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Reductions in Grass Control in 2018? (Prostko)

Getting plenty of calls about perceived reductions in grass control after applications of ACC-ase inhibiting herbicides, such as Select (clethodim) or Poast (sethoxydim), have been applied.  Some folks first reaction to this “lack” of control is that we suddenly have widespread ACC-ase resistance.  When its comes to the issue of resistance, I will never say never.  But, before traveling down that bumpy road, I would like for you and your growers to consider the following:

1) Currently, only 2 grass species have been “officially” confirmed to have evolved ACC-ase resistance in Georgia including large crabgrass and Italian ryegrass. Scientific confirmation of herbicide resistance takes lots of time, manpower, and greenhouse space.

2) Labeled heights for optimum control of various common grasses with Select, including crabgrass, Texas panicum crowfootgrass, and goosegrass, are 2″- 6″.  

3) The following is some data illustrating the effect of Select rate and timing on the control of goosegrass.  Please note that goosegrass control was reduced by 16-23%, depending upon rate, when applied at the 4-6 tiller stage of growth.

Figure 1.  Goosegrass control with Select applied at different rates and timings.

4) If Cadre (imazapic) was applied prior to the grass herbicide application, it is very likely that grass control will be reduced.   Research has shown that Cadre can reduce the photosynthetic rate of goosegrass which then reduces the sensitivity of the ACC-ase enzyme to clethodim (Burke and Wilcut.  2003.  Physiological basis for antagonism of clethodim by imazapic on goosegrass.  Pesticide Biochemistry & Physiology) 

5) At this time of the year, peanut plants are kinda tall (> 12″).  Thus, any grass plants peaking out of the top of the peanut canopy are not likely to be adequately controlled due to size and coverage issues.

6) Before dropping the R-bomb, please double-check use rates, stages of growth, adjuvants, rain-free periods, and field history.  The threat of herbicide resistance is definitely real but it does not happen in one night.

Row Crop Disease Update August 10, 2018

Dr. Bob Kemerait gives row crop disease update:

DISEASES of PEANUT:  White mold and leaf spot aren’t breaking lose in every peanut field in Georgia, BUT hot temperatures, high humidity and frequent rains have created near-perfect conditions for the development, spread and, sometimes, explosion of these diseases.  Growers need to stay on a good fungicide program, tightening spray intervals where disease is becoming problematic and/or where there is concern if the crops have received enough drying time after a fungicide was applied.

FOUR COTTON DISEASES:  Target spot, areolate mildew, Stemphylium leaf spot, and bacterial blight.

What a season it has become when target spot and areolate mildew are causing greater angst than bacterial blight.

 

EASY STUFF:

 

  1.  Bacterial blight is present and is affecting yield in some fields.  Susceptible varieties will get this disease and losses may occur.  THERE IS NOTHING TO BE DONE ABOUT IT NOW. However, growers should note the varieties where they find it and determine at the end of the season if the disease became severe enough to avoid planting those varieties again.
  2. Stemphylium leaf spot is present as well.  Stemphylium leaf spot is caused by a deficiency in potassium in the plant.  Dr. Glen Harris is our soil fertility expert; I believe he would agree that excessive rains could have leached potassium this year.  Fungicides ARE NOT a solution for Stemphylium leaf spot; Dr. Harris has the best information about managing potassium.

 

HARD STUFF:

 

