Managing a Variable Crop (Collins & Edmisten)
The 2019 crop is probably the most variable crop statewide that we’ve seen in quite some time. Many areas have been plagued with severe drought resulting in some cotton cutting out fairly sharply while it’s only the 2nd or 3rd week of bloom. Other areas have received plentiful and frequent rains, and the crop in those areas is quite strong, especially in areas with heavier soils with greater water holding capacity. The old adage “We are never more than 4-5 days away from severe drought” has certainly held true this year. When temperatures reach the 90’s, and especially crosses over the 95 degree mark, our soil moisture rapidly depletes. Heavier soils obviously maintain soil moisture for longer than sandier soils, however no soils are immune to severe drought when hot dry conditions prevail for a week or longer.
Lessons learned: Years like this are the reason we say to be cautious with pre-bloom PGR applications. Pre-bloom applications can increase risks of yield penalties, especially for earlier planted cotton, when conditions turn towards the unfavorable. During the past several years, we were fortunate enough to receive very timely and adequate rainfall during June and July, and in years like that, pre-bloom PGR applications rarely cause us any problems and growth is controlled adequately. In this year especially, pre-bloom applications were made when soil moisture was adequate and growth was good, however, the extremely hot temperatures we’ve had in the absence of rain caused some fields to go from “good” growth to severe wilting in as few as 4-5 days. Even though the decisions to apply PGRs during the pre-bloom period were probably made wisely and based on the information at-hand during that time, shifts from favorable to unfavorable conditions have been much more rapid this year, due to very high temperatures and intermittent rains. It’s important to note that beyond the first week of bloom, it is difficult to penalize yields with PGRs, but PGRs should only be applied when needed.
It’s way too early to even guess yields at this point, regardless of the scenario, however, I think it is wise to budget according to realistic yield potential, and perhaps adjust our inputs for what we are likely to harvest in some cases. Below are a few management considerations for various scenarios. As of now, the 2019 crop can be categorized into one of the following:
1. Good growth with strong yield potential: These are the areas with heavier soils that have received rain fairly consistently, have encountered little to no significant drought stress, or are irrigated. Stay the course on this crop. Be vigilant in scouting and treating for insect pests. Apply PGRs as needed. Depending on planting date, some more fertilizer may be needed, however most of our fertility program needs to be in soil solution prior to first bloom. For irrigated fields, keep close track of growth stage (week of development) and apply irrigation at appropriate rates as seen in our previous article, “Cotton Irrigation Decisions for 2019 (Collins & Edmisten)”. Use irrigation to bridge gaps between rains during those 5-day to 10-day dry spells. Be very timely with those irrigation applications, and remember that wilting is too late to resume irrigation. In years like this where hot dry conditions are the driver, it is wise to be proactive rather than reactive. If you’re on the fence about irrigating, and the forecast for rain is less than certain, go ahead and irrigate, then decide later.
2. Dryland, drought-stressed fields approaching cutout: These are the areas that have experienced noticeable drought stress, likely on sandier soils, but for whatever reason (later planted cotton, for example), cotton has not quite reached cutout. Ideally, cutout would not be reached until at least week 4-5 of bloom or even later. However, due to heat and drought stress, these fields are generally somewhere in week 1 to week 3 of bloom but are approaching cutout quickly and are showing signs of stress (wilting, toughened reddening stalks, larger squares in the terminal). Rain, obviously, is the best cure and greatest need in these fields. In these temperatures, every day counts…the sooner we get some relief from drought, the better. Every additional day that these fields are allowed to continue wilting in these temperatures drastically reduces its chances of recovery, and likely loses additional yield potential. Given that we are only in the early part of the bloom period, we badly need to avoid reaching cutout this early. If rains start now, and continue to occur every few days with no significant drought stress for quite some time, we COULD (not “will”) observe a “suspended” cutout, in which terminal growth renews and essentially grows at the same rate as the uppermost white bloom develops. This will allow the crop to stay at a poorly defined cutout, while setting a few more fruiting nodes, and thus more bolls. The rains that would allow for this, would also help retain and develop the small bolls currently on the plant, plus a few to several more yet to appear. As far as what we can do…..avoid any and all PGR applications unless cotton is already tall (too date, we have not seen a single case of cotton being too tall or anywhere close in fields that fall into this particular category). If it starts raining soon, yield potential is anyone’s guess….it’s simply too early to tell. If it doesn’t rain again soon (and continue for a time thereafter), a suspended cutout will become much less likely and we’ll know pretty quickly what our most realistic yield may be, as it becomes more like cotton in category 3 below. Stay the course on insects, but be cautious of your overall budget for this crop. Certainly DO NOT apply any PGRs, but also avoid other unnecessary inputs that aren’t likely to improve yields. Utilize your NC State University county agents/specialists or consultants when making decisions about these inputs. We need to start thinking about what we can realistically harvest, while avoiding false hopes in “miracle” inputs that aren’t likely to bring this crop around.
