39 



explains its almost total absence from California, where the 

 atmosphere is much drier during the growing season than it is 

 in Florida. 



Another important condition governing infection, is that the 

 tissue must still be growing to be subject to the invasion of 

 the parasite. The period of greatest danger to both leaves and 

 fruits is when they are young and tender, and growing rapidly. 

 This explains why old lemon and sour orange fruits are not 

 badly deformed when attacked by the fungus after the moist 

 weather of summer sets in. 



Treatment. — During the spring and summer of 1894 exten- 

 sive experiments were carried on by one of the writers to dis- 

 cover if possible, means of preventing scab on the lemon. 

 Owing to the irregular blooming of the lemon, the prevention 

 of the disease was found to be a difficult undertaking. How- 

 ever it was demonstrated that Bordeaux mixture and 

 ammoniacal solution of copper carbonate, if properly applied, 

 are efficient. The former is very effective against the fungus, 

 but is more or less injurious to the fruit and foliage of the 

 lemon, while the latter is almost an absolute preventive of the 

 disease and causes very little if any injury to the tree. 



It was found highly important that all infected fruits be 

 removed from the tree, and from the ground bentath before 

 blooming begins. This measure is absolutely necessary to 

 insure the success of any treatment, and is of itself a great aid 

 in checking the disease. All sour orange trees or sprouts from 

 the sour stocks should also be removed from the vicinity of 

 lemon trees, since they are even more subject to scab than the 

 lemon, and because not only the fruit but also the leaves can 

 support a luxuriant growth of the fungus. 



The disease can be prevented to some extent, by planting 

 the trees on dry soil and in localities having little rainfall 

 during and immediately after the blooming season. Directions 

 for treating the disease are briefly as follows : — 



1. Carefully remove, and burn or bury all diseased lemon 

 fruits, however small, either on the trees or on the ground. 

 Cut down and destroy all sour orange trees or sprouts from 

 sour stock in the vicinity of the lemon trees. 



2. Prepare ammoniacal solution of copper carbonate as 

 follows : — Take 5 ounces of copper carbonate and stir up with 

 about a pint of water to a thick paste; then dilute with one 

 and a half gallons of water in a wooden pail. Stir vigorously, 

 and at the same time add slowly 2 pints of strong ammonia (1) 



(1) Aqua ammoniae foriioi (28 per cent.) of druggists 



