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Several factors are critical to successful
ratoon crop production. The earlier
the ratoon crop matures, the higher
its potential yield. Therefore, rapid
stimulation of regrowth is an important factor.
Apply the planned preflood nitrogen rate
immediately after harvesting the main crop
and flood it into the soil to stimulate regrowth.
Keep soils moist with a shallow flood until
regrowth has advanced and retillering has
occurred. After retillering, maintain a flood
sufficient to control weeds.
1. Don’t flush fields after harvest.
Flushing permits the germination of rice
grain residue from harvesting. Germinated
rice seeds become weeds that compete for
nutrients and light. Time does not permit
them to produce panicles. Flooding immediately
after harvest prevents the germination of these seeds through the
formation of an anaerobic layer near the soil surface.
2. Consider main crop cutting height.
Traditionally, the main crop has been cut at about 18 inches above
the ground (depending on variety). Ratoon tillers may be generated
at any node below this height. Panicles from aerial nodes tend to be
smaller with smaller grain compared to tillers originating from the
crown. Panicles from different nodes may increase variability in
maturity and decrease milling yield. Plot research and field verification
tests have shown that reducing the cutting height will increase ratoon
crop yield and uniformity.
In small plots, yields increased as main crop cutting height
decreased to four inches. Yields did not increase below eight to 10
inches in field verification tests. Reducing main crop cutting height
will delay ratoon crop maturity by six to 10 days. This delay can be
offset by making a nitrogen application about seven days before
main crop drain and flooding immediately after harvest. The reduced
cutting height can be achieved during combining or by using a flail
shredder. Note: If your ratoon crop is late, you may not want to
reduce cutting height.
3. Fertilization tied to anticipated yield potential.
The recommended nitrogen rate for ratoon crop production is
dependent on the anticipated yield potential. That is, if all or most of
the following conditions can be met, rates as high as 70 pounds of nitrogen per acre for conventional varieties and 100 pounds of nitrogen
per acre for semidwarf varieties can be recommended. These
conditions include: 1) harvest before Aug. 15, 2) absence of disease
in the main crop, 3) limited field rutting by equipment, 4) good weed
control in the main crop and 5) yield of the main crop lower than anticipated
but good growth potential. Decrease or eliminate nitrogen if the
main crop harvest is delayed; ratoon tillers are few; disease is present;
fields are rutted; or weed pressure is significant. Any delay in nitrogen
and water application reduces the yield potential of ratoon rice.
4. Control broadleaf weeds.
Herbicide use for broadleaf weeds, particularly dayflower, is the
biggest concern in ratoon crop rice. Several herbicides are currently
labeled for use in ratoon crop rice. These include 2,4-D, Grandstand
R and Basagran. Be sure to check the label for rates, timing and
weeds controlled.
5. Be proactive toward narrow brown leaf spot (NBLS):
Drs. Mo Way and Shane Zhou discuss this topic on page 17.
For more information on ratoon crop production, please refer to
2012 Rice Production Guidelines.
Garry McCauley, Lee Tarpley, Fugen Dou and X.G. “Shane” Zhou
with the Texas A&M AgriLife Research & Extension Center at
Beaumont contributed information for this article. |
