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Cotton Defoliation Timing

Published on 08/29/19

Proper timing of defoliation is important decision for cotton growers

By Clint Thompson for CAES News

With harvest season less than a month away for some Georgia cotton farmers, knowing when to defoliate is an important decision all growers have to make, according to Mark Freeman, University of Georgia Cooperative Extension cotton agronomist.

Before cotton can be harvested, the plant’s leaves must be removed through a process called defoliation, which helps speed up the plant’s maturity. Farmers apply a chemical treatment and, approximately two weeks later, the crop is ready for harvest.

“The way cotton grows, bolls are going to open up in the bottom first because those are the oldest bolls. As you move up the plant, the bolls are younger,” Freeman said. “We have to take all of the leaves off of the plant to try to open up those younger bolls. We try to do it at the best time to optimize yield and quality. We want all the bolls on the plant open and ready for harvest at the same time.”

If farmers apply a defoliant too early, they could lose yield because of a lack of maturity. If defoliant is applied too late, losses from boll rot and weather can occur.

Freeman offers farmers three recommendations for how to determine if a crop is ready to be defoliated.

  1. Percentage of open bolls: Typically in Georgia, when a crop has about 70% open bolls, it’s safe to defoliate. If the crop is uniform without fruiting gaps, it is likely mature enough.
  2. Number of nodes above cracked bolls: With this method, farmers find the highest cracked boll and then count the number of nodes up the plant to the uppermost harvestable boll. If there are four or less nodes between the two, it is likely safe to defoliate.
  3. Sharp knife method: The safest method is to cut representative bolls open at a cross section. Check the seed for a fully-developed dark seed coat and lint that strings out.

“The (sharp knife method) is really the best indicator of maturity, but we want to use all three methods in conjunction to make the best decision that we can,” Freeman said.

Due to weather-related issues, Georgia’s cotton crop looks sporadic across the state, Freeman said. Areas that have had rainfall look promising, while other areas have struggled due to inadequate rainfall in July and August.

“The irrigated crop looks good. I wouldn’t say it’s excellent, but there’s going to be good yields from the irrigated part. Dryland, on the other hand — some areas look good, but more areas do not look so good,” Freeman said.

For more information about cotton production in Georgia, see the Georgia Cotton News website.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Cotton and Peanut Research Field Day

Published on 08/21/19

UGA Extension to showcase cotton, peanut research during field day

By Clint Thompson for CAES News

Cotton and peanut farmers and industry personnel are invited to the University of Georgia Cotton and Peanut Research Field Day on Wednesday, Sept. 4, on the UGA Tifton campus.

Members of the UGA cotton and peanut teams will talk about ongoing research at two UGA research farms, providing insight for growers on what they can expect for the next growing season.

The field day will start at 8 a.m. at the UGA Lang Farm at 276 Rigdon Aultman Road in Tifton, Georgia. Field day attendees will also visit the UGA Gibbs Farm at 226 William Gibbs Road in Tifton, Georgia, before returning to the UGA Tifton Campus Conference Center for lunch and a short program.

The field day is a free event, but attendees are encouraged to RSVP to Jeannie Evans at 229-386-3006 or jevans12@uga.edu to provide an accurate count for lunch.

UGA College of Agricultural and Environmental Sciences cotton and peanut specialists, including physiologists, plant pathologists, entomologists, agronomists, irrigation experts and plant breeders, conduct research aimed at improving Georgia’s top two row crops at UGA-Tifton. Cotton and peanuts account for nearly two-thirds of Georgia’s row crop production. The UGA specialists will present their latest research findings at the field day.

“This field day gives us an opportunity to share with producers in the industry some of the newest research that we’re doing with cotton and peanuts. It allows us to get into a field setting and actually put our hands on certain things, see what’s happening and talk about it together,” said Jared Whitaker, UGA Cooperative Extension cotton agronomist.

Georgia’s cotton farmers hope this year’s crop will rebound after being decimated by Hurricane Michael in early October 2018. According to estimates from UGA Extension agents and agricultural economists, there were between $550 million and $600 million in direct losses, along with an additional $74 million in agriculture sector losses.

Georgia’s peanut crop fared better, suffering between $10 million and $20 million in direct losses.

“The cotton and peanut research field day provides a perfect opportunity for growers to provide feedback on future research projects based on issues they are having on their farms,” UGA Extension peanut agronomist Scott Monfort said.

