A manual of rice seed health testing - IRRI books - International Rice ...

Seed treatment at IRRl
IRRI's Seed Health Unit treats outgoing
seed lots to meet the
phytosanitary requirement of various
countries. Hot water treatment
(52-57 °C for 15 min, after presoaking
for 3 h in cold water; Fig. 11.1) followed
by slurry treatment with 0.3%
benlate and 0.3% Dithane M-45 by
seed weight (Fig. 11.2) is applied to
all shipments intended for Southeast
Asian nations. ASEAN PLANTI
(1981) prescribed hot water treatment
at 52-57 °C for 15 min followed
by dressing seeds with 1 g benlate/
100 ml of seed.
At IRRI, all outgoing and incoming
seed lots are fumigated with
1.2 g phosphine/m 3 for 72 h, NAT,
NAP (Fig. 11.3).
Future biocides
Seed treatment has revolutionized
crop production and minimized
chances of spreading exotic pests
and pathogens. In the future, biocides
are needed that will do the following:
act against the target organisms
without having undesirable side effects;
not affect germinating seeds and
seedlings;
be compatible with all other
chemicals used in rice production
(for example, fertilizers and herbicides);
be environmentally safe; and
not have deleterious effects on
nontarget organisms and lives
(Bowling 1986).
Precautions
Seed treatment (physical or chemical)
requires utmost care. Improperly
applied, treatment can damage or
kill the seeds. Application modes
and doses should be correct. Most
biocidal chemicals are health hazards
if not properly handled.
Treated seeds should not be eaten
and should be adequately labeled to
prevent inadvertent consumption.
Some biocidal chemical formulations
color treated seeds, providing visible
warning to anyone who handles
them. Coloring also helps evaluate
the uniformity and thoroughness
of chemical application.
11.3 Fumigation
using atmospherictype
fumigation
chamber and
phosphine.
Seed treatment 61