Cotton Blue Disease (Whitaker)

In the fall of 2018, Cotton Leafroll Dwarf Virus (CLRDV) was confirmed to infect cotton in 14 South Georgia counties.  This virus is vectored by aphids and associated with Blue Cotton Disease (CBD) which causes symptoms of including leaf curling, reddening and drooping of leaves, subsequent distortion of leaf growth above the nodes where reddened leaves were first observed, and shortening of upper internodes and their discoloration to deep green along with subsequent lack of fruit retention.  Although the virus could be found widespread across Georgia in the fall of 2018, there were very few, if any, documented cases of yield losses in Georgia cotton fields which could be associated with CBD.  The UGA Cotton Team has and is working diligently to obtain as much information as we can and to help inform producers of what we know.  At this point, the impact from this virus to the 2019 Georgia cotton crop cannot be scientifically determined, but we have found CLRDV in ratooned cotton stalks from 2018 and in henbit over the past couple of weeks.  So, there may be two ways for us to potentially limit our exposure by trying to remove cotton stalks from 2018 and by controlling winter weeds well in advance of planting.  Both of these approaches are already endorsed and encouraged practices anyway and they may ultimately be helpful in breaking the green bridge for the virus.  If you have any questions on this or other issues, feel free to contact your local UGA county extension agent and visit the UGA Cotton Webpage at www.ugacotton.com.

Planting Techniques to Help Ensure a Successful Stand (Freeman)

As we get closer to planting season there are several factors to consider when trying to establish a successful stand. Early in the planting season, soil temperatures play a significant role in stand establishment as low temperatures will negatively affect germination and seedling vigor and also increases the risk of seedling diseases which can impact final plant stands. The “optimum” planting date will vary year to year but it is best to wait until 4 inch soil temperatures have reached at least 65° for 3 days and the forecast showing a trend for warmer weather.

Some other important aspects that affect stand establishment are seeding rates and seed placement configurations. In Georgia, plant populations of at least 1.5 to 1.75 plants/ft are needed to maximize yields. In our soils, seeding rates as low as 2 to 2.5 seed/ft can be successful however, seeding rates may need to be adjusted on a field by field basis to account for environmental circumstances that can affect germination and viability. Hill-drop seeding can also impact stand establishment compared to singulated seeding in tough conditions. Research has shown that when equal plant populations occur there is no yield difference between hill-dropped seed and singulated seed however, in some soils and soil conditions hill-dropped seed may increase germination and therefor impact yields by ensuring plant populations reach those that are needed for maximum yields.

Variety selection can also play a role in how successful our stands are. In particularly tough environments where establishing an adequate stand is often difficult, planting a larger seeded variety may be beneficial over planting a small seeded variety as the higher seedling vigor will be apparent in that niche environment. For more information on any of these topics visit our website www.ugacotton.com or contact your local UGA Extension Agent.

Thrips Management Thoughts for 2019 (Roberts)

Thrips are consistent pests of cotton in Georgia and the southeast as a whole.  Thrips are the only insect pests of cotton that a preventive insecticide is recommended.  For other insect pests of cotton, UGA recommends a reactive approach based on scouting and the use of thresholds.  Pests such as stink bugs, corn earworms, whiteflies, and remaining pests are less consistent and demand this reactive approach to maximize profitability.  With most insect pests there are agronomic and management practices which influence the risk and severity of infestations.  Below are a few thoughts to consider as you make decisions for your at-plant thrips management program.

