubs go every morning to find a refuge in the soil, to re-ascend the trunk in the evening. This method, now very common, gives perfect results. In arboriculture it is a powerful auxiliary to the liming of the tree, but it is necessary to watch that this sticky substance pre- serves its adhesive qualities and to renew the ring when these have disappeared. Young fruit trees being sensitive and liable to perish after an application of a ring of tar or birdlime, it is well to fix round the trunk a strip of cardboard well fitted and to coat it with the sticky svibstance. The same result is thus obtained without injuring the health of the tree. Preventive Treatment by Means of Chemical Agents. — The general conditions as regards the properties of the chemical agents used in the preventive treatment of plant diseases are the same as in the curative treatment. The chemical products must destroy the parasites and be more poisonous to it than to the plant ; they must adhere and preserve their poisonous power for a certain time, and enter into intimate contact with the parasite or with its elements of propagation. When such treatments are applied, as is often the case during the repose of vegetation, the comparative insensibility of the plant enables them to be used in doses, deadly to the parasite without injuring the plant. Most fungi living protected in the interior of the tissue are sheltered from the action of the poisons spread on the surface of the organ attacked, and are evolved in spite of the curative chemical treatment. The important point in plant diseases is to destroy the spores which propagate the disease. To attain this result, different spores must be attacked by different methods. If it be a case of destroying winter spores, very energetic treatment must be applied in winter, for these spores have an extraordinary power of resisting chemical agents. If it is a case of killing summer spores, which, on the contrary, are very sensitive and delicate, a treatment with dilute, anticryptogamic solutions will suffice. Preventive winter INTEODrCTION. 17 treatment can thus be distinguished from preventive summer treat- ment. Preventive winter treatment consists in destroying by chemical agents all parasites, and the elements of their propagation. To obtain this i-esult the trunks and branches are painted or washed, after a mechanical dressing with milk of lime, concentrated copper bouillies, 10 per cent solutions of sulphuric acid, hot concentrated solutions of sulphate of iron, boiling water, petroleum, and pure carbon disulphide. These chemical agents, used in such a high degree of concentration, do not injure the plant in winter, and permit of a radical destruction of the parasites. These preventive winter treatments are, generally, sufficient to prevent the diseases from appearing in the following year, especially when care is taken to destroy the decayed organs scattered around the plant, and to disinfect the soil, the dung, and the seed. This last precaution is of an undoubted utility in preventing the diseases of plants cropped annually, and the methods usually em- ployed have now attained a great degree of perfection. Moreover, it is necessary to destroy wild plants of the same species, which are preferred by the parasites which it is desired to destroy, plants which form seats of infection which are necessary to the cyclic development of certain parasitic fungi, such as the rust of cereals, which search for nurse plants of different species necessary for their normal evolu- tion, and the destruction of which brings about the radical su]^;prcssion of the parasite. These plants are the barberry and boragineae ("■■ p. 22). Preventive Summer Treatment. — In spite of preventive winter treatments they must be completed by summer treatments. Working so that the vulnerable organs of the plant are always protected by a fungicide very slightly soluble in the dew, the plant is prevented from succumbing to the incessant attacks of the spores, which the atmospheric currents lead to it. It is a case of very small doses of anticryptogamic agents, which suffice when the treatment is continued during the whole period in which the disease is to be feared. Weak injections of carbon disulphide in the soil and periodic washings of the stock with dilute solutions of potassic sulpho-carbonate have given the best results in the struggle against the phylloxera, without destroying all the parasites they so far diminish their number that they can nO' longer injure the plant. Sulphating every year with weak bouillies. yields analogous results and enables the trees to develop normally. Along with the rational and periodic use of chemical agents intended to kill the greater part of the germs of cryptogamic diseases and insects, it is well to use stimulants to furnish rational nutriment to the plants and to pay attention to their hygiene. Hygienic Prophylaxy. — Vegetable therapeutics does not consist, in fact, entirely in the struggle against the effective factors, but it ought likewise to suppi'ess the adjuvant causes. Plants are restored like animals by the art of healing regarded in its widest scope. Hygiene which plays so great a role in human prophylaxy ought to receive equal attention in the case of vegetables. This hygiene is based on a knowledge of their organs, and their mode of growth, on that of the environment where they live, and the climatic conditions which favour their development, and the mineral elements indispensable to 2 18 INSECTICIDES, FUNGICIDES, AND WEED KILLERS them. It is necessary to remove bad influences from plants, and to supply them, if need be, in a regular and abundant manner with the nutritive elements which they require. If it be asserted that a disease can be transmitted to a plant by artificial infection when placed in a laboratory where it has not all its means of reaction, it must not be concluded therefrom that this same plant will always succumb to this parasite in surroundings favourable to its develop- ment and in good hygienic conditions. Owing to a special immunity which is not acquired, except under certain conditions, the plant, on the contrary, will be able to resist the attempts of invasion