1028 DISEASES AND INSECTS 



addition a large number of other substances which 

 have fungicidal value and are in more limited use 

 for specific cases. The following directions are 

 taken, with modifications, from the author's part in 

 Bailey's "Farm and Garden Rule-Book." 



Practices. 



Destroying affected parts. 

 It is important that all 

 affected parts should be re- 

 moved and burned, if pos- 

 sible. In the fall all leaves 

 and fruit that have been 

 attacked by fungi should 

 be raked up and burned. 

 Diseased branches should 

 be severed at some distance 

 below the lowest visible 

 point of attack. Fungous 

 diseases often spread 

 rapidly, and prompt action 

 is usually necessary. Prac- 

 tise clean and tidy culture. 

 Rotation of crops. This 

 is one of the most effective 

 and practical means of head- 

 ing off fungous diseases. It 

 is especially applicable to 

 diseases of roots or root- 

 crops, but also to many 

 other diseases of annual 

 plants. 



Sterilizing by steam. 

 1291. Tip-bum of potato leaf. This is an effective fungi- 

 A physiological difficulty or disease, cidal practice for several 

 due to some so-called "constitu- s0 ^ ~ inhabiting organisms 

 tional" disorder or obstruction ^ hich Attack , r ots and 

 (Vermont Experiment Station). ^ J S S "fS^M* 



applicable in the green- 

 house, where it may be applied (a) through sub-irrigation tile or 

 through specially laid perforated steam pipes in the bottom of the 

 bed. Cover the beds with blankets, introduce steam under pressure 

 of forty to eighty pounds for two hours. Insert thermometers at 

 various places to see that the soil is being uniformly heated. (6) 

 A large galvanized iron tight box may be constructed with finely 

 perforated trays 4 to 6 inches in depth. Soil placed in these trays 

 and steamed for two hours as above will be freed from parasitic 

 organisms. In this case the frames should be sprayed with a solu- 

 tion of formaldehyde, one pint in twelve gallons of water. Steam 

 sterilization of soil may be used on intensively cultivated areas or 

 extensive seed-beds. A portable boiler is necessary. The beds are 

 sterilized after they have been prepared 'for seed, and just before 

 the seed is sown. A galvanized pan of convenient dimensions and 6 

 to 8 inches deep is inverted, and the edges are pushed down into 

 the soil 1 or 2 inches. The pan is connected with the steam boiler 

 by means of a steam hose and live steam is run into the pan from 

 twenty to forty minutes under a pressure 9f eighty pounds and up. 

 The higher the pressure the deeper the soil will be sterilized. The 

 pan must be weighted. Paths should be disinfected by spraying 

 with copper sulfate one pound to fifty gallons of water or with 

 formaldehyde solution one pint to twelve gallons of water. The 

 cost of sterilizing is approximately three-fourths of a cent the 

 square foot. It should be noted that soil-sterilization has an invig- 

 orating effect on many plants, and it will be necessary to run green- 

 Iwuses at a lower temperature (5 to 10) b9th night and day. 

 Field-sterilization also kills weed seeds, and with the reduction of 

 the cost of weeding makes the process practicable. 



Substances. 



Bordeaux mixture. A bluish green copper compound that 

 settles out when freshly slaked lime and a solution of copper sul- 

 fate (blue-stone) are mixed. Many formulas have been recom- 

 mended and used. The 5-5-50 formula may be regarded as stand- 

 ard. In such a formula the first figure refers to the number of pounds 

 f copper sulfate, the second to the stone or hydrated lime, and 

 the third to the number of gallons of water. Bordeaux must 

 otten be used as weak as 2-2-50, on account of injury to some 

 plants. 



To make fifty gallons of bordeaux mixture, proceed aa 

 follows: 



. (1) Pulverize five pounds of copper sulfate (blue vitriol), place 

 in a glass, wooden, or brass vessel, and add two or three gallons 

 ot hot water. In another vessel slake five pounds of quicklime in a 

 small amount of water. When the copper sulfate is all dissolved, 

 pour into a barrel and add water to make forty or forty-five gallons. 

 Now strain the lime into this, using a sieve fifty meshes to the inch 

 or a piece of cheese-cloth supported by ordinary screening. Stir 

 thoroughly, and add water to the fifty-gallon mark. The flocculent 

 substance which settles is the effective fungicide. Always stir 

 vigorously before filling the sprayer. Never add the strong lime 

 to strong vitriol. Always add a large amount of water to one or 

 tne other nrst. Blue vitriol used alone would not only wash off 

 quickly ma ram, but cause a severe burning of fruit and foliage. 

 .Lime is added to neutralize this burning effect of the copper If 

 the lime were absolutely pure, only slightly more than one pound 

 would be required to neutralize this burning effect. For many 

 purposes an excess of lime is not objectionable and may be desirable. 



For nearly ripe fruit and ornamentals an excess of lime augments 

 spotting. In such cases the least amount of lime possible should 

 be used. Determine this by applying the cyanide test (2). 



