Florida Agricultural Experiment Station


Fig. 11.-Rhinotrichum boll rot.


Bolls attacked by F. moniliforme
are shown in Fig. 10. The in-
juries caused by this disease may
be lessened by following the sug-
gestions made for the control of
the other boll rots.
 A large number of other fun-
 gi have been reported as caus-
 ing rots of cotton bolls, but they
 are usually of uncommon occur-
 rence or only appear abundantly
 on bolls rotted by more vigorous
 parasites, and as a whole are of
 little economic importance. Rhi-
 notrichum tenellum B. & C oc-
 curs commonly in Florida and is
 conspicuous on account of a
 dense felty growth of the gray
 to dirty white mycelium, as
 shown in Fig. 11. Another fun-
 gus that resembles Rhinotrich-
 um, though occurring less com-
 monly, is Olpitrichum carpophi-
 lum Atk. The extremely com-
 mon soil organism, Sclerotium
 rolfsii Sacc., which causes se-
 vere losses on some other crops,
 occasionally occurs on cotton
 bolls in Florida. The bolls at-
 tacked by this fungus are usual-
 ly in contact with or near to the
 soil, and are of a very character-
 istic appearance as they become
 covered with large numbers of
 the sclerotia of the fungus
 which resemble mustard seed. A
 boll of this type is shown in Fig.
 12. Injuries caused by these
 fungi may be reduced by the
 measures recommended for con-
trolling other boll diseases.


Fig. 12.-A cotton boll covered with
the sclerotia of Sclerotium rolfsii.