BETTER FRUIT 



STATE ASSOCIATE EDITORS 



OREGON— C. I. Lewis, Horticulturist, Corvallis. 



WASHINGTON — Dr. A. L. Melander. Entomologist; 

 O. M. Morris. Horticulturist; W. S. Thornber, Horticul- 

 turist. Pullman. 



COLORADO — C. P. Gillette, Director and Entomologist: 

 E. B. House, Chief of Department of Civil and Irrigation 

 Engineering, Stale AgricuUural College. Fort CoUina. 



ARIZONA— E. P. Taylor, Horticulturist. Tucson. 



WISCONSIN— Dr. E. D. Ball. Director and Entomologist. 

 Madison. 



MONTANA — 0. B. UTilpple. Horticulturist. Bozeman. 



CALIFORNIA — C. W. Woodworth. Entomologist, Berke- 

 lej- : W. H. Volck. Entomologist, Watsonville; Leon D. 

 Batchelor. Horticulturist. Riverside. 



INDIANA— H. S. Jackson. Pathologist. Lafayette. 



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Volume XIII 



Portland, Oregon, March 1, 1919 



Number 9 



Comparative Results in Controlling Codling Moth 



By Leroy Childs, Entomologist and Plant Pathologist, Hood River Branch Experiment Station, before Oregon State Horticultural Society, 1918 



SPRAYING for the control of the in- 

 sect pests and plant diseases of our 

 various orchard enterprises is one 

 of the most laborious and at the same 

 time costly practice pertaining to fruit 

 growing in most sections. The apple 

 particularly is subject to the attack of 

 many pests of widely different life 

 habits which demand the use of a vari- 

 ety of materials that control may be 

 effected. The application of this variety 

 of materials often means the necessity 

 of applying numerous applications in 

 the orchard each season. To the aver- 

 age orchardist of medium to large hold- 

 ings the time element is involved in 

 spraying practices is the all important 

 fact, or rather than the cost of inate- 

 rials. This time factor, together with 

 the recent shortage and high cost of 

 orchard labor, has led to much activity 

 in seeking out more rapid and at the 

 same time equally effective methods of 

 applying spray. The familiar three- 

 horsepower sprayer and 12-foot rods, 

 when used in competent hands, has 

 been productive of good results in the 

 control of our various troubles in the 

 apple orchard. Nevertheless, in the face 

 of six or eight applications a season 

 this protection was usually accom- 

 plished in orchards of twenty acres and 

 larger at the expense of some other 

 orchard practice of nearly equal im- 

 portance when looking into the future 

 demands of the plantation. 



The most promising outcome of in- 

 vestigations relative to the reduction of 

 this time element in spraying has been 

 the development of the dusting method 

 (the use of insecticides and fungicides 

 in the form of dust) and the spray gun. 

 The latter adaptable to the old power 

 sprayer or much more preferably to be 

 used on a machine developing much 

 more horsepower than is at present 

 generally used. 



Of the two methods the dusting sys- 

 tem is the older. Experimental work 

 has been under way in the apple or- 

 chards of the Kast (notably New York 

 State) for six or eight years. Reports 

 from this section as to all around use- 

 fulness and elfectiveness are more or 

 less contradictory. Some investigators 

 and growers are very enthusiastic in 

 the praise of the system; others are 



much less so, even to condemning it 

 altogether. 



The writer has had the opportunity 

 to test out the dusting method for the 

 control of codling moth and apple scab 

 during the past three seasons, 1916, 1917 

 and 1918. Two types of standard power 

 dusters have been available for the 

 work and extensive tests have been car- 

 ried out under typical orchard condi- 

 tions, in the Hood River Valley. 



From the standpoint of scab control 

 1916 proved to be the only year during 

 which scab was sufficiently prevalent 

 to enable the drawing of any reliable 

 figures. That was a very favorable 

 year for scab development, rainy, cold 

 weather prevailing throughout spring 

 and early summer. The fungus was 

 held well in check on the dusted block, 

 six applications of very finely-ground 

 sulphur being used. This was the first 

 season of the dusting investigations in 

 this section and it was deemed wise to 

 first determine whether there was merit 

 in the system from the standpoint of 

 actual control — hence the keeping of 

 the trees well coated with a fungicide 

 during the long wet spring and early 

 summer. In justice to the effectiveness 

 of the dust it must be said that very 

 good control of the disease was ob- 

 tained. The results obtained compared 

 very favorably with those obtained in 

 a nearby lime-sulphur block to which 

 four applications of lime-sulphur spray 

 had been given. The unsprayed check 

 trees developed 60.22 per cent infection, 

 while the dusted and sprayed blocks 

 developed but 4.25 per cent and 2.65 per 

 cent, respectively. A peculiar spray 

 injury developed in the orchard during 

 that season in the form of a calyx end 

 rot. This injury was very much more 

 pronounced in the dusted than in the 

 sprayed block — perhaps brought about 

 through the use of extra applications — • 

 amounting to 32.03 per cent as com- 

 pared to 14 per cent on the sprayed 

 trees. This particular type of injury 

 was quite prevalent throughout the val- 

 ley in 1916 and was probably intensified 

 by unfavorable weather conditions 

 which prevailed that season. One of 

 the most striking features in comparing 

 the sprayed and dusted trees, one with 

 the other, was their foliage condition 

 during the early summer. There is no 



doubt but that continued use of lime 

 sulphur during the early season retards 

 foliage development through burning 

 and in some instances defoliation of the 

 early-appearing leaves. On the dusted 

 trees no such injury occurred and the 

 trees obtained their maximum full 

 foliage fully three weeks earlier than 

 the sprayed trees. In the fall the dusted 

 trees turned yellow much earlier than 

 the sprayed trees, seemingly to indicate 

 that their functioning was completed 

 that much earlier than the sprayed 

 trees. These trees have been dusted 

 continuously for three years, but re- 

 gardless of this foliage condition there 

 seems to be no difference in the general 

 vigor and fruit-bearing qualities of the 

 sprayed and dusted trees. 



Scab developed sufficiently in but one 

 of the experimental orchards in 1917 

 to enable the drawing of any definite 

 conclusions from the standpoint of scab 

 control. The infection existing at har- 

 vest time on the unsprayed check trees 

 amounted to 24.21 per cent. In the dust 

 block the material was applied four 

 times and in an adjoining lime-sulphur 

 block the spray was three times, the 

 last application being omitted, due to 

 the fact that sulphur injury was feared 

 on account of existing hot weather. 

 The action of this material under such 

 conditions being thoroughly established. 

 Very good control of scab was obtained 

 in both experimental plots. The lime 

 sulphur again leading slightly with but 

 .75 per cent scab-infected fruit; .95 per 

 cent infection developed on the dusted 

 trees. The last application of sulphur 

 dust caused a typical sulphur injury to 

 the fruit of about 7 per cent; on the 

 sprayed trees one-half of one per cent 

 occurred. This indicates clearly that 

 sulphur dusting, along with other sul- 

 phur compounds, cannot be safely used 

 on apple trees at times when hot 

 weather can be expected. In 1918 no 

 scab developed on the unsprayed, 

 dusted and sprayed trees on account of 

 unfavorable weather conditions (from 

 the standpoint of the life habits of the 

 fungus) in any of the experimental 

 orchards, with a result no further data 

 from the experimental standpoint was 

 obtained. 



Continued on page 41. 



