I’ve spent the past several days walking replants and fielding last minute variety placement/selection questions. This post covers a few thoughts I’d like to share concerning replants, variety maturity, and determining when to stop planting cotton.
Many of our marginal stands were planted approximately two weeks ago. While we would expect emergence in a shorter time frame under ideal conditions, seedlings were beginning to push last week when a mild blackberry winter developed. These cold temperatures slowed growth and development. While air temperature (and to a lesser extent, soil temperature) may warm back up relatively quickly, many processes within the plant cannot respond as quickly. It is important to keep that slow-down in mind; many seedlings are still emerging 14+ days after planting. Many trouble areas reported Friday looked much better Saturday and pronouncedly different after Sunday’s rains. Although rains which fell Wednesday hampered planting, they helped several additional seedlings emerge. If your stand was on the cusp last Friday, there is a good chance it is more than adequate today.
In contrast, several fields I have walked clearly warrant a replant. Small, low-vigor seed is particularly sensitive to depth. Coupled with packing rains and cool temperatures, seedlings in some areas were unable to make it. Worse, I’ve walked several fields where seeds with adequate moisture failed to germinate. The seed pictured above had been in the ground longer than 2 weeks with no activity. If you planted low germ seed, watch those fields closely.
Variety selection in late May
Concerning varieties- ideally, we would have planted the last mid-maturing varieties a week ago and should be looking to transition from early-mids to strictly early maturing varieties in the next couple of days. If you look hard in the variety trial data you will likely find a few instances where a mid maturing variety wins a late planted trial. It happens, but it doesn’t happen often. Planting a mid maturing variety on May 20 something (or 30 something) is a gamble. A safer bet would be shifting into a true early maturing variety.
Yield potential of late planted cotton
I’ve included the planting date by population graph from a post a few weeks ago again (see Fig. 1 below). Focus on the top three lines; as you can see, our yield potential declines relatively quickly for planting dates after May 15th. However, our yield potential around June 1st planted cotton is still around 75% of what it would be if planted the May 1st. I’ve visited with several considering the last date on which they should plant. Each operation is different, but this curve should shed light into dates capable of providing break-even yield. Also note no difference in yield potential between 50,000 plants per acre and 30,000 plants per acre at later planting dates. This represents a considerable cost savings as we move into the last few days of May; you will likely see no yield penalty from dropping seeding rate at the later planting dates.
As always, best of luck. I know this has been a tough year for most. Reach out to your county agent if you have any questions on these points or others- we are here for you.