26 



and field investigations have been carried on continuously, with 

 highly gratifying results. Melanose, an entirely new disease, 

 has been studied and remedies for it discovered. Satisfactory 

 remedies or preventives have also been found for all the other 

 diseases mentioned above, foot rot being the only one which 

 could be said to be under control when the work was com- 

 menced. Much information has been collected in relation to 

 the causes of the various diseases and their effects on the plants 

 attacked. 



BLIGHT. 



This disease, also called wilt and leaf curl, is found only in 

 Florida, and so far as known at present is incurable. Nearly 

 all citrus fruits are liable to it, but in different degrees. Trees 

 grown on light hammock soil are most susceptible, but no 

 locality in the State is entirely exempt. The malady has been 

 known for at least twenty and possibly twenty-five years. The 

 first reliable account of it, however, was published in 1891 (1) 

 by Professor L. M. Underwood. 



Blight never attacks trees until they have attained consider- 

 able size and have begun to bear fruit. In any given grove 

 usually only a small per cent, of new cases occur in each year, 

 but the fact that the disease is apparently incurable and that it 

 attacks the oldest and most vigorous and fruitful trees in the 

 grove renders it one of the most destructive maladies known. 

 It is widely distributed over the State occurring, in the oldest 

 and best groves and on the land best suited for profitable orange 

 culture. The affected trees do not die at once, but apparently 

 revive when the rainy season commences. In this way false 

 hopes are aroused and the owner waits for years before he 

 finally removes the blighted trees and replaces them with 

 healthy one. Much time and money have been wasted on 

 supposed cures, the worthlessness of which does not become 

 apparent until after several years' trial. In some localities 

 from 1 to 10 per cent, of the trees blight annually. The annual 

 loss resulting from this disease in Florida is from one to two 

 hundred thousand dollars. Within the last ten years it has 

 caused losses probably amounting to several million dollars. 



Symptoms. — Blight usually appears very suddenly and on 

 trees that have previously seemed perfectly healthy. The first 

 symptom is a wilting of the foliage, as if the tree was suffering 

 from drought. At first the wilting is slight and can be plainly 

 seen only on hot dry days ; but it soon becomes very pronounced, 

 and often continues so during the wet season in summer, when 

 rains are almost a daily occurrence. Most cases of blight 



(1) Journal of Mycology, Vol. VII., p.p. 32—34. 



