Conservation tillage may be reducing the incidence of TSWV in some areas.
By Shannon Holman
If you think that strip tilling is a passing fad, think again. A growing number of producers across the Southeast are adopting this tillage practice hoping to save time and money.
However, some places have been slow to embrace the idea of reduced tillage. In Texas, Calvin Trostle, an assistant professor and extension agronomist with the Texas Agricultural Extension Service in Lubbock, says that producers in his area are not all that familiar with strip tillage, and when they see and understand more about it, they might develop more interest in it.
"Strip-till is something we would like to see producers thinking more about in this area, but at present, 95 percent of our peanuts are grown with conventional tillage," says Trostle.
What Is Strip Till?
According to David Jordan, a peanut agronomist at North Carolina State University, strip tillage involves tilling a small strip into the previous year?s crop stubble that is treated with a burn down herbicide, or into a cover crop such as wheat or rye that was established the previous fall and chemically terminated prior to planting.
"Most producers in North Carolina use wheat as a cover crop because it is easier to manage. It is not quite as tall and has less vegetative growth than rye, and seed is often more available," says Jordan.
John Baldwin, a peanut agronomist with the University of Georgia, says that although most people do not like a lot of winter vegetation because it is harder to manage and plant into, the increased residue leads to better water-holding capacity during the season.
Once the cover crop is established, producers essentially make a conventional tillage strip that can be anywhere from 12 to 20 inches wide with a special implement usually equipped with two to four coulters set up at the front, followed by an in-row subsoiler, Jordan explains.
"Most producers need to run a subsoiler shank on their strip-till rig that will go about 12 to 18 inches deep, especially where soils tend to be sandier and easily compacted down deep," Jordan says.
When fields are strip tilled in this method, Jordan says that roughly a third of the row is almost conventionally tilled, while the other two-thirds still has the cover crop or crop stubble intact.
Farmers then proceed to plant down the middle of the tilled portion of the row. This can be performed in several different ways according to Jordan.
"Some producers have their planter hooked up to their strip-till rig, but for most producers it is two different operations because of the waiting period needed between fumigating and planting," Jordan contends.
What he is referring to is fumigating for CBR or the organism that causes black root rot, which is one of the major diseases found in peanuts in North Carolina. When producers fumigate for this disease, there is a two week waiting period before they can proceed with planting. Thus, Jordan adds that many producers fumigate from the strip-till rig, but few plant because of the required waiting period.
"The timing of planting is also important with strip till," according to John Baldwin. "With strip till, the soils tend to be cooler than with conventional, so producers have to be careful not to plant too early."
However, lower temperatures are an asset in the summer, contends Baldwin, because with peanuts, excessively high temperatures can inhibit both blooming and pod set.
Weed Control in Strip Till
"The thing that is driving strip till is the high price of fuel, fewer number of trips over the field, and new technology that includes newer and better post-emergence grass herbicides," says Dallas Hartzog, a peanut agronomist at Auburn University.
In terms of the overall herbicide program used in a strip-till operation, it is basically the same as one would use with conventional tillage, except for the addition of a burn down herbicide used prior to planting, according to Baldwin.
Hartzog contends "most producers start out with an application of Prowl tank mixed with a burndown product such as Round Up, Gramoxone Extra or Starfire to burn the cover crop down."
The weeds dictate the rest of the herbicides. For instance, if producers have escaped grasses, most of them would use Poast Plus or Select, explains Hartzog. They also use post-emergence herbicides such as Cadre, Storm or 2,4-DB for weed control.
"Producers using strip till usually have to be more careful as to the timing of emergence of the weeds and the timing of the herbicide than do producers using conventional till," Baldwin says.
There is about a two to three week period that herbicides can sit on the soil surface waiting for a rain to activate them, otherwise they are not effective.
"One of the problems we ran into this year is that for most of our herbicides to work, they need to be put on the field within the first 28 days after the peanuts have emerged from the soil. This year we not only had very erratic peanut emergence, but often the weeds did not come up at all until 4 to 6 weeks later, which is outside of the normal spray window. Thus, we had to do a lot of work to clean up the fields," Hartzog says.
Tom Jennings, a county agent in Wilcox County, Ga., agrees that it was too dry for weeds in the early part of the season, forcing producers to spend more time late in the season trying to control them.
"In Georgia, they have primarily used Poast or Poast Plus to control grasses and Cadre to control the nutsedge. But the drought followed by some late rains has caused a flush of weeds late in the season because the peanuts just haven?t grown like they ought to," he says.
Because peanuts do not grow very tall, fighting weeds is always necessary, explains David Jordan. When comparing strip till to no-till, being able to incorporate some of the herbicide in the strip-tilled zone helps. Jordan says that with no-till, producers would be relying entirely on pre-emergence and post-emergence herbicides, and if they don?t get rain behind most of them, they generally fail.
Also, Jordan says with strip till it is often easier to get a good stand of peanuts than with no-till, which is essential for deterring weeds. And because it costs almost $100 to seed an acre, it is important to get a good stand initially.
When comparing strip till to conventional, strip till cannot incorporate herbicides nearly as well, says Jordan, because producers make more passes over the field with conventional and get the herbicides uniformly incorporated.
Advantages and Disadvantages of Strip Till
Although drought conditions might increase the need for herbicides in a strip-till operation, other advantages of strip till might make it more preferable in dry weather. Baldwin says one of the advantages of strip till is its increased water holding capacity.