by the parasites and will issue victorious from any struggle in all instances. Most cryptogamic parasites are incapable of attacking the living vigorous and healthy cell. Certain insects, even xylophagic, such as the Scolytes, only attack a sickly tree, the intense motion of the sap being injurious to the development of their larvae. On the other hand, most parasites find an easy shelter in the plant when the latter is enfeebled by an adjuvant cause, or when organs capable of being invaded have been laid bare by a wound. Stimulants of Growth. — We know from the researches of Raulin, Nageli, Pfeiffer, Richard, and Ono the favourable influence which certain metallic salts absorbed by the sap can exercise on the health of plants. Salts of iron, copper, mercury, zinc, nickel, cobalt, manganese, lithium, fluorides, and arsenites have in a certain dose a stimulating action on the vital functions of the plant, analogous to that which arsenious acid exercises on our own organism. The use of these stimulants may often be a useful means of stimulating the vigour of the plant, and of rendering it more capable of resisting ■cryptogamic diseases. Nutrition. — The researches of Liebig, Boussingault, Deherain, and others have shown that the development of plants depends greatly on the mineral elements which they find in the soil, and nothing is more easy than to supply them when the soil is deficient therein. The result of these researches has been intensive farming, which by supplying in great abundance the elements, necessary for the growth of plants has rendered it possible to double and triple the yield of crops. Encouraged by such success we have learned to prepare an exact account of the elements indispensable for each plant crop by the analysis of its ash, of the elements of the soil, and taking into account the nutritive elements that the preceding crop has removed and add- ing to the soil the elements in which it is deficient. It has been ob- served, however, that the plants obtained as a result of intensive manur- ing were more subject to diseases, and that such assumed a dangerous character. The great delicacy of the plants constituted a more favour- able medium for their evolution, however little the climatic conditions favour their development, and predispose the plants to infection. It must be admitted that the intensive culture now practised does not produce a normal condition of the plant, but a cultivated condition, and that the parasites have acquired a greater vigour and become more virulent owing to the great richness of the plant in nutritive INTRODUCTION. 19 elements. Too abundant feeding of our cultivated plants has created a danger which the farmer of to-day must face. Formerly the method of cultivation gave a mediocre and irregular yield, and the farmer did not disturb himself. There was in the opinion of our fathers, which was fatal, good years and bad years. Diseases existed even then, but they did not in their opinion contribute much to the annual variation in the yields. In our days they have a much more important role, for the cultivation expenses being higher, owing to increased attention and to the use of various chemical manures, the yield ought to compensate for the pecuniary efforts expended. Exhaustion of the Soil. — In spite of the annual supply to the soil of the elements required by the plant for its intensive growth, it is found that a time comes when the plant ceases to profit from the nutritive elements and thrives no longer. This is due to the fact that the enemies of the cultivated plant are accumulated in the soil. The ancient farmers attributed this condition to the exhaustion of the soil, and intercalated the bare falloiv between the crops when this ex- haustion manifested itself. In bare fallow the fields remained several years without a crop. Without being aware of it they thus abolished the provision stores of the parasites, and these disappeared or became reduced to their natural proportion. By this time the field had acquired new vigour, and might be again cultivated. This method cannot be adopted to-day, because it is a loss of time and money. The altei'nation of crops or of different plants having consequently different parasites succeeded each other, and where the same plant did not appear in the rotation except at long intervals it caused a great improvement in this condition of the soil. Rotations would * give perfect results in the absence of polyphagia parasites : Nematoides, Elaterides, grey and white worms which attack all our crops indiffer- ently, and the exaggerated multiplication of which operates through- out the most different crops ; the spores of Ustilaginece (smut, bunt, etc.), which resist the weather for several years, excepted. Against the exhaustion of the soil from the exaggerated development of these para- sites no efficient remedy exists, except disinfection of the soil by car- bon disulphide. This must be done either in a complete manner, and in massive doses every ten years, or in small doses each autumn. It frees our cultivated fields from all the parasites which our methods of cropping have allowed to accumulate in too great number. This method finds more adherents every day, as it enables rotations to be dispensed with and to cultivate the same plant intensively for several years in succession. Artificial manures as well as the metallic salts intended to stimulate the growth of plants should be used with dis- cretion, so as not to predispose the plant by a modification of the sap to certain diseases which formerly it escaped. Laurent found that bacteria, not parasites of the potato in a normal state, might invade it after manuring with lime. The Jerusalem artichoke becomes less resistant to the Sclerotina Libertiana ^ after phosphatic manure. These 1 Note by Translator. — Fungus which ravages potato, haricot beans, hemp, cucumbers, swedes, zinnias, petunias, chrysanthemums. Remedy. — Apply soot or lime to soil. '20 INSKC'TK'IDKS, FUNCtK'I]-)ES, AND WEKD KILLERS. two cases are easily explained, the lir?t by the fact that the bacteria seek an alkaline medium created by the lime, the second by the fact that the Sclerotina seeks, on the contrary, an acid