Bui. 907, U. S. Dept. of Agriculture. 



PLATE IV. 





Fumigation of Citrus Plants With Hydrocyanic Acid. 



A, B, Fumigation injury fo foliage at point of infestation with purple scale (Lepidosaphes 

 beckii). The injury appeared most prominent on the side of the leaf opposite the in- 

 festation. A, Upper side of leaf, showing purple scale. B, Lower side of same leaf, 

 showing collapsed tissue opposite scale infestation. C, An immature Valencia orange 

 injured hy exposure to sunshine following fumigation. The uninjured area was 

 shaded by leaves. D, Twig from a fumigated tree, showing how the leaves are ab- 

 scissed at the base of the blade, leaving the petioles clinging to the tree. 



