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Articles from 2005 In April


Long-term Insecticide Use Causing Neurological Problems for Farmers

New research shows that farmers who used agricultural insecticides experienced increased neurological symptoms, even when they were no longer using the products.

Data from 18,782 North Carolina and Iowa farmers linked use of insecticides, including organophosphates and organochlorines, to reports of reoccurring headaches, fatigue, insomnia, dizziness, nausea, hand tremors, numbness and other neurological symptoms. Some of the insecticides addressed by the study are still on the market, but some, including DDT, have been banned or restricted.

The research is part of the ongoing Agricultural Health Study funded by the National Institute of Environmental Health Sciences and the National Cancer Institute, two of the National Institutes of Health, and the Environmental Protection Agency.

"This research is really important because it evaluated the health effects of agricultural chemicals as they were commonly used by farmers. It's different from previous studies that focused on pesticide poisoning or high dose exposures, for example when large amounts of a chemical were accidentally spilled on the skin," says Freya Kamel, a researcher for the National Institute of Environmental Health Sciences (NIEHS).

The NIEHS researchers examined questionnaires completed by farmers on lifetime exposure to herbicides, insecticides, fungicides, and fumigants, and their history of 23 neurological symptoms. Those who reported experiencing more than 10 symptoms during the year prior to completing a study questionnaire were classified as having high levels of symptoms.

Researchers found that nearly 3,000 participants had a high lifetime exposure to insecticides — that is, they used insecticides more than 500 days in their lifetime. Nearly 800 of these farmers reported more than 10 neurological symptoms compared to those using insecticides fewer than 50 days. The researchers found no significant association between neurological symptoms and other chemicals, including herbicides or fungicides, and only a weak association between fumigant exposure and neurological symptoms.

Some of the insecticides used by the licensed farmers over the past 25 years are no longer available commercially. DDT, a well known example of an organochlorine, has been banned for use in the US since 1972. Organophosphates, such as malathion, chlorypyrifos, and diazinon, have been banned or restricted for home and garden use in the U.S. However, some of the pesticides examined, including carbaryl and some pyrethroids, are available to home gardeners, although in different formulations and in lower concentrations, which may make them less hazardous.

"Because the participants in this study are telling us they have never been previously diagnosed with pesticide poisoning or medically treated for any exposure to any pesticide, we are led to conclude that their symptoms are related to moderate lifetime exposure," says Kamel.

"Most studies of this issue have sample sizes ranging from 50 to 100 participants, making it hard to understand the detailed relationship between exposure and health effects. The large size of this study gives it great statistical power," adds Kamel.

Citizens Can Sue Pesticide Makers for Damage

The Supreme Court upheld the rights of citizens to sue for damages caused by pesticides, after Dow Chemical Company and the Bush Administration argued that the chemical industry should be shielded from such litigation. The Bush Administration filed a brief in support of Dow Chemical, arguing against the rights of citizens who are poisoned or damaged from pesticide use.

The case, Bates et al v. Dow AgroSciences LLC, involves Texas peanut farmers who argued that the Dow herbicide Strongarm (diclosulam) ruined their crops, but were prevented from suing after Dow successfully argued in a lower District court that registration of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) insulates it from citizen suits, or preempts litigation.

The Supreme Court decision upholds the preeminence of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), which remains the pre-eminent and long-standing federal statute governing the regulation of pesticides in the United States. The Court unanimously upheld the basic principle that FIFRA preempts any damages claims against a pesticide manufacturer, which would impose a labeling requirement different from those required by the U.S EPA. Equally important is the Court upheld the uniformity of labeling requirements.

Basically, the decision requires a lower court that had dismissed the plaintiffs claims to rehear their arguments even though some Justices suggested in opinions that the peanut farmers would fail again upon review and wrote: "If petitioners offer no evidence on remand that Dow erred in testing, design, or manufacture . . . these claims will fail on the merits."

Justice Breyer, in his concurring opinion, stressed that the U.S. EPA has the legal authority to promulgate rules and to determine the preemptive effect of those rules. Furthermore, he emphasized that a federal agency charged with administering a statute is "better able than are courts to determine" the extent of state tort liability in light of federal requirements. Justice Stevens, writing for the majority, concluded that "to the extent EPA promulgates such regulations in the future they will necessarily affect the scope of preemption."