naedium created by the acid phosphate. Intense nitrogenous manuring favours the de- velopment of phytophora. It is thus essential to avoid the use of manures which may place the plant in a state of subjection in the struggle whicli it has to sustain against inimical factors. Choice of Species. — One species may be more subject to disease than another, and possess a predisposition for certain pathological con- ditions. That occurs when the conditions favourable to the develop- ment of the plant are also those which favour the evolution of parasites at the time when the plant is young and possesses delicate tissues just when the parasites are most virulent. Care must be taken in sowing a plant that the germination of the seed does not coincide with the virulent development of the parasite, with the ripening of the spores of fungoid enemies, or the hatching of the eggs of certain insects. It suffices to sow a little earlier or later. But in spite of all that can be done to eliminate parasites, they none the less exist and ravage the tissues. The cells of the plant, like those of the human organism, react, and it is found that after this constant struggle they undergo certain modifications which are opposed to the develop- ment of the parasite, and the plant acquires a certain immunity. It is acknowledged that the deposits of tannin and other materials in certain cells and the concentration of the sap are conditions resulting from the struggle of the plant against insects, and destined to oppose an unsuitable medium to any attempt of development. Plant diseases do not, therefore, depend solely on the presence of a parasite, but as much on the conditions predisposing the plant to a want of reactive energy, and it has been found that this predisposition was an attribute of certain species or certain varieties. Meteorological Influences. — Although we are still badly equipped to struggle against atmospheric influences, each day brings new dis- coveries from which agriculture knows how to benefit. Thus hail and morning frosts may be effectively prevented — hail by artificial per- cussion of the atmospheric layer where hail is formed, morning frosts by means of artificial clouds. Without neglecting therapeutic methods it is necessary to take incessant prophylactic measures to prevent the evolution of diseases and their propagation, to treat the seed, the plant, the soil, and the crops by toxic products, to destroy the plants invaded, which form hot-beds of infection, to avoid the im- portation of plants from districts notoriously infected. Effort must be made to apply a general ti-eatment to the plant, to remove as far as possible all conditions favourable to the growth of parasites. The hygiene of the plant must receive careful attention ; sowing retarded or advanced ; the plants protected against eventual frosts and hail ; drain and lime the soil against humidity, the great predisposing cause of cryptogamic diseases ; apply appropriate strengthening manures ; choose hardy species obtained by crossing or by selection, and create new varieties combining great resistance to plant diseases with the necessary properties of production. So that the struggle may be sue- INTRODUCTION. 21 cessful measures must be general. Each cultivator ought to be able to work in full knowledge of the cause ; he ought to be able to obtain information on the nature of the diseases which he observes, and the means which should be used to combat them. All interested should be able to act simultaneously over a large extent of territory, a con- dition which will alone crown any individual effort with success. There now exist in certain agricultural centres laboratories where all questions are solved gratuitously. These institutions are intended to help cultivators, and to supply them with the means of combating the diseases which ravage or menace their crops. The movement in favour of these institutions where all phytopathologic questions are studied, and which centralize all the observations made by interested parties on the diseases, the presence of which they have observed, is especially accentuated in Germany. When the prosperity of a country is threatened by the appearance of a disease and by its generalization it is necessary to take general measures. These are made imperative in many cases on cultivators by arretes [an arrete is possibly equivalent to our Order in Council]. If one considers that the damages caused annually to French crops by injurious insects, according to the calculations of authorized persons, amount to several hundreds of millions (a million francs = £40,000), that the loss due to cryptogamic disease reaches a still higher figure, an idea can be gained of the great necessity there is to generalize the methods of struggling against parasites, and the neces- sity of simultaneous action by all under the control and the direction of official agents. The first order dealing with the protection of crops against injurious insects is that of the Parliament of Paris of date 4 February, 1732 ; then came the Act of the 26th Ventose Year IV, which rendered obligatory the destruction of grubs in general (modi- fied by the Act of 24 December, 1888). It especially prescribes the destruction of the grubs of Liparis chrysorrhea, the brown-tailed moth, the agglomerations of which in winter and in spring form silky wrappers between the branches of fruit trees. The Order declares that " After the date fixed by the Prefect, farmers who have not submitted to the prefectoral order, will be liable to a fine of six to fifteen francs, and obliged to pay to the administration the expenses incurred by it in grubbing on their domains ". The panic created by the appearance of the phjdloxera in 1863 was followed by an effect which has made itself felt in all branches of cultivation. Examination Commissions were fox'med, a National Agronomical Institute was founded in Paris. Chairs of Agriculture were created, new laws were passed, the Ad- ministration is working with equal solicitude at all cultural pests, and it has enacted the measures required to cope against the ex- tension of diseases. As a consequence of the International Phyl- loxeric Convention