Drought of 2008
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How dry? how long? How to cope?
by David Williams
While most growers will be glad to turn the calendar and put 2007 in the past, the 2008 growing season could well see many of the same tobacco growing conditions they found last year.
The 2007 drought had a devastating effect on row crops all over the Southeast, and tobacco took its share of damage despite its reputation as an arid plant that fares well in dry, hot conditions.
And while 2007 was a year that saw average yield and fair quality considering the curing troubles associated with the weather, 2008 is shaping up to offer more of the same struggles from Mother Nature.
The new year’s challenge—how will growers prepare to get a crop of high-quality leaf in what is expected to be less than favorable (to say the least) conditions?
Dry, drier, driest
The regional map of the Southeast on the U.S. Drought Monitor’s Web site resembles a brown blotch that extends north and east from western Alabama, cutting a wide swath through the southern United States up to Virginia.
As of early January (the Drought Monitor is updated weekly), 41 percent of the region was in either extreme or exceptional drought; 90.4 percent of the region is in some form of drought condition, with 22 percent of the Southeast in the worst stage—exceptional—of drought. End-of-year rains improved that number from 36.2 percent a week earlier.
In December 2006, just 1.7 percent of the region was in any stage of drought. The few tobacco-growing areas not in severe drought—Southeastern Georgia is the biggest—are forecast to develop drought conditions this year, according to the U.S. Seasonal Drought Outlook.
The cause is thought to be the storied La Nina weather phenomenon, which provides sustained conditions that dry out sections of the country and inundate others.
The Seasonal Drought Outlook predicts drought conditions to persist this coming year. For how long is anyone’s guess, but meteorologists are expecting no significant rain for the region at least into the spring.
Dr. Loren Fisher, crop science Extension specialist at North Carolina State University, said that the 2007 season was saved through growers extending their seasons.
“I think you will see that in the eastern part of North Carolina, in reality, the yields were not substantially lower than they are in an average year,” he said. “The Piedmont region yields were lower because of the drought, but most growers, because they had a very long season and their starts were somewhat later than normal, were able to extend the growing season enough that they were able to make a decent yield.”
Tennessee’s crop had irrigation problems. “Irrigation was of great benefit to those who had it, but probably no more than 15 percent of Tennessee’s burley crop is irrigated, in contrast to dark tobacco, where perhaps 50 percent receives at least some irrigation,” said Dr. Paul Denton, the University of Tennessee’s burley tobacco specialist.
Fisher said that the losses for growers in North Carolina were from lower quality, as dry conditions made curing difficult. “A dry-weather crop is difficult to cure,” he said.
Most of the Tennessee burley growing area was hot and dry in 2007 according to Denton. Yields were reduced considerably in most areas, with the current USDA estimate being 1,600 pounds an acre. “Early transplanted tobacco was generally less affected, and northeastern Tennessee was less affected than other areas, but overall probably 75 percent of the acreage was hurt by dry weather,” Denton said.
Denton said that a hot, dry curing season for tobacco harvested in August and early September compounded problems, resulting in variegated and light-colored leaf with lower-than-expected market prices.
Where’s the water?
The 2008 season will start off dry in some areas. “It’s certainly as dry as it’s been—or as dry as many people can remember—for a long time,” said Fisher. “If you look at the main tobacco producing areas, you see ranges of anywhere from eight to 20 inches behind for the year. In some cases, that’s 40 or 50 percent behind.”
That is not a bad situation for tobacco growers, according to Bob Pearce, Extension tobacco specialist for the plant and soil sciences department at the University of Kentucky.
Pearce said that dry starts are good for tobacco, and water can be saved for later use.
Denton said that rainfall totals in the Tennessee burley areas returned to near normal conditions in November and December, and soil moisture has been largely replenished in the topsoil and upper subsoil. Substantial winter rain is still needed to replenish deeper soil layers and to refill ponds and restore stream flow for irrigation.
Danny Peek, tobacco Extension specialist with Virginia Tech, said his region has fared a little better with some rain and snow on the ground.
“We are still in a drought situation, but we are not in too bad a shape,” he said. “It is still desperate, and we still need some rain—we are going to have to have some rain through the rest of the winter—but I think we are going to be OK, really.”
Denton was optimistic that rainfall would return in Tennessee, based on past history. “Our surplus of rain is usually pretty large even in drier-than-normal winters,” he said. “For May and early June transplanting, it is likely that soil water will be adequate, and it is likely that irrigation water supplies will be replenished.”
The problem—especially in the Carolinas and Virginia—is that there is just not that many irrigation sources left after growers scrambled to find water to save their 2007 crop.
“I do not know of any growers that have access to irrigation anywhere close to what they had in the 2007 season,” said Fisher. “They are going to have to take what Mother Nature gives them.”
Pearce said that some rainfall after the season in Kentucky has eased the farmers’ plight,
and forecasts for higher-than-normal winter rainfall in Kentucky has some growers cautiously optimistic.
