Variety SelectionSelecting productive cotton varieties is not an easy task,
especially in Oklahoma where weather can literally make or
break a crop. Producers need to compare several characteristics among many different varieties, then key the characteristics to typical growing conditions. The growing environment
from year to year cannot be controlled, but varieties can be
selected based on desired attributes. It is very important to
select and plant varieties that fit specific fields. Do not plant
the entire farm with a single variety, and try relatively small
acreages of new varieties before extensive planting. When
it comes to variety selection in Oklahoma, several factors are
important to consider.
Maturity (Earliness)
Scrutinizing the relative maturity rankings provided by
seed companies will be beneficial. Don’t expect a mid- to
full-season cotton variety to perform well in a short-season
environment, where an early or early- to mid-season variety
might work best. Many longer season cotton varieties are better adapted to areas with longer growing seasons, although
significant gains in yield may sometimes be obtained in years
with warm September and October temperatures. Longer
season varieties will typically do much better when planted
earlier, then provided an excellent finish. For later plantings,
early- to mid-season maturity varieties may be better. For late
plantings or replant situations, early maturity varieties may be
better. Relative maturity for most varieties gets compressed
when moisture stress occurs. With drought stress, maturity
of longer season varieties will not be expressed to the degree
that would generally be noted when under high water and
fertility regimes.
Pounds
Yield potential is probably the single most important agronomic characteristic, because pounds do drive profitability and
provides for the safety net of higher actual production history
(APH) in case of catastrophic loss of acres. The benefit this
can provide from the crop insurance perspective is important
in our high risk area. Yield stability across environments is going to be important, and finding a variety that has the ability
to provide high yield across varying water inputs is critical.
Fiber Quality
Producers should also consider lint quality. Progress has
been made in terms of fiber quality during the last several
years. Significant improvements have been seen in overall fiber quality packages associated with modern varieties. Staple
is generally good to excellent for most new varieties. Many
things can affect crop micronaire, including overall environment, planting date, variety, early season fruit loss with later
compensation, excessive late season irrigation or rainfall,
seedling disease, early season set-backs due to hail damage,
blowing sand, thrips, etc. Fiber strength has also significantly
improved and many newer varieties tend to be at least 30 g/
tex. Length uniformity can be affected by staple, maturity
and harvest method (picker harvested is typically higher than
stripper harvested). Higher maturity fiber generally results in
better uniformity. Leaf grade can be affected by density of leaf
hairs on specific varieties in some years. Generally, cool, wet
fall conditions can lead to lower quality leaf grades for varieties which tend to be hairy. In drier harvesting environments,
these differences tend to diminish.
Color grades are basically a function of weathering or
exposure of the fiber on the plant to wet conditions. The highest quality that a cotton boll can have is on the day that it
opens. After that, if conditions favor microbial growth (warm,
wet conditions). An early freeze can affect immature cotton
by reducing its color grade. Bark contamination is generally
also driven by significant late season rainfall followed by a
freeze. In some years, this can’t be easily managed if stripper harvested. Conversely, picker harvesting can significantly
reduce or eliminate bark contamination.
Storm Resistance
Storm resistance is still a concern for growers in our
area. Even though many producers have adopted less
storm-resistant cotton varieties during the last several years,
and generally done well with them, the overall management
system the producer adopts can be important. Under significant moisture stress on dryland, some newer varieties may
provide an unacceptable level of storm resistance, especially
if the field is left to a freeze. Producers planning to execute a
sound harvest aid program as soon as the crop is mature can
probably grow some fields with less storm-resistant cotton.
However, having large acreages of varieties with low storm
resistance might be a prescription for disaster if the right environmental conditions align at harvest. Do not plan to leave
looser cotton varieties in the field until a freeze conditions
the plants for harvest. Unacceptable pre-harvest lint loss is
likely to result. Higher storm resistance varieties are better
adapted to our harvesting conditions and they are more likely
to survive damaging weather prior to harvest without considerable seedcotton loss. Inquire about the storm resistance of any variety on your potential planting list. If choosing a variety
with low storm resistance, plan and budget ahead for a good
harvest aid program that will achieve an early harvest. Good
storm resistance data are now being provided by most companies and we visually evaluate all Extension and research
variety trials for this attribute. For those planning to harvest
with spindle pickers, varieties with higher storm resistance
may possibly result in reduced picker harvesting efficiency.
Disease and Nematode
Resistance/Tolerance
Producers should not plant the entire farming operation
to one cotton variety. A question should be “do I have plant
diseases or Root knot nematodes in this specific field?” Although we have not been able to identify substantial acreage
with this pest in Oklahoma, varietal tolerance or resistance
will be critical for management. It is important to know which
disease is present. If there is a problem with a wilt disease,
but don’t know what it is, then have the problem identified. If
known Verticillium wilt pressure is present, then take a look
at Texas A&M AgriLife Research and Extension testing data
from several locations investigating variety performance under
constraints from this particular disease. The same should be
considered for Fusarium wilt/Root-knot nematode issues.
Many times varieties which do well under Verticillium wilt
pressure may not be the same ones which are resistant with
Fusarium or Root-knot nematode. Bacterial blight is an occasional problem in the region, and the only way to manage
this disease is planting resistant or immune genetics. There
are several varieties that can provide high levels of resistance/
immunity.
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