Topics in this Newsletter
- Peanut Rx and Sentinel Plot Maps – Dr. Kemerait, UGA Plant Pathologist
- Beware of Google/AI Answers – Dr. Prostko, UGA Weed Specialist
- Burndown Bummers – Dr. Prostko, UGA Weed Specialist
- Gypsum Replacements – Dr. Scott Monfort, UGA Peanut Agronomist
- USDA Expediting $10 Billion in Direct Economic Assistance to Agricultural Producers – USDA/FSA
- 2025 UGA Peanut Quick Reference Guides
Peanut Rx and Sentinel Plot Maps – Dr. Kemerait, Plant Pathologist
Peanut Rx is a disease management tool that allows growers to assess their risk to tomato spotted wilt, leaf spot, and white mold before the season starts and then to make adjustments to reduce the risk. Attached is the 2025 version of Peanut Rx. Peanut Rx 2025 has been thoroughly updated by team members from the University of Florida, Auburn, Mississippi State, Clemson, North Carolina State, and the University of Georgia. Peanut Rx is best used to make pre-plant decisions. Once final risk is determined, growers can use “prescription” programs from participating companies to protect yield and profitability.
Sentinel Plot Maps is an online tool that growers can use to determine where in the US certain diseases have occured that year to better time fungicide applications. Attached are sites for Southern Corn Rust, Tar Spot of Corn, and Soybean Rust. I am hoping we can develop something similar for spread of areolate mildew.
https://cropprotectionnetwork.org/maps/southern-corn-rust
| Southern Corn Rust – CornipmPIPESouthern Corn Rust can occur in major regions for corn production in the US and Canada despite being a tropical disease. High humidity and temperatures around 80°F create a supportive environment for Southern Corn Rust to thrive.corn.ipmpipe.org |
| Crop Protection NetworkSouthern rust is caused by the fungus Puccinia polysora and can occur in important corn production areas of the United States and Canada. It can be difficult to distinguish common rust, from southern rust.We recommend submitting samples to an accredited diagnostic laboratory for confirmation. Counties or parishes that are highlighted in red on the map have had southern rust confirmed by …cropprotectionnetwork.org |
Sentinel plot updates for Tar Spot of Corn in 2025
(funding for this sentinel plot effort is through the Georgia Commodity Commission for Corn)
https://cropprotectionnetwork.org/maps/tar-spot-of-corn
| Tar Spot – CornipmPIPELike other corn diseases, the pathogen causing tar spot overwinters in infested corn residue. When conditions such as high relative humidity and prolonged leaf wetness are present the likelihood of tar spot is greater.corn.ipmpipe.org |
Sentinel plot updates for Soybean Rust in 2025
| Soybean Rust – Soybean ipmPIPESoybean rust is caused by the fungus Phakopsora pachyrhizi.Symptoms are most common after flowering, beginning on lower leaves. Lesions start to form on lower leaf surfaces as small, gray spots that change to tan or reddish-brown.soybean.ipmpipe.org |
https://cropprotectionnetwork.org/maps/soybean-rust
| Crop Protection NetworkSoybean rust is caused by the fungus Phakopsora pachyrhizi and often occurs in the southern soybean production areas in Alabama, Georgia, Florida, Louisiana and Mississippi.Symptoms can be confused with several other foliar diseases of soybean including downy mildew, Septoria brown spot and target spot.. Note that the map may display “gaps” where active monitoring and scouting for soybean …cropprotectionnetwork.org |
Beware of Google/AI Answers (Prostko)
Just got an interesting phone call from an established crop consultant. He asked me about the use rate for Sonalan (ethalfluralin) in field corn. I replied to him that as far as I know, after working in field corn since 1987, that Sonalan was never or is not now labeled for field corn and I that I would never recommend it, especially PPI or PRE. Remember, Sonalan is a grass herbicide for use in broadleaf crops. I then asked him where he got his information. His reply was that I “Googled” it. If you Google Sonalan and field corn, here is what shows up:
What would I expect if Sonalan was used in field corn? Stunting, stubby roots, poor stands, excessive lodging, replanting to a labeled broadleaf crop (i.e. soybean or peanut). A picture of “yellow” herbicide injury on field corn (Source: S. Berger, IFAS).
This is not the first time I have seen an error with a Google/AI search. Bottom line, growers/consultants/county agents should not be getting weed control recommendations from Google/AI.
Burndown Bummers (Prostko)
Over the last several days, I have received numerous inquiries about the reduced performance of preplant burndown herbicide applications. Several factors can help contribute to reduced performance of burndown herbicides including application rate (too low?), weed size (too big?), environmental conditions (too cold?), small grain cover crop stage of growth (generally more susceptible prior to boot and after heading), droplet size (too big?), and time (too soon after application?).
For today, let’s just focus on air temperatures. I like to use a cold temperature threshold of <50 F as a benchmark for when herbicides start to not work like they should, If you check out Table 1, there have been many days this month below that temperature threshold. On average, 73% of the days in March at these Georgia locations had low temperatures below 50 F. In my opinion, this may be one of the main factors that has influenced the performance of some burndown herbicides. Good news is that the low temperatures forecasted for next week will be above 60 F so that should help improve burndown efficacy. Although I usually am not a huge fan of using AMS with glyphosate, unless hard water has recently been confirmed with a lab test, I think AMS might help improve glyphosate performance when air temperatures dip below 50 F.
Gypsum Replacements – Dr. Monfort
We have been getting a lot of questions regarding gypsum replacements.
These are the recommendations I could stand behind:
For fields below 750-800 lbs/A of calcium based on calcium pegging test:
Gypsum is worth the investment even at $50.00/A for 1000 lbs. You could reduce the amount applied to 750-800 lbs/A to save some money.
Lime is another way growers can get their calcium needed for the crop as long as they need a pH adjustment. They need to apply prior to planting.
The only other products I would recommend are the following:
For fields above 800 lbs/A:
Growers can use the following products: — Need to mention that the products below will help reduce the risk of ca deficiencies for peanut but will not help in building ca in the soil for the next crops.
- Top Flow at 10-15 gal/A applied at planting or early bloom and watered in immediately after. You will likely increase pH by ½ point.
- Calcium Chloride at 10 gals/ per acre injected through the pivot at 50-60 DAP
- Calcium Thiosulfate at 20 gal/A through the pivot at 50-60 DAP
Remember, Gypsum still the best option on Seed Peanuts.
All other products will not supply enough calcium for seed peanuts. If it was me, I would not stand behind any other product than the 4 above.
USDA Expediting $10 Billion in Direct Economic Assistance to Agricultural Producers – USDA/FSA
FYI, USDA/FSA sent out a bulletin on March 21, 2025 informing that an Emergency Commodity Assistance Program is in effect and applications are due by August 15. See the link below for access to this bulletin for more information.
https://content.govdelivery.com/accounts/USDAFARMERS/bulletins/3d80968
2025 UGA Peanut Quick Reference Guides
Call the extension office if you would like a hard copy.