19 1 7 



BETTER FRUIT 



Page 



Cause of Scab Variation With Height 



The cause for the very pronounced 

 variation in the degree of infection of 

 fruit from the different locations on 

 the trees can be charged to but one 

 fact — lack of thoroughness in making 

 the applications of the fungicide em- 

 ployed. Theoretically more scab in- 

 fection should be found in the lower 

 portions of the trees, owing to the 

 proximity, during early spring, to the 

 source of ascospores, and later to sum- 

 mer spore infection when the spores 

 are washed down by rains from in- 

 fections above. Quite the reverse, 

 however, was found to be true, demon- 

 strating that the fungicides used have 

 been decidedly effective on portions of 

 the trees that have been thoroughly 

 covered. These difficulties can only be 

 corrected by facing the conditions as 

 they arise. In the young orchard, nat- 

 urally this variation does not exist for 

 the reason that the tops of the trees are 

 just as easily sprayed as the bottoms. 

 With the aging of the apple orchard, 

 the bringing of protection to the higher 

 fruits becomes more problematical as 

 time goes on. The spray outfit which 

 produced highly satisfactory results 

 five years ago must be made adaptable 

 to the growth in height of the trees, or 

 more modern equipment must be in- 

 stalled in its place; for it does not pay 

 to spray unless it can be done thor- 

 oughly from top to bottom. 



The Successful Type of Spray Nozzle 



The type of spray that has been 

 found to give the best results at Hood 

 River in controlling apple scab is 

 applied in the form of a fine mist; 

 double nozzles are usually used, since 

 they enable the operator to apply more 

 material in a given time. To effect 

 complete control of the disease, it has 

 been demonstrated that it is absolutely 

 necessary to cover not only the fruit 

 thoroughly in every application, but 

 also both upper and under surfaces of 

 the foliage — in other words, to prevent 

 literally both fruit and foliage infec- 

 tion. The mist spray, accumulating as 

 it does in fine globules over the sur- 

 faces, produces a much thicker, more 

 complete covering than occurs when a 

 drenching or driving spray is used. 

 The latter, breaking and running upon 

 hitting a surface, draws off much of 

 the spray material, leaving, upon dry- 

 ing, an extremely thin film which lacks 

 the lasting and weathering properties 

 of the thicker mist application. The 

 actual application of spray, however, 

 should be made adaptable to different 

 weather conditi(ms. Often it is abso- 

 lutely necessary to continue spraying 

 in windy weather in order that pro- 

 tection from scab be gained. I'nder 

 these conditions the mist nozzle should 

 be discarded for a coarser type. This 

 change will enable the rodman more 

 nearly to reach all parts of the trees 

 which would otherwise be impossible. 

 A thin film is much better than none 

 at all. 



Incomplete Protection Obtained in 

 Many Orchards and Causes for It 

 The average orchardist, regardless of 



the size or age of his trees, sprays 



I'n.iKi; :!. SLiiiiniary of results obtained in Block 3 



2 725 



Hight! IOTApri.ti|'ToT-Sc« «%S tA»ni<iywf$c 



343 12.58 



\ 



I ; 7.42 



•4 les 166 ! A.azf 



UNSPRAYED 62.5 



FiGURn 1. .Summary of results obtained in Block 4 



with two leads of hose and from the 

 ground. Considering that the rods are 

 twelve feet long (many growers use 

 ten-foot rods) the normal position of 

 the nozzles while in use is at a height 

 of about fourteen feet (see Figure 5). 

 The rodman, in working around the 

 tree, raises the nozzle at intervals to a 

 height of seventeen to eighteen feet 

 (see Figure 6). As a long day wears 

 on, the holding of a heavy rod at arm's 

 length becomes very tiresome; for this 

 reason the operator becomes uncon- 

 sciously careless and the tops are 

 slighted. By referring to the heights 

 of the fifteen-year-old trees it will be 

 seen that on the average eleven feet of 

 tree surface occurs between the end of 

 the spray rod, when raised to its high- 

 est i)()int, and the top foliage. Leaves 

 and fruit in this area, then, are depend- 

 ent entirely upon the pressure exerted 

 by the outfit and the air, to force and 

 carry the li(|iii(l to its proper place. 

 Under absolutely quiet atmospheric 

 conditions it is possible to cover fairly 

 well the under surfaces of the higher 

 foliage and the fruit of these large 

 trees, but a good many top surfaces are 

 missed. With the slightest wind blow- 

 ing the benefits derived from the air 

 as a carrier are largely reduced, and 

 are completely destroyed by the wind 



that normally occurs at Hood River 

 during a greater part of the spring. 

 In many instances the writer has ob- 

 served orchardists spraying in a wind 

 (spraying often has to be done under 

 such conditions) that prevented the 

 reaching of the trees at a greater 

 height than five feet above the end 

 of the rod. The average wind during 

 the spraying season prevents the 

 reaching of the trees at a greater 

 height than six or seven feet above 

 the end of the nozzles, and not very 

 thoroughly at a greater height than 

 four or five feet above. For example, 

 then, considering the tree being 

 sprayed as 28 feet high, the rodman 

 exerting himself to the extent of 

 holding the rod at arm's length 

 does not thoroughly cover anything 

 above twenty-two or twenty-three 

 feet. (Figure 1.) This leaves the 

 fruit and folitige, chiefly foliage, over 

 a surface of live or six feet entirely 

 ojjon to infection. The infection 

 which takes place is most advan- 

 tageously located to further the 

 spread of the disease over the tree; 

 for with each rain millions of spores 

 are washed down onto the fruit and 

 leaves below, which if not thoroughly 

 protected by a good coaling of spray, 

 become rcaililx infected. 