held at Berne, an order of 10 September, 1884, interdicted the exportation and importation of rooted-up stocks and of sprouts (shoots). Then the destruction of insectivorous birds has been forbidden. Cultivators too often misconstrue their precious collaboration in the struggle against parasites. Societies for the destruction of parasites have been formed in '22 insecticidp:s, fungicides, and weed killers. cantons, bureaux of gratuitous information opened, enabling interested parties to know the disease which i-avages their fields, and how to prevent it, or combat it, in the most economical conditions. These syndicates are cantonal or communal ; their bye-laws must have pre- fectoral sanction ; their budget consists of the subscription of adher- ents, individual subscriptions, communal, and Government grants. The Council of Administration places the instruments, the insecticides, and the anticryptogamic products at the disposal of those interested ; it publishes the right times to use preventive or curative processes, and gives the detail of the methods to follow ; it directs itself at propitious seasons all the operations tending to the destruction of parasites, and to restore the fertility of the fields through the intermediary of an executive committee which has the direction and the responsibility of operations. Societies have been formed against the " Apple-blossom Weevil," against the may-bug (cockchafer, Hanneton). The annual results obtained by some may-bug societies in a year are as follows : — Seine et Marne . destroved 282,500 kilogrammes.' . Brie Comte Eobert „ ^ 101,000 Aisne ... „ 13 thousand million cockchafers. Bernay dans Eure ,, 148,500 kilogrammes. These figures are eloquent. However, if they show the useful inter- vention of the syndicates established for the destruction of injurious insects, they enable us to foresee the results that these syndicates would be capable of obtaining if their programme was a broader one, and comprised all which concerns vegetable pathogenesis, prophylaxy, and therapeutics. Common action organized in this way under wise direction will be a perfect method to combat agricultural pests and blights so long as no medical specialists for cultivated plants, with the same rank as veterinary surgeons, exist. But there is much ground to be traversed before getting so far as that ; the science which should guide these medical specialists is only in its infancy, and the most important problems are still to be solved. It is, however, necessary to reach this goal so that this younger sister of medicine applied by special practitioners may render inestimable services to cultivation and increase the prosperity of the country. ' Note by Tra^islator. — From the peculiar style of numeration of French writers it is impossible to say whether 282,500 means 282^ kg. or 282,500 kg., that is 282^ metric tons, which seems impossible. Yet even in this country so great were the ravages of Bomhijx chrijfiorrhea in 1782 that pi'ayers were offered up in some churches for deliverance from the scourge and Is. per bushel was offered for the webs, and so abundant were they in Clapham parish that 80 bushels were collected in one day in that parish alone ! * Note by Translator (p. 17). — The tendency of present-day authorities is as regards evolution of rust of wheat to discard the theory of an intermediate host (barberry) in favour of Eriksson's theory of hereditary infection. CHAPTER I. COLD WATER— SUBMERSION— SPRAYING HOT WATEE^ IMMERSION— SPRAYING— HYDROGEN PEROXIDE. I. Water, H.^0. — Water is necessary to the plant (1) as food, (2) as solvent of nutritive matters. To a certain extent crops increase in proportion to the water used in the cultivation. Want of water injures the plant, causes deformities, anomalies, and troubles of which the chief are : pilosis, excess of hair on the stem and leaves, formation of tart substances (piquants), stony pears, lignification of the roots ; nanisme, potatoes with filiform rhizomes, fall of flower-buds, pre- mature drying of the leaves, honey -dew, barren flowers in the case of cereals. But on the other hand, if water is useful and even necessary to the plant, in excess, however, it is injurious thereto. In the latter case it is the cause of the following diseases : frisolee of the potato, rhytidome of the potato, germination of the same plant before potato lifting, hollow fruits, stems and roots, premature formation of seeds, dropsy, gourmands, hypertrophy of the roots, cellular rottenness, frondescence, phyllodia or chloranthia, asphyxia of the seeds and roots, putridity of the seedlings. Use. — Water serves as a solvent or vehicle for most of the agents used to combat plant diseases ; but it can by itself alone serve as an insecticide in many cases, and as it is cheap it is profitable to use it. Cold or hot water is used as follows, according to circumstances : Cold water : Submersion ; spraying. Hot water : Immersion ; spraying. (a) Cold Water, Submersion. — Submersion or artificial inunda- tion asphyxiates the insects living or refuging in the soil. It consists in placing the area of the ground to be treated under water for a period of from two to sixty days, according to the nature of the soil and the kind of parasites to be destroyed. The soil must only be slightly per- meable, the ground must not be on a slope, and it must be near a source of water capable of furnishing 6000-30,000 cubic metres per hectare (2| acres), and to maintain it at that for a certain time. Submersion is not efficient unless it be complete, so that it may soak deeply into the inundated ground and be executed under certain conditions. The submersion of fields and vineyards is in use in different countries of the globe, and everywhere gives encouraging results. The costs of submersion are not great when near a river from which the water can be led ; the expense in that case only amounts to 41 francs per hectare, say 13s. per acre. But when the water has to be brought by elevating machines then it may amount to 200 francs (£8) per hectare, say -63 4s. per acre. To this amount must be added the co=t of manuring. 