Saturday, December 3, 2022

Thinking About A Planting Do-Over?

From need and timing to placement and maturity determination – ongoing research provides answers on replanting peanuts. 

⋅ By Amanda Huber

Peanuts may not be the most difficult crop to achieve a quick germinating, uniform plant stand, but troubles do arise to create a less-than-optimal outcome. 

Problems with seed quality, improperly calibrated equipment, tractor operator error, unsuitable temperature or soil moisture conditions – all of these can affect producers’ ability to get a good stand of peanuts. 

Peanut Rx, backed by research and Extension, recommend a planting rate of six seed per foot of row in order to achieve a minimum of four plants per row-foot. If this isn’t what’s coming up in the field, then what is an acceptable stand and what level should trigger a replanting of the field?

Determining Need

University of Georgia cropping systems agronomist Scott Tubbs is in a fourth phase of replanting research that began eight years ago. What he says was interesting initially is that replanting often does not improve yield over a poor plant stand as often as you might think.

“Overall,” Tubbs says, “only when plant stands were as low as one plant per foot of row did replanting improve yield to a point that it would be economically viable to justify the cost of replanting.” 

However, skips in stands are a sure draw for tomato spotted wilt virus.

When an initial stand is less than 2.5 plants per foot in single rows or less than three plants per foot of row, supplemental replanting of peanut next to the initial stand will help recover yield. Do not terminate the initial stand.

At the UGA Cotton and Peanut Field Day in September 2021, Tubbs presented some of the replant research findings. In field plots, yellow flags represented the original plant population, with the flag in the crown of each plant, and orange flags were the replanted crop. 

“If you look at the rows with one plant per foot with no replanting, this plot has a tremendous amount of TSWV,” Tubbs says. That’s the real risk in not achieving the needed plant density.

Although peanuts are known to fill in gaps well, Tubbs says some individual data has shown the potential for yield improvement when plant stands were two plants per foot of row or less. 

“Hence, if plant stands are at least 2.5 plants per foot of row, whether twin row or single row, strip-till or conventional tillage, and the stands are relatively uniform without large gaps in the field, the chances of gaining a return on the investment of replanting a field is very low,” he says.

Decision Timing

Tubbs says producers will want to make sure they have the full plant population before making any decision about supplemental planting. 

“Give the seed plenty of chance to germinate. In a study on replant timing, we found that waiting four weeks after the original planting was unsuccessful in gaining an advantage over leaving the original plant stand alone,” Tubbs says. 

“At two weeks after, you would still be getting some straggler plants coming up and you would not know exactly what your plant population is. You’re okay to replant at two weeks, but you may not need to.

“We found that three weeks after the original plant was the timing that worked best in our replant projects thus far,” he says.

Replant Method And Placement

If the decision has been made that the current stand is not sufficient, Tubbs says the method of replanting is also an important factor.

Research shows that replanting 3 inches from the initial stand at a rate of three seed per foot is the best strategy to supplement stand and increase yield and grade.

“In our research, there were essentially no circumstances where burning down the original stand of peanuts with a herbicide and starting over with a complete replanting of peanut was worthwhile,” he says. “Any instances where replanting showed the potential for a benefit, it was when the poor plant stand was left in the field and peanut was replanted by offsetting the planter two to three inches to the side of the original row and placing supplemental seed in the ground.”

In research on single-row planting pattern, yield is increased by supplemental replanting when stands were below 2.5 plants per foot, and supplemental replanting was achieved by planting 3.5 inches off the original row. In this instance, a reduced replant rate of three seed per foot was used.

On twin rows, if initial stands are less than three plants per foot, the best option is also to supplement the initial stand with a seeding rate of three seed per foot.

The take-home message from Tubbs’ research is to make sure the original crop is germinated as much as possible by waiting two to three weeks. If the stand is one plant per foot, then replanting is warranted. When the stand is 2.5 plants per foot of row, supplemental planting may help increase yield. Offset the original planting by three inches and plant again, possibly at a lower seeding rate than the initial planting. Replanting may not be an easy decision, but these points are backed by years of research.

How To Determine Maturity In A Replanted Field 

Determining maturity in a crop that germinated quickly in a uniform stand is not always easy. It’s even more difficult in a field planted twice, weeks apart. Tubbs says while it is a challenge to determine maturity on a replanted field, it is also something they have studied in their replant series. 

“We did a study on that a few years ago, and we took the original plants and the replanted plants and did a maturity board on those separately. Then, we dug some areas based on original planting, some on replant maturity and some areas half-way between the two. 

“Based on our research, you’ve got to get to at least that halfway point. You don’t want to dig based on original plant maturity. You need the replanted plants to reach maturity.” 

Tubbs says you will lose some of your original plants’ finished pods, but what you’re gaining in yield on the back end in the replanted plants more than makes up for that, especially if it’s a higher plant population. 

“What you’re gaining from the replanted plants helps spread out your digging window. 

At a minimum, take the average between the two planting maturities, but trend toward the replant maturity as much as possible.”

Research shows grade is consistently improved by waiting later to dig if the vines are healthy and environmental conditions are favorable to promote maturity. PG

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