  1.  Target spot and areolate mildew are present in a number of fields this year.
  2. At times, target spot and areaolate mildew appear late enough in the season that the defoliation resulting from these diseases does not affect yield and use of fungicides is not needed.
  3. The question for both diseases is not, “Can we protect the cotton in this field with a fungicides?” but rather, “Should we protect the cotton in this field with a fungicide?”
  4. We have very very little data on areolate mildew, but from what I do have, I am confident that we can easily control this disease using strobilurin products like Headline or Quadris, or mixed products like Priaxor or Elatus.  Proline may work as well but I don’t have data.
  5. Though we can control areaolate mildew, does it make us any more yield than if we didn’t control it?  When conditions are favorable, areolate mildew can rapidly defoliate a cotton crop.  If a grower is withing 3-to-4 weeks of defoliating anyway, I would NOT use a fungicide.  If the crop still had 4 or more weeks to go, I would consider weather, yield potential, how much disease is in the field and then decide to spray or not.
  6. If areolate mildew, or target spot, is already well-established in the field (i.e. causing significant defoliation, then there is little hope that a fungicide will help.
  7. Target spot is a significant concern this year and is widespread.  Not every cotton grower in the state needed to spray a fungicide for target spot, but I encourage growers to carefully consider their options.
  8. Target spot is of particular concern this year because a) the wet and warm conditions are perfect for an explosion of the disease, b) the disease has been found early in many fields, and c) the price of cotton makes protection 100-250 lbs lint/acre attractive.
  9. I believe the best window of opportunity for managing target spot is from the first week of bloom to the sixth week of bloom.
  10. A little target spot in a crop (meaning scattered spots on lower leaves and no defoliation) during the first week of bloom and favorable weather IS a concern, as it would be at the third week as well.  A “little target spot” at the 4th-6th week of bloom is much less of a concern.
  11. When a fungicide program begins as early as the first week of bloom because of the disease situation; a second application may be beneficial two-to three weeks later.  I don’t envision an application, follow-up or otherwise, after the 6th week.
  12. It will be quite difficult to control (impossible?) target spot if there is already significant defoliation in the field before an application is made.  If 25-30% of the leaves are already gone, a fungicide likely won’t work.
  13. THE  THREE MOST IMPORTANT POINTS TO MANAGE TARGET SPOT, in order of importance, are 1.  TIMING  2.  COVERAGE  3.  SELECTION of FUNGICIDE.

Peanut Tank-Mix

Peanut Tank-Mix Thoughts (Prostko)

Rain delays and/or late planting have resulted in continual inquiries about peanut herbicide + fungicide tank-mixes and their potential effects on weed control and crop injury. UGA will never be able to adequately address all concerns with 90,000+ potential tank-mixtures in peanuts. Here is a quick review of some of the published data:

1) When 2,4-DB is tank-mixed with a postemergence graminicide, grass control can be reduced by 8% to 15% approximately 45% of the time.

2) When averaged across 5 grass species, Cadre (imazapic) + Select (clethodim) tank-mixtures provided 19% less effective grass control than Select alone.

3)  Abound (azoxystrobin), Absolute (tebuconazole + trifloxystrobin), Bravo (chlorothalonil) and Headline (pyraclostrobin) are 4 fungicides that have caused significant grass antagonism when tank-mixed with Select (~12% to 30% reductions in grass control).

4) Grass efficacy with Poast (sethoxydim) and Select has not been consistently reduced by tebuconazole (various trade names including Folicur, Orius, TriSum, Integral, Ebustar, Muscle, Tebuzol).  However, when reductions have been significant, grass control was reduced by 4% to 13% with tebuconazole mixes.

5) Palmer amaranth (PA) control was not reduced when 2,4-DB was tank-mixed with Bravo, Provost (prothioconazole + tebuconazole), Headline, or Absolute.  But, 2,4-DB is not that great on PA anyway though?

6)  Sicklepod control with 2,4-DB was reduced by 14% when applied with Abound but not with Bravo or tebuconazole

The Impacts of China Trade Tariff on Georgia Row Crops

By Yangxuan LiuAdam N. Rabinowitz, and Don Shurley

China announced plans to implement a 25 percent increase in import tariffs on major agricultural commodities from the United States, which includes soybeans, corn and corn products, wheat, sorghum, cotton, and tobacco and tobacco products. The overall United States export value for these agricultural commodities to China are worth around 44.7 billion dollars (USDA FAS, 2018a).

