Monday, June 14, 2021

Herbicides For Bloom And Early Pegging

emi kimura
EMI KIMURA
Texas A&M AgriLife
Extension Peanut Specialist

Most Southwest peanuts have been planted, although it was delayed five to seven days because of the cold soil temperatures and rainfall. By now, herbicides applied preplant and at planting have dissipated, and new weed flushes may be observed following rainfall or irrigation. Herbicides are available that can be applied to peanuts in bloom to early peg stages.

Texas A&M AgriLife Research and Extension looked at injury potential of applying herbicides, including imazapic, imazethapyr, acifluorfen, 2,4-DB and lactofen, during this timing. However, we have not observed a problem when these herbicides are applied at that time during the growing season. Pay attention to the preharvest interval, crop rotation restrictions and read the label carefully.

In addition, it is important to know that 2,4-DB is different from 2,4-D, which is not labeled for use in peanut. The herbicide 2,4-D may cause yield loss or even plant death, depending on the rate and stage of growth at application.

2,4-DB may be used in peanut at various rates depending on the formulation. Applications should be made between two to 12 weeks after planting. Avoid applying it to peanuts suffering water stress. The second application should be made no later than late bloom, and do not apply later than 100 DAP or within 60 days of harvest. 2,4-DB has good activity on several annual broadleaf weeds including morningglory, smellmelon, sunflower and silverleaf nightshade.


Protecting Yield Potential

Scott Monfort
SCOTT MONFORT
University of Georgia

Growers have been blessed with milder temperatures and good moisture for most of the planting window. This has allowed them to plant without any major delays. Growers have also achieved better plant stands this year, which is directly related to having better seed quality. Compared to the last few years, the peanut crop is off to a great start. Now, growers need to swap to managing the crop for high yield and quality. A few things to consider in the early season are as follows.

Good seed quality has reduced stand issues. However, with growers still planting, late-season stand issues can be a problem. Visit each field 12 to 15 days after planting to ensure you have an adequate stand. Hopefully, every field will be good.

During the early part of the growing season, around 30 DAP, growers need to ensure there is a sufficient amount of available calcium in the pegging zone for the developing pods. The best way is to take a pegging zone sample at about 4 inches deep shortly after emergence. You can judge your needs by the winter soil sample results, but those tend to be less reliable than results from pegging zone samples.

A word of caution for growers needing to apply calcium. Foliar-applied calcium products do not supply nearly enough calcium, and it does not translocate through the leaves to the developing pods. That is why foliar calcium is not recommended on peanuts by the University of Georgia.

Once the crop is up and growing, growers need to shift gears to protect their yield potential. One of the most important steps is initiating a strong pest management program and remaining timely. Remember, Extension specialists and agents are here to provide research-based recommendations to help determine the most effective pest management program for your situation. Reach out to your local office for guidance. Another important step in this protection plan is to hire a consultant or scout to examine your fields on a weekly basis to ensure your pest management program is working or to alert you when you have a developing problem. Lastly, stay the course with proven products and be cautious about ones that have not been tested by the university specialists in your state.


Break Up Compacted Soil

Kris Balkcom
KRIS BALKCOM
Auburn University

We not only missed the weather prediction for April, but it also appears we have missed May as well. I know everyone was looking to get an early start at planting this year.

However, it didn’t happen because of the frequent rain. It’s true what they say, no two years are ever the same. By the middle of May, only 20% of Alabama’s peanut crop has been planted. I know everyone has been pushing lately to get the remainder of the crop in the ground. As I have said before, at least our seed quality is good this year. Therefore, we shouldn’t lose any time to replanting, which is good because more time is something we don’t have this year with 80% of the crop still to plant from mid-May on.

