IQII 



BETTER FRUIT 



Page 41 



The powdery-mildews of the grape and 

 of the rose also belong to this group. 

 These diseases may be prevented by 

 proper fungicidal treatment, the same 

 as disease of group one, and, in addition, 

 they may also be cured by such treat- 

 ment. The mycelium, being exposed 

 upon the surface of the host, may be 

 reached and killed by proper fungicides. 



For years paris green was used more 

 extensively than any other poison. It 

 first supplanted London purple, but has, 

 in turn, been supplanted by arsenate of 

 lead and various other compounds of 

 arsenic. Pure, it is among the most 

 reliable of insecticides, but has -the dis- 

 advantage that it is a rather coarse crys- 

 talline substance, which settles rapidly 

 to the bottom of the spray-tank unless 

 the contents are kept thoroughly stirred. 

 For codling moth, bud moth, tent cater- 

 pillars and many other insects of group 

 one it is generally used as a spray in the 

 following proportions: 



(1) Paris green 1 pound 



Quick lime 4 to 5 pounds 



Water 160-200 gallons 



Slake the lime, stir the poison into a 

 thin paste with a little water, add this 

 to the lime, then strain the mixture 

 through a sieve into a tank containing 

 the required amount of water. If it is 

 desired to spray for both fungi and 

 insects, lime-sulphur No. 25, or bordeaux 

 mixture (15 or 16) may be used in place 

 of the water in the above formula. For 

 peach or other tender foliage 300 gallons 

 of water or bordeaux (17) should be 

 used. It is necessary to keep this mix- 

 ture well stirred while spraying. 



Arsenate of lead is now the chief poi- 

 son used in spraying for the codling 

 moth, although paris green gives approx- 

 imately as good results, and is preferred 

 by some. Many brands of commercial 

 arsenate of lead are now to be had, and 

 so far as our observations go, niearly all 

 are reasonablj^ pure. The various brands 

 may, however, be arranged into the two 

 definite groups, which may be termed 

 the acid arsenates and the ortho or neu- 

 tral arsenates. While the evidence is 

 not conclusive, it appears to be true that 

 the acid arsenates have some tendency 

 to injure foliage, and cannot so well be 



Figure 1— SPOTS ON STEM OP ANTWERP RED RASPBERRY, CAUSED BY 

 ANTHRACNOSE FUNGUS 

 Read article by W. H. Lawrence, page 7.3 of this issue 



used with lime-sulphur solutions as can 

 the neutral arsenates. 



Most manufacturers advise the use of 

 three pounds of arsenate of lead to 50 

 gallons of water. The Washington 

 Experiment Station has demonstrated 

 that in the dry climate of Eastern Wash- 

 ington one pound to 50 gallons gives 

 equally good results in controlling cod- 

 ling moth. We have found that two 

 pounds are sufficient in the Willamette 

 Valley. It is quite probable that one 

 pound may be sufficient here, but since 

 this has not been demonstrated we think 

 it best to advise two pounds to 50 gal- 

 lons for the more humid portions of 

 this §tate. 



The following table represents the 

 composition of the various commercial 

 lead arsenates which have been exam- 

 ined by the department of chemistry, 

 Oregon Agricultural College: 

 (2) 



Contents Swift Star Grasselli Lion 



Moisture 43.45 54.02 38.95 58.40 



Total lead oxide 34.47 32.99 43.11 26.19 



Total arsenic oxide 16.68 10.72 14.85 12.26 



Soluble impurities 1.82 .31 .16 .61 



Soluble arsenic oxide 45 .10 .39 .12 



Totals 96.42 98.04 97.07 97.46 



Dissolve the arsenate of soda in two 

 quarts and the arsenate of lead in four 

 quarts of warm water in wooden vessels. 

 When dissolved, add them to the 

 required amount of water. 



This formula is especially valuable for 

 spraying very delicate foliage, or for use 

 against insects which are killed only by 

 large amounts of poison, since it can be 

 used upon plants in much stronger solu- 

 tions than the other food poisons with- 

 out injury to the foliage. 



If it is desired to use a combined 

 insecticide and fungicide, arsenate of 

 lead may be added to bordeaux or to 

 lime-sulphur solution in the same pro- 

 portion as when water is used. 



It is often convenient to apply poisons 

 by dusting. Dry paris green may be so 

 applied, either pure or adulterated with 

 various substances. If used pure it 



Sherwin- 

 Williams 

 49.55 

 41.00 

 5.17 

 2.85 

 .15 

 98.57 



Sherwin- 

 Williams 

 51.84 

 33.11 

 12.35 

 1.58 

 .11 

 98.88 



Bean 

 41.68 

 42.19 

 13.47 

 1.60 

 .10 

 98.94 



Heming- 

 way 

 32.46 

 42.64 

 21.45 

 .93 

 .31 

 97.48 



Some growers prefer to prepare the 

 arsenate of lead as it is used. This is 

 but little, if any, more troublesome than 

 to mix the prepared arsenates in water, 

 and should be somewhat cheaper. It can 

 be readily prepared after the following 

 formula : 



Arsenate of soda 4 ounces 



Acetate of lead 11 ounces 



Water 15 to 20 gallons 



EXHIBIT OF FRUITS AT THE IDAHO STATE HORTICULTURAL SOCIETY MEETING HELD 

 AT THE BOISE COMMERCIAL CLUB ROOMS, BOISE, IDAHO, JANUARY, 1911. 



should be dusted from a cloth sack of 

 suitable texture and only the faintest 

 trace of the poison should appear upon 

 the plants treated. One or two pounds 

 should be sufficient to treat an acre of 

 any low-growing crop. 



To avoid using excessive and danger- 

 ous amounts of the poison it is usual to 

 adulterate it as follows: 



(3) Paris green 1 pound 



Wheat flour or finely slaked quick 



lime 25 to 50 pounds 



Mix the ingredients thoroughly and 

 dust until the plants show a faint trace 

 of white. For dusting only a few plants 

 use a perforated tin can or other sifter. 

 To cover a large acreage use one of the 

 "dust sprayers" which^are on the market. 



The so-called "dust spray" for use in 

 orchards is cheaper than spraying with 

 liquids, but results so far obtained indi- 

 cate that it is less efTective for most 

 purposes. Dust spraying has not been 

 tested by this station, but the results of 

 three years' careful work at the Illinois 

 Experiment Station in testing dust 

 sprays in comparison with liquid sprays 

 has been summarized by Professor C. S. 

 Crandall, apple specialist, as follows: 



"With regard to effect upon foliage the 

 results were identical in all orchards, 

 and in all seasons. Trees sprayed with 

 liquid bordeaux and paris green retained 



