Page 10 



BETTER FRUIT 



March 



Suggestions for Control of More Serious Plant Diseases 



By Leroy Childs, Entomologist and Plant Pathologist, Hood River Branch Experiment Station 



[Editor's Note. — "Better Fruit" has published 

 in previous years the methods of control for 

 plant diseases, as recdmmended by the state 

 experiment stations in the Northwest, and 

 spray calendars. While it is generally true 

 that the methods of control and the remedies 

 used are nearly the same in the different sec- 

 tions, it is important that the fruit growers 

 should bear in mind that in different sections 

 and under different climatic conditions the 

 dates of the different sprayings, the number of 

 the different sprayings and the strengths vary 

 to a greater or less extent. Therefore fruit 

 growers should not adopt this program for 

 their particular sections without interviewing 

 their own experiment stations or their consult- 

 ing horticulturists. Particular attention is 

 called to the fact that while three sprayings 

 for codling moth are generally ample in Hood 

 River districts, in some districts four or five 

 are frequently considered necessary. Growers 

 are cautioned to use care and judgment in the 

 application of lime and sulphur, both as to 

 strength and the weather conditions at the time 

 of application, as more or less burning is apt 

 to occur from the application of lime and sul- 

 phur if applied late in the year when the 

 weather is becoming extremely warm.] 



Apple Scab. — At the present time no 

 more satisfactory recommendation can 

 be given for the control of apple scab 

 than that outlined for the past season, 

 which includes five applications of 

 lime-sulphur, dilutions of which are re- 

 duced as the season progresses. 



Several new features were included 

 in experimental work directed toward 

 the control of scab during the past year. 

 These include the experiments pertain- 

 ing to the following: First, the dusting 

 of trees instead of spraying for the 

 control of both scab and codling moth; 

 second, the consideration of greater 

 dilutions of lime-sulphur than at pres- 

 ent used in the many sprays for con- 

 trolling scab; and, third, substitutes for 

 lime-sulphur in the latter spray, in 

 order to avoid injury from burning. 

 Considerable time has also been given 

 to the study of the life history of this 

 disease, and its relation to our present 

 control measures. Much valuable data 

 have been obtained in these various 

 fields of endeavor. The work is not 

 sufficiently completed or tested, how- 

 ever, to warrant drawing conclusions 

 at this time. 



The following program will not only 

 be found effective in controlling this 

 disease, but it is so arranged that by 

 combining other ingredients with the 

 lime-sulphur powdery mildew, codling 

 moth, brown and green aphis can be 

 readily controlled at the same time. Of 

 the list of sprays that are included in 

 this program it will not be necessary in 

 all cases to use the materials present, as 

 some of the orchards are free from 

 some of the pests mentioned. Before 

 it is time to put on the application rec- 

 ommended, the orchardist should deter- 

 mine whether his orchard contains the 

 pest or not. 



Powdery Mildew. — From the experi- 

 mental work which has been in prog- 

 ress now for a year, and which is still 

 not completed, it is safe to say that up 

 to the present time control measures in 

 Hood River have not been attempted 

 early enough to bring about entirely 

 effective results. The disease becomes 

 active shortly after the semi-dormant 

 period, blighting from that time on, 

 fruits spurs, terminal growths and 



foliage. In the work which has been 

 conducted, several combinations have 

 been used during the past season, the 

 most effective of which has been found 

 to be iron sulphide mixture used at the 

 rate of 10 gallons of the mixture to 100 

 gallons of water. Atomic sulphur, used 

 at the rate of 12 pounds to 100 gallons, 



was observed to be fairly effective, but 

 did not reduce the disease to the extent 

 that did the iron sulphide mixture. 



Last year the disease was kept under 

 control with four applications, iron sul- 

 phide being used in the first four scab 

 sprays. These are the recommenda- 

 tions given in the spray program. The 



TABLE v.— SPRAY PROGRAM FOR THE CONTROL OF INSECT PESTS AND PLANT 



DISEASES OF THE APPLE. 



(This is adapted chiefly for Hood River conditions.) 



* See dilution table for lime-sulphur at different degrees Beaume. 

 tSee method of preparation of tnis mixture in accompanying article. 



TABLE VI.— DILUTION FOR LIME-SULPHUR .\T DIFFERENT DEGREES BEAUME. 

 Prepared by Mr. R. H. Robinson, Assistant Chemist, Oregon Experiment Station. 



Degrees 

 Beaume 



36 



35 



34 



33 



32 



31 



30 



29 



28 



27 



26. .. 

 25.... 



24 



23 



22 



21 



20 



Delayed 



dormant spray 



1 to 22.7 



Pink 



to 22.0 

 to 21.3 

 to 20.7 

 to 20.0 

 to 19.4 

 to 18.7 

 to 18.0 

 to 17.3 

 to 16.6 

 to 16.0 

 to 15.4 

 to 14.7 

 to 14.0 

 to 1.3.3 

 to 12.6 

 to 12.0 



1 to 



spray 



28.3 



27.5 



26.7 



25.8 



25.0 



24.2 



23.3 



22.5 



21.6 



20.8 



20.0 



19.1 



18.3 



17.4 



16.5 



15.8 



15.0 



Calyx 



1 to 

 1 to 

 1 to 

 1 to 

 1 to 

 1 to 



spray 



40.0 



38.8 



37.5 



36.2 



35.0 



33.7 



32.3 



31.0 



29.7 



28.3 



27.0 



25.7 



24.3 



23.0 



21.6 



20.3 



19.0 



10 day spray 

 45.6 

 44.2 

 42.8 

 41.3 

 40.0 

 38.6 

 37.1 

 35.6 

 34.2 

 32.8 

 31.3 

 30.0 

 28.7 

 27.2 

 25.8 

 24.5 

 23.0 



30 day spray 

 57.4 

 55.6 

 53.7 

 51.9 

 50.0 

 48.2 

 46.4 

 44.5 

 42.7 

 41.0 

 39.0 

 37.2 

 35.4 

 33.5 

 31.7 

 30.0 

 28.2 



This table was prepared considering lime-sulphur at 32° Beaume as a standard. Concentrates 

 testing higher or lower arc arranged so that they will contain the same amount of sulphur in the 

 diluted spray. 



