Remember drawing a treasure map as a kid. You drew elaborate
lines and plotted landmarks leading the treasure awaiting the end of the hunt.
I relived those days many times in the past week. In this
case, the treasure is a sea of fluffy white cotton fiber awaiting growers during
the fall harvest. I spent hours mapping the fast-growing cotton plants across
the Valley.
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| - Graphic by Texas AgriLife Extension Service |
Plant mapping can be rather simple.
You don’t need to be a Van Gogh or make it complicated. In fact, by making it easy, you are likely to
continue mapping the development of your cotton plants. The work will help you
make future management decisions and give you a good indication of the yield in
the fall.
I’m seeing plants with 80 to 100
percent fruit retention – a very good rate. For Acala upland cotton, growers normally can expect a 60 to 70 percent
retention rate. Pima cotton is a little less precise to predict.
Lygus, however, is in full force in
the cotton fields. It’s not surprising to see numbers rise following the third
cutting of alfalfa in nearby fields. On the positive side, the lygus population
could be even higher in cotton if growers didn’t follow best management
practices and leave strips of uncut alfalfa to keep the pest from migrating
into cotton.
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| Growers need to keep an eye on lygus in the coming weeks. |
Still, cotton growers need to continue monitoring their
fields and follow the trends carefully. You
can download a pdf of UC Integrated Pest Management’s guidelines about fruit
retention and lygus monitoring. It
includes a handy chart to record your monitoring information.
I want to caution growers about jumping the gun on pest treatments.
For example, I checked a field last Monday and found eight to nine adult lygus
in my sweep net, which would put you at the threshold of treating your field.
But a few days later, I re-checked the field and found the numbers had dropped
to three to four lygus per 50 sweeps of my net.
The likely reason for the drop is the lygus “took a drink” in the cotton
field and then returned to the nearby alfalfa field. Lygus actually prefer the
conditions found in alfalfa.
So far, I haven’t heard or seen growers treating their
cotton fields for spider mites and lygus. That’s good. Usually you will see
growers on their first or second treatment this time of year. My guess is the
strip alfalfa and the increase in hay acreage is dampening the pest pressure in
cotton this year.
We’ve finished collecting petiole, or leaf stem, samples and
sent them off to the lab. The results should be back in about a week. That will
give us an idea whether plants need more nitrogen or have been fertilized too
much.
Before the season heads into July, I want a take a look back
at the spring. With the recent heat wave, plants are developing ahead of
schedule. I wouldn’t be surprised to see cotton planted early in the season to
starting blooming by the end of this week. Normally, you see bloom around the
Fourth of July. An early bloom extends the growing season. It also gives
growers a little insurance against early fall rains.
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| Beet armyworms are on the rise in Valley alfalfa fields. - UC IPM photo |
Looking at alfalfa, I’m finding a slight increase in beet armyworms.
It’s important for alfalfa growers to conduct weekly pest monitoring and scout
their fields before cutting. That way, you can determine if treatment is needed
to prevent pests from migrating to nearby fields such as tomatoes and cotton.
The good news is I haven’t heard of any growers treating for worms. Good
management practices do pay off.
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