“Most of our growers who have irrigation use surface water sources and often have only enough water for two irrigations,” said Pearce.
In North Carolina, Fisher said that nearly all the on-farm water sources he has seen are either dried up or too low to be able to use. Any moisture Tar Heel farmers get will likely come from the sky.
Peek said there are some farmers with access to some irrigation sources, and he is encouraging them to look into using drip irrigation.
“If they have a water source, then I would strongly be looking at it,” he said. “If I have the available water, I would definitely be looking at irrigating.”
Control what you can
Fisher said that variety selection will not help in 2008 since most seed is not bred for higher drought tolerance. Pearce agrees but said choosing a variety with a disease resistance package can be a key decision in any season.
“Plus, we know that some varieties tolerate dry conditions a little bit better,” he said.
Fisher said that usually clipping in the greenhouse will harden the plant in preparation for transplant. Water can be used during transplant, but that usually is “just enough to settle the soil around the roots, and not much to aid in survival for any extended period of time.”
Peek said not to over-fertilize the seedling and to subject the plants to cooler weather to help the hardening-off process.
“We have some growers that will even pull the water away from them for a few days just before they go to the field,” he noted. “Sometimes that helps, not to where they wilt down, but they have a lot of water up in the cell anyway, and it seems to toughen them up some.”
Damage from diseases that are enhanced by wet weather was understandably light in 2007, including blue mold, target spot and black root rot. Denton said that the dry weather early also helped reduce the severity of black shank. “In fields where tobacco follows tobacco, there could be some beneficial carryover effect in 2008 on black shank and black root rot, which are soil-borne diseases [that] ‘build up’ in the soil,” he said. “However, this will not prevent damage to susceptible varieties if conditions are unfavorable in 2008. There will not be any carryover effect on blue mold and other foliar diseases, which are largely dependent on conditions within each growing season.”
Denton said that choosing good land—deep, well-drained soils with high water-supplying capacity for tobacco—was an often-overlooked factor. “In wetter years, rolling clayey hillsides may give yields equal to the deeper soils on ridge tops and bottoms,” he said. “But in dry years, there will often be hundreds of pounds of difference between them.”
Pearce said a good key to more tolerant plants is an early start.
“Most tobacco here is transplanted from May to mid-June,” he said. “If we transplant early in that window, most of the growth will be done before we hit our typically dry months of August, September and October.”
Fisher said that rainfall is important close to transplant, but a more critical time in terms of effect on yield would be between the time the plants are 18 inches tall and when flowering occurs.
The 2008 crop may struggle with sucker control as dry conditions will make the plant less able to absorb the chemicals used to prevent suckers—MH and Flumetralin.
“You also tend to have more residual nitrogen at topping time, which causes greater sucker pressure,” said Fisher.
Fisher also recommended using a minimal rate of nitrogen and adjusting the rate as needed later in the growing season for leaching.
“I think nitrogen is the main one we talk about,” he said. “In terms of potassium and phosphorus, we don’t generally talk about adjustments to those in dry weather.”
“Wasting money on excess fertilizer is always a bad idea,” said Denton. “It is particularly costly in dry years, when lack of water will eliminate even a small chance of a profitable response to extra high rates … more than recommended nitrogen not only wastes money, it can cause problems with fat stems and green tobacco in dry years, when excess nitrate accumulates in the plant late in the season. Some Tennessee producers are struggling with this problem now.”
Peek said that nitrogen application late, coupled with an early or late harvest, can cause a greener leaf to go to the curing barn and create curing challenges. He recommends growers harvest or cut in a window of three to five weeks after topping.
“You will start to lose yield if you cut before then,” he said. “If you can get it cut in that three-to five week window, you should be all right, and if you cut after that you start losing it the other way.”
Denton said that hot, dry conditions like 2007 during curing can result in rapid drying and ‘flash curing’ giving a light color or, worse, variegated “K” grade leaf, also called pawpaw or piebald color.
“Producers have no control over the weather, but they can have some control over the actual temperature and humidity in curing tobacco by stick spacing and ventilation control,” he said.
Peek agrees. “If I can manage the barn depending on the structure, I’ll keep it closed up during the hotter, drier times of the day and open it up at night,” he said. “Maybe I’d hang it just a little closer together if I am anticipating drier days, as well, and proceed with caution when you do that.”
Water is the wild card in the equation. With even a little rainfall—at the right time—2008 can be better than the past season. But with sustained dry conditions—and everyone scrambling for water alternatives as the dry days linger on—even hardy tobacco will suffer.
“I don’t know what to tell growers in that case,” said Fisher. “I think they have used the resources they had, such as ponds for irrigation, and they are very limited in what they can do next year.
“Our options are limited now. What we are left with is whatever we get from the sky. And every forecast I have seen says this is to hold for an extended period of time.”