24 INSECTICIDES, FUNGICIDES, AND WEED KILLEKS. which must be abundant as the immersion exhausts the soil. Sub- mersion was recommended for the first time in France in 186-4 for the destruction of insects in meadows and fields. In 1870 the same treat- ment was applied to vineyards attacked by the phylloxera, and lately it has been used to render forests wholesome. Submersion of Fields and Meadows. — The inundation of meadows and fic'lds destroys the larvue of Coleoptera (beetles, weevils, etc.) and the grubs of the Lepidoptera, of which the following are the most important : (1) Melolontha vulgaris (white worm), larvae of the may-bug (cockchafer). — Artificial inundations have been in general use in Hungary since 1888 to destroy this larva. The meadows are sub- insrsed for eight days, and after that time all the white worms have disappeared. De- la Blanchere has, however, seen water remain more than a month on ground infested with white worms without these being destroyed. That is explained by the fact that the larva of the cockchafer, very sensitive to moisture, to avoid contact there- with buries itself at such a depth as protects it from inundations. But it is only in impermeable ground that the white worm has the time to withdraw itself from the action of water. In such ground recourse should not be made to artificial inundation but to carbon disulphide. During the two years of its evolution, the white worm descends into the soil in October, to a depth of about 2 feet, so as to pass the winter, beyond the reach of cold, and it is only in spring that it ascends to the level of the roots to gnaw at them. Ac- cording to the habits of this insect it is, therefore, in spring and in summer that the ground should be flooded. (2) Phytonomus jnmc- tatus, Fb. — The larvae of this weevil are destroyed by flooding almost at the very outset. In America the cotton plantations are flooded to destroy the numeious parasites in the soil. (3) Agrotis segctVDi, W.V. (grey worm grub of the dart moth). — Flooding to destroy this insect ought always to take place in summer. In many cases flooding of the fields by the excess of moisture exerts a vexing effect on plants by retarding the ripening of the crops, or by developing adventitious plants or parasitic fungi. It is not so, however, with all crops, and it has been observed that submerged beets have more vigour and resist the fungi which ravage them better during drought, such as the Plioma tabifica, the disease of the petiole of the leaves, the Pleospora jmtrefaciens or the heart rot, and the bacillus of the hacillary gummosis of vine. These diseases being less intense after submersion the method is advantageous. Submersion of Forests. — Anderlind has shown the great service which the submersion of forests can render in the destruction of the insect ravagers of w'oods, the larvae of which find a shelter under the moss and humus surrounding the stocks. In the different countries where submersion is in use the most dangerous insects only occasion insignificant damage, it is therefore one of the most powerful preven- tive measures against great invasions of cei'tain forest parasites. The following insects are destroyed by submersion : Melolontha vulgaris, L. (common cockchafer). Weevils injurious to conifers : Hylobius AbiAis, L. (large spruce fir weevil). The Scolytides so injurious to deciduous SUBMEESION OF FIELD AND FOEEST. 25 trees : Hylesinus ater, F, ; H. oi)acus, Er. ; H. angudatus, Hb. ; H. cunicularius, Kn. The sawflies, very injurious to coniferae, because their larvse not only attack the adult needles but prefer to devour the young shoots : Lyda campestris, L., and L. jyratensis, L., the larvae of which bury themselves in August in the moss at the foot of trees to pass the winter there. L. erytlirocejihala, L. (red-headed Lyda), the larvae of which hide at the foot of trees in the month of June. Lo-plmjrus Pini, the larvae of the second generation metamorphose into grubs in the humus of the forest after passing the winter there. Gryllotalpa vulgaris, Latr. (mole cricket). Winter submersion has little action on it, because like the white worm it descends deeply into the ground at the approach of cold. The following Lepidoptera : Lasiocamjna Pini (or bombyx of the pine), the grub of which hibernates as chrysalis in moss at foot of ti-ee. Trachea jnnipercla and Fidonia piniari, L., both hibernating in ground in the state of chrysalis. Submersion also frees the forest from the rodents which undermine it, and which in winter nibble the bark of young trees. But if on the plain the difficulties of submersion are not great, on the slopes where it is necessary to trace a series of parallel channels which flood the ground, by overflowing, this method becomes very costly, especially if it is necessary to raise the water by means of turbines or pumps. Antiphylloxeric Submersion. — In the beginning of the phyllo- xeric invasion in 1868, the sands of the dunes (sandhills) were found to be unfavourable to the propagation of this dangerous homoptera. The fact was observed at Aigues-Mortes, where vines planted in the dunes remained flourishing, whilst those planted in the neighbourhood died without exception. According to Foex the sands exhibited a certain immunity to the phylloxera when they contained at least 80 per cent of silica, but a small amount of clay or limestone sufficed to deprive the soil of this precious property. This immunity, studied by Van- nuccin at the viticulture laboratory of Montpellier, would appear to be due to the asphyxia produced by the water retained by capillarity between the grains of sand. Is that water sufficient to cause the asphyxia of the insect ; is it not rather the physical constitution of the sand which hinders the passage of this insect from one stock to another? That is a point which has not yet been proven. Balbiani disputes the theory of the asphyxiant action of water in permeable ground consisting almost exclusively of silica ; he has in fact caused young phylloxera which he had hatched in a sand medium to live under water for fifteen days. On the other hand, Faucon has observed that it takes forty-five days' immersion in water to kill the phylloxera. Now, sands are never impregnated so long by rain-water. Be that as it may, it was this immunity of the sands which gave the idea of submersion for the destruction of the phylloxera. It had formerly been remarked that long-continued rain w^as unfavourable to it, and that it shunned moisture by burying itself in the soil at great dej^ths, only dying when the soil was thoroughly soaked. Eminent vine- growers, Faucon and P. Castelnau, concluded that submersion might be efficient, and since 1870 have submitted a part of their vines to this treatment. The results obtained were surprising. The following 26 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. table prepared by Faucon gives an idea of the improvement in the crop by the submersion of the vine : — TABLE l.