RA 00015.pdf - OAR@ICRISAT

all performed well for shoot fly-none having
more than 1 percent dead hearts. However they
were moderately susceptible to Chilo partellus -
the most resistant line was IS 4829, with a mean
of 49 percent of the stems affected. Maximum
head production per unit area was obtained from
IS 4002, 4036, EN 3362-1, and EN 3308-the
latter being extremely productive. The best grain
yields were obtained from IS 4036 and EN 3308.
The lowest number of larvae in stems at harvest
was on IS 4002 (9 % of stems) and the highest was
on IS 4829 (23 %). IS 1082 x WABC 4062 had 20
percent. More than 5 800 breeders' lines were
scored for shoot-fly attack.
Stem Borer. Production of Chilo larvae, using
an artificial diet, was sufficient to initiate artificial
infestation studies on germplasm lines. Lines
showing promise in two seasons of testing were E
302, E 303, BP 53, IS 1044, 1056, 1151, 2122,
2205, 4747, 4776, 4799, 4866, 5030, 5470, V-2-1-
1-1, and V-2-1-1-2. In "grow out" trials of much
of this material under high natural infestation
conditions, E 303, 1044, 1151, and 5470 all had
less than 30 percent damage compared to CSH-1
with 69 percent.
Midge. Studies on the damage, biology, and
resistance to midge were intensified, but work
was hampered by the low levels of attack at
ICRISAT Center. Seventy-six lines suspected of
having some resistance to midge were sown at
Sillod and Selsoor with the cooperation of the
Maharashtra Department of Agriculture. These
preliminary trials indicated that SC 173 (IS
12664 C), SC 175 (IS 12666 C), SC 423 (IS 2579
C), SC 329 (IS 3574 C), SC 63 (IS 12573 C), and
SGIRL-MR-1 should be further tested.
Other Studies
Some work was initiated on storage pests of
sorghum as a preliminary to work on storage
characteristics of sorghum cultivars. There were
distinct differences in Sitophilus oryzae multiplication
rates in CSH-1, "Swarna," and Local
sorghums.
Our insecticide trials failed to elucidate
reasons for the apparent failure to control Atherigona
soccata with carbofuran, but did confirm
that the insecticide was less effective than in
previous use.
Pathology
The main objective of the sorghum pathology
program is to minimize the possibility that
improved high-yielding sorghums will be vulnerable
to disease epidemics. To achieve this, stable
broad-spectrum resistance must be located and
incorporated into high-yielding genotypes.
Screening for Grain-mold Resistance
Short-cycle sorghums need resistance to grain
mold as they often mature under wet conditions
and produce grain with low market acceptability
and poor viability, and may contain mammaliotoxic
fungal-produced mycotoxins.
Seventeen fungal species in 11 genera were
isolated from moldy sorghum grain. The most
frequently isolated genera were Fusarium, Curvularia,
Tricothecium, and Olpitrichum, in that
order.
More than 5000 germplasm lines were inoculated
with pathogenic isolates of Fusarium
semitectum and Curvularia lunata, either singly
or together, and then compared with noninoculated
heads in the same row. Conditions in
rainy season 1975 were favorable for mold
development and only 90 lines with little or no
mold were selected for further tests. Unfortunately
in rainy season 1976, September and
early October had but little rain and this was not
conducive to profuse mold growth. However,
mold development was sufficient for differentiation
of low and high susceptibility; of 1421
lines tested, 33 were selected. The best material
from 1975 was tested at several locations in the
International Sorghum Grain Mold Nursery,
discussed in a subsequent paragraph.
Screening for Downy M i l d e w , L e a f
Diseases, and Stalk Rot
Work on diseases other than grain molds was
41