Sorghum Diseases in India

Dalmacio: Mainly due to lack of market. Seed
millers are somewhat reluctant to utilize sorghum
as a feed ingredient.
Guiragossian: Since we have several new diseases
that are not included in the Sorghum and
Pearl Millet Disease Handbook, maybe it is time
to update the handbook?
Is tar spot on sorghum different from the tar
spot on maize?
Dalmacio: I have not seen the Phyllachora isolate
from sorghum attacking maize in the
Philippines.
Giorda:
1. What are the parameters that you use to determine
the relative importance of a disease?
(You are considering sugarcane mosaic a
minor disease, when it causes an estimated
yield loss of about 50%?)
2. What strains of SCMV do you have in your
area?.
Dalmacio:
1. Parameters used were incidence and severity
of disease under natural conditions. The 50%
yield loss from sugarcane mosaic virus was
based on artificial inoculation, not on natural
infection.
2. We do not know the strains of SCMV occurring
in sorghum in" the Philippines.
Mughogho: It might be useful if you would inform
us about your extensive research program
conducted at various centers in India.
Anahosur: In India the different centers, situated
in different agroclimatic zones, have been
working on diseases of regional importance primarily
and major diseases in general. These are
detailed in Tables 2 and 3 of my paper.
Vidyabhushanam: In view of the increased incidence
of virus diseases, some strategy needs to
be developed to contain them.
Anahosur: Some work is being carried out at
Parbhani by Dr Garud. This program will be
strengthened in the future.
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Theuri: You have shown excellent control of
downy mildew in India by the use of fungicides.
Has somebody looked at the economic returns
realized from sorghum harvests treated with
these fungicides? Would you recommend the
use of these fungicides to farmers, especially because
many of the farms are small-scale?
Anahosur: We primarily look for resistant genotypes,
and farmers prefer these. Fungicides
are used to treat susceptible lines used in experiments,
to maintain experimental material, and
for seed production.
Dalmacio: Is the other ingredient combined
with Ridomil ® also effective against the downy
mildew fungus? So as to minimize the occurrence
of Ridomi ® -resistant strain?
Anahosur: The other ingredient with metalaxyl
(mancozeb or ziram) may help minimize the development
of a metalaxyl-resistant strain as well
as reduce damage caused by other pathogens.
Laing:
1. You have explained that you are doing
research with metaiaxyl against sorghum
downy mildew; are you worried about metalaxyl-resistant
races?
2. Have you tested etridiazole, propamocarb, or
hymexazol in this role?
Anahosur:
1. We are worried about metalaxyl-resistant
races but we are using Ridomil ZM ® , a metalaxyl/mancozeb
mixture, and this should
slow down the development of resistant
races.
2. No.
Laing: Is there any evidence of the monogenic
resistance to sorghum rust being differential/
vertical resistance and therefore vulnerable to
new virulent pathogenic races?
Anahosur: Yes, the resistance is monogenic or
digenic, but we are looking for polygenic resistance.
It also depends on the genetic background
into which it is bred.
Frederiksen: Have you seen ladder spot of sorghum
in Brazil?