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Pomona College Journal of Economic Botany 



us in some experimental tests against the fungus. Apparently it was in- 

 creasing in the orchard, both on twigs and fruit, especially affecting the 

 young lemons just setting from the bloom. 



Within two days the most startling evidence of what wither-tip may 

 do to an orchard impressed itself upon us. In one of the healthiest of the 

 grove we suddenly discovered that half of the leaves had fallen from the 

 trees so recently that many of them showed no evidence whatever of wilting. 

 For a few days the petioles still clung to the tree. Some of these fallen 

 leaves were turning brown beginning usually at the tip and extending down 

 the midrib while others contained irregular yellow-green spots of irregular 

 shape. A slight jarring of the boughs by the hand precipitated still more 

 leaves, apparently vigorous and healthy, save for the pale yellowish-green 

 spots described above. 



The next day, June 5th, 1909, we had one of our power spray outfits in the 

 field and sprayed three small groups of trees with the following: 



FORMULA no. 1. 



Resublimed sulphur _ 1^4 lbs. 



Sodium Hydroxide 98% _ \ l / 4 lbs. 



Water 50 gals. 



This we prepared by first passing the sulphur through a fine sieve and 

 adding just enough water to make a thick soup. To this we added the pul- 

 verized caustic soda, stirring vigorously to prevent burning. After a few 

 minutes the sulphur was almost entirely dissolved. The solution was then 

 strained directly into the spraying tank which already contained the extra 

 50 gallons of water. This amount treated 7 trees. 



formula no. 2. self-boiled sulphur 



Resublimed sulphur 8 lbs. 



Unslacked lime - 8 lbs. 



Water _ 50 gals. 



This we prepared as per directions given in Circular No. 27. (See under 

 heading of control.) 



This quantity sprayed 8 trees. 



FORMULA NO. 3. BORDEAUX MIXTURE 



Bluestone 5 lbs. 



Unslacked lime 6 lbs. 



Water 50 gals. 



Eight trees required all of the 50 gallons. 



Of course we knew that we could not expect to save the leaves and twigs 

 already affected and that any results from the spray might not be clearly 

 noticeable for months. The presence of black scale and more or less red 

 spider in the orchard suggested the possibility of a spray combining both the 

 merits of a fungicide and an insecticide. Accordingly we sprayed another set 

 of rows, adding to each of the above formulae 28° Beaume spray distillate 

 in sufficient quantity to make the mixture contain 2 l / 2 % distillate. 



