Peanut Pointers: April 2023

Avoid A TSWV ‘Perfect Storm’

Scott Monfort
SCOTT MONFORT University of Georgia Extension Agronomist

County production meeting season has ended, and now growers are trying to decide on how many acres they will plant in 2023. After talking with growers throughout the state, the vibe is Georgia will increase peanut acres 5% to 10%. If this is a true estimate, growers need to be cautious about planting in April. The risk of Tomato Spotted Wilt Virus in April-planted peanut remains high; therefore, growers need to utilize as many of the practices listed in the Peanut Rx to reduce TSWV risk as possible. 

These practices include planting date (May 10-26), varietal resistance (Georgia-12Y, new varieties), at-plant insecticide (Thimet), row pattern (twin row), tillage (reduced tillage with cover) and no Classic herbicide. Along with these practices, growers also need to pay attention to seed quality and environmental conditions as they can affect final stand, thus potentially increasing the risk of TSWV. 

A main concern for me this year regarding seed quality is the potential reduction in vigor as a result of lower grades last year. I am not saying our seed will have low vigor … only that there is a risk. Low seed vigor can cause slower plant emergence, which can result in skippy stands and a higher risk of TSWV infection. However, if lower seed vigor, subpar environmental conditions and planting in the high-risk window (April-May 10) are all tossed together, you will have the perfect storm for a high risk of TSWV infection and potentially a loss in yield. 

I know we sound like a broken record talking about this situation with TSWV, but after last year, the UGA Peanut Team wants you to be prepared should TSWV pressure be high again in 2023. With this in mind, be cautious about planting early. Please call a county agent if you have any questions.

Rotate Herbicide MOAs To Slow Resistance

emi kimura
Texas A&M AgriLife Extension
State Extension Peanut Specialist

Variety selection is the most important decision a grower can make prior to planting for any crops, including peanuts. Unlike herbicide or fungicide decisions that can be changed during the season to address specific conditions and pests, variety selection is made only once, and it dictates the management of a field for the entire season. Growers may have limited options to choose from; however, it is important to review available peanut types and varieties in your local area, and select a variety that includes an appropriate disease package and maturity characteristics. 

When variety trial results are used to evaluate the performance of a variety, we highly recommend looking at two- to three-year-average results in your area. If a variety is consistently performing well, the probability is higher that the variety would perform well in your region. 

Herbicide-resistant Palmer amaranth in cotton.

We recently updated a publication on weed control for peanuts. This will help you plan weed-control options for your fields. It is critically important to rotate modes of action and avoid repeated use of the same ones as there are eight known herbicide-resistant weeds in Texas. These include common sunflower, palmer amaranth, tall waterhemp, johnsongrass, kochia, barnyardgrass and perennial ryegrass. Many of these weeds are widespread in Texas peanut fields. In addition to the officially registered herbicide-resistant weed species, there could be unregistered herbicide-resistant weeds in peanut fields. These are not registered because it is not widespread yet; however, growers should realize quickly if herbicide-resistant populations are in their fields. Those weeds would survive following applications of effective herbicide. We can slow down the development of herbicide-resistant weed populations by rotating herbicide modes of action.

Thrips Control Options And Cautions

David Jordan
North Carolina State University
Extension Agronomist

As we move into April, planting is just around the corFthripner. My columns may seem repetitive; I’m certainly guilty of that. But in a short article, it’s important to get to the core elements. With peanut production, some of those have remained the same over time. 

Based on the current southern corn rootworm index for the Virginia-Carolina region and, in particular, North Carolina, the most probable way you can minimize damage from this insect pest is to plant early. The reason this is somewhat effective is because pods tend to be more developed when this insect becomes an issue in soil in July and August. A stronger hull limits the insect’s ability to puncture pods. 