The court decision also reads, "The long history of tort litigation against manufacturers of poisonous substances adds force to the presumption against pre-emption, for Congress surely would have expressed its intention more clearly if it had meant to deprive injured parties of a long available form of compensation."

Jay Vroom, CropLife America president and CEO, says, "Looking ahead, we will further analyze this decision and consult with the states, federal regulators, congress, our members and farm customers — all of whom appear to be impacted by the decision — to develop other policy directions that will respond to the court ruling."

Moisture is still key to Clearfield rice success

For the past two seasons we have experienced wet springs. At the time I am writing this article we are rained out of planting our rice weed control plots, so it appears we may be headed for another rainy rice planting season. This is good news if you are growing Clearfield Rice and using Newpath herbicide.

Newpath is a moisture-loving herbicide. As you know by now, the Clearfield system calls for two 4 ounce per acre applications of Newpath for effective red rice control. Whether you are applying it prior to planting, incorporating it prior to planting, applying it after planting (pre-emergence) or making your first application post emergence, one of the keys to success with Newpath herbicide is to get an activating rainfall after making the first application. Most of the failures I have been called about (there have not been too many) have been where the first Newpath application was not adequately activated by either rainfall or flush. The first Newpath application sets up the red rice and other weeds for the second application around 14 to 21 days later to finish the weeds off. In addition, Newpath will make some weeds sick and eventually unable to survive when the permanent flood is established. Typically if red rice turns yellow and is stunting either when it first emerges following a soil application or 14 days after a postemerge application, you know you got it. When it comes up and is green and growing you may have missed it with the first application. In this situation you still have another application, but getting 100 percent control may be out of reach. In these situations a third application of Beyond herbicide will likely be needed to prevent out-crossing.

During the development of Newpath herbicide for Clearfield rice there were several years where it did not rain all spring. These years gave us examples of what might happen if the first application of Newpath is not activated. That is why a flush is recommended across the board following Newpath applications. If red rice emerges following an application of Newpath and the seedling is allowed to establish a larger root system prior to herbicide activation, then it becomes harder to control.

Newpath failures occur more often when the first application of Newpath is made pre-emergence and no rainfall occurs or the field is not flushed. Applying Newpath pre-plant incorporated can buy you a few days, but the field will still need to be flushed if it does not rain. Since the introduction of CL161 and Clearfield XL8, which have a higher tolerance to postemerge applications of Newpath, the sequential POST program for Newpath has gained popularity. Although, these applications are typically made after the red rice has emerged, a rainfall or flush is still needed to activate the soil and residual aspects of Newpath. However, later in the season when these postemergence applications are made, the levees are typically already pulled and the rice may need to be flushed anyway if it has been dry. Newpath performance is better if the weeds are actively growing and not moisture-stressed at the time of application. So, even with the sequential POST option, good soil moisture is still required to reach 100 percent control of red rice and other rice weeds.

Thus far, the Clearfield system has resulted in some of the cleanest rice fields out there, especially at the end of the season. Do not let this fool you into thinking the system is foolproof. In Arkansas, I have had several farmers tell me that we are never more than a few days away from a drought. If the rains let up and it turns dry, be ready to start the wells.


Bob Scott is the University of Arkansas Extension weed specialist. e-mail: bscott@uaex.edu

Stay on top of rust, do your own homework

Asian soybean rust has been the topic of almost every meeting I have attended this winter. A lot of information has been made available; sort through it all before making any decisions. Almost everyone has your best interest at heart, but you must do your homework and stay on top of this issue.

Rust probably will be one of the biggest production issues most of us have ever dealt with, but it will remain so only for two to three years. Almost everyone is guilty of using Brazil as an example. While Brazilians have been an excellent source of information, I believe their experience will differ greatly from ours.

I am not downplaying the magnitude of rust, just letting you know it will be a couple of years until we get a better handle on it on our turf.

For starters, our winter is often ignored. This may not be much of an advantage, but it helps in China.

Second, if rust has to re-enter the United States (some years) and weather conditions vary from year to year, the impact of the disease will be different.