—Showmg the Effect of the Systematic Immersion of Vineyards on the Volume of Wine Produced. Year. 1867 1868 1869 1870 1871 1872 1873 1874 1875 Remarks. Year before the phylloxera invasion First year of invasion vines fumigated, non-svib merged Second year of invasion vines fumigated, non-sub merged First year with submersion without manure . Second „ ,, ,, Third year with submersion and manure Fourth „ „ „ (frost) Fifth Sixth Wine in hectolitres. 40 35 1-20 450 849 736 1135 Wine in gallons. 20,350 880 770 2,640 9,900 18,678 16,192 24,970 58,960 Henceforth submersion was not slow in finding numerous partisans. It has been practised a little all through France, and its use has ex- tended to abroad. At the present time its efficacy is entirely accepted, and also the manner in which it is necessary to operate without injur- ing the submerged plants. In many districts the vines have been saved from complete destruction, and in other districts, formerly un- cultivated, productive and flourishing vineyards have been created. Camargue is an example. In this district, where, however, the inun- dation water is chai'ged with salt, submersion presents special difficul- ties, and good outfalls must be organized if it is wished to avoid seeing the salt appear at great distances. Submersion in Actual Practice. — To submerge certain privileged vineyards the water of a neighbouring river may be deflected in part and brought on to the land by a natural slope. In countries where water is scarce it has to be propelled on to the land by powerful cen- trifugal pumps working day and night. In all cases of winter submersion the vineyard is divided into compartments of 4-6 hectares (10-15 acres), separated from each other by small dams and communicatory through small ditches. Before running on the water, care must be taken that the surface is well levelled so that the water spreads regularly. In very windy districts, such as Vaucluse and I'Aude, Barral advises the vineyard being divided into more numerous compartments, the divisions between which serve to break the waves raised by the wind before they attain too great an amplitude. Duponchel, an advocate of undei-ground irrigation, advises, in execut- ing the latter, to excavate around each stock so as to lay bare the roots of the tree, thus forming as many closed basins which communicate with each other by small channels. Water is made to flow therein and is imbibed to a great depth by the soil around the stocks. When the ground is sufficiently wet and all the water has been absorbed, all SUBMERSION OF VINEYARDS. 27 that has to be done is to fill in the excavation with the dry soil placed on one side, to spread it and rake it. Submersion is performed either in winter or during the active period of the vegetation of the vine. A. Winter Submersion. — Winter submersion is a process which cannot evidently be applied everywhere, and which requires special conditions, of which the following are the principal : (1) The ground must be slightly permeable, or very permeable but with an imper- meable subsoil, such as is met with in the low plains of the French coast, and in isolated spots in the river alluvial soils of some of the chief water-courses. It is evident that too great a permeability of soil would require too large a volume of water. The daily decrease in the level of the water should not exceed a maximum of 10 centi- metres (4 inches), a centimetre in depth corresponding to 100 cubic metres of water per hectare, say 1404 cubic feet per acre. (2) The ground ought to be perceptibly flat or very slightly inclined, a slope of 3 centimetres per metre (3 in 100) rendering submersion impracticable. (3) The vineyard should be situated, if possible, near to a stream of water, to an abundant spring, or to an artesian well, for it requires at least 6000 cubic metres of water per hectare, 84,780 cubic feet per acre. During the duration of the submersion, there is a daily loss of water, not only from absorption by the soil but also from evapora- tion into the atmosphere. The amount of water absorbed daily and the duration of the submersion have been studied by Chauzit and L. Tronchaud-Verdier, who have prepared the following table : — TABLE II. — Showing the Daily Loss of Water b\ during Submersion. Absorption by Various Soils Soil. Duration of Autumn. Submersion. Winter. Daily Loss of Water. Slightly permeable Fairly 1 ermeable .... Very permeable . 50-55 days 55-60 „ 65-70 „ 90 55-60 days 60-65 „ 70-75 „ 90 „ 1 centimetre 1 to 4 centimetres 4 to 7 8 to 9 Evaporation into the atmosphere averages 6 millimetres in twenty- four hours in winter, though it reaches 10 millimetres in summer. (That is at the rate of an output of 1 litre per second per hectare, which is calculated in general as the general output of the channels serving to irrigate meadows.) (4) The duration and efficiency of the submersion, moreover, depends on the climate. It is known that in France it can only be practised in the centre and south. In the north the vines would have to pass the winter surrounded by ice, which w^ould seriously injure them. The duration of the submersion should average sixty days in south and thirty days in central France. B. Submersion During the Active Period of the Vine. — Where large quantities of water are deficient, summer irrigations, recom- •Ir> INSECTICIDES, Ef N(tK l DKn, AND \\i;i;i) KILI.ERS. mended by Dupouchel, Chauzit, and Dr. Debray, may be adopted. Debray has, in fact, remarked that the phylloxera