Dr. Jordan April 25-27, 2023 Peanut Notes

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Acephate for Thrips Control in the Seed Furrow Peanut Notes No. 42 2023

With imidacloprid performing less consistently and growers not set up of in-furrow granular applications in some cases, there have been questions about using acephate (often referred to as Orthene) in the seed furrow to control thrips. Acephate in the seed furrow controls thrips relatively well. However, growers and research/extension personnel have seen peanut stand reductions when acephate is applied in the seed furrow. Not every time but occasionally. We do not have a good feel for what conditions create the risk. We do not recommend acephate in the seed furrow for thrips control.

Comments on Thrips and Nematode Control Peanut Notes No. 43 2023

I had a question about alternatives to imidacloprid (Admire Pro and generic products) for thrips control. Resistance in thrips to imidacloprid has been documented in peanuts. The NC State Extension agent indicated that the grower has challenges getting back to peanut fields in a timely manner for foliar sprays of acephate. They wanted to know what product was the one that would most likely give complete thrips control and would not require a follow up postemergence spray of acephate.

My answer was that all of the in-furrow products we use need a follow up spray in some cases. However, AgLogic is the insecticide that often does not need a follow up spray of acephate. It is the new version of Temik (active ingredient is aldicarb.) However, it is the most expensive product. A second product that performs well is Thimet/Phorate (active ingredient is phorate.) It does a good job controlling thrips but is less effective in some instances compared with AgLogic. If using Thimet/Phorate, it is critical to calibrate accurately. On sandy soils with low organic matter, we can get significant chlorosis and necrosis on lower leaves. If you have never seen the chlorosis before, it can be disconcerting. Nevertheless, peanuts recover. AgLogic and Thimet/Phorate are applied as granular materials in the seed furrow. The farmer mentioned earlier was considering using an older planter with granular boxes because he was concerned that imidacloprid was going to be ineffective. This is a transition back to what we did over a decade ago for many farmers.

The in-furrow spray options are imidacloprid and Vydate. Data on Vydate are somewhat limited. However, it does provide suppression of thrips and is more effective than imidacloprid (due to imidacloprid resistance in thrips) in many fields. The jury is still out on how consistent performance will be relative to AgLogic and Thimet/Phorate. In 2022, Vydate performed well and competed with Thimet in a trial I had in cooperation with Rick and Brian. I did not have AgLogic in the trial.

Vydate is more expensive than a generic imidacloprid and Thimet/Phorate. It is considerably less expensive than AgLogic.

In many of our fields, we will need two sprays. One applied in the seed furrow and one applied about 3 weeks after planting. For April and early May plantings, the period needed for protection can be quite long. Peanuts can be slow to emerge when planted early and do not grow off quickly.

In a lot of the research Rick, Brian and I have conducted, the difference in thrips control with AgLogic, Thimet/Phorate, imidacloprid, and Vydate is often similar about a month or so after planting when acephate is applied postemergence 3 weeks after planting. That is to be expected. Of course, it depends a great deal on when you think you can get back to the field for the acephate spray. If you are usually on the late side, the performance of the in-furrow spray is more important.

The same grower indicated that they were going to spray Velum in the furrow to suppress nematodes. In the rotation research I have conducted with significant populations of nematodes, I have observed only minor effects on nematodes with Velum or Velum Total and no measurable yield response. However, if the grower decides to apply Velum, they will need to include a partner in the tank or they will need to apply a granular insecticide in the seed furrow to suppress thrips. The logical tank mixtures are imidacloprid and Vydate for thrips control. We have not mixed Vydate with Velum. This mixture, however, should control thrips well and increase the likelihood of nematode suppression (Vydate has some activity on nematodes.) However, this combination is not recommended because I am not aware of any research in North Carolina looking at this mixture. It is also a relatively expensive treatment.

The agent also asked about using AgLogic and Velum together. Thrips control would be good due to the AgLogic. The AgLogic and Velum would suppress nematodes better than either product alone. However, in my view, the combination of AgLogic and Velum is cost prohibitive.