Third, 2005 will be our inaugural year. It has taken rust 102 years to reach the continental United States. In every country it has entered, yield losses have been minimal the first year. I do not envision us being different from any other country.

Soybean rust is difficult to identify. Under ideal conditions it can move fast. I believe growers in the Mid-South are doing a better job of in-field management, but rust can be confused with other diseases.

We keep hearing that you must spray prior to reaching 3 percent infection level. That is three plants per 100 plants with one pustule per plant (whole plant determination). That is virtually impossible. No one will take the time or make the effort to look that closely. Even if you did, by the time you identified that level, under ideal conditions yield losses will have occurred.

To aid you, all Mid-South states are planting sentinel plots. Sentinel plantings are an indicator crop; they will serve as an early warning system. In Mississippi, 23 fields were planted earlier than the bulk of the Mid-South crop.

The accompanying map shows the location of the sentinel plantings. The fields transect the state from the Mississippi-Alabama line above Lucedale to south of Natchez. Fields are also planted every 50 to 75 miles north of Natchez up the Mississippi River to north of Cleveland.

In addition, several fields are scattered in the central and eastern side of the state, and we will monitor the 27 fields in our SMART program.

Sentinel maps for other Mid-South states are available on the Internet at www.soyrust.org.

As of mid-April we had planted 18 fields. We are planting a late Group 3, a mid-Group 4, a mid-Group 5 and a late Group 5.

In mid-April, we started a second planting. By varying the maturity groups and having multiple planting dates, the sentinel fields will remain in the reproductive period for a long time. From bloom on, rust appears to have a greater impact on the crop. Our hope is that by using the indicator plots we can find rust early (if it is present) and give you a two- to three-week heads-up regarding control strategies.

Individual state control guidelines may vary slightly, but you may not get to use your first fungicide choice due to supply. If history repeats itself, rust should have a minimal impact on yield this first year. If that proves true, sufficient time will be available to fill the pipeline with needed products before next year.

All products are not created equal as far as rust is concerned. We have ranked the various materials based on efficacy, but this year we will be relying mainly on other countries' experiences. In addition to efficacy, cost and availability are factors to consider.

Several co-packs on the horizon will be priced in the neighborhood of single products. The supply problem I mentioned earlier is not your dealers' fault. Late labeling of products, the uncertainty of needs in the United States and other countries' needs will greatly affect supplies this first year.

A new Mid-South Web site is now online. The address is www.soyrust.org. Take a moment to look at it and give us any feedback since this is a work in progress.


Alan Blaine is the Mississippi Extension soybean specialist. e-mail: ablaine@pss.msstate.edu

Farmers examining 15-inch-row cotton

Cotton farmers who shied away from ultra-narrow-row systems because of price discounts are beginning to look at 15-inch-row picker cotton as a solution to a variety of production problems.

Scott Fullen was one of those growers who studied ultra-narrow-row cotton extensively in the late 1990s and early 2000s, but decided against trying UNR because of questions about whether textile mills would pay full price for it.

“There is a lot of ultra-narrow-row cotton in Tennessee, and that's one reason we went to this (15-inch picker cotton) so quickly,” said Fullen, who farms with his family near Ripley, Tenn. “We liked the idea of ultra-narrow-row planting, so when we heard about the new 15-inch picker system, we jumped at it.”

Fullen, a speaker at a seminar on 15-inch-row cotton at the Beltwide Cotton Conferences in New Orleans, planted about 900 acres in 15-inch rows last spring.

He and his family made more than a casual commitment to the concept, according to John Deere crop systems specialist Andy Pace, who moderated the seminar. (Deere, Monsanto and Delta and Pine Land Co. sponsored the seminar.)

“This past year we had a limited build of our new Pro-12 VRS Row units for cotton pickers to see if we were on the right track,” said Pace, referring to the harvesting system that makes it possible for growers to spindle pick 15-inch rows.

“We had a little trouble finding growers who were willing to take us up on our offer to test them. But Scott and his family took a big chance and purchased a 9996 picker in a six row with the Pro-12 VRS Row units and grew some substantial acreages of 15-inch cotton.”