For more information about cotton, see the Georgia Cotton News website.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Row Crop Disease Update

Corn:  Southern corn rust is now confirmed in 7 adjoining fields in Baker County.  I don’t think it is a coincidence that we are finding it now; development is following the rain periods of recent weeks.  I expect (stay tuned) to have more identified very soon.  Bottom line:  I think that the amount of southern rust is fairly low in the state right now, but that could change fairly quickly.  Wind and more wind yesterday and rains certainly were PERFECT for moving spores.

 Recommendation:  Any corn in the dough/dent stage as of now, i would likely not advise spraying for rust in SW Georgia, or anywhere else.  Corn in  late milk stage, I would likely not spray either, because, again, the amount of rust is low.  Any corn in SW Georgia that is at early milk, silking or tasseling stages in SW Georgia, I would certainly think about protecting with a fungicide.

 IF YOU THINK YOU FIND SOUTHERN RUST, PLEASE LET US KNOW

 Peanuts:  We are in a combat situation I believe now with white mold.  I am getting pictures of young plants that are affected.  Very warm soil temperatures followed by moisture followed now by hot temperatures creates PERFECT white mold conditions (southern stem rot, Nickie).  Typing this at 7:30 AM, it is already 79 degrees and 100% humidity.  I can almost hear the white mold…..

 Recommendations:  Now is not the time to be timid on white mold control.  The weather is here, teh crop is developing, protect the crop with fungicides from leaf spot and white mold.

 Cotton:  No target spot or areolate mildew, but conditions are favorable.  Please advise your growers to pay attention and scout.  FIRST BLOOM is an important time to check your crop for target spot.  Even if you don’t spray, be aware.  Also, keep your eyes open for reddened, stunted, distorted plants that COULD be our new viral disease.  If you find plants like that, please let me know so we can check them out.

 Soybeans:  Asian soybean rust is present in kudzu across the Coastal Plain.  Conditions (windy and passing storms) are PERFECT for moving it to soybeans.  IF THEY WERE MY BEANS, I WOULD DEFINITELY APPLY A FUNGICIDE BY R3, POD SET STAGE, especially if I was putting out dimilin and boron, and even if I wasn’t.  GOOD INSURANCE.

By  Bob Kemerait 

UGA COTTON TEAM APRIL NEWSLETTER

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 10th). 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: http://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:

 

http://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 Losses From Hurricane Michael

Published on 10/31/18

UGA economists estimate up to $600 million in cotton damage from Hurricane Michael

By Clint Thompson for CAES News

University of Georgia agricultural economists believe that Georgia cotton farmers in the path of Hurricane Michael have only begun to feel the impact of the storm that took 90 or 100 percent of many area growers’ crops.

This week, Yangxuan Liu, assistant professor of agricultural and applied economics in the University of Georgia’s College of Agricultural and Environmental Sciences (CAES), and UGA Cooperative Extension agricultural economist Amanda Smith released preliminary cost estimates of Hurricane Michael’s damage to Georgia’s cotton industry.

Their initial estimates of farm gate value loss range from $550 million to $600 million. This includes losses related to cotton lint, cottonseed and reductions in fiber quality.

UGA’s estimated loss value for cotton is still preliminary. Updates will be provided as more data is collected, Liu said.

“We took into consideration yield loss variation across the state and adjusted our estimates accordingly,” she said.

“We are still in the process of gathering more data from cotton farmers and county agents.”

Because heavy rains and winds occurred when the bulk of Georgia’s cotton crop was at risk, Liu cautions farmers that quality issues may be a problem.

“Some harvested cotton modules in the field were damaged by wind and rain, which might degrade quality. The cotton harvested after the hurricane might face quality discounts as well, because more mature bolls of possibly higher quality were lost,” she said.

Liu cited U.S. Department of Agriculture (USDA) estimates that only 12 percent of Georgia’s cotton crop had been harvested prior to the storm’s arrival. Eighty-eight percent of cotton bolls were open and susceptible to the hurricane’s destructive winds.

Hurricane Michael’s path up through southwest Georgia significantly impacted the region that is responsible for some of the top cotton production in Georgia. Southwestern Georgia counties Colquitt, Crisp, Decatur, Dooly, Early, Mitchell and Worth were hit hard by the hurricane — and make up seven of the top-10 cotton-producing counties in the state, according to the USDA’s figures for 2017.

Cotton is the largest row crop in Georgia. According to the USDA, the farm gate value for Georgia-grown cotton and cottonseed in 2017 was $867 million with more than 1.2 million harvested acres.

Producers should contact their local UGA Extension agents to report any losses or for more information about estimating storm damage.