United States agriculture relies on the export markets to absorb its excess supply in order to support domestic agricultural prices. The United States is the largest exporting country for corn, cotton, and sorghum, and the second largest exporting country for soybean and wheat (USDA FAS, 2018b). China is the largest trading partner for United States sorghum and soybean, and the second largest trading partner for cotton (USDA FAS, 2018a). In 2017, China bought 81.4% of the United States sorghum exports, 57.3% of the United States soybean exports, 16.7% of the United States cotton exports, 5.7% of the United States wheat export, and 1.6% of the United States corn export (Table 1).

The Chinese tariffs, if implemented, will increase the United States agricultural prices faced by the Chinese consumers relative to other countries. Thus, it will reduce demand for United States agricultural commodities by Chinese consumers. As a result, the United States needs to find alternative foreign markets to export its excess supply in order to sustain current prices. China is the largest importing country for sorghum and soybean (USDA FAS, 2018b). Developing alternative markets for these commodities might be difficult. Although much of the soybeans going to the European Union typically come from Brazil, the European Union (import 14.8% of soybean traded globally) can serve as an alternative market for United States soybeans. Globally, it is a very competitive supply market for soybeans. China could diversify its suppliers in the long run and purchase more soybeans from Brazil (export 39.8% of soybean traded globally) and Argentina (export 17.0% of soybean traded globally) (USDA FAS, 2018b). In the short run, there will not be enough capacity for these countries to increase their production acres. China will still need to buy American soybeans and sorghum to satisfy their domestic consumption.

China is the third largest importing country for cotton, importing 13.1% of cotton traded globally in 2017 (USDA FAS, 2018b). If the Chinese tariffs on U.S. cotton are put into effect, it might provide a near term opportunity for global cotton suppliers like India, Australia, and Brazil to supply more cotton to China. However, the longer term situation could involve more of a re-routing of U.S. exports to other cotton importing countries, like Vietnam, Bangladesh, Indonesia, Pakistan, and India, than a reduction in U.S. cotton production. Recent history of the change in China’s internal cotton policy has shown that the disruptions of Chinese raw cotton imports stimulates the importing of duty free yarn from countries like Vietnam, Indonesia, and the Indian subcontinent (J.R.C. Robinson, personal communication, April 2018; Shurley, 2018).

A study conducted at Purdue University found that the prices of United States soybeans would fall by 2 and 5% under the 10 and 30 percent tariff, respectively (Pack, 2018). Similar effects of price reduction are expected to the other agricultural commodities. The tariff impact on the sorghum price is expected to be larger than the impact on the soybean price, while the impact on the cotton price is expected to be smaller than the impact on the soybean price.

The potential 25 percent increment in tariff for corn, cotton, sorghum, soybeans, and wheat could have a negative impact to Georgia’s agricultural industry. Cotton is the largest crop produced in Georgia with more than 1.27 million acres harvested last year, and contributes $794 million to Georgia’s economy (Table 2). Georgia produced 10.6% (2.25 million bales) of the total United States cotton production in 2017, and is the second largest cotton producing state after Texas. It is also the second largest cotton export state after Texas. Last year, Georgia exported $441 million of cotton, of which $26 million of cotton was exported to China (USDA FAS, 2018a). The Chinese tariffs will have a direct impact on the cotton exported from Georgia because tariffs will impact the entire United States cotton market and the prices received by every United States cotton farmer. It will also have an indirect impact through the prices received by Georgia cotton farmers. Even though Georgia does not export corn, sorghum, soybean, and wheat directly to China, the lower price of these commodities due to Chinese tariffs would impact Georgia farmers.