Fullen told a standing-room-only crowd at the seminar that he planted the 15-inch cotton on several different soil types in the Tennessee Delta, the narrow strip of land that lies between the Mississippi River and the rolling hills in west Tennessee. Some of the land was irrigated; some not.

“The biggest reason we were looking at it was to shorten the growing season,” he said. “If we can take a week off at the first of the season and see where the level of the Mississippi River is and whether we're going to be flooded, it can make a big difference for us.

“The 15-inch-row cotton did mature quicker without a doubt. I think a week would be very easy to achieve.”

2004 may not have been the best year to try 15-inch-row cotton. “We had plenty of rain, and I would think this system would tend to work better than our 38-inch-row system in a dryer year,” he said.

“We had wet conditions, but we really didn't have a problem controlling the cotton. We probably didn't use much more Pix on the 15-inch rows than on the 38-inch rows. We did start our plant growth regulator applications quicker and with higher rates, but at the end of the year the amounts were virtually the same.”

Fullen's growing conditions were almost the exact opposite of those experienced by Gill Rogers, a farmer who cooperated with the seminar sponsors on a 15-inch-row study on his farm in Hartsville, S.C., in 2004.

“We had almost no soil moisture at planting time,” Rogers said. “We planted the cotton fairly easily, but we had no moisture to work with. And since we planted flat, we had no beds to retain moisture. So we were at the mercy of the rain.”

Rogers said most of the cotton didn't germinate until June 5, and the stand was weak in places. The very late start could have meant trouble for Rogers when last year's hurricanes begin blowing through the Southeast.

“Some of the cotton was blown over by the hurricanes,” he said. “Some of the varieties were more suitable for 15-inch rows, mainly in their maturity dates and the way they withstood the wind in the hurricanes. The taller, upright-growing plants seemed to weather better than the shorter plants did.”

Rogers said he tried ultra-narrow-row cotton for three or four years in the late 1990s, “and I thought it was a better production method in some ways. I tried different row spacings and plant populations, and it turned out real well. But the second year I found that the mills just did not want the stuff.”

When John Deere began talking about 15-inch-row picker units, Rogers decided to try them in 2003. The start of the 2003 season was almost as wet as the 2004 season was dry.

“It was a little bit hard to plant, but we got a good stand,” he said. “It was almost impossible to work the crop because we were getting so much rain. We had a dry fall, and harvesting wasn't difficult. We got it harvested on time.”

The 15-inch system doesn't permit growers to do a lot of fieldwork in the crop during the growing season, he noted. “We didn't have a lot of intense labor during the season. You can't run big tires in the rows, and it was pretty much one application of Roundup over the top.”

Rogers said yields from his 15-inch-row fields were comparable to the 30-inch-row cotton he grows on the remainder of his farm. “I think the yields would have been a little higher if we had replanted some of the cotton where we had a bad start in 2004,” he noted. “Quality was about the same as our conventional, 30-inch cotton.”

(The Hartsville study had three test plots — two 90-acre plots planted with DP 444 BG/RR, DP 449 BG/RR, DP 555 BG/RR and a 40-acre plot planted to DP 444 BG/RR, DP 449 BG/RR and DP424 BGII/RR.)

Fullen planted most of his 15-inch cotton in Paymaster 1218 — “the variety we're most familiar with” — and the balance of 150 to 200 acres in DP 444 BG/RR. “I was trying to take out some variables,” he said. “I felt like I understood the 1218.”

He said the DP 444 BG/RR produced higher yields, “but that may have been because the 444 was on the better land. The 444 was the best cotton in the narrow row.”

A representative of Delta and Pine Land, which conducted nine studies with 15-inch-row cotton with John Deere and Monsanto in 2004, said the company was pleased with the results of the trials.

“We saw an increase in yield and an increase in earliness,” said Peter Peerbolte, director of marketing for Delta and Pine Land and a speaker at the seminar. “We think this planting system has a lot of potential.”

The jury is still out on some aspects of 15-inch-row cotton, according to the speakers. Take plant populations, for example.

