As we move into late May in the Virginia-Carolina region, there are a number of things that need to be done. As one checks off the list, field (and the previous rotation), tillage system, variety selection, preplant burndown or preplant incorporated herbicides, preemergence herbicides, inoculant and in-furrow systemic insecticide treatments are in place.
Timely application of postemergence herbicides, and an insecticide to suppress thrips if present, is next on the list. Hopefully everyone has 5 plants per foot of row, and peanuts are growing well in a pest-free environment, at least for now.
It is likely that most folks will apply herbicides three times after peanuts emerge, and one of those applications generally involves paraquat, Basagran and residual herbicides. The critical period of weed interference is generally 3 to 6 weeks after planting for many of our crops, including peanuts.
Keeping peanuts weed-free during May and into June helps establish optimum yield potential, at least with respect to the impact of weeds.
As we plan for the next steps, outside of weed control (and thrips clean up) we often find ourselves in late May and June with a bit of down time during the first 30 to 45 days after planting. This is a good time to think ahead and develop plans related to gypsum and southern corn rootworm.
The next column in this magazine will come out well into June, and in my view if gypsum is already out, that it is on the early side. As climate change gets debated in some circles, I have observed, and the weather data back this up to a degree, more intense rainfall events in June during the past couple of years compared to a decade or so ago.
When we get a big rain right after gypsum is put out what should we do – has enough been lost to need to reapply? One way to minimize risk is to let the peanuts get bigger and cover more of the fruiting zone. Peanut plants serve as a cushion and decrease some of the impact of intense and heavy rains on soil movement, especially on the edges of beds where some pegs will eventually form. Peanuts do not need gypsum until well into July when pegs are growing into definable pods.
How about planting dates and replanting? In 2018, we had a substantial amount of peanuts planted in North Carolina in early to mid-June, around 20 percent, and in many cases they did well.
We were fortunate in that we had adequate water in many of those areas through the latter part of the summer, and on average we had four to five more heat units than the 10-year average during August, September and a part of October to really push the crop forward.
I wouldn’t bet on that coming together again, so trying hard to plant in May, preferably mid-May, continues to be the best approach. With respect to replanting – I wouldn’t encourage someone to destroy what is out there if you have a poor stand.
If you have 3 or less plants per foot of row, a replant is warranted. Plant 5 seed per foot if you only have 1 plant, 4 seed per foot if you have 2 plants, and 3 seed per foot if you have 3 plants. If you have more than 3 plants per foot, I would not plant more seed. This can be a difficult decision.
Next Step In Weed Management
Weed management is a season-long process. We had a good start, and now we need to be ready for the next step! Dinitroaniline herbicides are the foundation to successful weed management. These herbicides, when used at the full rate and uniformly incorporated in the upper two inches of soil, will provide early season control of annual grasses and small-seeded broadleaf weeds.
Valor is another herbicide that is commonly used at-plant. If any early emerging weeds like Russian thistle or kochia were present at planting, Gramoxone can be used to control these weeds and ensure a clean start.
The dinitroaniline herbicides and Valor have a finite length of soil residual activity, and growers need to be prepared with follow up early season postemergence options. There are some fast-acting contact herbicides, such as Cobra and Ultra Blazer, that are effective on most annual broadleaf weeds less than 4 inches tall. These herbicides need an adjuvant to improve herbicide uptake and activity. Some peanut leaf burn is likely following the use of these herbicides.
Dual Magnum (metolachlor), Warrant and Outlook are labeled for use postemergence, but must be applied before weeds emerge because they have activity on germinating seedlings and not emerged weeds. Butyrac (2,4-DB) will control or suppress many annual and perennial broadleaf weeds. When weed size has exceeded what contact or ALS-inhibiting herbicides will control, then Butyrac can be added to improve control.
There are several grass herbicides that can be applied postemergence, including clethodim (Select, generics), sethoxydim (Poast, Poast Plus) and fluazifop (Fusilade DX). These herbicides are effective on most annual and perennial grasses and are sometimes used in conjunction with broadleaf herbicides. Antagonism may occur with some tank mixtures, so check the product labels that warn against certain tank mixes. Be careful to follow days-to-harvest restrictions when applying herbicides mid-season.
Plant Into A Clean Field
Planting season is in full swing. Hopefully, Mother Nature will continue to bring showers and allow us to get the peanut crop planted on time this year. Growers also need to do everything they can to ensure this crop gets off to a good start.
We have talked a lot over the last few months about the importance of planting high quality seed in setting the stage for producing a high-yielding and quality crop. The problem is, that is only part of the puzzle. Growers also need to make important decisions on moisture, weeds, diseases and nematodes at planting that can significantly affect the crop.
Moisture is a necessity in getting an adequate stand in peanut. Please do not plant peanut in a moisture-deprived soil even if you have irrigation. If moisture is depleting quickly in non-irrigated fields, you need to decide, “Do I chase the moisture and plant 3 to 3.5 inches deep or do I wait for a rain?”
Please be aware that seed vigor might be an issue this year, which could impact emergence at deeper depths. Also in irrigated fields, it is not recommended to plant in hot and dry soil and then irrigate. This could shock the peanut seed causing stand loss or sporadic emergence. Growers are always recommended to irrigate fields before you plant and then again after you plant to activate herbicides.
Managing weeds are also key to getting the crop started on the right foot. Peanut planting needs to begin with a clean field. If not, you will be battling weeds all year. Try to apply your pre-emergence herbicides as quickly as possible behind the planter.
This would allow for timely irrigation and/or rain to activate the herbicide(s) preventing the initial flush of weeds along with minimizing Valor injury on the crop as it is emerging. Often the injury we get from Valor is less than the weed issues you would face without it.
Below are a few things to consider:
► Do I have fields with fertility issues? Have I adequately addressed them?
► Know the percentage germination of each lot of seed and adjust seeding rate accordingly.
► Planting early — Use Thimet to reduce the risk of TSWV
► Make sure all applicators are calibrated
► Use an inoculant — a good insurance policy after the excessive rains this winter
► Never apply fertilizer products at any rate in-furrow with peanut seed
Contact your Extension agent with any questions.
Peanut Water Requirements
With planting season underway, I wanted to stress the importance of two things. First is the use of residual herbicides. The only way for us to stay in the fight with Palmer amaranth is to continue to apply residual herbicides at the appropriate times.
There are still some producers that try and put these residuals out with the big sprayer after planting. I know that you can cover a lot of ground in a hurry, but timing is everything. Sometimes these showers keep us from being timely like we need to be. It is better to mount the sprayer to the planter so that both are done together and in a timely fashion.
Another issue I see is people overwatering too early in the season. So, I want to remind everyone to be mindful of what kind of water demand is required for their peanuts. Peanuts require approximately 0.05 inches per day, which is very little water for the first 30 days of the growing season.
The water demand increases to about 0.2 inches per day when the peanuts begin pegging around 45-50 days of age. The critical watering period is at 65-90 days of age, which is during peak flowering with a water demand of 0.30 inches per day.
After this stage of development, the water demand starts to decrease gradually for the final two weeks to maturity, only requiring around 0.70-1.0 inch/week. Knowing the water demand will help in supplying irrigation water.