1. Use a preventive insecticide at planting. Positive yield responses are consistently observed in UGA research when an at-plant insecticide is used for thrips control.
2. At-plant insecticide options include in-furrow granule applications of aldicarb, in-furrow liquid applications of imidacloprid or acephate, and commercial seed treatments of imidacloprid, thiamethoxam, and acephate. Imidacloprid seed treatment is the most common at-plant insecticide used.  In-furrow applications of aldicarb, imidacloprid, and acephate tend to provide greater residual control of thrips compared with the commercial seed treatments.
3. Historically thrips infestations and plant injury is greatest on early planted cotton (ie planted prior to May 10^th). However, this high thrips risk window is a moving target from year to year.  Temperature and rainfall during winter and early spring have a significant impact on thrips population development and the severity and timing of infestations moving to cotton.  As we near planting you are encouraged to take advantage of the Thrips Infestation Predictor for Cotton.  This web-based tool will predict thrips risk by planting date by geographic location and can be found at: https://climate.ncsu.edu/CottonTIP.
4. Thrips infestations are significantly lower in reduced tillage systems compared with conventional tillage. In general the more cover on the soil surface the greater the reduction in thrips.
5. Seedlings are most sensitive to yield loss during early developmental stages. 1-2 leaf cotton is at greater risk to yield loss from excessive thrips injury compared with 3-4 leaf cotton.  Once cotton reaches the 4-leaf stage and is growing rapidly, thrips are rarely an economic pest.
6. A rapidly growing seedling can better tolerate thrips feeding. Conversely, seedlings which are growing slowly from cool temperatures or some other stress are more susceptible to thrips.

Scout for thrips and thrips injury early.  Use thresholds and only make foliar applications when necessary.  Optimal timing for supplemental insecticide applications (when needed) is the 1-leaf stage.

Snapshot of the Agriculture Improvement Act of 2018 (Liu)

On December 20, 2018, the Agriculture Improvement Act of 2018 (the 2018 Farm Bill) passed into law. The 2018 Farm Bill continues the programs for Title I commodities from the 2014 Farm Bill including the Agricultural Risk Coverage (ARC) program, the Price Loss Coverage (PLC) program, and the Marketing Assistance Loans (MAL) program. The decisions that producers need to make for this new farm bill include reelecting between ARC and PLC programs and updating PLC payment yield. In the 2018 Farm Bill, producers are allowed to first elect between ARC and PLC in 2019 for 2019 – 2020. For 2021 – 2023, producers will also have a yearly option of re-electing between ARC and PLC. If producers fail to make a unanimous election in 2019, there will be no program payments for 2019, and the farm is deemed to elect the same program between ARC and PLC for each covered commodity for 2020 – 2023 as what they chose for 2015 – 2018. The PLC payment yield updates are based on the farm’s (FSN) crop yield history from 2013 to 2017 for each covered commodity. Other major changes in the 2018 Farm Bill includes creating a new effective reference price, increasing marketing assistant loan rates, changes in the geographical definition of the ARC-County program, and changes in family members’ eligibility.

Pre-Season Equipment (Porter)

From the equipment perspective now is the perfect time of year to ensure that you have everything ready to go for planting and irrigation.  UGA has a very good factsheet that can guide you through the Irrigation System Checklist to make sure your pivot is ready to go before you put the seed in the ground to ensure that you minimize breakdowns and issues during the season when you really need to get water to your crop.  That factsheet can be found at:

https://extension.uga.edu/publications/detail.html?number=B1452&title=Spring%20Center%20Pivot%20and%20Lateral%20Irrigation%20System%20Preparation

In addition to your irrigation system, the planter is one of the most critical pieces of equipment for producing a successful crop.  For in-depth information on setting your planter please contact your county agent, but here are a few quick components to check.  Start with the seed metering system, check to ensure all seals and brushes are good and do not need to be replaced.  In some areas dealerships will check your seed meters for singulation issues for a small fee.  Check your seed plates for any warping or wear and ensure you are using the correct plates for the correct crop, and match up the number of cells correctly to your gear ratio on your planter to make sure you obtain the correct seeding rate.  Check you downforce system, based on soil type and tillage conditions it should be set somewhere between 50 to 200 lbs of force for cotton (do not exceed 200 lbs of force for cotton).  Next check your gauge wheels for free movement and but no wobble in the bearings.  Check your depth settings on all row units.  In addition check your seed tubes and closing system to ensure both are working properly.  Spending some time on your planter now will pay off at the end of the season.

