Pa^e 8 



BETTER FRUIT 



April 



•'2 8 Teet- 



14 Feet 



Normal Fob- 

 iTioN or 



5) "PR AY Rod 



FicuRE 5. This shows relative position of the nozzles to the height of a large 

 tree \\hile spraying in a normal position 



*2 8 Teet- 



Limit ot 



2 2 Teet- 



Ett 



EOTIVt WORK- 



i-i^' 



17 Te^T- 



E ND E P TO 



THE Limit 



5 T" E E T. 



Figure 6. This shows the relative position of the nozzles to the height of a 



large tree when the rod is held at arm's length. Note that there is nmch tree 



surface above this point 



Is the Fifth Scab Spray Necessary? 



The secret of growing scab-free fruit 

 lies in the absolute prevention of leaf 

 infection. If this is accomplished, the 

 apples will incidentally be kept clean. 

 With a portion of the trees left open to 

 infection, even though it be only a few 

 leaves in the top, chances of serious 

 fruit infection, taking place early in 

 the summer, are greatly increased, 

 especially if the 30-day lime-sulphur 

 sjjray is omitted. The sixteen days of 

 rain which occurred during late June 

 and early July, produced at least 75 per 

 cent of the scab which occurred at 

 Hood River during 1916. Infection 

 could not have taken place if fruit and 

 foliage had been kept clean up to this 

 time. As shown in Block 4, though the 

 results from the standpoint of scab con- 

 trol were not as complete as obtained 

 in Block 3 with five applications, the 

 7.42 percentage of infection that re- 

 sulted must be considered a very 

 effective reduction. The trees in this 

 experiment were last sprayed on May 

 24. On June 17, nearly a month later, 

 rain began falling, continuing some 

 every day until July 3. There is no 

 doubt that a good deal of the protec- 

 tion derived from the last application 

 of spray had disappeared through 

 weathering and expansion of both the 

 fruit and leaves before this favorable 

 scab-infection weather was over. In 

 spite of this long-continued rainy spell, 

 infection of but 7.42 per cent of the 

 fruit resulted. During this time scab 

 increased on the unsprayed check trees 

 from 20.5 per cent to G2.5 per cent. The 

 trees in this plot were known to be 

 practically free from scab at the time 

 the "30-day" spray was applied to the 

 other experiments. The infection of 

 fruit at that time was only .39 per cent, 

 and since it was so clean to begin with, 

 infection failed to develop in serious 

 proportions regardless of the prevail- 

 ing weather conditions favorable for 

 scab development. There is no doubt 

 that the first four scab sprays sched- 

 uled by the Experiment Station are 

 necessary; whether the fifth is recpiired 

 (if we dare draw inferences from one 

 season's work) depends upon the 

 amount of infection present at the time 

 the "30-day" spray should be applied. 

 If the trees are absolutely clean at this 

 time, it appears from the excellent re- 

 sults of the test just described that they 

 need no further applications regard- 

 less of the weather conditions. .\t the 

 present time, however, few orchardists 

 are sullkiently competent to determine 

 whether their fruit and foliage are 

 clean. Clean does not mean that one 

 can find a spot here and there. AVe 

 have called an infection of .39 per cent 

 fairly clean, and that means the find- 

 ing of a little more than three scabb> 

 apples in each 1,000 examined. Until 

 growers can properly analyze their 

 crop and determine the amount of scab 

 present in actual ])ercentages, it will 

 not be safe to omit the "30-day" spray. 



Spray Outfit for Older Orchards 



To overcome some of the dillicultics 

 that have been discussed, it is neces- 

 sary for the orehardist to develop and 

 Continued on page 36 



I 



