Hale, Swisher, & Floyd Sugarcane
Aphid Update August 10, 2016
It
seems this rascally invasive insect loves to keep us confounded and confused. In 2014 they discovered late in the growing
season we do raise quite a bit of sorghum in West Texas, which made the fall and
period right before harvest interesting to say the least. In 2015 they hit the area sorghum fairly
early with a massive population invasion that felt like a full speed locomotive
that smashed sorghum fields and bank accounts alike as we struggled to learn
about the pest while using control tools designed for another region. Then
they successfully overwintered in Hale County and made their intimidating
presence known in Lubbock and Swisher Counties early in the spring only to fall
completely off the radar without a trace of the pest to be seen. Meanwhile, their 2015 impact and spring intimidation
was enough to impact planting intentions and / or force a full IPM plan in
sorghum devoted to managing this one pest.
Now they are back for 2016 and their behavior and impact is a puzzling
as ever.
We
certainly have sorghum fields in Hale, Swisher, & Floyd replay this insect’s
incredible reproductive capacity that we have seen over the past two
seasons. In these fields, we witnessed a
mere three weeks or so time frame from detection to treatment level. Our producers and entomologists for the most
part seem to have taken the threat very seriously and implemented our new Texas
High Plains Sugarcane Aphid Threshold to some substantial effects at holding
and cleaning this aphid from those troubled fields. While there are some escapes and fields with
less than ideal control levels, it is nothing like last year. But then again, the aphid is not behaving as
badly as last year either.
The
sugarcane aphid is very far flung in its 2016 invasive march through the ‘northern’
sorghum territory of Texas but this march does not seem to be the rolling fog
of devastating aphids that the 2015 movement was. Meaning to say that applied entomologists are
detecting establishing sugarcane aphids in sorghum fields well into Kansas, the
western counties of the Texas Panhandle (if not New Mexico) and northeast into Virginia
already but not every field between detection sites was infested and / or devastated
along the way. We can say the same thing
in micro across my three counties of responsibility. There are fields in southeastern Floyd, which
had the aphid first, and fields in northwestern Hale and southwestern Swisher
that needed to be treated for economic populations of sugarcane aphids
alike. However, in between these two opposite
sections of adjoining counties are plenty of healthy sorghum fields without any
detectable sugarcane aphids. By the way,
this also includes our research plot trials still awaiting the arrival of the
aphid so that we can gain better knowledge on understanding the aphid and how
to best control it economically.
There
are a lot of unanswered questions here.
Why were these fields passed over?
Is the aphid population just so low today that they can be choosy about
which fields they infest? If so, why are
they choosing certain fields? Is it
variety related? We have resistant lines
but this feels larger than the known “slight resistance” factor. Are they just following some geographical
feature to skip over fields, say the draws that cross the area? Is it wind and weather patterns that carry
them in what appears to be random patterns?
Or are we just getting better about finding the lighter populations
before the aphid really gets rolling? Could
the aphid’s choice in fields be plant stage related? Is the aphid population smaller due to less
sorghum in the area? Is this more of a
typical behavior patter for the aphid? Will
the aphid fill in and eventually attack the passed over fields? And the really big question might be, will
another wave of aphids invade the area and be as heavy as we know the aphid can
be?
A
lot of us have hypothesis to these questions, but with only one true year of
research on this aphid few of us on the Texas High Plains have definitive answers
for this aphid’s many questions at this time. What we can state with certainty is what is
before us. Based upon the current distribution
of the sugarcane aphid in Hale, Swisher, & Floyd Counties, every sorghum
field is at risk for sugarcane aphid damage and will remain at risk until the
grain is in the bin. Only about half of
our program fields currently have aphids in them. I do not expect all sorghum fields to need
treatment this year based upon what I am seeing today. We all know this can change rapidly so we
must remain vigilant. Honestly, we have
no idea when or why aphids are choosing some fields and not others, but we must
identify the aphid infested fields as early as possible. I believe the least likely fields to require
treatment are early planted fields already going into hard dough stage right
now. These fields have a smaller window
of damage opportunity from the aphid now.
Conversely, late planted fields still in the whorl have a wide window of
damage opportunity today.
Of
the fields that are infested, there are no guarantees that they will need to be
treated as the predators are having a big impact on the aphids, but most
earlier infested fields have already needed treatment and that happened
typically about three weeks post detection.
If a field reaches our new High Plains Sugarcane aphid Threshold, we
need to act quickly. Not only do we need
to act quickly in making treatment, we need to make that treatment with one of
the two proven to work and labeled products Sivanto or Transform and we need to
be very particular in terms of getting good coverage that reaches to the very
bottom of the canopy with solid rates.
The gallons of mix per acre for these treatments must be minimum 15
gallons per acre via ground and 5 gallons per acre via air, but higher rates,
almost without limits, practicality aside, are very advisable.
While
I feel the SCA pressure is much litter this year, they still demand
respect. The bottom line in treatments is
this; if we are forced into treating, we must make this one treatment count and
last. We cannot give the aphids a day or
two to see if they continue increasing as the population will become too large
for one treatment to contain. We cannot
try a cheaper, predator harsher product that is not likely to work as we will
not clean the aphids out, if we impact them at all, and we will take out all
predators and have a larger more expensive mess on our hands than if we had
done nothing at all. We cannot fudge on
our GPA for convenience, or we will not get good treatment coverage on the
lower leaves and the aphids will re-infest the upper portions of the plants in
a matter of days. Our two 2015 High
Plains SCA research efficacy trials on the High Plains (Hale Center &
Bushland) proved these trends are very likely.
So
far, by following the High Plains SCA Threshold, acting quickly and using the recommended
products in the best recommended manor, we have had some really good success in
controlling this aphid when needed.
Behind a “good” SCA treatment, we are not seeing aphids.
Blayne