If you do plant early, in part to avoid southern corn rootworm, make sure you have an effective thrips control program in place. We often need more than one insecticide treatment for thrips in the upper V-C region, especially when we plant early. This will be the case if you are using imidacloprid. This insecticide is less effective now in controlling thrips than it was five or so years ago. Peanuts are also slower growing when planted early, and we often experience higher populations of thrips in early May. 

Thrips injury on peanut.

Keep in mind that we are also at greater risk for Tomato Spotted Wilt Virus when we plant early. Thrips are the vector for this virus. If planting early, in addition to effective insecticide treatments for thrips, make sure you establish four to five plants per foot of row across the entire field. This is a buffer against TSWV. Consider using Phorate/Thimet if you plant early.

Weed control starts early with either effective tillage or burndown herbicides. Overlapping residuals play an important role in weed management. Investment early in the season is often more effective than spending the same amount of money cleaning up fields later in the season. If possible, incorporate a DNA herbicide and apply a Group 15 (usually Dual Magnum) with Valor right behind the plant. In a few weeks, you will likely need to apply a contact herbicide (Gramoxone plus Basagran) with another residual herbicide (often a Group 15). This approach takes a lot of pressure off the PPO inhibitors as we move through the remainder of the season. It also helps us control ALS-resistant weeds that are in many of our fields.

In North Carolina, we have used imidacloprid for many years. While there is concern about having more spotted wilt when this insecticide is used, in our region, the level of spotted wilt has been low enough and the resistance within our varieties good enough to have allowed this use pattern. Unfortunately, thrips control with imidacloprid has dropped dramatically over the past five years. For this reason, growers need to use care when applying Gramoxone if peanuts have significant damage from thrips. You will need to correct the thrips issue before applying Gramoxone. Applying acephate with Gramoxone can help but not before the damage from Gramoxone and thrips take their toll. Always add Basagran when applying Gramoxone.

We recommend that you establish four to five plants per foot of row. If planting early, I would make sure I had five plants per row-foot across the field for TSWV management. 

When it comes to in-furrow products, outside of a systemic insecticide and inoculant for nitrogen fixation, ask questions about the potential impact on peanut emergence and stand establishment before you use something. There can be issues.

To optimize yields, we need to have a good start. Starting clean with no weeds, minimizing thrips injury and making sure you have four to five plants is an outstanding start. Don’t forget that if you are in new ground or have been out of peanuts in a field for many years, inoculating for nitrogen fixation will be your most important input. We see a positive response to inoculant even in rotated fields, but inoculating peanut in new ground is critical. 

A Good Variety For Deer Pressure

Kris Balkcom
Auburn University
Extension Specialist

Since planting season is just around the corner, we begin by thinking about which variety we want to plant, where and when. I wish we knew how much TSWV pressure we would have this season ahead of time. However, being that it’s an unknown, we must plan and prepare like it could be a heavy-pressure year. Therefore, when planting early, use the varieties that has the most resistance to TSWV. Look at the Peanut Rx to see which varieties have the most resistance. 

Aerial of crop deer damage.

For instance, Georgia-12Y and TifNV HiOL are both rated with five points on the risk index and are excellent choices for early season planting. I know that many people like to plant Georgia-12Y last; that way, it helps space out the harvest interval. However, it’s better to plant it first due to its resistance. This may create some issues at digging time, bunching up more to be harvested at one time versus spacing them out if you planted everything back-to-back. Therefore, try to leave a longer gap between plantings, or if your acreage is small enough, you may have time to plant all of them back-to-back and still harvest the Georgia-12Y last. The other answer, which many of you would not like, is to increase harvest capacity. 

Also, if you start planting with one of these more-resistant varieties, I still recommend you apply an at-plant insecticide because, even though they have more resistance, it doesn’t mean they won’t get TSWV. So, take the necessary precautions and apply that insecticide in furrow because once that seed furrow is closed, we can’t go back and do it over again. 

Georgia-12Y is also a good choice for fields that typically have heavy deer pressure. This variety would help due to the excessive vine growth, but I wouldn’t recommend planting it after the third week of May. 

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