(2) Secure from the druggist 10 cents' worth of potassium 

 ferrocyanide (yellow prussiate of potash) and dissolve it in water 

 in an eight-ounce bottle. Cut a V-shaped slit in one side of the cork, 

 so that a few drops 9f the liquid can be obtained. Now proceed aa 

 before. Add lime with constant stirring until a drop of the ferro- 

 cyanide ceases to give a reddish-brown color. 



(3) When bordeaux mixture is desired in large quantities, stock 

 solutions should be made. Place one hundred pounds of copper 

 sulfate in a bag of coffee-sacking, and suspend in the top of a fifty- 

 gallon barrel, and add water to the fifty-gallon mark. In twelve 

 to fifteen hours the vitriol will be dissolved and each gallon of 

 solution will contain two pounds of copper sulfate. Slake a barrel 

 of lime, and store in a tight barrel, keeping it covered with water. 

 Lime so treated will keep all summer. It is really hydrated lime. 

 This is often dried, pulverized, and offered on the market in paper 

 bags of forty pounds each, under such names as ground lime, 



Erepared lime, hydrated lime, and the like. If the paper is not 

 roken, the lime does not air-slake for a long time. One and 

 one-third pounds of hydrated lime equals in value one pound of 

 quicklime. Air-slaked lime cannot be used in preparing bordeaux 

 mixture. 



Arsenical poisons can be combined with bordeaux mixture. 

 Ammoniacal copper carbonate. For use on nearly mature fruit 

 and on ornamentals. Does not discolor. Weigh out three ounces of 

 copper carbonate, and make a thick paste with water in a wooden 

 pail. Measure five pints of strong ammonia (26 Baum6) and 

 dilute with three or four parts of water. Add ammonia to the paste, 

 and stir. This makes a deep blue solution. Add water to make 

 fifty gallons. 



Copper carbonate. For use in the above formula, it may be 

 secured as a green powder, or may be prepared as follows: Dis- 

 solve twelve pounds of copper sulfate in twelve gallons of water in 

 a barrel. Dissolve fifteen pounds of sal-soda in fifteen gallons of 

 water (preferably hot). Allow the solution to cool; then add the 

 sal-soda solution to the copper-sulfate solution, pouring slowly in 

 order to prevent the mixture from working up and running over. 

 A fine precipitate is formed which will settle to the bottom if 

 allowed to stand over night. Siphon off the clear liquid. Wash 

 the precipitate by adding clear water, stirring, and allowing to 

 settle. Siphon off the clear water, strain the precipitate through 

 muslin, and allow it to dry. This is copper carbonate. The above 

 amounts will make about six pounds. 

 Copper sulfate. See Sulfate of copper. 



Corrosive sublimate (mercuric chloride). Used for disinfecting 

 pruned stubs and cleaned-out cankers, at the rate of one part in 

 1,000 parts of water. Can be secured from the druggist in tablet 

 form in vials of twenty-five each, and costing 25 cents. One tablet 

 makes a pint of solution. Make and store solution in glass and label 

 "poison." 



Formaldehyde (40 per cent solution of formaldehyde gas in 

 water). A pungent, clear liquid, very irritating to eyes and nose. 

 Obtained at any drugstore at about 40 cents a pint. Used for 

 potato-scab, oat smut, bunt in wheat, soil disinfection, and so on. 

 Lime. Offered for sale in the following forms: (a) Ground 

 rock or ground limestone; air-slaked lime is of the same composi- 

 tion, i.e. a carbonate of calcium. (6) Lump, barrel, stone, or quick- 

 lime; this is burned limestone, and should test at least 90 per cent 

 oxid of calcium, (c) Prepared, ground, or hydrated lime; this is 

 water- or steam-slaked quicklime, dried and pulverized. Used as 

 an applicant to the soil to correct acidity, for club-root of cabbage, 

 and for preparing spray mixtures. 



Lime-sulfur. In the many possible combinations, lime-sulfur 

 is C9ming to be equally 



as important as bor- A 



deaux mixture, in the (/ 



C9ntrol of many plant 

 diseases. 



(1) Flowers of sul- 

 fur or very finely 

 powdered sulfur is 

 often dusted on plants 

 for surface mildews. 



(2) A paste o'f 

 equal parts of lime, 

 sulfur, and water. 

 This is painted on the 

 heating-pipes in the 

 greenhouse, and is 

 valuable for keeping 

 off surface mildews. 



(3) Ho me -boiled 

 dilute lime -sulfur. 

 This solution has been 

 widely used in the 

 past as a dormant 

 spray, particularly for 

 San Jose' scale and 

 peach leaf-curl. It is 

 likely to be sup- 

 planted by (4) or (5). 

 For preparation see 



page 1043. 



(4) Home-boiled 

 concentrated lime-sul- 

 fur. When a great 

 deal of spraying is to 

 be done, a concen- 

 trated lime - sulfur 



\\ 



1292. Perithecium of apple scab, 

 showing spores. 



