Of course it varies considerably across areas, but tarnished and clouded plant bugs numbers are continuing their onslaught of some cotton fields, and stink bug numbers are jumping quickly in many places.  In our plots, we are finding an explosion of nymphs this week following treatments last week.  No insecticides appear to be holding them completely back.  Reminder: it is almost mandatory to make back to back insecticide applications on a 4-5 day window when battling numbers that are well above threshold (2-3 fold or higher).  The short spray interval is really more important than the choice of insecticide (as long as you are using a recommended product).

It is time to switch to a drop cloth in much of the cotton.  Recall, that the treatment threshold for tarnished plant bugs in blooming cotton is 3 bugs per drop cloth.  You should count clouded plant bugs and stink bugs as equivalent to 1.5 and 3 tarnished plant bugs, respectively, when making treatment decisions.  We suggest this once blooming begins because clouded plant bugs and stink bugs are more damaging to bolls than are tarnished plant bug.  Fortunately, they tend to be easier to control.

I’ve already heard some rumblings about turning some of the lagging acres loose and abandoning any further management.  This is an extreme and unnecessary consideration for the vast majority of the crop.  At the time I am writing this article, we have 15-20 days before reaching the average, last effective boll  date (approximately August 10-15 for West Tennessee).  This is the average date that a bloom has a 50% chance of contributing to yield based on typical frost dates.   For a crop beginning to bloom now, you have almost 3 weeks to set bolls that will contribute to yield (less if an early frost and more if a late one).  Also consider that you have 90% of your investment already in the field.  It is taking an awful risk to just leave it unattended.

I hoped to include some data from several tests sprayed last week, but there is not enough time in the day.  In a nutshell, nothing provided great control.  Our sprays mostly targeted adults, but 8-9 days after treatment, we were finding about 7-10 immature plant bugs per drop cloth in untreated plots.  The “tier 1” treatments such as Bidrin, Orthene, Transform, and Centric were among the best treatments but only providing about 50% control at this time.  This is not surprising considering the high pressure we’ve had at this location.  One spray targeting adults was not going to take out all the hatching eggs over the next 8-10 days.

I’ve had a couple of conversations (really complaints) about Diamond not doing any good.  This is not uncommon, and sometimes even true, but mostly because the impact of this product is difficult to evaluate.  You are really looking 10-20 days post application to see the benefits of Diamond.   I’ve provided an example below where we sprayed a test early last week.  You can see that by 12 days after treatment, Acephate alone was no longer doing much compared with untreated plots.  Whereas, the Acephate + Diamond treatment was holding the nymph populations down a little better.  One consultant recently summed it up best by saying “Diamond doesn’t always save me a spray, but I’m spraying lower numbers”.  This ultimately can lead to saving a spray further down the road when we are no longer thinking about the Diamond put out earlier.  Don’t get me wrong, I don’t think we need Diamond on every acre.  However, it has a nice niche in high pressure environments, and it’s unique mode of action is nice to get into the mix.