Sorghum Diseases in India

Mexico, particularly in Tamaulipas. Severe damage
has not been reported.
Grain molds. (Curvularia spp, Fusarium spp,
Alternaria spp.) These are important on the
coastal areas of Mexico, including Tamaulipas.
Curvularia spp, present in 90% of the molded
heads, are the most common, followed by Fusarium
spp.
Storage molds. These include several species;
they occur occasionally in some areas, but are
not reported to be important.
Abiotic Diseases
Chlorosis. (Iron deficiency.) It is common in
the most important sorghum-growing areas of
Mexico; entire fields of dwarf-yellowing plants
appear. The problem has been more severe in
recent years.
At Guanajuato, an estimated 10 000 ha are
iron-deficient, and the chlorosis can prevent
grain yields. The condition is common in calcareous
soils with iron deficiencies.
In 1985, two lines were identified as tolerant
to iron deficiency when grown in a greenhouse;
resistance was later verified in field trials
(Gonzalez and Galvan 1987). Tolerance of iron
deficiency is being incorporated into elite material,
and studies on the inheritance to this character
are underway.
Pesticide injury. Chemical damage to sorghum
plants is now a common problem in Mexico,
becoming more so as chemical control of
greenbugs is becoming more important. Many
of the organophosphate products can burn up to
80% of the foliar area, reducing yields by an estimated
5% or more. Herbicides such as parafuat
produce similar damages. Most of the RTAM 428
hybrids will show pesticide damage because the
pollinator is susceptible to parathion.
Salt damage. It is caused because of salt residues
from irrigation waters, occuring in large
areas in northern Tamaulipas. Data on the area
affected are not available, but the problem is increasingly
important. Some hybrids seem to be
more tolerant of salt than others. In severely affected
areas, sorghum cannot be produced
profitably.
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Mycoplasm Diseases
Yellow sorghum stunt It is the only sorghum
disease known to be caused by a mycoplasm. It
occurs occasionally in central Mexico, but incidence
in susceptible lines has not been greater
than 10% (Narro and Betancourt 1983).
Research Strategies in Mexico
Sorghum disease problems in Mexico are being
approached mainly through the development ofresistant
hybrids and studies of chemical control.
At Rio Bravo, Tamaulipas, research is focused
on downy mildew and head smut. At
Celaya, Guanajuato, the program includes
studies of stalk rot and head blight, virus diseases,
rust, and leaf blight. At Ocotlan, Jalisco, a
program is underway for leaf blight and stalk
rot resistance.
Mexico wishes to reinforce its sorghum research
programs by:
1. Training personnel in sorghum pathology.
2. Determining yield losses to diseases.
3. Promoting international cooperation through
establishing international disease nurseries,
sharing elite resistance inbreds, and control
technologies.
Acknowledgment. The authors express their
gratitude to Leopoldo Mendoza Onofre for his
assistance, and to agronomists Flores Gaxiola, J.
Abel, A. Viscaino Guardado, Grajales Solis, M.
Teniente Oviedo, Rodrigo F. J. Cruz, Ch. F. Monjaras.
A., for information on sorghum diseases in
southern Mexico.
References
Aguirre, R.J. 1984a. Razas fisiologicas del carbon
de la panoja en el cultivo de sorgo en el norte de
Tamaulipas. Page 73 in Proceedings XI Congreso
Nacional de Fitopatologia, San Luis Potosi, 16-
18 Jul 1984.
Aguirre, RJ. 1984b. Patotipos de mildiu velloso
en el cultivo de sorgho—en el norte de Tamaulipas.
Page 74 in Proceedings XI Congreso National
de Fitopatologia, San Luis Potosi, 16-18
Jul 1984.