DISEASES OF CROPS 949 



FIG 



Rust (Kuehneoal fici [Cast.], Butler). — This very common disease 

 causes numerous rusty red spots on the lower surface of the leaves. When 

 severe the trees are almost defoliated. It can be controlled by frequent 

 spraying with Bordeaux mixture. 



Cankers (Libertella ulcerata, Massee). — This disease is sometimes 

 severe where figs are grown under glass. It starts as small radiating cracks 

 which develop into cankers, sometimes completely girdling the branch and 

 causing the death of the parts beyond the point of attack. 



Another canker (Tubercularia fici) causes a shrinking and drying out 

 of the tissues surrounding the fruit scars, followed by a drooping of the 

 dead parts. 



Fruit Rots (Glomerella rufomaculans [Clint], Sacc). — This disease is 

 due to the same organism as the bitter rot of the apple. It causes sunken, 

 rotten spots, usually covered with a whitish growth and later by numerous 

 pustules of salmon-pink colored spores. If the fruit is attacked when young, 

 it becomes dry and hangs on the tree. 



Ripe fruit rots may be due to various fungous organisms. 



Other important diseases of the fig are the yellow rot (Fusarium 

 roseum, Lint), the leaf spot (Cercospori fici, H. and W.) and the limb 

 blight (Corticuem loetum, Karsten). 



PINEAPPLE 



The pineapple is subject to several diseases, all of which should receive 

 more attention. Growers who have reason to complain of these troubles 

 should consult with the state agricultural experiment station. 



MANGO 

 Bloom Blight (Colletotrichum gloeosporioides, Penz). — This most severe 

 disease of the mango is due to the same organism that causes the 

 wither top of the orange. It attacks the blossoms, causing them to turn 

 black and fall. Unfortunately, the blooming is during the rainy season, 

 which makes spraying impractical. 



AVOCADO 

 Leaf Spot (Colletotrichum gloeosporioides). — This is due to the same 

 organism as the wither top of the orange. It is frequently so severe as to 

 cause a heavy loss of foliage. It also attacks the fruit, frequently causing 

 a pronounced cracking. 



OLIVE 

 Olive Knot (Bacterium savastanoi, Smith). — This disease originates as 

 irregular, more or less hemispherical swellings on trunk, branches and 

 leaves. They are firm and fleshy, but finally become woody and crack. 

 Badly infected trees frequently die as a result of this disease. 