It is with rainfall like we have had that I have seen some peanuts with a yellow tint. This  could be one of the biggest issues we see this planting season. One of the only times I recommend cultivating the crop is with this type flooding rains. When we receive this much rain and the soil is super saturated, I advise grower to run the middles with the cultivator in certain parts of the fields with some of the heavier soil types or just traditionally wetter areas of the field. This is mainly to disrupt the compacted soil from the heavy rains by breaking the soil crust to allow oxygen to get to the plant’s roots. Again, it doesn’t occur everywhere in field, but plants tend to respond relatively quickly to green back up.


Ways To Avoid Flaring Spider Mites

David Jordan
DAVID JORDAN
North Carolina State University

 

In early June in the Virginia-Carolina area, the two most critical pests are thrips and weeds. Hopefully, most growers were able to get adequate suppression of thrips with systemic insecticides applied in the seed furrow at planting. If not, acephate applied to foliage in a timely manner will help protect yield. Best results are when this insecticide is applied three weeks after planting. About 50% of growers make this application, often in combination with herbicides. It is important be make the application before excessive injury.

June is also a good time to firm up residual weed control. As with systemic insecticides, hopefully the preplant incorporated or preemergence herbicides were activated and gave adequate control for the first three or more weeks in the season. Paraquat plus Basagran applied with residual herbicides, such as the metolachlor products Outlook, Warrant, Zidua or Anthem Flex, is a good option at this time. Paraquat can be applied up to 28 days after peanuts emerge but earlier is better, generally three weeks after planting if possible. Basagran reduces peanut injury from paraquat.

Residual herbicides can increase foliar burn, but in most cases, it is no more than 20%. Of these residual herbicides, Anthem Flex can cause the most stunting, but peanuts recover. Warrant can occasionally stunt peanuts but generally only when heavy rains occur and peanuts absorb a substantial amount of acetochlor at one time. A non-ionic surfactant at 1 pint per 100 gallons should be added.

As a note of caution, if thrips injury is excessive, which systemic insecticides usually keep from happening, do not apply paraquat. Peanuts can handle thrips injury or paraquat injury but not the combination without a significant yield hit. Our work in North Carolina shows that paraquat, Basagran and residual herbicides are compatible with acephate. However, if thrips injury is excessive, take care of the thrips first and then apply herbicides after peanuts have recovered.

There is less information on combinations of paraquat, Basagran and Anthem Flex applied with acephate, and I am concerned about the impact of Anthem Flex if there is excessive thrips injury. We are working on this potential issue in 2021. Some growers will opt out of paraquat and move to Cobra, Ultra Blazer, Storm or Cadre for weed control. Residual herbicides can be applied with these herbicides as well. The key on all of these herbicides is timing. Don’t cut rates, and spray small weeds.

During the last part of June, growers with Virginia-market types need to apply gypsum. Try not to be too early on the application. Peanut foliage helps limit the movement of soil and gypsum off of beds if there are heavy rains.

Growers in the upper Virginia-Carolina region can run into southern corn rootworm damage under irrigation or on soils that are poorly drained or have a fine texture. These conditions promote survival of larvae that feed on pods. Use the risk index to decide if chlorpyrifos is needed in those fields. Keep in mind, applying this insecticide under hot and dry conditions in fields that are at low risk for southern corn rootworm can flare spider mites. This is where the risk index can help you avoid applications when it is not needed and when it can cause a secondary pest like spider mites to become established.

Finally, in late June, begin thinking about fungicide sprays for leaf spot and stem rot. Our recommendation is to apply fungicides beginning at the R3 stage of growth. Chlorothalonil is an important part of leaf spot control programs and should be included in the first spray. More on the remaining sprays in your fungicide program in the July column.

Use good stewardship with all products for pest control. They all carry risk to the person mixing and making the application and to environment. When handled and applied properly, the risk from pesticides is minimal. When pests are present, the benefits of pesticide use far exceeds the risk of using them. But this statement carries a major assumption: Be diligent in making sure you stay safe when using them and keep pesticides in the field where applied. Applying the correct product, one that is legal on peanuts, at the correct time is essential.

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