 

References

Pack, D. (Producer). (2018). Study: U.S. soybean production, exports would fall if China imposes tariffs. Purdue University Agriculture News. Retrieved from https://www.purdue.edu/newsroom/releases/2018/Q1/study-u.s.-soybean-production,-exports-would-fall-if-china-imposes-tariffs.html

Shurley, D. (2018). Shurley on Cotton: More Tariff Talk.  Retrieved from http://www.cottongrower.com/market-analysis/shurley-on-cotton-more-tariff-talk/

USDA FAS. (2018a). Global Agricultural Trade System Online Dataset. Retrieved from: https://apps.fas.usda.gov/gats/default.aspx

USDA FAS. (2018b). Production, Supply and Distribution Database.  Retrieved April 25, 2018 https://apps.fas.usda.gov/psdonline/app/index.html#/app/advQueryVegetables Industry

Thrips Monitoring 2018

UGA  peanut  entomologist  Dr. Mark Abney shares some information on thrip  monitoring,  he has seen across the state and offers recommendations for treating. Peanuts are being planted, and tobacco thrips are moving in Georgia. Trap captures increased significantly at four of our six monitoring locations last week. This means that peanuts emerging over the next couple of weeks will be at relatively high risk for infestation. Using an at-plant insecticide with proven efficacy will usually be sufficient to keep thrips injury low, but growers are still strongly encouraged to scout fields for thrips activity. Growers who are not using an at-plant insecticide should be prepared to make foliar applications (usually acephate) for thrips if they want to avoid injury. Remember that phorate (Thimet) in-furrow is the only insecticide that has been proven to reduce the risk of tomato spotted wilt disease in peanut.  We are in the first two weeks of thrips dispersal, and we do not know how long flights will continue or how large populations will be. We will continue to post weekly updates of trapping data as the planting season progresses.

These data are being provided for informational purposes only and may not be representative of thrips dispersal at your location. Peanut fields should be scouted regularly to quantify actual thrips populations.

If you have questions about thrips or thrips management please contact your local county Extension agent.

Peanut tillage trials

2016 2017
Chisel Plow 6033.2 b 7489.9 b
Rip and bed 6207.1 ab 7552.9 b
Bottom Plow 6422.8 a 7782.2 a

The following is the impact of tillage on yield potential. Tillage trials were conducted at  the Midville station the last two years. This information was provided by Dr. Scott Monfort UGA peanut specialist.

Georgia Peanut Farm Show

The Georgia Peanut Farm Show and Conference will be held in Tifton next Thursday, January 19th. Show opens at 8:30. There will be vendors set up and also educational sessions.

Lowndes County Peanut Production Meeting

Lowndes County Peanut Production Meeting is scheduled for Tuesday, January 10th at noon. Dr. Monfort and Dr. Abney will be talking about peanut production and insects.Commercial (cat. 21), and private pesticide credit will be given with each meeting to all license holders who attend and sign in.  Please call the office (333-5185) a few days ahead if you plan to attend so that plans can be made for the meal. I look forward to working with you this year and please contact me if you need anything.

2017 Production Meetings

Five row crop and vegetable production meetings are currently scheduled in Lowndes County. Commercial (cat. 21), and private pesticide credit will be given with each meeting to all license holders who attend and sign in.  Please call the office (333-5185) a few days ahead if you plan to attend so that plans can be made for the meal. I look forward to working with you this year and please contact me if you need anything.

Don’t let your license expire put these meetings on your calendar now.

  • January 10, 2017 Peanut Production andPeanut Insects
    12:00 noon Lowndes Extension Office
    Dr. Scott Monfort
    Dr. Mark Abney
  • January 13, 2017 Vegetable Production
    9:30 a.m. 4-H Center-Lake Park
    Dr. Stormy Sparks
    Dr. Tim Coolong
    Dr. Bhabesh Dutta
  • February 6, 2017 Row Crop Disease and Fertility
    12:00 noon Lowndes Extension Office
    Dr. Glen Harris
    Dr. Bob Kemerait
  • March 2, 2017 Cotton Production Cotton Insect
    6:00 pm Lowndes Extension Office
    Dr. Jarod Whitaker
    Dr. Phillip Roberts
  • March 8, 2017 Row Crop Weed Control
    12:00 noon Lowndes Extension Office
    Dr. Eric Prostko