51 



of the tree much reduced. The growth of young tree9 i8 re- 

 tarded, and they are apparently permanently stunted if the 

 disease is allowed to continue. The fruit produced is mostly 

 disfigured, some of it so badly as to be unsaleable. This is 

 particularly the case with lemons, they, unlike russet oranges 

 being almost wholly unsaleable At Stanton where the milady 

 occurs in lemon gro res to some extent, from 3 to 4 per cent, of 

 the fruit was affected in 1394, and about 2 per cent, rer lered 

 unsaleable. The t )tal damage produced by this malady is as 

 yet slight, being about $5,000 annually. It appeal's to be 

 spreading rapidly, however, and may ere long bec r bme ?<ne of 

 the most 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 occurrence of small dark brown spots on the leaves, young 

 stems and fruits. On the leaves and fruits the individual 

 spots, when distinct, are nearly round and are slightly elevated 

 above the surrounding surface. On the stems the spots are 

 usually roundish, but are frequently 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. Very commonly 

 the underside of the leaves shows minute depressions, corre- 

 sponding to the spots located on the upper surface. On young 

 and partially grown leaves this latter character is usually very 

 evident, each brown spot occurring on a slight elevation of the 

 leaf. The spots vary considerably in size, ranging usually 

 from j to I mm. ( 1 1/100 to 1/25 inch) in diameter. On the 

 common sv\eet orange and sour orange they range in size from 

 I to | mm. (1/100 fco 1/50 inch) in diameter. On the grape 

 fruit they are from \ to 1 mm. (1/50 to 1/25 inch) in diameter, 

 the individual spots being usually much larger and more 

 conspicuous than on common orange or sour orange. On the 

 common orange 388 spots were counted on a square centimetre 

 of a badly infected leaf, and 44 spots on a square centimetre of 

 one slightly infected. In the grape fruit only 130 spots to the 

 square centimetre were found on a badly infected leaf ; these 

 were partly confluent, forming an almost continuous blotch. 

 Where the spots are very abundant, they frequently run 

 together, forming large irregular dark brown blotches. This 

 frequently occurs on all species of citrus trees affected with the 

 disease, and is found on stems, leaves, and fruits. On the 