“We planted 90,000 seed per acre, and we just kind of picked that number out of the air,” said Fullen. “We figured that you plant 100,000 to 120,000 on 7.5-inch, UNR rows and 50,000 on 38-inch rows, and we just picked 90,000. We pushed the population a little because I wanted a good, thick stand because of weed control.”

“The first year we were buying our own seed,” said Rogers. “The second year we were getting them from Delta and Pine and we upped the rate a little bit. We tried some the first year at 35,000 and 70,000 and tried some the second year at 50,000, and I really couldn't tell any difference. If you knew how much it was going to rain, it would be easy to set the plant population.”

Peerbolte said Delta and Pine Land will not have a single, recommended plant population. “We've been involved in the project for one year, and we saw plant populations everywhere from 65,000 to 90,000. “We will have a recommendation for that part of the country where it will be planted.”

Fullen's experiment with 15-inch-row cotton in 2004 attracted the attention of his neighbors, according to agronomists.

“We've talked to some farmers in his area who wanted to try 15-inch cotton because they couldn't believe how much cotton they saw in his 15-inch fields,” said David Guthrie, director of technical services for Emergent Genetics. “The concept is beginning to attract attention.”


e-mail: flaws@primediabusiness.com

Louisiana's mystery rice pest identified, provided new name

When he began working in Louisiana rice fields two years ago, Boris Castro began seeing an unfamiliar insect.

“I was taking many pictures of rice pests I came across,” said the LSU AgCenter entomologist. “That's when I noticed some larvae affecting two plants. Maggots were going inside a rice plant's stem. Taking everything together, this didn't seem to match any larvae I was familiar with.”

Interested to see if others had found anything similar, Castro called Mo Way, an entomologist with Texas A&M University. Way reported he'd seen the same larval behavior and was also unsure what it was.

“So we agreed to keep an eye out for this again in 2004. We both thought it was weird,” said Castro.

Then, last year, the pest hit some Louisiana rice very hard. Fields were severely hurt — denuded, in several cases — in Acadia, St. Landry, Vermilion, Jefferson Davis and Concordia parishes. Way said the larva was also in several Texas counties including Wharton, Jefferson and Calhoun.

“If you look at the range of the pest,” said Castro, “it's obviously already well-distributed across the southern rice belt now.”

Name proposed

Only recently, with the help of the Smithsonian Institution, were Louisiana entomologists able to find the actual name for the mystery pest species: Hydrellia wirthi.

“In March, the Smithsonian was able to compare our specimens from others gathered in South America. They matched. This is a pest that hasn't been reported in the United States previously. It's commonly known as the ‘rice leaf miner’ in South America.”

The pest is so new it doesn't have a common name established in this country. Together, the LSU Agcenter, the Smithsonian and Texas A&M University have proposed “South American rice leaf miner.”

The proposed name has yet to complete a process shepherded by the Entomological Society of America (ESA). The ESA must post the name and allow time for comments. That usually takes 3 or 4 months.

In the meantime, “we're using the ‘South American rice leaf miner’ name among producers,” said Castro. “Doing so will allow us to differentiate from the rice leaf miner (Hydrellia griseola) already in the country. It's very important to differentiate between the two.”

The differences

The two species, to the naked eye, are the same. The differences in the morphology of the pests can be seen under the microscope.

But while the two species may look alike, what each is capable of in a rice field show clear differences. That, said Castro, is what's important to know.

The species of leaf miner U.S. rice farmers are already familiar with is considered a secondary, sporadic pest. It causes “mining” damage to the leaf blade — normally on leaves touching water. That's why a common practice to control the pest is to drop water levels so the leaves aren't wet.

“Often, just dropping a flood down can take care of the problem.”

However, the new South American rice leaf miner isn't so easily dealt with. The maggots — or larvae — begin by scratching the leaf surface and then eat their way inside the stem or tiller. This behavior is the reason many began calling the pest “whorl maggots.”

“Last year, for the most part, we saw the maggots already inside the plant tissue. So the damage is much more problematic. This new leaf miner is far, far more aggressive than the one we already know.”

Leaves damaged by the pest tend to dry out and sometimes curl or even break off.

“When inspecting the plant, you'll usually find a maggot inside the stem. Last year, we found one or two maggots per tiller typically. But sometimes, especially in Jefferson Davis Parish, we found up to five maggots per tiller.”

