The cotton crop is for all intents and purposes in the ground across south Georgia. USDA-NASS Crop Progress reports the state at 99% planted, 39% having reached first square. In the week leading up to June 22nd, crop progress reports 72% of cotton acreage falling in the good to excellent range, with additional 24% considered fair. Soil moisture dropped over the past week, down 28% in the adequate to surplus range in our topsoils, and 23% percent in subsoil. Much of the drier conditions occured in Central and southwest corner of the state.
In spite of the reduction in soil moisture, especially in our top soil, last week was still nearly a perfect scenario for our 2020 cotton crop. Cotton planted after the heavy rainfall events in the middle of April have experienced excellent environments, very little climatic stress, with average temperatures remaining in the high 70's to low 80's and showers spaced just enough to be able to get into the field, but keep emerging seedlings happy. Actually maybe too happy.
The excellent quality and vigor of PhytoGen cottonseed has resulted in seedlings exploding out of the ground. Vegetative growth is rapidly progressing with the blend of heat and moisture. Additionally, we have bounced between sunny and cloudy conditions with coastal fronts moving in from both the Gulf and Atlantic. At this stage, our cotton crop has not experienced much environmental stress to both improve plant hardiness and thicken up the waxy cuticle protective coat of our young vegetative leaves.
Fortunately, from an insect management standpoint, much of the later planted cotton of Central and East GA was able to rapidly generate new leaves, aiding in outgrowing early thrips pressure. However, as we approach flowering stages more rapidly and with the very mild winter we experienced, insect pests such as tarnished plant bug and spider mites have been showing their head much earlier than the norm in 2020. It is 2020, what else could we expect? We will certainly need to pay close attention to insect thresholds in our scouting efforts with an increased potential for these pests.
In regards to our herbicide programs, adaptations have been made across the Belt due to weather conditions and product efficacy on an almost daily basis. The last week of May and first week of June, about the only calls received were on burned cotton following herbicide application. We usually can rely on s-metolachlor (Dual,EverPreX) products to provide some foliar burn and slight leaf strapping, but other chloroacetamide actives, such as acetachlor (Warrant) and dimethenamid (Outlook) have also fairly consistently demonstrated similar symptoms. When constructing our spray programs, more times than not we are tank-mixing 3 and 4 single products, many with their own surfactants. With a lot of this thin cuticle cotton, if we want to minimize burn, we need to split our tank-mixes to two applications to reduce surfactant load. With that being said, if you are used to this type of foliar burn, feel comfortable running tank-mixes of Enlist One + Liberty + s-metolachlor prior to the 5-leaf stage, as all W3FE varieties offer full tolerance to both Enlist and glufosinate products.
Earlier I referenced the reduction in topsoil moisture as more of a good thing than bad for the current state of our cotton crop. Based upon root systems, cotton is one of our more naturally drought tolerant crops, with taproots reported to reach depths of 9-10 feet below the ground. Our cotton roots are currently trying to follow both water and nitrogen, leaching deeper into our soil profile. With excess topsoil moisture, our secondary roots will start to set up shop in the upper 12 inch of our soil profile, the area that typically will dry out very quickly in dry periods across our sandy coastal plains soils. As our roots systems our rapidly developing, with the potential to reach 3 foot depths below ground attached to only a 12 inch above ground plant, we really want these roots to track deeper into the soil profile, establishing itself in areas of more consistent moisture to avoid wilting if rains decide to shut off later in the summer months. Additionally, cotton water use efficiency is greatest prior to first flower and following first open boll. Generally, our cotton crop does not require an inch of water per week until we reach first flower, around 8-10 weeks after planting. Water prior to first square/first flower is essentially building excessive vegetative growth, reducing our ability to hold lower first position money bolls, and leading to rank growth once reaching flowering stages.
The last management decisions to consider are our plant growth regulator and nitrogen applications. I'll start with nitrogen. Historically, we rarely see a yield response to increasing nitrogen above 80-90 lb range. With the tough market and excellent early season environment, I would highly recommend not climbing over this range for total in-season use. This is especially true on full season varieties, such as PHY 580 W3FE, PHY 500 W3FE, and PHY 480 W3FE. Between the strong fruiting horsepower of these varieites, and the exceptional root-knot nematode resistance, our nitrogen requirements may not be as great, as our healthy root systems are actively mining soil nitrate, and these varieties will continue to bloom with late season heat. The longer we can reserve these applications to be made closer to first bloom, the greater ability our cotton crop will have to uptake and utilize our nitrogen investment.
If you have followed along, you have probably gathered I'm a huge fan of low rate PGR applications around first square. There is no greater plant growth regulator than fruit load. I like to reduce vegetative branching that can lead to late season rot of our money bolls, as well as get the plant to set fruit as quickly as possible. Again, our more full season varieties of PHY 580 W3FE, PHY 500 W3FE, and PHY 480 W3FE are attempting to be themselves, which is a tropical, perennial tree. These varieties will usually require a scheduled mepiquat application at first square to properly hold them in check early. Earlier season varities such as PHY 350 W3FE and PHY 400 W3FE will need to be scouted more closely for growth rate. In a typical year, these varieites should begin fruiting in the 5-6 node range, where we want our fruit to start. With the exceptional conditions in June, we need to pay close attention to our height-to-node ratio, as well as internode spacing. These varieties are best suited for a mepiquat application once internodes begin elongating to the 2" range.
Cotton management is always so easy right? We understand it's quite challenging, and that's what makes cotton one of the most unique, enjoyable, and rewarding crops to grow. After 20 days of great weather for a cotton plant, a little droughty heat over the next 10 days that will stress our young cotton plants could be the best thing for us. Our Central and Eastern GA PhytoGen team is out actively checking on crop progression. Traveling the roads, it appears we are setting an excellent crop for 2020, albeit the continous challenges this year looks to throw our way. For a customized recommendation or management plan, contact myself or your local PhytoGen Sales Agronomist.For more information about cotton production practices in your area, contact your state Extension cotton specialist. As always, your PhytoGen cotton development specialist also is available to discuss agronomic options.
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