The best North Carolina flue-cured tobacco crop in years could have been even better. Most growers, especially in the east, topped too late, used too much nitrogen and applied systemic sucker controls too early.
That combination of mistakes cut yields as much as 18 percent in many fields, with most of the loss in the valuable upper leaves. Early maleic hydrazide applications stunted upper leaves. Growers added nitrogen to fill out the upper leaves, and the excess nitrogen made the crop more difficult to cure.
To put these losses into perspective, consider a grower making average yields of 3,100 pounds per acre. An 18 percent loss in poundage adds up to 558 pounds. Multiply that lost weight be an average sales price of $1.70 and the loss in potential income soars to $948.60. If the loss in weight is actually in the upper leaves, with an average sales price of $1.80 per pound, the loss jumps to more than $1,000 per acre.
"That's something we learned a long time ago," says Duplin County, N.C., tobacco grower Major Lanier. "We top early, when we can just see the buttons getting ready to run up. I don't want to see any flowers in the fields. We keep the suckers controlled with contacts until the tip leaves are filled out. Then we put on the MH. It's kind of amazing how big these tip leaves get if we just wait a little longer to apply the MH. The other thing we try to do is use as little nitrogen as we can. Some of this tobacco didn't get but 45 pounds of nitrogen, and that's plenty. We used a little more where the land is real sandy.
Extension Tobacco Specialist Gerald Peedin praised Lanier and his son Joe for cooperating in on-farm research and demonstration tests. The elder Lanier has been a cooperator for 40 years. The test fields on Lanier's farm were among dozens featured on the recent North Carolina Flue-Cured Tobacco Tour.
"We can do this kind of work in test plots, but for most farmers to believe our data, we need to do the work on farms," says Peedin. "We know we're getting good data when we work with farmers like the Laniers. There is a lot for farmers to learn from these fields."
Peedin points out that there is more at stake than individual farmer profits when growers apply MH too early. Cigarette manufacturers, both domestic and export, prize the upper leaves for their chemistry and smoking characteristics. They also value leaves with a high percentage of leaf lamina to stem. When early applications of MH stunt upper leaves, the lamina to stem ratio drops. Late topping further reduces the size and value of the upper leaves.
"One problem leads to the next," Peedin says. "They top late. Then they apply more nitrogen to fill out the top leaves. That extra nitrogen makes suckers grow. Then they apply MH early and stunt the upper leaves. When suckers continue to grow, some growers are tempted to use more MH. That leads to bronzing and maybe higher than acceptable MH residues. Growers are sacrificing yield and maybe even quality when they top too late. Growers in nutrient sensitive areas need to be especially careful about the amount of nitrogen they are using. Topping early and waiting to apply the systemic sucker control chemical reduces the desire to use excess nitrogen."
Bill Collins, coordinator of tobacco programs at North Carolina State University calls stunted tip leaves "mule ears."
"You have a choice, mule ears or long tips," he says. "If you don't let the tip leaves grow, you don't get the B3 and B4 grades that bring the highest prices. Tip leaves weigh about two and a half times what lower leaves weigh. As expensive as labor is, it makes sense to pull one tip leaf instead of two and a half lower leaves. You're going to get more weight in fewer leaves and you're going to get leaves the export buyers want, if you top early, wait to put on the MH and let those upper leaves develop."
Wilson, N.C., tobacco grower David Blalock says he knew his tip leaves were not filling out or graining up like they should, but he didn't know why.
"The first few years I farmed, I was concerned about controlling suckers. I jumped out there early with the MH, thinking I was doing the right thing," he says. "When it didn't fill out in the top, I tried adding more nitrogen. Some of it was hard to cure. I couldn't get the green out. Until I started working with Gerald Peedin, I didn't know what was wrong. I never would have figured it was because I was applying MH too early."
Peedin points out that most MH labels at least imply that the systemic sucker control chemical has no effect on tip leaves that are at least eight inches long when the chemical is applied.
"We have seen that that is not an accurate statement," Peedin says. "Any time we put MH on leaves less than 12 inches long, we stunt the leaves. We also get significant bronzing of the upper leaves when we put the MH on too early."
Peedin's research shows that applying the labeled rate of MH at the correct time, when tip leaves are at least 12 inches long, adds weight to the crop. Additional MH does not add additional weight. And, applying the MH on time, five to seven days later than many growers currently apply the product, does not increase MH residues on the cured leaf.
On the Buckhorn Crossroads farm of David and Kenneth Hinnant, Tobacco Specialist David Smith showed how it is becoming practical to vary nitrogen rates on tobacco based on the depth of the sandy topsoil to the clay layer. Such precision nitrogen application can help growers apply optimum nitrogen rates, increase yields, reduce sucker growth, improve curing and keep excess nitrogen out of surface and ground waters.
"This is a stepping stone toward precision agriculture in tobacco," Smith says. "We are varying the nitrogen rates based on the depth to clay. The sandier soils get more nitrogen. It's easy to see that we have a better color in tobacco on sandy soils where we applied more nitrogen. We are able to get that good color and growth where we applied less nitrogen where the clay is closer to the surface."
David Hinnant says he has typically applied one rate of nitrogen, even in fields where soil types vary significantly.
"We're in the Neuse River Basin and I'm on the basis oversight committee. We can't afford to apply any nitrogen the crops don't need. With this kind of information and the ability to precision apply nitrogen, we can cut back on the heavier spots and put a little more on the sandy spots. What I see this doing is not so much saving money as evening out yields in fields where we have a lot of variable soil types. This is good, practical research. We'll have a more even crop. It will be easier to control suckers. We won't be wasting nitrogen. And, the environment will be better off."