is killed more easily during the active period of the vine, and that the duration of the submer- sion can be reduced to eight days in September, while fifteen to twenty days are required in October, and forty to sixty daj^s in winter. In this connexion the underground irrigation described by Duponchel produces the best effect. So that submersion may be complete and efficacious, i.e. so that the water can penetrate 2 feet into the soil, it requires 1000-1200 cubic metres of water per hectare, say 250-300 litres (55-66 gallons) of water per stock. It is executed during dry periods, when vegetation is not very active. It has been found, on the other hand, that short, r3peated irrigations lasting forty-eight hours in summer, especially if underground, are as injurious to the phylloxera a3 long winter irrigations. Whilst even three days' immersion in cold districts are injurious, underground irrigations of forty-eight hours in the dry regions of the South have a favourable action on the development of this plant. The causes, which in the exceptional con- ditions of the French climate insure the prosperity of the vine and the quality of French wines, are none other than the climate itself and the method of culture applied, the hoeing of the soil. It creates on the surface of the soil a shallow layer of friable earth, which by break- ing the continuity of the capillaries arrests all evaporation from below. The rain-water thus imprisoned in the soil without com- munication with the exterior air constitutes that lasting store of underground moisture, which can only be evaporated by the plant which aspirates it by the roots and which loses it by the leaves. The sap thus elaborated acquires that peculiar property of being specially apt to develop fruits, whilst in moist districts submerged too often the more aqueous sap perfectly produces herbaceous vegetation and yields few grapes. To produce grapes of superior quality the fruits must be developed in a warm medium, and the roots be in a moist and warm medium. These essential conditions are awanting when prolonged superficial submersion is practised, but are not greatly affected by the underground irrigations recommended by Duponchel. Superficial sprinkling of the soil never gives useful results as regards grapes, l)ut develops branches full of leaves {pampres). The super- ficial evaporation of the water so sprinkled by cooling the soil must retard the ripening of the crop. Submersions would therefore in general be rather prejulicial to the quality of the crop of a healthy vine. As a curative agent, they produce, on the other hand, two effects equally advantageous, they enable the vine to reconstitute its radicular apparatus (root hairs) more or less atrophied by the gnawing of this lous3. From this point of view, the irrigation of the vines may be regarded as of practical utility, but it should be executed with the greatest of precaution so as to modify as little as possible the special conditions which insure the quality of the grape. A sufficient imbibition must be created to be injurious to the phyl- loxera, and favourable to the development of root filaments, avoiding all loss of heat by superficial evaporation. These conditions are realized by underground irrigation, especially if it be accompanied by SUBMERSION OF VINEYAEDS. 29 the addition of nitrogenous manures. In spite of the good results obtained by submersion and underground irrigation, these can only be regarded as a palliative and not as a curative method. Long winter submersions, short summer irrigations, do not kill all the phylloxeras which ravage the roots, and a new invasion always occurs ; thus the treatment should be annual. To diminish the number of the insects and stimulate the vegetative energy of the plant is not a sufficient remedy, and to re-establish the health of the plant it is well to destroy the parasites by pow^erful insecticides, such as carbon di- sulphide and sulphocarbonates, at the same time as the radicular system of the vine is strengthened by subterranean irrigations. Simple submersion along with strong manuring, by stimulating grow^th by moisture and fertilizers perceptibly diminishes the action of the phyl- loxera ; but it only creates, in reality, a modus vivendi between the parasite and the plant. In these conditions the latter may produce abundant growth of leaf, but it will only give in the majoiity of cases a mediocre grape. It follows from the interesting researches of Maquenne and Deherain, that when a soil is withdrawn from the action of oxygen, as happens when it is covered by a sheet of water, the nitrates which it contains disappear rapidly, owing to the action of certain reducing ferments. On the other hand, Muntz has tried to find out how the roots of vines immersed for two months can respire. This long privation of air ought to be injurious. To prove it, Deherain and Vesque submitted vines for fifteen days to immersion in. distilled water, and found that they rapidly died, whilst others placed in aerated water were in perfect health. It is, therefore, the want of oxygen which in submersion may well prove fatal to vines, and that more readily when it is practised during the period of activity of the sap. Eiver water used for submersion is the best, because it always contains air and nitrates, and vines submerged in these conditions resist for two months at least. That is an established fact which it is interesting to explain. The above-named scientific observers believe that the nitrates reduced by the ferments are converted into laughing gas which contains oxygen, and may support the respiration of the roots. This reduction observed in submerged land may become useful to vegetation, as it prevents the asphyxia of the vine. It is thus necessary to spread on the land an appreciable amount of nitrate if it be desired that the submersion should not injure the vine. French vine growers use in fact 600 kilogrammes of nitrate per hectare (528 lb. per acre), which is in no way exaggerated, but appreciably increases the cost of immersion. Certain muddy waters, such as those of the Dordogne and Garonne, for example, enable the amount of manure to be reduced a little. How^ever, in