A new pest found

Louisiana rice fields hurt by the South American rice leaf miner were affected mainly well into last growing season. Most of the damaged fields were late-planted from mid-May through June.

“The first report of damage we received was in the second week of June,” said Castro. “That field had been planted in mid-May. The rest of the damage reports came between the end of June through July.”

The pest caused a lot of stand density reduction, according to the entomologist. “One thing we've noticed is it tends to really hurt young plants: from one week post-emergence through 6 weeks post-emergence. The larvae either kill the plant outright or cause growth to be retarded. Floods then drown weakened plants and, if a weed flush occurs, it can reduce density even further.”

Last season, Castro was first alerted to problem fields by an Extension agent in Acadia Parish. “He called me and said, ‘You need to come over because we've got a severe infestation of leaf miner.’ So I went and it was obvious this wasn't our known leaf miner.

“At that time, he said he'd seen similar damage before. He just assumed it was the known leaf miner. He had no reason to think otherwise, you know.”

In speaking with Extension agents and farmers since, Castro has found others who say they've seen such damage in the past few years. For this reason, the entomologist is reluctant to guess how — or how long ago — the South American rice leaf miner found its way into the United States.

“This is a tiny fly (larvae are typically an eighth inch to a quarter inch long), that could be driven by the wind for long distances. It just took a severe outbreak before we found this it. That's why I can't guess when or how this pest got here. It probably entered in the last few years. But, whatever the case, now we must deal with it.”

From the damaged fields, Castro and colleagues collected many larvae and grew them in a lab. He then sent the adults to the Smithsonian Institution.

Control options?

Castro wonders where the new pest is overwintering and how it has adapted to its new home. Now that he knows it comes from South America, he's looking for literature and studies that will provide good leads.

“As far as habits and biology in this country, we'll be studying that very hard this year,” he said. “The first thing we're going to check is to see if management techniques already proven to help with other pests can help with this one. Will floods or draining make a difference? Hopefully we'll find out the arsenal of cultural practices we already use will help. If so, that will help avoid additional costs for producers.”

If that doesn't work, Castro said a chemical “backstop” will be needed. Currently, there are no pesticides labeled for the pest. And even if there is a pesticide proven to work, Castro worries that application timing will be crucial.

“The way this insect goes inside the plant, it's likely an insecticide must be sprayed at just the right time. If it comes too late, it's unlikely the larva will be killed. That's why we need to know about infestations very early, before they cause plant kills. It'll be hard but we must try. It will be interesting to see if any of the insecticides we already use will be effective on this leaf miner.”

A more vulnerable crop?

Much of the Delta's rice acreage is being planted late — especially compare to last year. Castro said this creates a better opportunity for the South American rice leaf miner to gain a toe-hold.

“With a late-planted crop this year, we're set up for seeing this pest more. The fact that our planting is behind schedule is a concern.”

He said that's one reason the LSU AgCenter developed a state survey protocol to deal with the pest. Originally planned just for Louisiana, the survey is being taken national.

“With the help of some universities, the USDA plans to take the survey to every county where rice is produced: Louisiana, Arkansas, Texas, Mississippi, Missouri and California. Everyone will be watching. We want to know how far this insect has been distributed. And we want to know how intense infestations can be.”

Castro said he has no proof, but wouldn't be surprised if the pest has already moved outside Texas and Louisiana borders. “It's been found in Concordia Parish, right next to Mississippi. I also found two infested plants in Franklin Parish which also borders Mississippi. Hopefully they don't have it there, but it's something to really watch for.”


e-mail: dbennett@primediabusiness.com

Drip irrigation techniques helping fine-tune scheduling recommendations, say scientists

University of Arkansas researchers and scientists are using subsurface drip irrigation techniques to help refine irrigation scheduling recommendations. They're also trying to determine if the technique can provide better yield stability and reduce water usage.

Phil Tacker, Arkansas Extension irrigation specialist, said the university provides farmers with a powerful irrigation scheduling tool. “We've conducted soybean irrigation studies with the help of the Arkansas Soybean Promotion Board, and we want to make sure our irrigation scheduling program recommendations address newer production practices.”

