. Bulletin. 1901-13. Agriculture; Agriculture. 10 WITHER-TIP AND OTIIKK DISEASES. WITIIER-TIP. The smaller twigs of the sweet orange and pomelo are very fre- quently and severely attacked. In a great many cases the death of twigs from an attack of wither-tip is supposed to be the result of die- back. This may, however, be easily distinguished from die-back, as indicated on page 11. It not infrequently happens that die-))ack and wither-tip occur on the same twig. Any material weakening of the health of the tree is very likely to induce an infection; this, however, is not a necessary antecedent
. Bulletin. 1901-13. Agriculture; Agriculture. 10 WITHER-TIP AND OTIIKK DISEASES. WITIIER-TIP. The smaller twigs of the sweet orange and pomelo are very fre- quently and severely attacked. In a great many cases the death of twigs from an attack of wither-tip is supposed to be the result of die- back. This may, however, be easily distinguished from die-back, as indicated on page 11. It not infrequently happens that die-))ack and wither-tip occur on the same twig. Any material weakening of the health of the tree is very likely to induce an infection; this, however, is not a necessary antecedent to infection. The fruit of these two varieties appears to be exempt from attack. DESCRIPTION OF THE FUNGUS. Acervuli located on the surface of the leaf, twig, or fruit; 90-270/i in diameter, erumpent, superficial. Shape various, not uniform, occur- ring on either surface of citrous leaves; disposed irregularly or in more or less concentric lines; pale to dark colored. On tender lime twigs, tender lemon twigs, lemon fruits, and lime fruits, pale colored, dull red in masses (see PI. V), conHuent. Epidermis breaks Fig. 1.—Section of acervulus. (Drawn by L. H. McCiillongh.) Set» fuliginous, ranging in length from (50 to 1(30/^, frequently once or twice septate, disposed at margin of acervuli. Frequentl}' absent, and on tender lime twigs, tender lemon twigs, lemon fruits, and lime fruits usually absent. Conidia broadly oval or oblong, 10-16/< by 5-TyM, hyaline; size vari- able in same acervulus, usually with one or two oil drops. Developing from a well-detined stroma; basidia, 8-18/^ In moist chamber the conidia stream from the break in the epidermis. Intra-basidial sette, variable 8-30/^ by 3-6/^, cylindrical or sometimes enlarged at distal end; hyaline. SYNONYMY. CoUetotriclium glcvoaporioidcs Penzig. VcDiiicularia gkcosporioidi's Penzig. Funghi Agrumicoli, No. 90, p. 66, fig. 1188, Padova, 1882. Phi/llostida adusta, E. c<: M. Jour. Myc, II, p. 130, November
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