Make sure you take getting your equipment prepared seriously so you do not incur penalties during the season from equipment that was not properly maintained.  For more information on either of these topics please see your local county agent.

Cotton Defoliation Considerations for 2018 (Freeman and Whitaker)

Most of our early planted cotton is quickly approaching (and has approached in some areas) time for defoliation. Cotton defoliation tends to be one of the most important aspects of cotton production each year. Timing and product selection are two of the more critical components regarding defoliation and confusion occurs not only by the thousands of tank mix concoctions but also the differences in personalities of growers with some wanting to pull the trigger too early and some wanting to wait on the very last boll to crack.

Timing of cotton defoliant application can be determined in many ways. However, the methods which we feel are most beneficial involve monitoring boll opening.  The cotton plant has bolls of different ages and those bolls will typically open in the order in which they were set on the plant (such that bolls on the bottom of the plant will open before those on the top of the plant).  Research in Georgia has clearly shown defoliation application should be made when 60 to 75% of the bolls on the plant are open.  Whether one should lean towards 60 or 75% depends upon how uniform the crop is, as a plant that grown under optimum conditions can often be defoliated earlier than one that has gone through periods of stress.  In any situation, it is almost always most profitable to defoliate the crop when the crop reaches 75% open boll.

The process of actually determining open boll percentages can be quite time consuming considering that multiple plants in each field should be assessed (and averaged) and this process should be conducted for each field separately.  Therefore, there is another method to determine proper defoliation timing which is much quicker and easier.  This process involves counting the number of main-stem nodes between the uppermost first position cracked boll and the uppermost first position boll we want to harvest (in some cases there are late set bolls which will not have time to mature that are set in the top of the canopy).  With this method in Georgia we consider it is most profitable to defoliate the crop when it reaches 3 to 4 nodes above cracked boll (NACB).

Another method, which can be used in conjunction with determining open boll % and counting NACB is the “sharp knife technique.”  This method involves using a knife to cut the bolls in half so that you can see the cross section. A harvestable boll should have lint that strings out as you cut it and the cotton seed should have a darkened seed coat with developed cotelydons.  When we say “harvestable” we mean that the boll should be able to be opened with the use of an ethephon product.  In some cases, we use this method to determine the uppermost harvestable boll when figuring NACB.

In general, the best way to determine proper defoliation timing is to employ a combination of these methods.  A proper timing of defoliation is the first step to a successful harvest.  We should point out that most producers could defoliate their crop earlier than they typically do.  In Georgia, we have always had to balance peanut digging in with cotton harvest and cotton is typically much more forgiving than peanut when it comes to harvest timing.   However, we should make an effort to defoliate the crop when it is ready, as delays in defoliation applications can turn into lost profit.  Specifically, delays in defoliation relate into delays in harvest and those delays often turn into lost yield and fiber quality.

Defoliation of a cotton plant can impact it in four ways.  We consider those four functions to be (1) removal of mature leaves, (2) removal of juvenile leaves and plant tissue, (3) preventing regrowth of new leaves after defoliant application and prior to harvest, and (4) opening bolls.  A particular cotton crop may need a defoliant application to impact one or more, typically all four, of these functions.  Since one product is not effective on all of these functions, tank mixtures of products are applied to enhance the overall effect of the application.    Product selection and application rates are determined by the condition of the crop (which functions need to happen) and condition of the environment (temperature, rainfall forecast, soil fertility, etc.).

