INSECTS AND DISEASES 



37 



the public prints convey little intelligence to the general reader. Perhaps Figs. 56, 57 and 58 will help 

 to a vague understanding of what these parasitic fungi are, and how they work. These fungi are species 



the parts and organs that we usu- 



nor leaves, for they do not abstract 



in the presence of sunlight. They 



have already been formed or 



mals. They run their vegetative 



of plants, without flowers or seeds or leaf-green or any of 

 ally associate with plant forms. They have neither roots 

 mineral food from the soil nor construct organic food 

 live on organic compounds, — that is, on foods that 

 organized by other plants or, through them, by ani- 

 root-like threads, or mycelium, into the food supply; 

 and they propagate their 

 kind by means of special- 

 ized cells known as spores. 

 The injury they do to their 

 host is of two kinds, — they 

 appropriate food, and they 

 impair the tissues by punc- 

 turing them or breaking 

 them down and by plugging 

 the vessels or natural open- 

 ings. 



We are just now in the 

 epoch of the control of insects and plant diseases by means 

 of applications of substances. This epoch will never pass ; 

 but in time we shall give greater emphasis to such an organi- 

 zation of the business of plant-growing as to circumvent the 

 difficulties. We seem to have passed the epoch of mere plant 

 doctoring, — a suggestion, no doubt, from the prevalent medi- 

 cine-habit in man — whereby we hope to kill the insect or cure the disease by putting some substance 

 into the " circulation " of the plant ; but the day of quacks has not gone by. It would seem to be 

 needless to say to any person that he would better get expert professional advice, when he is in diffi- 

 culty with insects or plant diseases, were it not for the fact that it is necessary to say it. Howbeit, the 

 person to whom this needs to be said will not read this book, so that we may at once pass on to profit- 

 able matters. 



Formulas. 



The chemical materials used for destroying insects and plant diseases are very many, and they can- 

 not be discussed in full here. The cultivator must keep himself posted by consulting the most recent pub- 

 lications of experiment stations and the United States Department of Agriculture. The materials used 

 for seed diseases are mentioned on page 49 ; those employed in fumigating for insects, on page 45 ; 

 soil diseases are also treated in Chapter XIII, Volume I. The main insects and diseases of the various 

 crops are mentioned with the discussion of those crops in Part III. (See also pages 44, 45.) 



Spraying materials are either insecticides (to kill insects), or fungicides (to kill fungi). The insecti- 

 cides are, again, of two kinds, — poisons for chewing insects, and corroding astringent or oily compounds 

 for sucking insects. Some of the leading materials are now mentioned: 



Fig. 55. The life -cycle ol an insect. 

 Tent-caterpiUar: eggs, enlarged; 

 mass of eggs on >i winter twig; 

 larva; cocoons, on a board; motli. 



Insecticides that kill by external contact. 



Lime-Sulfur Wash (for dormant trees and bushes). — 

 Lime, 15 pounds ; sulfur, 15 to 20 pounds ; (salt, 15 

 pounds, was formerly added, but does not appear to be 

 necessary); water sufficient to bring the boiled product 

 up to 50 gallons. 



The lime and sulfur must be boiled or steamed. The 

 mixture may be made by boiling in iron kettles. Heat the 

 water before adding the lime and sulfur All the sulfur 

 should be thoroughly reduced. Pour into the sprayer 

 through a strainer and apply to the trees while warm. 



Steaming is liked best by those who have tested 

 both. The following method is recommended by Geo. E. 

 Fisher, former San Jos6 Scale inspector for the Province 

 ef Ontario, Canada : " Steam is employed to dissolve the 



lump sulfur and cook the mixture. Provide yourself with 

 eight barrels. Put one-quarter the full amount of sulfur 

 and fresh stone lime in four barrels, with a proportionate 

 amount of water. Turn the steam under a pressure of 80 

 to 100 pounds (15 to 20 pounds pressure works well) 

 into these four barrels. When the water has boiled for a 

 few minutes in these barrels, turn off the steam. It may 

 then be turned on to four more barrels which have been 

 prepared in the same manner as the first set. The full 

 amount of lime and sulfur is then added to the first set 

 of barrels slowly enough to prevent boiling over by the 

 heat generated by the slaking lime. When the lime is all 

 slaked, turn on the steam again for two or three hours or 

 till the mixture is thoroughly cooked. It is quite possible 

 to feed each barrel during the boiling process with a 

 small stream of water, which will gradually fill the barrel 



