. Cottony rot of lemons in California. cjflflplclfl ^o o o o o o o o o o o w ? = fl S P. fl S P S Fl S S OfkJcD CD CD CD CD CD CD CD Z Eh f3 O oj P el 03 5H W H-H ^ vn S *«S «s ..S »2 (is .5 S -- > a -§ - 9 Ssa §| §| S| § s || «s §§ a £ §^ « - 5 3h_jHJHJ^J rn c3 OS C?H fl P gCD CD CD fl CD <B^_, CD 0 -1 CD CD CS fl fl • rH — at oS — S fl a COTTONY ROT OF LEMONS IN CALIFORNIA 251 On Citrus Twigs.—These are very readily infected artificially withthe cottony rot fungus. Infection has been repeatedly caused by usingapothecia and spores, mycelium and sclerotia. In the inoc
. Cottony rot of lemons in California. cjflflplclfl ^o o o o o o o o o o o w ? = fl S P. fl S P S Fl S S OfkJcD CD CD CD CD CD CD CD Z Eh f3 O oj P el 03 5H W H-H ^ vn S *«S «s ..S »2 (is .5 S -- > a -§ - 9 Ssa §| §| S| § s || «s §§ a £ §^ « - 5 3h_jHJHJ^J rn c3 OS C?H fl P gCD CD CD fl CD <B^_, CD 0 -1 CD CD CS fl fl • rH — at oS — S fl a COTTONY ROT OF LEMONS IN CALIFORNIA 251 On Citrus Twigs.—These are very readily infected artificially withthe cottony rot fungus. Infection has been repeatedly caused by usingapothecia and spores, mycelium and sclerotia. In the inoculation of thetwigs a sloping cut through the bark into the wood was made and con-siderable of the mycelium was placed in this injury. To insure the bestinfection, the injury was then wrapped with paraffin waxed paper toprevent drying out. By this method the injured part of the woodand bark would be rather easily attacked by the fungus, starting as asaprophyte. From the injury the infection gradually spreads until. Fig. 9.—Cottony rot affecting the blossoms of a Eureka lemon tree. Thiscondition only appears under certain very favorable conditions. it completely encircles the branch. Gumming takes place, especiallytoward the margin of the infection. The affected bark of the citrustwig differs from normal tissue in color, being greyish or may or may not be produced in the infected bark (Fig. 7b),which is at first soft, becoming at length fibrous. The infection mayextend 1 or 2 inches in length of twig, gradually surrounding andkilling it. The infection appears to die out when healing takes place. The conclusion drawn from these experimental inoculations withdifferent strains of Sclerotinia is: (1) That the different strains usedmust belong to a common species, or (2) that the citrus host mustbe especially susceptible to infection from different species of thisgenus. 252 UNIVERSITY OF CALIFORNIA—EXPERIMENT STATION METHODS OF CONTROL In F
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