By Guy Collins and Keith Edmisten
There have been quite a few calls over the past few days from growers asking when they should consider switching to early maturing varieties. This is largely driven by the significant delays in planting during late April and the first two weeks of May (prolonged, unsuitably cool weather) and the likelihood of substantial rainfall in the forecast we are now facing, which will likely force planting to resume next week (last week of May). The answer to this question is rather complex but is not complicated. Below are a few considerations for planting cotton from this point forward.
Timeliness is Everything! Later planted cotton requires management for earliness due to the compressed time in which to produce a suitable crop, however this can be taken too far. Planting a very early maturing variety on sandy soils for example, may be a poor decision even though it is planted late, if drought stress occurs later in the season and forces this crop into a premature cutout, and thus results in lower yields. The same goes for PGR management….hammering cotton with PGRs for the sake of earliness can significantly reduce yields, especially if excessive rates are used during the prebloom period and a stressed period follows. However, TIMELY management can effectively promote earliness by retaining the earliest set bolls. This is done through proper fertility (optimal N rates, but avoid excessive rates than can delay maturity), very thorough and frequent scouting AND very TIMELY applications for insects (losses due to insects are more costly for later planted cotton due to the lack of compensation time), and appropriate TIMING of PGR applications (use rates appropriate for plant size/variety/field history etc, but avoid delayed applications when PGRs are needed).
So when should we switch to earlier varieties? The answer to this question is more complex than most growers want to hear, but is also not that complicated. First and foremost, varieties should be chosen based on yield potential, stability, traits, etc. and matching those characteristics to the environment (soil type, irrigation vs. dryland, etc.). As previously mentioned, you don’t want to plant an early variety in a field prone to drought stress just for the sake of earliness. In other words, choose the best variety for your farm and match it to the field characteristics, and manage it appropriately. In many cases, the more full-season varieties may be the better variety choices, especially for many of our sandier soils that are prone to drought stress. It is important to realize that even the more full-season varieties in modern times are not as late maturing as they once were. With that said, very generally speaking, we can safely plant our more full-season varieties throughout most of May with proper and TIMELY management, assuming those are the best varieties for the type of ground where they are being planted. This includes all of the timeliness factors we previously mentioned, plus planting slightly higher seeding rates (later planted cotton is more sensitive to skippy stands or thin stands), planting when rapid emergence is likely (warm conditions, good vigor, adequate soil moisture, low likelihood of crusting etc.). Planting in June is when things begin to get a little tricky and erratic. During early June, it is absolutely critical that management be timely, and at this point, a switch to somewhat earlier or mid maturing varieties that are appropriate for your soils becomes more logical. There are also several situations in NC where the more full-season varieties are unsuitable regardless of planting date. These include situations such as fields that retain significant soil moisture or have a history or rank growth or delayed maturity. In these cases, an early or mid-maturing variety may be the best choice season-long, therefore a variety switch may never be required.
Disclaimer: We only recommend planting according to your crop insurance guidelines and deadlines. Planting beyond the crop insurance deadlines is done at your own risk, and it should be known that risks increase as planting is delayed beyond these deadlines.
Let’s be honest with ourselves: Let’s face it….some growers are better equipped to be more timely than others. As previously explained, the success of later planted cotton is strongly dependent on TIMELY management. Therefore, it would behoove us all to evaluate ourselves in our ability to be timely managers. If you’re the type of grower that does your own scouting but you struggle to get around to every field once or twice per week and cant do it thoroughly, or if you’re one that’s chronically 7-10 days late on every spray or application, maybe planting in the last week of May or early June isn’t for you. Conversely, if you are equipped to, and are habitually timely with your scouting and sprays, your chances of success are far greater with later planted cotton.
Source : ncsu.edu