Varieties vary substantially in their response to PGRs, and this variance is greater today than when I started years ago. Although most varieties we’ve planted this year fall within the moderately responsive to responsive category, we have a few that are on the far ends of the spectrum. 

DeltaPine 1646 B2XF is a very aggressively growing variety that requires aggressive applications. On the opposite end of the spectrum is NexGen 4936 B3XF - that variety is very responsive and requires much lower rates to slow growth. 

If you are uncertain how a variety will respond, start with lower applications and follow-up with additional applications based on plant growth measurements. Feel free to reach out to me or your seedsman for more insight into specific variety responses to PGRs.

I am typically a big supporter of using the internode between the fourth and fifth nodes down from the top of the plant to gauge current growth potential and guide rate. If the distance between fourth and fifth nodes is:

Less than 2”: Growth not adequate. Application is not warranted.

Between 2” to 3”: Growth is adequate; a low application may be warranted on ‘strong’ ground, but applications in this range are not universally warranted.

Exceeds 3”: Growth is excessive. The potential for rank growth is high and an application should be strongly considered

For the initial application this year, given our rough start, I would also consider the HNR ratio. On stressed plants, an aggressive application will likely be detrimental. Incorporating this measure into your rate selection will help give insight into plant health and help you pick an appropriate rate. 

This is a big one that bit us last year; several (myself included) made aggressive applications based on a forecast that included rains. Those rains failed to develop and as a result those applications ended up being more aggressive than necessary. If the forecast holds rain, an increased rate may be necessary to slow growth into a reasonable range. However, if you don’t see a substantial chance for rain in the forecast, it might be wise to either hold or reduce the rate you apply.

Similarly, we must take into account field history. Cotton grown on deep, silt loam bottoms tends to grow cotton with more horsepower. A rolling hill that could be characterized as shallow depth-to-fragipan will not have the same growth potential. Rates on those two farms should vary, with the bottom receiving slightly more than the hill, even at this timing.

The very first fields that begin to square often receive the brunt of the plant bugs until more fields start squaring. Watch them closely.

The goal is to maintain at least 80% square retention through early bloom. There are a number of methods to count square retention. It is often suggested to focus just on first positions, but the most important thing is to count the number of missing squares in ‘X’ number of fruiting sites.

You’ll want to look at multiple plants in several, representative places of the field. Usually, checking retention for 100 total fruiting sites is enough, especially if square retention is well above or below the 80% mark, but you may want to look closer when you are riding the edge.

‘During the first two weeks of squaring, I think full rates of imidacloprid, Centric at 1.75-2.0 oz per acre, or combinations of these two products will protect against square loss, despite some “slippage” of efficacy. Transform at 1.5 oz/acre is another option and Vydate at 10-12 oz/acre is worth consideration, but honestly, I’d try to reserve those products until at least the third week of squaring and beyond. Once we hit the third week of squaring, mixing in Diamond at 4-6 oz/acre is common to delay and reduce the build-up of nymphs.