The program has been revised over the years and is used by other states, but it can always be made better.

Larry Purcell, a UA physiologist on the project, said most of the irrigation scheduling recommendations are based on production practices that are many years old. Purcell is an advocate of using earlier maturing cultivars, narrower rows and higher population densities with quicker canopy closure.

Current recommendations don't take into account the higher populations and narrower row spacings used on earlier maturity groups.

Tacker said the three-year research project can also lay groundwork for developing recommendations if subsurface drip irrigation becomes a practical and affordable alternative for row crop farmers. “There's an interest in subsurface drip irrigation, but we're not currently promoting it as something many row crop farmers should switch to. We've put some in to see what it takes to install and to evaluate how it works.”

Tacker said the first drip irrigation was installed in cotton near Keiser, Ark., in 2002. Soybeans were added this year.

What's the verdict so far?

“As far as a really precise control of irrigation water, it's good,” Tacker said. “The water is put in at the roots in a controlled amount with better efficiency. Subsurface drip is 95 to 100 percent efficient as compared to center pivot irrigation at about 85 percent and flood and furrow irrigation, which is something less. Drip also requires significantly less pumping capacity on a per-acre basis than flood or furrow.”

Subsurface drip irrigation also offers the advantage of being able to apply precise amounts of nutrients directly to the roots for quick crop uptake.

Much of the well water in Arkansas typically has high pH and iron levels that can cause problems for drip irrigation. Drip tubing has small openings that can be plugged by and calcium and iron deposits.

“Drip shows promise as an irrigation system, but the real question is how does it compare cost-wise to conventional irrigation systems? We already have some effective irrigation methods,” Tacker said. “Does it give enough advantage to warrant the cost?”

Chris Tingle, Arkansas Extension soybean specialist, has been involved in devising planting systems and plant populations for the research. He's enthusiastic about the project. “Being able to use this new technique is allowing us to better define the water use curve for Arkansas soybeans.”

As an irrigation tool, Tingle said, drip irrigation may be more justified for commodities other than soybeans. “We could see it used in soybeans if the economy someday justified it. But it's a sizeable investment for the landowner and farmer.”

Dick Oliver, a UA researcher, said vegetable producers can justify the use of subsurface drip irrigation because they're watering a smaller area and a high value crop. He said the system has the advantage of slowing weed emergence and growth.


Lamar James is an Extension communications specialist with the University of Arkansas.

New Pentia PGR does more, better, quicker

It might be stretching it some to say that BASF's new plant growth regulator formulation moves into the cotton plant faster than you can say mepiquat pentaborate, but not much, according to the company's product manager for Pentia.

“One of the things Pentia has been shown to do is to get into the cotton plant from 22 to 25 percent quicker than other formulations of plant growth regulators,” Scott Asher, BASF market manager. “So six hours after application, we have 22 to 25 percent more compound in the cotton plant.

“Once it's in the plant, we obviously have more product to give us some of the benefits we've been looking at such as yield enhancement, earliness enhancement and height control enhancement.”

Speaking at the Mid-South Farm and Gin Show, Asher said the quicker uptake proved its value all across the Southeast and the Delta in 2004.

“Some of these areas of the Cotton Belt received showers on almost a daily basis,” he said. “With the quicker rainfastness of Pentia, growers were able to treat their cotton and not worry about it washing off.”

The improved rainfastness and other features of the mepiquat pentaborate compound have led to recent label changes for Pentia that will be in effect for the 2005 growing season.

The new labeling specifies a two-hour rainfastness when used alone and one-hour when applied with a high quality adjuvant. It also provides an updated application timing-chart that specifies the first application of Pentia should be made at pinhead square.

“This early application, followed by sequential, as needed Pentia applications, has been shown to improve fruit set and retention which has led to improved earliness and increased yields,” Asher.

In 149 trials conducted by university researchers, consultants and growers over the last two years, Pentia provided 58 pounds more lint than the mepiquat chloride-based compounds. Growers were able to harvest from three to six days earlier in cotton treated with Pentia.

“We asked our cooperators to do late-season plant mapping,” said Asher, “During that time, we were averaging 13 percent more open bolls with Pentia than we were with mepiquat chloride-based compounds. And that leads to an earlier harvest of about three to six days.”