"Depending on the amount of residue that is on the surface, generally you delay wilting of peanuts for several days to weeks according to the drought severity," Baldwin says.
He explains that with conventional tillage, the harrowing involved dries the soil out. However, he also warns that waiting too long to kill the cover crop with strip till can also sap moisture from the soil, but generally strip till can withstand drought for a longer period of time.
Roger Smith, a producer in Wilcox County, Ga., has been using strip till in all his peanuts for the past six years. Sticking strictly to strip-till practices, he contends that he has seen many advantages.
"The land became more mellow, we held moisture better and held down weeds easier," he says.
He also feels that strip till seems to fair better in drought conditions.
"It seems to come up with a more uniform stand because that litter on the ground is holding in moisture."
However, even though he is committed to strip tillage and plans to continue using it in his farming operation, he claims that he hasn?t increased yield or saved much money from it. He basically swapped money from tillage to chemicals.
Jordan contends that the least expensive strip till program, which would involve spraying a burn down on the cover crop or crop stubble and possibly using some Gramoxone Extra when you plant, would be in the neighborhood of $15 to $20 less expensive than a conventional tillage system involving disking and moldboard plowing.
"Although $15 or $20 is real money, in the grand scheme of production, it is not that much if it is a risky operation. The variable cost that you save is not what should make you go into strip till," Jordan says. "The big advantage comes with the time saved in the spring. You can get on the field and spray sooner than you can till, and you will need to make fewer trips for your peanuts at a time when you may need to be involved in other farming operations."
Jordan claims that one of the disadvantages of strip-tilling peanuts is that the yields are not as consistent as conventional yields. Although most researchers do not think strip-till yields will outperform conventional yields, they at least think strip till has the possibility of producing yields equal to conventional.
"By and large, most producers found that yield and quality were comparable to conventional," says Mike Williams, a county agent in North Carolina.
Jordan thinks one possibility for the peanuts not performing as well in some parts of North Carolina might be because they are harder to dig with less tillage. He says that harder soils are especially evident when strip tilling for the first year on a field previously tilled conventionally. When digging in hard soils, peanuts can get stripped off and left in the field.
"Some soils compact so hard over the winter that you can strip till, plant, get a good stand and have good growth, but have a problem digging unless the moisture is just right," Jordan says.
Thus, he stresses that what producers do all season long has to be geared toward the digging operation in the fall because this is where producers can lose 20 percent of their yield.
Jerry Rhodes, a producer in Wilcox County, Georgia agrees, "With good moisture, it is just as easy to dig. However, if it is a little dry, it gets harder to dig so you have to be more timely in terms of weather."
However, Smith, also a producer, does not think strip till has negatively affected his digging operation at all. He believes every year the ground gets more mellow and softer than conventionally tilled ground.
"I dug 180 acres of peanuts last year with one set of points. With conventional, we have had days we changed the points every 30 acres," Smith says.
Although the debate is ongoing over which tillage system works the best, it is clear that strip tillage has made a place among producers in many areas of the South. Some producers do not think strip tillage has a place in their production system; others are embracing it 100 percent.
According to Jordan, other than digging and managing weeds a little differently, there are no major reasons not to try strip till. There are no major changes in diseases or insect pressure from conventionally tilled peanuts, at least in the Virginia-Carolina region.
He contends that "what it comes down to is the producers with really good sandy loam soils can do just about anything they want in terms of tillage. Those soils are very forgiving in terms of digging and getting the peanuts out. However, growers on marginal peanut soils have to be a little more cautious about going into reduced-till systems because they may not dig as well."
Jordan also points out that many of the benefits of going to reduced till are not enjoyed until 4 or 5 years down the road. In his mind, "You have to start with year one to get to year five, but I worry about the transition years, especially when the commodity prices are low and so much of farming profit hinges on peanuts." PG
Shannon Holman is a freelance writer based in Lonoke, Ark.
Tomato Spotted Wilt Virus - 2000
Although Tomato Spotted Wilt Virus (TSWV) was evident all over the South, it seems that its timing might be the critical factor in 2000. Most producers in the South reported signs of the virus, but were hopeful it developed late enough to cause less damage than previous years.
"We saw a lot of TSWV here in Georgia in all of the peanuts. However, with the drought it was hard to spot at first because the peanuts were all so wilted. When it rained, we began to see more evidence of it," says Tom Jennings, a county agent in Wilcox County, Ga.
Mike Williams, a county agent in North Carolina, says they also had a bad TSWV problem.
"There was as much of it around as I have ever seen. Although many fields had at least some virus, a substantial number of North Carolina fields had tremendous amounts of the virus, especially compared with previous years," Williams says.
Areas in the Southeast that experienced drought were also hard hit by the virus due to the erratic stands, according to Jennings.
"Anywhere you have a skip is where TSWV tends to get started because that is where the thrips start feeding," Jennings says.
Fortunately, strip-tillage and other reduced-tillage systems are showing signs of reducing the incidence of TSWV in some areas. The reason being because "the residue or cover crop on the field confuses the thrips, which are the vector for the virus," explains David Jordan, a peanut agronomist with North Carolina State University.
Furthermore, twin row peanuts are also being used to combat TSWV. As Jordan explains it, with twin-row you tend to get the canopy covered quicker, leading to a more uniform plant population to combat the virus.
According to Jennings, "We have seen less TSWV and white mold in strip-till and twin-row. It seems to be a definite advantage of these reduced-till systems."