We are almost
into July and have not seen the arrival of the sugarcane aphid (SCA) onto
sorghum in Lubbock or Crosby county. Many are wondering how this is possible
and what this means for the rest of the season.
Dr. Pat
Porter, Extension Entomologist in Lubbock, has posted an update to the Texas Sugarcane
Aphid News website, summarizing what may be happening with the
aphids this year. I've copied the text below.
From Dr.
Porter:
Given that we
know sugarcane aphid overwintered as far north as Plainview, and that it was
found on Johnsongrass in Lubbock County in early May, the question we are most
frequently asked lately is, "Why don't we have sugarcane aphids yet?"
That is a good
question, and I wish I could be totally certain of the answer. I suspect that
our beneficial insects wiped out the overwintering aphids. We had extremely
high numbers of ladybugs, syrphid flies and the other predators that went into
overwintering last year after feasting on sugarcane aphids. In what should be
considered to be good news, we also had fairly heavy aphid numbers in wheat
this spring, but not enough to do significant economic harm. But these wheat
aphids, which were not sugarcane aphids, provided food for our early season
beneficial insects, which in turn were available to start munching on the
overwintering sugarcane aphids in the area. This is just conjecture on my part,
but it is the simplest explanation of why sugarcane aphid was here in the early
season and is now gone.
The next most
common question we are getting is, "When will the aphids arrive?" Of
course no one knows the answer, but later is better, and growers who planted
early are seeing a benefit from that practice. Last year the first sugarcane
aphids found on the High Plains were discovered in Lubbock County on June 27th,
and within three weeks we were scrambling to get fields sprayed. I think that
last year we had some colonies beginning to build locally in late June, but,
given the wide area infested a few weeks later, it is most probable that one or
more flights of winged aphids came up from the south on wind or storm events.
This year we probably do have some small pockets of sugarcane aphids locally.
The good news is that aphids are not extremely numerous on the Gulf Coast and
in the Hill Country. Our colleagues south and east of here are reporting that
they have only light to moderate infestations (although some fields required
treatment). They are also saying that beneficial insects are catching up to the
aphid populations and decimating them. This is means there will be fewer aphids
traveling on the winds and landing on our front door. If we have fewer aphids
colonizing our plants then the beneficial insects we have in the system will
have a better chance of suppressing those that do arrive.
I wish I could
predict what will happen in the next few weeks, but of course I can't. If you
find sugarcane aphids in your fields then please give us a call. The telephone
numbers for your High Plains IPM Agents and Extension Entomologists are listed here. We sincerely appreciate
people who take the time to call and report pest problems.
