An ugly, beat-up cotton plant may still yield more than its pretty, younger sibling. Replanting, says Bobby Phipps, is not a decision to make lightly.
“If you replant, you shouldn't be thinking of the yield potential that was available early in the season,” the Missouri Extension cotton specialist told those attending the Missouri Cotton and Outlook Conference in Kennett, Mo. “It's hard to replant and make more money. The crop has to be very, very bad before it's worth it.
“I know there have been instances where farmers have wanted to replant and I've talked them out of it. They hate me for the next six weeks, but then harvest shows putting up with the ugliness was worth it. You're behind the eight-ball if you have to replant.”
One aspect of Phipps' recent field studies compares the yield potential of a replanted crop to the original crop. Field plots were planted at many different dates to see what the yields would be.
“The first year, we found a yield drop of 21 pounds per day. That's a big difference between May 1 and May 31. So if you planted on May 3, and come month's end you're considering replanting, it's worth tallying up what you've already lost in yield potential.”
Farmers sometimes ask Phipps about June-planted cotton. “I almost never recommend planting that late.”
The second year of the test, it didn't matter when the test plots were planted, the yields were similar. In 2003, the study's yields held until mid-May and then dropped. Last year, “the May 20 planting date was the high yielder and then began dropping off rapidly after that.”
Crunching the numbers shows “we need to be done planting by mid-May to avoid yield drops.”
Phipps has been in many fields where farmers contemplated replanting because plant spacing was so poor. “We set up a test based on populations at the end of the season, not the number of seeds planted.”
Phipps admitted he thought plants spaced a foot apart was where the yield line would be drawn. That wasn't the case.
“The high yielder was 1.5-feet apart. Cotton has an amazing ability to compensate and keep production levels even. In both 2003 and 2004, we found that two plants per foot were best. There was a good drop-off past 1.5 feet.”
Thin stands don't always equate to lower yields. In fact, “we've found rather steady yield levels regardless of plant spacing. If you've got a thin stand and replanting means dropping 20 percent or 30 percent in yield, that's hard to justify. It surprised me to find that thin stands could do so well.”
But there is a drawback with thin populations: more vegetative branches. Studying percent open bolls shows the trouble. The higher the population, the larger the percent open bolls. Thinner stands can make your crop later, said Phipps.
Another problem from sparse populations: weeds are “quite a bit” worse. “That was very obvious in our plots.”
Some may be tempted to plant thin right off the bat. Phipps said that's a shaky idea.
“Some might think, ‘Well, seeing the data on spacing and considering the tech fees, maybe I should just plant thin.’ Think about what that can mean, though. If you plant a seed every foot and germ is 85 percent, some of your seed won't sprout anyway. On top of that, there will be some further mortality even in good conditions.”
Producers need to strive for a uniform stand over the entire field, insisted Phipps. “What happens if you have an uneven stand throughout the field? I've replanted only the ends of a field. Don't ever try that — you just can't time it right with the rest of the field. Learn from my mistake.”
Phipps also wanted to look at how far to take a hail-damaged crop. In his native west Texas, “hail was always an issue. I remember getting into an argument with my father after a hail storm. We couldn't agree where the beds or rows were to plant over. It can be a real mess there.”
For the hail test, all plots were planted in DPL 1218. “We removed the leaves by hand. In some plots, we removed one leaf per plant, in others two, three or four. On four-leaf plants, we took all the leaves and left the cotyledon, if it was there. On plants where we removed the terminal, we left the leaves. A lot of these plots had pitiful looking cotton.”
After their trauma, plants would often branch. “I thought when you took four leaves off, it would cut yield in half, or worse. I was wrong. Those plants' yield was very close to the top yield. It did look horrible, but it still yielded. The second, third and fourth year of the test, we found much the same with yield.”
Knocking leaves off did affect maturity, though. “Your crop will be later maturing following hail damage.”
Another thing to check before replanting is below the soil crust.
“I've been in fields where almost nothing is up. Sometimes it's easier to run a rotary hoe than it is to replant. And there's a wire-tooth rotary hoe that allows you to control how far it penetrates.”
Also, before making a replant decision and destroying a thin stand, consider seed supply. The variety you want to replant may not be available.
“One practice I see and have a hard time going along with is replanting while leaving the old stand. That's kind of like replanting an end. You'll have a crop in two stages and your timing will be thrown.
“On 38-inch rows, I recommend planting four seed per foot and hope you wind up with 2.5 to three at the end of the season. Don't go with pounds, go with seed per foot. If you plant really early, you may want to raise that seeding rate slightly.”
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