33 



new growth so rapidly and in such quantity that the amount of 

 wood that is killed by the fungus and the number of leaves des- 

 troyed will form only a small percentage of the total number of 

 leaves and twigs present. The same number of leaves and the 

 same quantity of twigs destroyed on a tree of only indifferent 

 growth would form a much larger percentage and, consequently, 

 weaken the constitution of the tree to such an extent that it would 

 actually die before the atmospheric conditions would become ad- 

 verse to the disease. Seedlings and nursery trees not carefully at- 

 tended are frequently killed in this manner. It is thus possible for 

 a tree that has been properly fertilized and cultivated to with- 

 stand an attack that would prove fatal to one not in the best 

 physical condition. While it does not seem possible to reader a 

 tree proof against attack excepting by the use of fungicides, the 

 probability of infection and the damage to the tree can be greatly 

 reduced by putting it in the most healthy condition possible. 



FERTILIZERS. 



In choosing fertilizers to aid in warding off these diseases a large 

 percentage of potash should be used in the compound. The source 

 oj potash does not seem to be important, but sulphate of potash 

 has proved a general favourite 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 it is especially subject to attack 

 from the fungus unless well balanced by a generous supply of po- 

 tash. 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. 



SUMMARY. 



(1) Wither-tip was not known to exist in Florida until 1 886. In 

 1891 it was recorded as only of passing interest but it is now 

 present in every citrus-growing region of the State, as well as in 

 many citrus-growing countries. Such is the severity of the disease 

 that many requests for advice as to remedies have come to the 

 Department of Agriculture from extensive growers. 



(2) The diseases caused by the fungus Colletotrichum glocospori- 

 oides Penz. manifest themselves as wither-tip on orange, pomelo, 

 and lemon twigs ; as leaf-spot on leaves of various citrus species ; 

 as anthracnose on lime-blossoms, recently-set limes, lime twigs, 

 and lemon twigs ; as lemon-spot on ripe lemons, and as canker of 

 limes. 



(3) On the orange and pomelo the fungus causes the most severe 

 damage by defoliating young twigs and causing these to die, thus 

 reducing the amount of wood that may produce bloom in the bear- 

 ing trees and cutting back seriously the growth of young trees. In 

 lemon groves the most severe damage is done to matured fruit, 

 while in lime groves the greatest loss occurs during the blooming 

 season, the disease often causing all the bloom to fall. Trees less 



