In Preparation for Harvest (Collins & Edmisten)
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September is always a time for anxiety and anticipation for NC cotton growers, and we always seem to be on edge this time of year as we watch our crop approach defoliation and harvest season. Rightfully so….in several years past, we’ve seen our crop diminish in both yield and quality due to extended cloudy, wet conditions for more than a few days on several occasions in September, not to mention heavy winds or rains resulting from hurricanes or tropical storms. Currently, we have a variable crop across the state, but there are several areas with above-average to exceptional yield potential. Thus far, September weather has been favorable (mostly dry, warm, and sunny) for boll opening in early planted cotton, and we certainly hope that continues through October or beyond. Lighter rains every now and then dont usually hurt anything, as long as dry, sunny conditions return quickly and rainfall amounts aren’t excessive. The weather is beyond our control, however there are a few things that we can control that might help us capture most or all of our yield potential.
Evaluating Root Growth: This is more applicable to next year than the current one, but now would be a good time to evaluate the root system of your cotton crop in each field, in order to make tillage decisions for later in the fall or spring. Especially on sandier ground that is prone to forming a hardpan, look for j-roots or shallow root systems as an indicator that a particular field or soil type should be strip-tilled for the following year. This is more important for fields that have been in no-till for several years. There are other factors that occur early in the year that can cause root distortion (water saturation, damage to seed, so you would’ve needed to evaluate root growth during the seedling stage to determine if any root issues are related to tillage practices or not, but it never hurts to take a look during this time of year if evidence of a hardpan is present.
Last Effective Bloom Dates: As mentioned in our most recent newsletter, last effective bloom dates vary within the state and from year to year as it is dependent on fall weather. Generally speaking, this occurs around August 25th for most of the state in most years. Last effective blooming most commonly concerns later planted cotton, or other situations such as early planted cotton that does not have a very strong bottom crop, or any other circumstance where we are more reliant on the top crop than normal. For earlier planted cotton with a strong bottom crop, last effective blooming is of little concerns as most blooms that occur at that point will likely abort or contribute very little to overall yield. As discussed in the previous article, flagging a few plants at the highest node with a white bloom, on or around our last effective bloom date, will help determine which bolls have a reasonable chance of becoming harvestable when we are making defoliation timing decisions later. Hopefully, growers and/or consultants were able to flag a few plants during that time.
Defoliation Timeliness: We see scenarios every year where the crop is ready to be defoliated but we aren’t. Growers should be going through their harvesters now, if they haven’t already, to make any necessary repairs or maintenance before harvest. There are a few fields of earlier planted cotton that are ready to be defoliated now, or will be very soon. Watch the weather forecast, and if long-term forecasts are favorable, go ahead and defoliate fields as they reach maturity and be ready to harvest them within two weeks. This may not follow the same order as planting, and may only apply to a few fields, but this could enable us to harvest some cotton before a tropical storm occurs, if one occurs.
We certainly hope that this next statement is unnecessary to even write, but IF a hurricane appears in the 10-day to 2-week forecast, DON’T DEFOLIATE until it passes. The only plausible exception would be if all or nearly all of the bolls are opened and you have a reasonable chance of harvesting it before the storm hits. If any meaningful bolls are closed, or you know you can not harvest a field before a storm hits, DON’T DEFOLIATE. We hear the arguments to the contrary every year…..”if I don’t defoliate beforehand, I’ll get behind” or “I want to knock some leaves off to reduce boll rot, or maybe crack open some bolls that might otherwise rot”. It does us no good to stay on time if there isn’t a crop to harvest. Yes, severe lodging and flooding can occur, both of which can rot bolls, but a closed boll is a protected boll compared to one that is fully opened or cracked when a storm hits. During a hurricane, fully opened bolls will likely fall to the ground and will be lost. Likewise, bolls that are cracked when heavy rains set in are very likely to hardlock. Bolls that remain closed have a chance, a decent chance, of opening in more favorable weather and being harvestable. The best we can do is try to defoliate and harvest low-lying or flood-prone areas first, when there is no storm in the forecast, assuming that they are earlier-planted fields or are otherwise mature enough to be defoliated. In fields that are more likely to dry quicker or are less prone to flooding or standing water, let closed bolls remain closed through a storm, unless, again, you think you can harvest it before the storm hits.
Harvest Timeliness: We also see several scenarios every year where a large acreage is defoliated before the picker cranks up. It does us no good to defoliate more acres than can be effectively harvested within two weeks time. The yield contribution and quality of any given boll is the best it will be on the day that boll opens. Fully opened cotton is subject to any sort of weathering and potential quality degradation, therefore it is not necessary for fields to be defoliated for longer than two weeks time before harvest, unless cool weather slows the boll opening process. It is good practice to only defoliate the fields that are likely to be harvested within two weeks time, and the sprayer should progress at a similar rate as the picker throughout the season. If you use harvest aids that are likely to accelerate boll opening, such as Finish/Terminate or CottonQuik, take advantage of the few days these products may offer, and harvest that cotton as soon as it is ready for harvest.
On a similar note, we certainly hope that the weather throughout the remainder of September and October, or beyond, remains favorable. A rain here and there wont hurt anything, but we don’t want excessive rains, prolonged wet or cloudy conditions, or worse, heavy winds such as a hurricane. Inevitably though, even in the best years, there is always a proportion of our crop that gets pushed on into November for some reason or another. At this point, cotton that is most likely to face this scenario is late-planted or later-emerged cotton. The “November Trap”, as we call it, can drastically slow down harvest progress as cooler temperatures and shorter days chip away at our effective harvest hours and prolong drying time of morning dews or previous rain events. Within our power, it would behoove us to harvest as much as we can before this type of weather pattern sets in. Generally speaking, we can achieve much more harvest progress during October than we can in November.
Defoliation in anticipation of a frost: This will likely apply more so to later planted or later emerged cotton this year, but the recommendations are similar to that of years past. For any fields that are later maturing for whatever reason, or you are more reliant on the top crop than normal, and you want to push these fields to the bitter end, pay close attention to the weather forecast. Our first frost date can range from early October to early November depending on your location within the state, but generally speaking, we can expect one towards the end of October. It is generally best to take action before a frost if you have a crop with several closed bolls that could reasonably be harvestable. We don’t always have the luxury of advanced notice or precise forecasts for when a frost is likely, but ideally, we would like to take action at least 2-3 days ahead of any meaningful frost, preferably in somewhat warmer, sunny conditions. Our planting conditions calculator now has a frost advisory built into the framework of it, which can be viewed by scrolling down below the planting conditions ratings to view the National Weather Service 7-Day Forecast table.
In these situations, when a frost is likely and your crop has not been defoliated, it is best to defoliate using products containing a high rate of ethephon, preferably Finish/Terminate, or in cooler weather, CottonQuik. This will enable ethylene build-up inside the plant in hopes of forming abscission zones properly for both leaves and bolls, so that boll opening will be maximized once the frost occurs. In similar situations, when a frost is likely and your crop has already been defoliated using ethephon in the tankmix, but some upper bolls have yet to open, the use of paraquat can sometimes aid in boll opening by lightly burning the carpal walls of bolls to promote drying of burrs and thus opening bolls. Label restrictions state that harvest should be delayed at least 3 days after application, however, there is no need to wait much longer than 4-5 days, as desiccation of stalks are likely, which could increase lint trash and/or bark content. As with any approach, there is always a risk and there are no guarantees for success, but these methods have been shown to offer some benefit in these situations in prior years.