Jan. 21, 1918 Irrigation Experiments on Apple-Spot Diseases 



115 



kept practically free from stigmonose by means of a late dormant spray 

 of lime-sulphur and nicotin sulphate. 



The irrigation of the orchard was not satisfactory because of a short- 

 age of water resulting from trouble with the canals. A cloudburst on 

 July 26 gave an indiscriminate watering to all the plats. Irrigations 

 were made according to plan on August 24 and September 12. The soil 

 moisture conditions for the latter part of the season are shown in figure 2. 



It will be noted that in spite of the unfavorable conditions a decided 

 contrast in soil moisture was secured on the different plats. Plat i 

 was given heavy irrigation throughout the season; plat 2, medium; 

 plat 3, light; and plat 4, medium, followed by heavy. The percentages 

 of soil saturation given do not indicate any decided contrast between 

 plats 2 and 3, but the condition of the trees in the two plats made it 

 very evident that a distinct contrast in soil-water conditions had been 

 secured. 



The yield in the orchard was light, being about a bushel to the tree. 

 The fruit was gathered on September 22, about 10 days later than the 

 average commercial picking of Grimes apples in that section. It was 

 placed immediately in cellar storage at a temperature of about 50° F. 

 Notes were taken on bitter-pit seven days later. The results are shown 

 in Table II. 



Table II. — Percentage of bitter-pit on Grimes apples. September 2g, igi§ 



Plat 

 No. 



Irrigation treatment. 



Heavy 



Medium 



Light 



Medium till Aug. 24, then heavy 



Total 

 num- 

 ber 

 of 

 apples. 



299 

 222 

 156 

 175 



Percentage of apples 

 affected with bitter-pit. 



Wind- 

 falls. 



90 

 36 



77 



Picked 

 fruit. 



43 

 17 

 14 

 49 



Total. 



56 

 25 

 23 

 59 



The contrasts are quite striking and make it evident that heavy 

 irrigation tended to increase the amount of bitter-pit. It is interesting 

 to note that plat 4, which was heavily irrigated late in the season, 

 showed a greater percentage of the disease on the picked fruit than 

 plat I, which was heavily irrigated early as well as late. 



All of the fruit that was apparently free from bitter-pit was returned 

 to cellar storage and notes were taken again on November 9. The 

 results are given in Table III. All of the percentages but those in the 

 last column are based on the number of apples returned to storage 

 and not on the number in the original yield from the plats. 