Additional Comments:

• Application water volume and pressure greatly impact overall performance. Often, these two factors are as if not more important than choosing which products and what rates to utilize.  One should apply at least 15 GPA when using ground rigs (the more the better, 20 GPA is better than 15 and 25 is better than 20, etc.) and as much water volume as possible with aerial applications.  Aerial applications can be extremely effective when products are applied such that spray is blown into the canopy.
• Follow product labels concerning the addition of additives. Additives may aid in uptake of some hormonal defoliants but may also increase the chances of leaf desiccation when combined with others especially with high temperatures. In general, when tribufos (Def) is used in the mixture, additives are not needed to improve efficacy.
• Rainfastness is always a concern with all products however thidiazuron requires a 24 hour rainfree period. However, when thidiazuron is used with other products (especially when mixed with tribufos) the actual rain-free period is reduced. If rainfall occurs before the rain-free period is reached, we suggest that you wait about 7 days and evaluate effectiveness and then make decisions on follow-up applications.

A few comments on cotton defoliation in 2018 with a limited supply of Thidiazuron

Many around the state are concerned about the limited availability of thidiazuron and how that will affect cotton defoliation in 2018. Thidiazuron (TDZ) is a key component of many cotton defoliation tank mix and is excellent at preventing regrowth after defoliation. Below are our thoughts and suggestions on the issue.

• First, go ahead and make plans with regards TDZ for this growing season. In general we vary rates of TDZ based on weather, potential for regrowth and amount of juvenile tissue present at defoliation.    If one were to use the three-way on their entire crop, they could budget around 2.5 to 3.0 oz of TDZ per acre of cotton and vary rates in particular situations.  With a significant portion of the state’s crop being planted after June 1, a lot of our cotton will be defoliated when conditions are cool enough where regrowth will be less of an issue.
• Logistics – Be timely when defoliating and harvesting. Try to defoliate only what you will be able to harvest quickly and try not to leave cotton in the field for extended periods of time which will allow for regrowth to occur. Without TDZ, regrowth will certainly be much more of an issue in some cases and harvesting quicker after defoliation can limit the impact of regrowth and cotton quality.
• Use proper rate for conditions – since TDZ does not cause leaf desiccation, producers can use higher rates in some places compared to others and get more out of the TDZ we have. Typically, we would suggest using more early during the defoliation season and where more green tissue is present (3 to 4 oz/A on the high end and 1.5 to 2.5 on the low end).  When temperatures drop into the lower 60’s at night for several consecutive days the overall effectiveness of TDZ is limited and we could drop it out of the three-way mix.
• Calibrating equipment and use proper GPAs – Make sure your equipment calibration is correct. You may be applying more product than you think. Be sure to use as much water and pressure as possible to get more out of the TDZ that you apply. Defoliants are typically not mobile in the plant and to prevent regrowth TDZ should actually hit the part of the plant where regrowth occurs.
• The three-way is our typical standard for cotton defoliation in Georgia. If TDZ becomes unavailable, the next most effective option is usually ethephon and “Ginstar” (a pre-mix of thidiazuron + diuron).  This application can be an extremely comparable option in most situations.
• Lower rates for lower regrowth potential – If all else fails and you cannot get the full rates of needed product, you should evaluate individual fields for their potential for regrowth. There are many factors that contribute to juvenile regrowth after defoliation but fields that are at the highest risk would be high fertility fields that experienced a premature cutout due to drought stress followed by good soil moisture and warm weather at the time of defoliation and after. These crops still have some “horsepower” left and will likely need a full rate. Fields that are at the lowest risk for regrowth are fields that have a heavy boll load, used all of its available nitrogen, and have begun naturally senescing leaves. These are fields that may only require a reduced rate of TDZ.
• So, in general our suggestions are:
  • Use the TDZ you have wisely, if regrowth potential is low then consider rates between 1.5 to 2.0 oz/A, if regrowth is expected and there is a lot of juvenile tissue is present consider higher rates between 3.0 to 4.0 oz/A
  • If no TDZ is available, mixtures of ethephon + Ginstar (TDZ + diuron) can be very effective at removing juvenile tissue and preventing regrowth. An 8 oz/A rate of the Ginstar products has 2.0 oz of TDZ (a 4 lb ai/A TDZ product) and 1.0 oz of diuron (4 lb ai/A diuron product)
  • If TDZ isn’t available and Ginstar products are not used, be aware that regrowth can be more troublesome and harvest as timely as possible.
  • If no TDZ is available and regrowth potential is lower, then the mixture of ethephon + tribufos (Folex) can be very effective.
  • Mixtures of ethephon + PPO herbicides (ET, Aim, Display, etc.) can also  be effective.  However, these mixtures are sometimes less consistent than mixtures of ethephon + tribufos (Folex) and in general are more consistent later in the defoliation window.