If the goal is as much thrips control for as long as possible, AgLogic is the best option. Expense tempers its use and setting up for granular applications is an issue for some growers.

In-Furrow Fungicide Question Peanut Notes No. 44 2023

Question:

I had a grower considering using Provost Silver versus Proline in-furrow. Looked over your Peanut Science article from 2003 about tebuconazole in-furrow and talked with David Langston. Looks like tebuconazole in-furrow was of no benefit.

Jordan:

The tebuconazole caused peanuts to emerge more slowly. Provost Silver has prothioconazole plus tebuconazole. I would not apply this product in the seed furrow. Propulse is an option. It has prothioconazole plus fluopyram (the components of Proline plus Velum.) My understanding is Proline might be in short supply. Provost Silver is also not labeled for this use. Regardless, I would not put it in-furrow. Cost might be in favor of Provost Silver for the prothioconazole but label and impact on emergence are not.

Seeding Rate in 30-Inch Row Spacing Peanut Notes No. 45 2023

The in-row seeding rate for row spacings of 30, 36, and 38 inches is the same. Establishing at least 4 plants per foot is important to optimize yield. In-furrow insecticide and inoculant need to be the same under each row regardless of row spacing. However, make sure the amount of insecticide applied per acre does not exceed the label.

With twin rows, establishing a total of 6 plants per foot of row (3 plants on each of the two rows in the twin-row pattern) is recommended. As with 30-inch rows, make sure the insecticide rate per acre does not exceed the label.

For twin rows and single rows, there is more flexibility in inoculant rates per acre. However, the full recommended rate is needed under each row regardless of pattern or row spacing.

Saving Money at Planting Peanut Notes No. 46 2023

I had a question about plant population in 30-inch rows. I addressed this question in Peanut Notes No. 45. However, in this particular conversation, the consultant indicated that the grower was going to apply insecticide, Proline and Velum. To minimize cost, the grower was interested in reducing the seeding rate below the recommended 5-seed per foot. Of all of these inputs at planting, I think reducing the seeding rate is the most risky. In my work, Velum has been marginal in terms of suppression of nematodes, especially if populations are variable across the field. Depending on previous rotation, Proline can make a marginal contribution at best. It turns out that soybeans are frequently planted in the farmers rotation. Proline would be good insurance against CBR. However, if CBR was not present the last time peanuts were present in the field, the benefits of Proline would be marginal. If field history is unknown, Proline serves as insurance. With that said, Bailey II and Sullivan have good resistance to CBR. In contrast, Emery is more susceptible. However, in context, Emery has better resistance than our older varieties like CHAMPS and Gregory.

To me, it all starts with a good stand of peanuts. Seeding rate is the first step.

