Dry and hot conditions
have promoted early maturity of grain sorghum and as a result sorghum hybrids have accumulated enough
growing degree units to reach “black layer” or physiological maturity. Thus harvest time is beginning here in the
Coastal Bend, that is if you were fortunate enough to get some timely
rain. Some folks were not so lucky in
the rainfall department and as a result, sorghum has been declared a total loss
and is being cut for hay or plowed under.
Here are some tips to
prepare grain for harvest as grain sorghum growers can obtain higher prices if
their sorghum meets market moisture specifications. To help meet those specifications, growers
may apply harvest aids.
When harvest aids are
applied properly, harvest is made more efficient and combining is faster, with
no reductions in grain weight. Grain from the entire field will have a uniform
moisture content, resulting in few “hot” loads and price discounts. To keep the grain from losing weight, it is
critical that growers apply the harvest aids at the proper time, which is once
the grain reaches physiological maturity and the average grain moisture drops
below 30 percent. If harvest aids are applied prematurely, both yields and
grain quality will be reduced.
Physiological maturity
can be determined by sampling grain with a grain moister tester and also looking
at the kernels for a black layer which indicates that the crop is mature. Pictures of a black layer can be found in a
publication L-5435 - “Harvest Aids in Sorghum,” that can be found at the
following web address: http://publications.tamu.edu/CORN_SORGHUM/PUB_Harvest%20Aids%20in%20Sorghum.pdf
There are only two
products labeled for use as harvest aids: sodium chlorate (containing a fire
retardant) and glyphosate. For satisfactory results, good spray coverage is
needed for both products. Eight to 10 gallons per acre (GPA) of solution by
ground or 3 to 5 GPA by air is recommended.
Sodium chlorate, which
can cause fires if it is not mixed with a retardant, is a chemically active
salt that desiccates the plant. Growers may apply up to 6 pounds per acre. This
product is sold under various trade names and concentrations of active
ingredient per gallon. For good desiccation, the weather must be hot and dry.
Glyphosate, a common
herbicide, will kill the plant. Producers may make a single application of up
to 2 quarts per acre. Since formulations
can vary, be sure to check the product label for correct rates per acre. Once it is applied to sorghum, the plants move
the glyphosate to the growing point over a 5- to 6- day period. Weeds that are
actively growing when the product is applied will also be destroyed. Use a sprayable grade of ammonium sulfate at
a rate of 17 pounds/100 gallons of water or a prepackaged sulfate formulation
to condition the water and improve effectiveness. There is a 7-day waiting
interval between application and harvest. The crop is usually ready seven to 10
days after application.
Growers should only
treat those acres that can be harvested within 10 days to two weeks after
application. Weather and storms in the
Gulf should also be a consideration.
To avoid any premature lodging, inspect the field before the
application. Look for stalk degradation from diseases such as charcoal rot, which
will cause premature lodging during natural dry down or after harvest aids are
applied. Picture may be found on web
at http://www.ksre.ksu.edu/library/plant2/L741.pdf
Conditions under which charcoal rot is favored include stressful hot
soil temperatures and low soil moisture during the post-flowering period. Host
plants are usually in the early-milk to late-dough stage when infection occurs.
The fungus is common and widely distributed in nature. To check the plants
before treatment, split the stalk lengthwise and look for a hollow stem or
black rot just above the root crown. If the stalk is unhealthy, it will
generally fall, whether or not it has been treated.
As always when using farm
chemicals, read and follow label directions carefully before applying the
product.
