14^^ 



Jbuit than on the other varieties. It is known to aflect the grape fmit, 

 . common sweet orange, sour orange, lemon, mandarin, and Satsuma. 

 The disease develops most freely on young, rapidly growing, vigorous 

 shoots. It resembles to some extent the injury produced by the rust 

 mite, and was for a time confounded with this disease. Its refusal to 

 yield to the treatment for rust mite, however, led to the discovery that 

 it is distinct from rust. (^) 



The disease is undoubtedly of very recent origin or introduction. 

 It has spread rapidly in the region about Citra, and many of the 

 groves there are badly affected. The malady has also been found to 

 occur to some extent at Ocala, Stanton, and Sandford, and is apparently 

 spreading rapidly. 



The foliage of trees attacked by this disease is greatly injured, and 

 consequently the general vigour and productiveness of the tree much 

 reduced. The growth of young trees is retarded, and they are appar- 

 ently permanently stunted if the disease is allowed to continue. The 

 fruit produced is mostly disfigured, some of it so badly as to be unsala- 

 ble. This is particularly the case with lemons, they, unlike russet 

 oranges being almost wholly unsalable. At Stanton where the malady 

 occurs in lemon groves to some extent, from 3 to 4- per cent of the fruit 

 was affected in 1894, and about 2 per cent rendered unsalable. On 

 badly affected grape fruit and orange trees fully 90 per cent of the 

 fruit may be more or less disfigured by melanose. Probably 1 par cent 

 of these are rendered unsalable. The total damage produced by this 

 malady is as yet slight, b»ing about 8-5,000 annually. It appears to 

 be spreading rapidly, however, and may ere long become one of the 

 moat common and most injurious diseases. Great care should be taken 

 to prevent the introduction of this malady into California and other 

 orange-growing countries where it is not yet known to occur. 



Symptoms — The most conspicuous symptom of melanose is the occur- 

 rence of small, dark broivn spots on the leaves, young stems, and 

 fruits. On the leaves and fruits the individual spots, when dis- 

 tinct, are nearly round and are slightly elevated above the surrounding 

 surface. On the stems the spots are usually roundish, but are fre- 

 quently somewhat elliptical or oblong and elevated, as on the leaves. 

 Only the elevated spot is discoloured, the surrounding tissue being of 

 normal colour. The spots are at first very minute and yellowish. They 

 gradually increase, however, and swell up, changing to dark brown or 

 nearly black. Many of the spots finally burst near the centre and show 

 a small irregular fissure. Yery commonly the under side of the leaves 

 show minute depressions, corresponding to the spots located on the 

 upper surface On young partially grown leaves this latter character 

 is usually very evident, each brown spot occurring on a slight ele- 

 Tation of the leaf. The spots vary considerably in size, ranging usually 

 from J to 1 mm. {yho 2V i^^h) in diameter. On the common sweet 

 orange and sour orange they range in size from J to -J mm. (-j-J^ to ^ 

 inch). On the grape fruit they are from \io\ mm. to inch) in dia- 

 meter, the individual spots being usually much larger and more conspi- 

 cuous than on common orange or sour orange. On the common orange 388 



(1) A brown diBcolour&tion of the fruit, caused by the attaeka of a sarfcc^feed- 

 Jng mitt, "Plfiytoptus, 



