July 1, 2013
The 2012 peanut production season was literally one for the record books, with growers throughout the U.S. making record-high yields and production. Having accomplished such a feat, many in the industry are asking, “What’s next?” For the answer to this question, it’s important to take a look at what is in the peanut research pipeline — those problems, issues and initiatives currently being addressed that will lead to even more efficient and profitable peanut production. This series on “Pipelines to Peanut Profitability” is taking an in-depth look at these areas of research, what they could mean to growers, and when producers can expect to see practical, on-farm applications of this research.
Researchers across the Southeast’s Peanut Belt have long known the devastating impact of nematodes on crop yields and have made significant strides in developing delivery systems to significantly reduce the risk.
However, in recent years development of site specific delivery systems on row crops has been virtually stopped by a lack of reliable nematicides to deliver.
At Clemson University, Plant Pathologist John Mueller and a team of researchers headed by Ag Engineer Ahmad Khalilian developed a workable system to deliver varying rates of the two most popular peanut nematicides, Temik 15G and Telone II.
The problem is Temik is no longer on the market and Telone II is frequently in short supply.
“Over the past few years we’ve done on-farm work with growers who have used a simple on-off system of delivering either Temik or Telone, and some have been very successful with it.
“With Telone II, if it’s available, it will cost a grower $40-$60 per acre, so they first have to be very sure they have a nematode problem that is severe enough to warrant this expensive type of nematicide treatment,” Mueller says.
Doug Jarrell, who farms near Estill, S.C., has used the Clemson-developed nematicide delivery system successfully.
Working with Thomas Ag Crop Management, Jarrell developed a soil map for most of the 1,500 acre farming operation he operates with his father B.L. Jarrell. The map shows fields categorized as low, medium and high risk for developing damaging nematode populations.
Using a simple off-on system developed by Clemson University researchers, he uses this variable rate application method to apply higher rates of nematicides in fields with higher risks of nematodes and applies less or none to fields with low risk of nematode damage.
When he first started working with variable rate nematicides, he used Telone II in fields with high risk of damaging nematode populations.
In cotton, even in high risk fields in which he used Telone II, he says he still used the standard five pounds per acre of Temik 15G. Now Temik is gone, so the option of using it is off the table for now.
Looking for Temik replacement
Hopefully, a similar aldicarb product, Meymik, will be available in the future. Though cleared for use by the EPA, production of the new product has been delayed by numerous problems. Company officials had hoped to have the product available for growers for the 2013 growing season, but it appears that will not happen.
Having an aldicarb product, like Meymik, would be a big help to growers dogged by persistent yield losses to nematodes.
Cotton has been the dominant crop on many peanut farms in the Southeast for the past few years, and it is frequently plagued by nematode related yield losses.
“In extreme cases, with really high levels of nematodes, we think we were losing as much as 400 pounds of cotton lint per acre.
“Over all our sandier fields, the ones at the highest risk of building up high levels of nematodes, we improved our yields by 250 pounds or so per acre, Jarrell says.
The simple system the South Carolina grower uses was developed by a research team at Clemson University’s Edisto Research and Education Center in Blackville, S.C.
Khalilian says the system, technically named Site Specific Nematicide Placement System, is ready for commercial deployment and use by farmers, but concurs that in peanuts its use has been limited by the scarcity of viable nematicides.
For growers wanting to use a simple ‘shut off-shut-on’ delivery system of nematicides on peanuts, Khalilian says, “The first step is to develop an accurate geo-reference soil texture map. This can be done inexpensively using an electric conductivity meter, commonly called a Veris rig.”
Jarrell, with the help of his consultant, developed his farm maps using a Veris machine that measures electric conductivity of the soil.
Among other data, the Veris map includes color variations that denote different levels of electrical conductivity that varies from lighter, sandy soils, to heavier soils. Nematode populations and damage is known to be higher in lighter, sandier soils.
Readings can be dramatic
Readings from the Veris system can be dramatic, Khalilian says. For example, in one field on the Edisto REC a nine percent increase in the Veris reading resulted in 57 percent less nematodes.
Finding viable research on how much yield advantage on peanuts comes from reducing nematode numbers is difficult, though using Veris readings to develop on-farm maps of high, medium and low risk areas is a good starting point.
Several variables affect the readings this system gives. If soil moisture, salt content or organic matter is high, the system will give high numbers. Soil texture is the critical factor, the Clemson researcher stresses.
“If I map here at the Edisto Station today and we get a big rain tomorrow, the readings would change, but the zones would be the same,” he says.
Jarrell says the nematode management plan developed by Thomas Ag Crop Management was right on target for his farming operation.
“There is no doubt using Telone on our nematode hot spots paid off. We monitor nematode samples closely and you can see the results in lower populations and in higher yields,” he says.
Crop rotation is another big factor in managing nematodes.
“We started growing peanuts in 2004, and noticed cotton yields went up in fields following peanuts. We had always known we had a nematode problem, but this really demonstrated how much yield we were losing,” Jarrell adds.
South Carolina Peanut Specialist Scott Monfort has worked with nematodes throughout much of his professional life, including a number of years in the University of Georgia and University of Arkansas systems.
He points out that South Carolina is fortunate to not have peanut root knot nematodes — by far the greatest nematode threat to peanuts.
Much of the research done on variable rate application of nematicides in the Southeast has been done on cotton, Monfort says.
Crop rotation is best solution
“By far, the best solution to nematodes is crop rotation. Or, if the problem is significant, we do have one root knot nematode tolerant variety, TiftGuard, but it has some other limitations,” Monfort adds.
Mueller says the high cost of using Telone II intensifies the need of what he calls ‘ground truthing’.
“The first step in deciding whether to use variable rate application technology is to determine whether you have a nematode problem that is costing more than the $40-50 per acre cost of applying Telone II, regardless of how it’s applied,” he says.
The Veris-generated soil map can be used to help make a variety of management decisions.
These maps can’t tell you whether you have nematodes in the soil, but they can tell you where the highest risks are in a field.
By using these maps a grower can map some logical decisions as to which fields are in a high risk category and save some money by sampling first in these areas for nematodes.
“If these samples come back with high populations of nematodes, the next step will be to determine how much yield damage they are likely to cause and then make a decision as to whether to apply Telone or some other nematicide, like Vydate, which can be used on peanuts, but rarely is used,” the South Carolina plant pathologist says.
“If hot spots of nematodes occur sporadically across a field, a simple on-off system of applying Telone may be a good option. Certainly, it would be considerably less expensive than applying a uniform application of the material,” he adds.
Mueller points out that the nematicide application system used by Doug Jarrell, and a few other South Carolina growers, isn’t technically a variable rate application.
“A true variable rate applicator would be much more expensive, and in truth, we don’t have the data set to support using a highly sophisticated variable rate application system,” he says.
“The growers who have used the on-off system developed by Khalilian and others here at the Edisto Station works fine, and if the nematicides we tested are available, I am confident in some situations with high nematode pressure, it could save growers some money and improve yields,” Mueller adds.
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