Terminating Insecticide Applications (Phillip Roberts)

 The decision to terminate insect controls can be challenging in some fields but a few basic considerations will assist in that decision.  When evaluating a field a grower must first identify the last boll population which will significantly contribute to yield (bolls which you plan to harvest).  In some situations the last population of bolls which you will harvest is easy to see (i.e. cotton which is loaded and cutout).  In others, such as late planted cotton, the last population of bolls you will harvest will be determined by weather factors (the last bloom you expect to open and harvest based on heat unit accumulation).  Once the last boll population is determined the boll development or approximate boll age should be estimated.  Depending on the insect pest, bolls are relatively safe from attack at varying stages of boll development.

Cooler temperatures will slow plant development and subsequent boll age values may increase in such environments.  It is assumed that the field is relatively insect pest free when the decision to terminate insecticide applications for a pest is made.

Late Season Management Considerations for Diseases and Nematodes (Bob Kemerait)

Though not over yet, it will not be too much longer until pickers are in the field and modules and round-bales fill the gin yards.  Diseases and nematodes have been much more of a problem in 2018 than in any other year that I can remember.  This was and continues to be, in large part, due to the frequent rain events and wet weather throughout much of the season.  Spread of fungal and bacterial diseases are favored by such.

There are seven significant disease/nematode conditions present in Georgia’s cotton fields now and while there is not much growers can do or need to do about it now, still they should pay attention so as to make the best management decisions in 2019.

1. Stemphylium leaf spot is present in many fields and is identified as small-to-moderate sized lesions, often encircled by a dark, purple ring, on leaves showing signs of nutrient (potassium) deficiency.  Stemphylium only occurs in conjunction with a potassium deficiency in the plant and can lead to rapid defoliation and significant yield loss.  Stemphylium leaf spot is a very important problem in the state and is likely overlooked as growers have either become too familiar with it or do not think that there is much that can be done.  Stemphylium leaf spot typically occurs in the same areas of a field year after year- sandier areas, sometimes infected with nematodes.  Grower should take special steps to manage soil fertility (and nematodes) to reduce losses to this disease.
2. Target spot has been especially widespread this season because of extended periods of wet weather. As I have often said, use of fungicides is not always profitable if the level of target spot is low because of hot and dry conditions.  However, I believe most growers who protected their cotton crop with fungicides in 2018 will see some benefit in doing do.  We should have some interesting data to share with the growers during the winter meeting season.
3. Areolate mildew has been problematic again for the second year in a row across a large section of the cotton production region of Georgia. I am not really sure why that is, but suspect that the fungus successfully survived in crop debris from last year and was brought on again by the rainy season.  I am hoping that this disease does not become an every-year occurrence and problem for our cotton producers.  We should have some data to share on control and yield after use of fungicides in the upcoming winter meeting season.
4. Bacterial blight became established in some fields very early in the season and I had expected it to be a major problem. Statewide, bacterial blight has been a very minor issue in 2018, demonstrating that the development and spread of a disease can be difficult to predict.  Growers are reminded to be careful in their selection of varieties for 2019 as resistant varieties are THE most important measure for managing this disease.
5. Fungal boll rots are likely to be quite severe in the 2018 season, especially in fields with excessive, rank growth. In some situations, limited defoliation from leaf diseases could actually be a good thing by opening up the canopy and allowing airflow to reduce humidity and dry the bolls.  Fungicides are not an effective management tool for control of boll rot.
6. Fusarium wilt is becoming an increasing problem in Georgia’s cotton fields. I don’t know if this is because the problem is spreading or simply because growers are paying greater attention to it.  Nonetheless, at this point Fusarium wilt can ONLY be managed in our fields by managing the parasitic nematodes associated with it, often by treating the field with a nematicide.  Again, we should have some excellent data to share after this field season.
7. Nematodes in general (root-knot, reniform, sting and lance) are a significant problem in our cotton fields. Growers are encouraged to take the time after harvest and before cold weather hits to take soil samples from areas of poor growth in order to determine if nematodes are indeed a problem.

