450 
with the three forms of the disease, vascu- 
lar, brown rot, and basal dry rot, have 
been published by McCulloch (1944), 
Massey (1926), Nelson (1948), and Mc- 
Clellan (1947). The symptoms common 
to all three forms of the disease are a 
brownish to black dry rot of the corm tis- 
sues; yellowing, browning, and death of 
the foliage; and browning and destruction 
of the roots. 
The three forms of the disease have been 
distinguished mainly by effects on the 
corms. In the vascular form of the dis- 
ease a sectioned corm will reveal a brown 
discoloration of the core and dark-colored 
vascular bundles extended laterally into 
the flesh, fig. 1B and C. In an advanced 
stage of the disease, the infected strands 
reach the surface of the corm at the nodes, 
and brown lesions develop at these points. 
Intinoris NatuRAL History SurvEY BULLETIN 
Vol. 26, Art. 6 
In the brown rot form of the disease, 
tan, brown, or blackish lesions may occur 
anywhere on the corm but most commonly 
near the base, fig. 2. The rotted tissue is 
often quite thick and may extend all the 
way through the corm, fig. 2, bottom row. 
Vascular discoloration is not associated 
with this form of the disease. 
The basal dry rot form of the disease 
differs from the brown rot form mainly in 
the thickness and position of the lesions. 
Basal dry rot lesions occur only on the 
bases of the corms and are usually re- 
stricted to the first and second internodes, 
fig. 3. The lesions are visible when the 
corms are dug and, under favorable curing 
conditions, they do not enlarge after har- 
vest. They rarely, if ever, extend deeper 
than 2 to + millimeters into the flesh. The 
diseased tissue is dark brown to black, 
Fig. 2—Picardy gladiolus corms affected with the brown rot form of the Fusarium disease. 
Above: bottom views of six corms with lesions of various sizes. 
showing thickness of rotted tissues. 
Below: sections of three corms 
