Pomona College Journal of Economic Botany 



55 



Every possible means should be exercised to keep the orchard in excellent 

 physical condition. As cultivation is a very important factor in this work 

 it should receive its full quota of attention. In groves subject to this disease 

 the soil should be stirred deeply enough and often enough to insure all that is 

 demanded from it by the tree. 



Irrigation. — The first attack brought on in the Blanchard orchard was 

 believed, by us, to be occasioned by a lack of water. This belief was sub- 

 stantiated by the fact that the ravages of the fungus stopped shortly after 

 the water was applied. That this was not the seat of the whole trouble 

 was demonstrated by the fact that later the best cared-for portions of the 

 same orchard were likewise infected. 



A starved condition of the tree cannot be brought about more effectually 

 than to cut off the water supply. Thus such a condition favors the attacks of the 

 disease. It is not necessary to warn watchful growers against this state 

 of affairs for it is a condition not desirable in any grove. 



Fertilization. — The lack of fertilizers might cut off the food supply and 

 have a tendency to bring on wither-tip, but it is not in this regard that I 

 wish to call attention to this point. It is what Prof. Rolfs has to say in 

 this regard : "In choosing fertilizers to aid in warding off these diseases 

 (various stages and phases of wither-tip) a large percentage of potash should 

 be used in the compound. The source of potash does not seem to be important, 

 but sulphate of potash has proven a general favorite among growers of citrus 

 fruits. 



Sulphate of ammonia is somewhat slower in acting than nitrate of soda, 

 but gives a firmer leaf. Nitrate of soda will produce a very quick growth and 

 a large leaf, but these are especially subject to the attack from the fungus 

 unless well balanced by a generous supply of potash. Organic ammonia in 

 the form of dried blood, cotton-seed meal, and bone meal should not be used 

 in combating this trouble, as it is very likely to produce die-back in addition 

 to the softening of the wood, and so lay the tree doubly open to attack." 



A very interesting observation was made in the Blanchard orchard in 

 connection with the use of nitrate ofj soda. Last year an application of 

 9 pounds per tree was made in three applications. In previous years only 

 6 pounds per tree at two applications was the most ever given. It is strange 

 that following the heavier application came the only severe attack of the 

 wither-tip known in this orchard. It is not claimed that this was the 

 cause, for the fertilizer had been used previously without bringing the 

 disease, but might it not have something to do with the seriousness of the 

 attack? Had there not been severe attacks in other orchards, which had 

 received no nitrate of soda at all, this belief would have been well founded. 

 The attacks have been general and the first severe ones noted in the orange 

 groves in this county. 



packing house methods 

 It is interesting to know that the "red-spot" does not cause infection of 

 other fruit in the packing house. To demonstrate this Mr. Field, manager of 