“The impact of Hurricane Michael will extend beyond the farm gate level. Cotton gins, local communities and the entire Georgia economy are likely to experience the ripple effect of Hurricane Michael for years to come,” said Jeff Dorfman, a professor of agricultural and applied economics at CAES.

For up-to-date information on Georgia’s cotton crop, see www.ugacotton.com.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

Cotton Outlook 2018

Download the PDF version of this newsletter.

In 2018, Georgia’s farmers planted 1.43 million acres of cotton, up 150,000 acres from 2017. The average cotton yield is forecast at 946 pounds per acre. Production is forecast at 2.8 million bales, which would be the second highest on record. There are two major contributing factors to the increase in cotton acres in Georgia. First, the relatively high cotton price in 2018, especially during planting season, makes cotton more competitive with other row crops. Second, the Bipartisan Budget Act of 2018 authorized seed cotton as a covered commodity and eliminated generic base and thus the eligibility for payments when planting other covered commodities on farms with generic base.

U.S. cotton planted acreage is 14.04 million, up 1.43 million from 2017, which is the highest planted acres since in 2011. The 2018 U.S. upland cotton is forecasted at 18.9 million bales, down 1.31 million bales from 2017. The reduction in production is largely due to the severe drought conditions in Texas. Even though Texas planting acres increased by 12 percent, the production level reduced by 30 percent from 2017. The forecasted production number might be further negatively impacted by Hurricane Florence on North and South Carolina.

World cotton use or demand has improved significantly in recent years and currently forecast at a record level. Even though U.S. cotton faces an additional 25 percent increase in tariffs on cotton exports to China due to the on-going trade dispute between U.S. and China, U.S. cotton exports are doing very well and are expected to continue to be strong for the 2018-2019 crop year. Exports are currently forecasted to be 15.7 million bales for the 2018 – 2019 crop year, which would be the second highest on record.

The U.S. ending stocks for the 2018 – 2019 crop year are expected to increase to 4.7 million bales. The U.S. cotton industry has benefited from the growth in mill use in other countries. If U.S. sales of cotton into China decline as a result of a Chinese tariff, it is possible that sales to mills in other countries could increase to offset part of the decline in China. A Chinese tariff on U.S. raw cotton could continue to stimulate Chinese imports of duty-free yarn from Vietnam, Indonesia, and the Indian subcontinent. The demand for higher-quality U.S. cotton in those markets could continue to expand. Thus, the impact of a bilateral Chinese tariff on U.S. cotton may lead to a reshuffling or rerouting of, rather than a reduction in, U.S. cotton exports.

China is the world’s largest user of cotton but now the world’s third-largest cotton importer behind Bangladesh and Vietnam. Starting in 2011, the Chinese price support policy had resulted in buildup of ending stocks. In 2014, the Chinese cotton policy shifted from price supports and building government reserves to paying growers with direct cash payments in order to reduce the government cotton reserve. China’s ending stocks for the 2018 – 2019 will continue to decrease and are forecasted to total 29.9 million bales. For 2018, China has approved 800,000 tonnes of additional cotton import quota, which is in addition to the annual 894,000 tonnes of low tariff rate quota that China issues as part of its commitments to the World Trade Organization. This is the first time that China has issued any additional quota since 2013.

Futures prices (Dec 18) for the 2018 crop are currently at or around 82 cents per pound. We have been seeing favorable cotton prices this year, the cash prices for the current calendar year of 2018 ranges from low of 74.60 to high of 94.21 cents per pound. USDA is forecasting the marketing year average price for the 2018 – 2019 crop year to range from 70 to 80 cents per pound, compared to the 2017 – 2018 crop year average of 68 cents per pound.

Good luck and let us know if we can help,

Yangxuan Liu and Don Shurley

Department of Agricultural and Applied Economics

University of Georgia

Whitefly Pressure in Late Planted Cotton

Whitefly pressure a concern for cotton growers with late planted crop

By Clint Thompson

Georgia cotton farmers who planted their crop late this year need to be mindful of potential whitefly pressure, according to Phillip Roberts, University of Georgia Cooperative Extension entomologist.

Because whiteflies prefer green, lush cotton over cotton that is near maturity, most of the cotton that was planted early in April and May avoided whitefly problems. However, Roberts has observed whiteflies on late-planted cotton, or cotton planted in June.

“Over time, whiteflies have adapted to infest plants which will remain green or be a suitable host for the insects to complete a generation,” Roberts said. “It takes between 15 to 20 days for a whitefly to complete development on a cotton plant once an egg has been laid. Also, the nutritional value may be higher on late-planted cotton.”