Crop consultants said faster uptake was beneficial in the weather conditions many growers suffered through in 2004.

“The consistency of Pentia in bad weather and wet conditions is by far the best to me,” said Eddie Cates, a cotton consultant from Marked Tree, Ark. “I think it also helps with earliness. That's the reason I put it out at the front end to set the plant up to set and hold early fruit.”

“When you get that amount of rainfall and heat, you have a lot of cotton getting out of control, especially if you have fertilizer underneath it,” said Asher. “Some of our newer varieties are very aggressive. Pentia has been able to manage that cotton crop a little better.

Asher said BASF will also be launching a new formulation of its pendimethalin herbicide to be called Prowl H20 in 2005.

“Prowl H2O is a water-based compound in contrast to the standard pendimethalin EC-based compounds that are on the market today,” he said. “The new Prowl formulation is encapsulated so that it is low odor. It doesn't stain and can be washed off with water.

“As far as performance, the new compound has an improved surface stability; it can lay on the soil surface a lot longer than EC-based formulations will, making it a good application for a pre-emergence treatment behind the planter. It will wait for a rain or irrigation to be incorporated.”

The new Prowl may also be a better fit for no-till or strip-till planting because it will wash off crop residue and onto the soil surface more readily than older pendimethalin herbicides.

Choose weed control program, apply early

I have had several calls from consultants asking about options to use in place of Command as the price increased some this year and growers are looking for ways to reduce costs anywhere they can. While I may sometimes sound like it, I do not sell the herbicide. There are a lot of ways to control weeds in rice and my only interest is that you have a clean crop in the most efficient manner possible. I would simply remind you where Command put you in terms of being able to control grass in rice. I agree that this was not a good year for anyone to increase herbicide prices. When asked “what I thought” about the price increase earlier in the spring, I told the company rep the same thing. However, Command remains the standard for comparison for grass control.

Several have asked about using Prowl in place of Command to save money. There was a lot of Prowl being used in rice before Command was labeled. Most growers switched to Command for a reason. Prowl provides good grass control sometimes but it is far less consistent compared to Command. In addition, the rice needs to have imbibed its germination water before the Prowl is applied. There is a good fit for Prowl around incorporated areas, nurseries and other sensitive areas where Command can not be used.

Several have also asked about reducing Command rates and what the effect would be. On silt loam soils, studies I have conducted showed that Command rates as low as 0.5 pint per acre provided initial grass control comparable to labeled rates. The difference was in the length of the residual period. Length of residual can be important, but controlling that very first flush of grass that emerges with the rice is more important. Therefore, if a reduced rate is an alternative to using no Command, some Command is better than no Command.

Much of the rice is planted. If no Command was used preemergence, there is still the option to apply it postemergence. The more I have used the Super Wham, Duet, Ricestar HT and Clincher combinations with Command, the better I have liked them. In a lot of grass situations, the Command mixtures perform comparable to the same herbicides mixed with Facet. However, the Command combinations are much better on sprangletop. When the grasses are small, the Command in the mixtures is contributing more to the postemergence control than I initially thought it would.

My concern is if you try to save too much money on the front end in the weed control program, it will bite you. Through the years, I have seen a lot of attempts at early savings cost far more later on. We have some herbicides now that are more effective on bigger grass. However, little grass is much easier to kill than big grass. In addition, big grass robs yield even when controlled.

I like Command in rice because it immediately became the standard for comparison in our research program. It quickly became the grower standard as well. Most of the alternatives available today were being used when Command came along. Yes, it costs less then than it does now. However, the reason it became the standard was because it provided superior grass control. I get very few grown up mess calls where it has been used. Also, keep in mind we have a lot more trouble getting post-emergence herbicides applied than we do pre-emergence herbicides. If this spring is windy, extremely dry or extremely wet, postemergence control becomes more difficult.

Whatever program you choose this year, get the grass under control as quickly as possible. The sooner you can do that, the sooner you have things going your way and these will wind up being the most economical programs in the long run.


Ford Baldwin, Practical Weed Consultants. e-mail: ford@weedconsultants.com.