S06 ANNUAL REPORT OF THE Off. Doc. 



e&t point is where the water drips off, the sediments go to that point 

 and drip along with the liquid, thus leaving actually less material 

 on the fruit or leaf than when a smaller quantity is properly applied. 

 Or, if it does not drop off it will accumulate at this lowest place, often 

 in quantity sufficient to cause injury, while the upper portions are 

 left bare and thus exposed to attack. 



Plate III illustrates the running together and settling to the low- 

 est point. This effect was produced by spraying two glass plates, 

 (a) just to the proper point and (5) beyond that point until the 

 globules ran together. In (a) it will be noticed that the surface of 

 the glass is uniformly covered by the dried material. But note what 

 toolc place when the spraying was carried beyond the proper point. 

 The globules ran together and the liquid flowed down in little streams 

 and carried with it the suspended material, leaving bare streaks, and 

 either accumulating it at the lowest point or carrying it away where 

 it dripped off' the plate. 



It must be emphasized that the material must be so applied that 

 it forms an unhrolcen thin coating over the entire surface of the leaf 

 or fruit. This is especially true of the Bordeaux mixture. That 

 remedy, as has been shown, is wholly preventive in its action. Any 

 breaks in the coating are exposed to attack, and if attacked, become 

 centers of infection, the birthplace of new crops of spores, thus in- 

 creasing the chances for new infection. The more numerous the 

 spores, then, the more carefully must the application be made, for 

 when the spores are very abundant the chances for some of them to 

 settle on the exposed places are correspondingly greater. Plate IV 

 {a) shows an apple properly sprayed. The photograph shows the dis- 

 tinct marks of the separate globules of mixture. In addition, there 

 were.' many exceedingly fine globules too small to be seen in the 

 picture. Plate IV (5) is an example of an apple which has been 

 sprayed long enough to allow the globules to run together and drip 

 off' or accumulate in spots. Notice how unevenly coated is the sur 

 face. In an orchard where the fruit rot or the scab is very abundant 

 an apple or a leaf sprayed as that one shown in the plate is little bet 

 ter off than if it had not been sprayed at all. 



The injury due to the excessive aooumulation from the material 

 running down and evaporating at the low^est points has been men- 

 tioned. Plate V exhibits examples of leaves so injured. These 

 leaves were taken from a tree sprayed with nearly ten times the 

 usual strength of ammoniaeal copper carbonate solution until the 

 licjuid began to drip. The leaves were badly burned around the edges 

 and at the tips, while the leaves of another tree properly sprayed, or 

 without dripping, were not injured at all by the same solution. Thus, 

 it will be seen, that two evils may result from improper spraying: 