Scouting remains the best course of action against whiteflies, sucking insects that feed on the underside of leaves and excrete a sugary substance called “honeydew” that serves as a host for sooty mold fungus. The accumulation of honeydew and sooty mold leads to quality problems on open cotton bolls. When uncontrolled, whiteflies can reduce cotton yields and affect cotton quality.

“(Immature whiteflies) are on the underside of the leaves and excrete honeydew, which is a sticky, sugary solution. This can be a serious issue in terms of fiber quality or the spinnability of fibers at mills,” Roberts said.

Growers need to be timely with their insecticide applications to avoid an outbreak. However, UGA Extension encourages growers to conserve beneficial insects, only applying insecticides when infestations are observed.

According to Roberts, approximately 30 percent of Georgia’s cotton crop, or about 435,000 acres, were planted in June this year.

Late-planted cotton still has a couple of months left in the field before harvest. Whiteflies remain a potential threat to cotton until all the leaves have dropped from the plant, Roberts said.

“From a yield standpoint, cotton becomes less susceptible to yield loss the more mature it is and much of the cotton planted in April and early May has reached that stage. June-planted cotton remains susceptible to yield loss,” he said.

Compared to the 2017 cotton crop, whiteflies had been largely undetected for most of the summer. However, during late August and early September, numbers have increased to the point where producers need to be on alert during the final months of the growing season.

“Only a small percentage of cotton in Georgia has required treatment to date, but we still have a long way to go with the lateness of this crop. Most acres that have required treatment so far were planted in June,” Roberts said. “We learned a lot of hard lessons with whiteflies in 2017, and it is imperative that control measures are applied in a timely manner.

Once established, whitefly populations are very difficult to control and can easily reach outbreak levels in a field. Control costs are higher if farmers are late with initial control measures.

For more information about Georgia’s cotton crop, see www.ugacotton.com.

Clint Thompson is a news editor with the University of Georgia College of Agricultural and Environmental Sciences based in Tifton.

UGA Cotton Team Newsletter September, 2018

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 5th

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

Row Crop Disease Update August 27

Dr. Bob  Kemerait gives a row crop disease update

  1. Soybeans: Asian soybean rust is still lightly scattered from Decatur County to Appling County, but has only been found so far in KUDZU.  Soybean rust is certainly not a major problem at the moment; however it could become so.  Management options are to protect the crop with a fungicide sometime between the R1 (early bloom) and R3 (early pod set) stages.  Such timings may correspond well with other disease and insect control measures.  Some “Cercospora leaf blight” is being reported; this disease causes much of the upper foliage to take on a “bronzed” cast and then leaves drop prematurely leaving the “bony” petioles like skeleton fingers to the sky.  Cercospora leaf blight also causes purple seed stain.  Fungicide applications at pod set (R3) can help manage this disease.
  2. Late-planted corn: Southern corn rust is now commonly observed on older corn across the Coastal Plain, corn that is too late for it to matter.  However, southern corn rust does pose a threat to younger corn and preventative protection with a fungicide is something to consider, especially as the crop approaches the tassel growth stage.  Also, I am receiving numerous reports of young corn affected by northern corn leaf spot (Bipolaris zeicola) which produces numerous, small-to-medium sized red/brown spots, sometimes with appearance of concentric rings.  Typically, corn is most severely affected by northern corn leaf spot early in the season and then grows out of it; however I cannot be sure that this will always be the case.  I have no data on fungicides for management of northern corn leaf spot, but as it is closely related to northern and southern corn leaf blights, I am confident that mixed mode of action products we already use will be helpful for the “spot” disease.  If a grower does spray, applications as early as V6-V8 would be appropriate. But again, I just don’t know if it matters.
  3. Cotton: I hear you.  And I feel your frustration.  We have three diseases of significant importance in the field right now.    Boll rot.  The rain and heavy vegetative growth we have seen this year has created perfect conditions for fungal boll rot.  We are seeing a lot of it.  We are not seeing a lot of bacterial boll rot, though some is certainly there.  Fungal boll rot is most severe in lower bolls deep in the canopy or where insect damage also occurs.  Fungicides are not an effective treatment; only opening the canopy up to increase airflow and reduce humidity can help reduce boll rot.  2.  Areolate Mildew.  First, Andrew S. and others, I didn’t make the name up.  Second, I know that there is great concern and I have heard growers complaining that there fungicide applications did not stop the disease.  Here are some thoughts.  For the second year in a row, Areolate mildew is early and widespread.  Areolate mildew can cause significant premature defoliation.  I do know that fungicides like Headline and Quadris and certainly Priaxor can slow the spread of the disease, though not necessarily stop it, especially when it is well established in a field.  It is not clear how much yield is at risk or that can be protected; but it is believed that significant premature defoliation is not a good thing, unless one is trying to open the canopy up to slow boll rot.  Here are my recommendations, though they have not been proven with any hard data.  If a grower is within 4 weeks of defoliating the crop anyway, save the money and don’t spray.  If the grower is more than 4 weeks of defoliating and the areolate mildew is not too severe (i.e. already causing significant leaf drop) then there may be a benefit to treating with a fungicide.  This may not stop the disease but will slow its development.  3.  Target Spot.  Target spot has been severe and widespread in this rainy season.  I believe well-timed fungicides have been helpful this year.  I don’t believe there is any benefit to a fungicide application after the 6th week of bloom.  Either there is too much disease already to stop it or there is not enough time for disease to develop.  In this season, a second fungicide application 2-3 weeks after the first application is something to consider.
  4. PEANUTS: Getting lots of questions these days about late-season peanut disease problems.  Just a few thoughts.    Three weeks to go until you dig the peanuts and little-or-no disease in the field?  I wouldn’t put out any more fungicides unless there is threat of a hurricane or tropical storm.  If three of more weeks out and on your last spray and you are seeing some leaf spot develop, applying a pint of chlorothalonil tank-mixed with 7.2 fl oz of  tebuconazole or 5.5 fl oz of Alto or 5 fl oz of Topsin or 2.5 fl oz of Domark.  If time for your last spray and very little leaf spot is present, then 1.5 pints of chlorothalonil may be all you need.