spite of all the care brought to bear on immersion, there are vines which do not support the treatment. Espitalier cites the following species which die very rapidly : La Carignac, le Grenache, le Mourvedre, la Clairette, le Malbec, le Merlot, and in general all the valuable species, whilst the Cabernet, the Petit Bouschet, and I'Aramon accommodate themselves well to it. This explains why simple immersion has been replaced in large vine-growing countries like the Gironde by irrigations with 30 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 8ulphocarbonate. Another dvawback of submersion is that the vines planted in low grounds are attacked by all the cryptogamic parasites which multiply in moist districts and sutfer more therefrom than anywhere else. Moreover, the following, according to Tisserand, is the increase in the use of immersion and of insecticides in the treatment of the vine : — TABLE III. — Sliowing the Increase in Area of the Submersion and hisecticidal Treatment of Vines in France. Year. Suhmersion. Carbon Bisulphide. Potassium Sulphocarbonate. Hectares. Hectares. Hectares.'^ 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 8,093 8,195 12,543 17,792 23,303 24,339 24,500 33,455 30,336 32,738 5,547 15,933 17,121 23,926 33,446 40,585 47,215 66,705 57,887 62,208 1472 2809 3033 3097 6286 5227 4459 8089 8841 9377 To sum up, submersion, if of undeniable efl&cacy, is a barbarous pro- cess, with many drawbacks, which should be advantageously replaced by irrigations with sulphocarbonate or with carbon disulphide. Amongst the antiphylloxeric treatments we should advise, according to circumstances, the following choice : Annual submersion may be applied where exceptional conditions combine, accompanying it, howevei", by very abundant manuring. Irrigations with sulpho- carbonate and carbon disulphide are' reserved for de luxe vineyards, such as those of Bordelais, Burgundy, and Champagne. Carbon disulphide, applied by means of the Pal injector, to be adopted pre- ferably in small and medium cultures, and especially where the want of water renders submersion too costly. Spraying. — Spraying with cold water destroys the following parasites : Gapnodium {Fumagine or smut of fruit trees). — Sorauer re- commends playing a jet of cold water on the crown of the trees after pruning that part. However, this operation must be repeated every evening in summer. Cajmodium salicinum, Mntgn. (hop black), may be prevented by spraying the leaves with cold water and repeating the process several days (Niajels). Tingis Pyri, Fb. — The pear tiger- beetle is fought against in the same way by spraying night and morn- ing under the attacked leaves with cold water, or with a little soap ^ A hectare is 2J acres approximately. — Tr. ACTION OF DRY AND MOIST HEAT ON SEEDS AND SPORES. 31 added (Montillot). Tetranychus telarius, L. (red spider), which forms on different plants a disease called " la Grise," is very sensitive to moisture and does not stand repeated cold-water spraying long (Thomas). Bryobia ribis (gooseberry acarus) may be fought against by frequent sprinkling of the leaves. Spraying with water can thus be used as a preventive against different species of Fumagine or smut (Capnodiinn), as a means of killing acari, of which the Tetranychus (red spider) is the most widespread and injurious. (b) Hot Water acts very energetically on insects and fungi, which die in contact with boiling water. Plants and their seeds generally stand heat better. That enables their parasites to be destroyed with- out injuring themselves. Resistance of Insects to Heat. — All insects in seed are destroyed below 100° C. (212° F.). Bruchideae (small weevils, pea-weevils) die in five minutes at 60° C. (140° F.). Ordinary weevils do not stand 50° C. (122° F.). Grubs touched by water of 50°-80° C. (122°-176° F.) die without exception. Coleoptera (beetles) which sometimes stand great heat never bear 100° C. (212° F.) (Schribaux, Bussard, and Etienne). Resistance of Seed to Heat. — Seeds can undergo a dry heat without injury, whilst the action of moist heat, and of water above 60° C. (140° F.) is often injurious. Seed-corn, with the exception of maize, can support a heat of 100° C. for an hour without its germination being affected. In spite of the considerable loss in water which the grain undergoes in such conditions, seed- wheat, for example, which contained 13 per cent of water before being heated lost 9*4 of water during the operation. Their vitality is not diminished. Of Japhet seed- wheat heated for an hour in a stove at 105° C. (221° F.) 97 per cent still germinated; at 115° C. (239° F.) 95 per cent; at 116° C. (240-8° F.) 93 per cent ; at 120° C. (248° F.) 56 per cent ; at 125° C. (257° F.) 4 per cent. [Potatoes dipped in boiling water do not germinate.] During researches on the Alucite Doyere likewise succeeded in heating seed-wheat dried in vacuo to 100° C. (212° F.) without it losing its faculty of germinating. By previously drying seeds at a low temperature Jodin heated grains of seed-wheat to high temperatures without alteration. Peas and garden-cress seed heated directly to 98° C. (96-4 F.) for ten hours were no longer capable of germination, whilst others submitted to the same heat for the same time stood the heat perfectly, after being heated for twenty-four hours to 60° C. (140° F.). The peas retained a germinating capacity of 60 per cent. Therefore, if seed be heated in such a way as to allow the water to evaporate pre- viously, by heating in an open vessel or in presence of such substances as sulphuric acid, calcium chloride, and quicklime, they undergo no alteration. Seed-peas under such conditions stood heating for 206 days at 40° C. (104° F.). Resistance of Fungi to Heat. — Fungi spores are generally re- markably sensitive to moist heat, but per contra they stand dry heat well. Schindler found that the spores of the Ustilaginecs which re- sist very great dry heats, are rapidly injured if the hot medium is saturated with water vapour. In these conditions the spores of black 3-2 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. rust perish at GO" C. fliO° F.), those of l)rown rust at 45''-50'' C. (113°- 122° F.). Herzber