Sorghum Diseases in India

Table 2. Comparison of disease intensities between sorghum heads inoculated with a 72 h sporidal
inoculum and with fresh teliospores of Tolyposporium ehrenbergii.
Disease intensity With sporidial inoculum With fresh teliospores
no. of sori head -1
(no.) (no.)
(0) 33 1
(1-20) 26 20
(21-50) 13 11
(51-100) 9 10
(10-200) • 3 10
(>200) 3 3
Total heads inoculated 87 55
Total heads infected 54 54
Infection (%) 62% 98%
Mean disease intensity 2.2 3.3
Cross inoculation with long smut isolates
Tarr (1955) reported pearl millet as a host of
T. ehrenbergii The causal organism of long smut
on the wild sorghum, Sorghum purpureosericeum,
in India was classified as T. ehrenbergii var grandiglobum
(Uppal and Patel 1943). Other wild sorghum
species are predominant in most areas
where cultivated sorghum is grown. Cross inoculation
tests carried out by the authors indicated
no difference between isolates infecting sorghum
and the wild sorghum, S. purpureosericeum,
but millet in the Sudan was not
susceptible to T. ehrenbergii; neither did long
smut isolated from millet infect sorghum (Table
3).
Control of long smut
At this time, the control of long smut by host
resistance is under consideration. Clearly, differences
in reaction exist. Some old sorghum culti-
Table 3. Cross inoculation with long smut isolates.
vars, such as BTx 378, are resistant whereas
BTx 623 is not. Currently, the sorghum improvement
program in Sudan inoculates sorghums for
reaction to long smut and a similar program is
being considered for Niger and Mali. Evidence
of good resistance among the cultivars tested in
the Sudan is reported in Table 4. QL 3 (India), SC
326-6, and SC 630-11 E were among the best performers
in two seasons' testing.
Uniform flowering of sorghum should reduce
plant-to-plant spread of the pathogen and
lessen the impact of the disease. Study of the
effects of the level of smut on disease development
has not been carried out. However, the
relationship between the level of infection and
damage appears to be linear.
The Kernel Smuts
Covered kernel and loose kernel smut are seedborne
seedling-infecting smut fungi. While early
workers exploited host resistance and detected
Pearl millet
Long smut isolate S. purpureosericium Sorghum feterita Baladi Ugandi
S. purpureosericium
S.bicolor
Pearl millet
250