3. Dryland, drought-stressed fields that have cutout sharply: These are the worst cases we’ve seen. The crop is way too short to support an adequate boll load, but has clearly and sharply cutout, which is far premature as it is only within week 2 to week 4 of bloom. So what COULD happen?…If rains start now, and occur frequently for quite some time, these fields will first try to develop the fruit load currently on the plant. After some time, the terminal will slowly start to re-grow as long as rains continue for a good while, developing several compact fruiting nodes. We generally see this in September, after our last effective blooming date, when boll demands have been met and rains cause the plant to cycle around again and develop what we generally call “terminal regrowth”. Normally we ignore terminal regrowth as it appears too late and doesn’t generally contribute to additional yield. We are a long way from our last effective bloom date, and there is currently a very small boll load (relatively low demand for nutrients and carbohydrates) on the plant. Although, it would require several weeks of rain with little or no further drought stress to pull this off, these fields COULD (not “will”) develop several more fruiting nodes in the terminal with a much later-maturing top crop. This will improve overall yield potential, but is often a management nightmare with regard to late season insect management and defoliation timing. The portion of the crop in this scenario is likely to start shedding younger fruit, and if rains return, will set a “top crop” that is much younger than the bottom crop. This can make for difficult decisions later on concerning whether it is advisable to wait on the top crop to mature. Pay attention to the bloom date of the top crop, and it wouldn’t hurt to flag a few blooms around the last effective bloom date so you can know which bolls may have a reasonable chance of being harvested. It is probably not advisable to chase blooms that occur in September. So we mentioned that this COULD happen, but what is likely to happen? If any noticeable or prolonged drought occurs in the next few weeks, the aforementioned scenario becomes much less likely. Evaluate each field as it develops and begin counting harvestable bolls to try to gauge a realistic yield estimate. As in category 2, we need to reel back our input costs within reason. PGRs are useless on fields in this scenario. Focus efforts on the most important issues such as insect management to avoid additional losses. Avoid other (even the cheaper) inputs that are either not proven, or don’t consistently improve yields. We don’t need to spend much money on false hopes, unless Mother Nature turns things around for us. We are unaware of any products that negate severe drought stress, so inputs at this point can only hope to retain and develop our current fruit load or those that appear fairly soon. Try to economize within reason on the products that ARE necessary. We sincerely hope we’re wrong here, and it is still early yet so there are no guarantees. But for fields in these cases that don’t receive frequent rains starting soon and haven’t shown any signs of potential recovery during or by the first half of August or so, we need to be honest with ourselves about yield potential and be prepared to draw a line in the sand and walk away. These decisions are generally easier to make when you keep good track of your production costs, your break-even yields at the current (or likely) pricing structure, and details about your crop insurance policy (historic yields, APH, coverage levels and type, etc). Also, before making any drastic but important decisions, get all the advice you can from your consultant, county agent, Extension Specialists, etc. But again, it’s way too early to tell with any degree of certainty. Time will tell, but timely rains sure would help.