Dan Anco Comments Peanut Notes No. 48 2023

Peanut is once again coming out of the bag and going in the ground. The end of April typically marks our early portion of acres starting to be planted. Soil temperatures have fluctuated some with changing air temperatures, although for the most part soil temperatures in the state are currently in the mid 60s F, with our rule of thumb being at least 65 F for 3 days at 4″ (with weather ahead forecast to be favorable). This guideline is primarily for good germination, emergence, and stand establishment. Temperatures into next week are currently projected to be fairly stable. One night in the mid 40s should not cause a great disruption. In years where a more extended cold snap moves in following planting, that tends to increase instances of delayed emergence, j-rooting and skippy stands.
Several options can be effective for preplant burndown. If a product that has residual activity like Valor is used for burndown (alongside glyphosate, for example), and we are looking at coming back with planting peanut about 3 weeks later (w/ strip tillage), an application of residual at-plant/pre-emergence herbicide would still be needed following the planter. In addition to the benefit of starting the window of residual activity nearer to when planting starts, at-plant residual application would also be needed following the tillage’s mixing action of the soil negating the prior protectant application.
In general, the NC State thrips model is predicting thrips pressure to be similar to last year. Thrips pressure (and risk of TSW infection) typically decreases as we move into early and then mid May. Several questions have come up regarding Velum (+ imidacloprid), often compared to Thimet. I commented on this in an earlier article comparing several other products, but briefly, our results over multiple years have shown Thimet to be more consistently effective and profitable in managing thrips, TSW, and yield/economic value. AgLogic has also shown effective thrips/yield performance across years. If putting out a granular is not going to occur, imidacloprid does still provide thrips control, though depending on the variety and related factors, it can increase TSW infection. Postemergence acephate is another available option for where addition management may be needed. Before considering adding a product (and additional cost) for nematode management, I would carefully look at the results of a nematode soil test for the field.
FloRun T61 is starting to be a little more available. While we are still collecting data on its performance, currently it appears to have better TSW resistance compared to FloRun 331, being comparable to TR 297. Leaf spot susceptibility also looks comparable to 297. Yield performance looks competitive overall, with seed size approximately similar to 06G (~650/lb). Maturity seems to be in and around 145 days, though that is something we are continuing to look at more.

Imidacloprid and Tomato Spotted Wilt Peanut Notes No. 47 2023

Question:

Will increasing the rate of Admire to 16 oz help with tomato spotted virus or is it better to use another product and no Admire? YOUR thoughts?

Jordan:

Increasing the rate will not help on tomato spotted wilt. A higher rate might help on consistency of thrips control but not spotted wilt. In fact, research in the southeast (GA, FL, AL) and SC shows that spotted wilt increases with use of Admire Pro or generic imidacloprid. We have been able to use these products because we have generally planted towards the middle of May, increased or seeding rates and our varieties have good resistance to spotted wilt (Emery being an exception.) There is a clear relationship of imidacloprid use and more spotted wilt in areas of the US where the virus is found at high levels. We don’t know the exact mechanism of increased spotted wilt, but it may be that imidacloprid makes thrips “annoyed” and they move around, and more plants receive the virus. Many of them die from the insecticide but not before they infect more plants. Resistance in our thrips populations to imidacloprid is only going to allow more movement of thrips and more transmission of virus.
Thimet/Phorate is the best approach for spotted wilt. Across the peanut belt we consistently see less virus with these products. This insecticide turns on an immune response to the virus. Sometimes we need to apply acephate after Thimet. But that is no different than what we have been seeing with Admire Pro and generics. Control by Admire Pro has clearly dropped off. We are needing a follow up of acephate almost all the time these days.
We are sliding back to earlier planting dates and some folks are cutting back their seeding rates. That creates much greater risk for spotted wilt. We may see more issues with greater spotted wilt after Admire Pro because we are opening the door for this virus by our practices. Thimet can serve as a good buffer against it. We just need to get our insecticide boxes up and going again.
Brandenburg:
I agree 100% with everything David said. AgLogic remains our most effective at plant treatment, but phorate provides some level of protection against the virus in addition to the thrips control.

Marestail Control Peanut Notes No. 49 2023

Question:

What is the best herbicide option for marestail (horesweed) control? What is the preplant interval for 2,4-D?

Jordan:

There needs to be an interval of 30 days between 2,4-D application and planting peanut. I have seen some labels state “or until residues have dissipated.” Not sure how easily to measure that. With the expense of peanut seed, we really need to be careful about applying products that could impact peanut stand establishment. Liberty or generic glufosinate has good activity on marestail but this herbicide can be expensive. But there are no residue issues. We have to assume glyphosate resistance. Burndown rates of paraquat are often not completely adequate.

For contact herbicide like Liberty and paraquat, coverage is essential. Slowing down sprayer speed and using more water can help with coverage. If using nozzles that create large droplets (and are good for drift reduction,) control can be compromised because of coverage. But there are lots of acres to spray and there are often sensitive plants not too far from the fields being sprayed that we don’t want to hurt.

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