Note – This is a message from UGA Cotton agronomists Dr. Jared Whitaker and Mark Freeman. For more information on the UGA Cotton Team, visit http://www.ugacotton.com.
The 2018 Georgia cotton season has started off as a tale of two extremes. Rainfall during April and the first two weeks of May was almost non-existent, which delayed planting in some dryland situations and even made stand establishment with irrigation challenging. Since then, rainfall has been plentiful if not excessive across the entire state. The wet conditions have left many producers waiting to get back into the field to resume planting operation. Now, as if conditions were not wet enough, the tropical system Alberto in the Gulf of Mexico has been forecasted to bring several more inches to most of Georgia this week. Undoubtedly, this course of events will force producers to plant a significant portion of the cotton crop during the month of June.
Typically, the majority of the cotton crop in Georgia is planted in the month of May. However, a portion of Georgia’s cotton crop each year is planted early June, but most often those acres are this late due to planting only after harvesting wheat or another winter grain crop. This year a much larger portion of the crop will be planted in June than normal and there are several things to consider which may dramatically impact the relative success of these acres.
There is a reason that most of the crop is typically planted prior to early June. It is because of yield potential. Research in Georgia has indicated that yield potential usually starts to diminish with plantings after the first week to 10 days or so of June. The relative success of late-planted cotton is certainly dependent upon the weather in September and October as well as the date of the first frost, but we can also impact it by a couple of management decisions.
The most important thing to consider when planting late is that there is very little, if any, room for error. When it is this late in the season, we are only going to get one shot to get a stand. If a replant is required we are likely past any window for maximizing yields and past any insurance deadlines. Conditions need to be ideal and if irrigation is available, utilize water as needed to prevent soil crusting or enhance stand establishment. If planting in dryland situations, it would be best if the soil were to slightly crust prior to planting, as the planting operation would break the crust and allow for quick emergence (but as late as it is, go when it’s possible). A rotary hoe is a great tool to help with compacted soil around germinating and emerging seed, but be sure to use this tool early rather than later (typically 2-3 days after planting is best).
Considerations should also be made in regards to seeding rates when planting late. Generally we shoot for final plant stands of at least 1.5 to 1.75 plants per row-ft (in 36” rows) which can usually be accomplished with seeding rates as low as 2.0 seeds per row-ft. In all situations, lower than adequate plant stands can significantly reduce yield potential, delay maturity, and delay canopy closure which can allow for more pressure from weeds. In the situation where we are planting late, these issues are even more apparent. In addition to the impact of limited stands, in late-planted cotton there is likely a benefit to a thicker than usual stand due to the fact that late-planted cotton has less time to make cotton on outer and upper fruiting positions and more stalks often equates to higher yields. Therefore, we should adjust our seeding rates to aim for a final stand of around 2 plants per row-ft rather than 1.5.
Preemergence herbicides are a necessity in Georgia cotton and there are quite a few combinations of products which can provide excellent residual control of Palmer amaranth and other weeds that can limit yields. It is extremely important to eliminate weed pressure as much as possible in late-planted situations. However, the impact of cotton injury from PRE herbicides can be worse on late-planted cotton than earlier planted cotton due to less time for growth and development. One additional comment that we feel is worth mentioning is related to one particular PRE herbicide. Although Warrant is an excellent PRE herbicide for cotton, remember that UGA recommends that if Warrant is applied PRE to cotton, a total of 21 days should pass before replanting OR a tillage operation is needed. With the extremely limited amount of time that we would have if we did have to replant, this could be a deal breaker. For example, if we planted a field this week (June 1) and on June 10th we realized a heavy rain event caused compaction and left a less than desirable stand, we would not be able to jump out there and replant if we used Warrant PRE (we’d need tillage or another eight days).
Overall crop management is always an important issue but this importance is magnified for a short season crop. If irrigation is available all care should be taken to ensure rapid stand establishment, decrease any stress, and enhance fruit retention during episodes of dry weather. Careful consideration should also be made to the plant growth regulator program (PGR). Mepiquat containing PGRs should be applied to prevent any excessive vegetative growth and boll rot and to promote crop earliness.
The crop should be scouted regularly for insects to prevent stresses from feeding damage and gaps in fruit development which can delay maturity. Thrips are the biggest threat to seedling cotton. Later planted cotton is usually less at risk of infestation compared to early planted cotton however, this is not always the case. To monitor your thrips risk index locally visit the Thrips Infestation Predictor by using the following link: http://climate.ncsu.edu/CottonTIP. Once fruiting is initiated all threats from plant bugs, stink bugs, and other insects should be monitored and apply insecticide as soon as economic thresholds are reached.
A lot of the questions we get starting at the end of May with late-planted cotton are centered on variety selection. In particular, should we shift to earlier-maturing “short season” varieties and if so, when should we do it? In theory, this is something that makes sense, as we have a shorter amount of time to produce a crop an earlier or short season variety should more appropriately fit the system and improve the chances of maximizing yield. However, in reality there are a couple of things worth considering before making a change. First, the modern varieties that we are planting in Georgia are all “early” compared to some of the earlier “full-season” varieties we were accustomed to (nothing we have now is close in maturity to DP 555 BR). Another thing to consider is the difference in maturity between what we now consider early maturing and late maturing as in most situations, there is no more than a few days to a week difference at the end of the season. Last, for the most part earlier maturing varieties will perform relatively better at the end of the planting window but we typically find that our best varieties perform best even in late situations. For example, we used data from the 2017 UGA On-Farm Cotton Variety Evaluation Program comparing the performance of varieties across all locations to the locations that were planted on May 25th or later (Table 1) and it indicates that varieties that performed well early performed well late.
The story of 2018 will certainly have late-planted cotton as a storyline. Hopefully, we will make the most of the situation and “great yields” will be a part of the story as well. Late-planted cotton can still be quite productive if a few minor strategy changes are made. For more information and help with getting this cotton crop planted, contact your local UGA County Extension Agent.
Good luck and let us know if we can help,
Mark Freeman and Jared Whitaker
UGA Cotton Agronomists