Taking stock of disease and nematode issues at the end of the 2018 season should help growers to make effective management decisions for 2019.

Gin Talk (Kane Stains)

 As summer winds down, the advent of fall, Dawgs football, and harvest-time rapidly approaches.  In just a few short days or weeks, rural Georgia roads will be inundated with cotton pickers, module trucks, and various other harvest-related machinery.  Before we know it, all of the blood, sweat, and tears that were poured into this year’s cotton crop will culminate in a string of 500 lb. bales.  Throughout the growing season, farmers and managers have labored over their crop, weighing every management decision against the ultimate bottom line.  After all, farming and especially cotton farming is the ultimate game of dollars and cents; some would argue that it’s more cents than dollars.  One of the final management decisions that one can make is to ensure that once the cotton is defoliated and ready for harvest, it arrives at the gin free of any contamination.

As most are aware, global cotton buyers frown upon receiving contaminated cotton; as they should.  Most often, one’s mind immediately gravitates to plastic products when discussing cotton contamination.  Of the leading contaminants plastic certainly shows up most often, but cotton contamination is technically any substance in the bale other than ginned cotton lint.  Items such as oil, grease, red shop rags, wrenches, chains, cotton string or rope, or the occasional extension ladder have all found their way into harvested seed cotton and some even making it as far as the bale press.  Most frequently, yellow module wrap and black horticultural plastic take the “wrap” (no pun intended) for cotton contamination.  However, the occurrence of plastic shopping bags found in post-harvest seed cotton is most certainly on the rise.

The problem with plastic contamination is exponentially magnified once the contaminated cotton enters the gin plant.  As the seed cotton flows through the system, plastic and other contaminants may become lodged in various nooks and crannies of the machines.  Once the contamination reaches the gin stand, thousands of sharp saw teeth grind it into miniscule pieces, thus rendering it nearly impossible to remove at the gin level.  This scenario usually creates a two-fold problem because the plastic can remain lodged until a later time, during which another grower’s (potentially contamination-free) cotton is being ginned and thus becomes contaminated.  With the use of Bale ID Tags, contaminated cotton can be traced back to the individual farm that produced it.  Unfortunately, someone could potentially pay the price for another’s negligence.  As a side note, your local cotton gins are doing everything in their power to detect and remove contamination as soon as the module arrives on their yard but they need the help of growers, managers, consultants, and farm staff to ensure that the problem is minimized.

The moral of the story is that Georgia has developed a reputation for producing, ginning, and shipping extremely high levels of superior quality and contamination-free cotton.  As you’re riding the farm roads and scouting your crops, or as you’re spending those countless hours aboard a cotton picker, I encourage you to take the time to stop and remove any items that may have found themselves in a cotton field.  Whether it’s yours or your neighbor’s, taking the time to remove that “dollar-store” bag from the turn rows will pay dividends in the long run for us as an industry.  If Smoky Bear were to advocate for cotton, he’d say “Only You Can Prevent Cotton Contamination.”  Safe harvest to all!

 Important Dates:

 Field Days:

Tifton – Cotton and Peanut Field Day – September 5^th

For more information on any of the discussed topics please contact your local UGA Extension Agent