If white mold is popping up in your field late in the season and is confined to individual plants scattered across the field, then you may want to mix tebuconazole with your last leaf spot spray.  If the disease is more severe, or you are really worried about it, then you might consider using 16  fl oz or Convoy rather than tebuconazole.

It is generally advisable to wait to dig the peanuts until they are “ready” based upon the hull-scrape test.  This is true even if there is significant tomato spotted wilt in the field or some white mold.  HOWEVER:  if there is significant defoliation from leaf spot or significant white mold in the field, it often best to dig the peanuts earlier than planned to avoid excessive digging losses.

UGA Cotton and Peanut Research Field Day

Cotton & Peanut Folks,

 

On Wednesday September 5th 2018 in Tifton, GA the UGA Cotton and Peanut Teams will be hosting 2018’s UGA Cotton & Peanut Research Field Day.  This annual event provides an excellent opportunity for anyone who is interested in learning more about our two most widely planted row crops here in Georgia.

 

We have planned a day which we hope will be both interesting and informative while allowing plenty of opportunities for the fellowship and fun we come to expect at a UGA Field Day in Tifton.

 

There is no cost to attend, we only ask that you RSVP if you plan to attend (just for a lunch headcount – call Mrs. Jeannie Evans at 229-386-3006 or email her at jevans12@uga.edu ).  The Georgia Cotton Commission and the Georgia Peanut Commission have graciously sponsored the field day’s lunch, in addition to continually providing the funding needed to support UGA’s research and education efforts.

 

For more details on speakers, locations and specific times be sure to take a look at the agenda (see attached).  The agenda, as well as maps for traveling to and from the research farms we’ll visit, can also be found at www.ugacotton.com .

 

In summary, the field day will start at the Tifton Campus Conference Center (TCCC) in the North Parking Lot at 8 AM.  After a brief welcome, the trams will leave for the RDC Pivot at 8:15 AM.  After four stops around the RDC Pivot, we will drive to the UGA Ponder Farm to tour several trials and hear from more of our speakers.  We will finish up the outdoor program prior to lunch (which will be at the TCCC) and hear from our economists inside as well as representatives of UGA’s administration and the Georgia Cotton & Peanut Commissions.

 

We look forward to seeing you there.  Please feel free to share this email and invite anyone who may enjoy learning more about cotton and peanut production in Georgia.

 

See you Wednesday, September 5th in Tifton!

 

Jared Whitaker & Scott Monfort

(UGA Extension Cotton & Peanut Agronomists, respectively)

 

 

 

Jared Whitaker, Ph.D.

The University of Georgia

Cotton Extension Agronomist
2360 Rainwater Rd.

Tifton, GA 31793

 

229-938-2448

jared@uga.edu