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We
encourage you to send in your questions on anything related to Asian soybean
rust or other soybean management issues, and we'll match your question with
the expert best-suited to answer it. Here are recent questions and answers and some "Letters to the Editor" with your opinions and experiences, too.
2006 Q & A
Posted 10/13/2006:
Q. My family lives and farms in Southwestern Indiana. On a yearly basis,
we sell non GMO beans and will often keep some to clean for next year.
With the Rust now in Kentucky, we became curious as to if we could
accidently plant a field of rust-infected beans in the spring. Will it
stay on beans after being cleaned? Can it live in beans over the
winter?
Thank you,
Indiana soybean grower
A. The soybean rust fungus does not infect seed, so it will not be transmitted by that means to a new crop in the spring. If the rust that made its way into western Kentucky also reached Indiana, there are so few green soybean leaves at this time that only fields planted very late are likely to show any rust. Even if rust can be found in Indiana at this time, it won't be here long. Frost is predicted during the next couple of nights over much of the state, even in the far south. Once leaves are killed by frost, if there is any rust infection in them, it will die also.
As frosts extend into the southern states, the rust will be eliminated there also. For rust, each year is a new cycle, unrelated to how far north the disease progressed the pervious year. The rust fungus will only survive in the deep south, below the frost line, and from there southerly winds must transport spores to more northern regions each summer.
Saving seed from this year's crop, even if the plants did have some rust, won't increase the risk of infection next year. The risk next year depends on how early in the spring rust starts to develop in the South, how severe the disease becomes down there, and how early in the summer viable rust spores reach Indiana.
Regards,
Gregory Shaner, Professor
Department of Botany and Plant Pathology
Purdue University
Posted 8/7/2006:
Q. I live in southern Indiana. Our soybeans are starting to bud. If rust was coming, would it be better to spray preventive, or wait and see if the rust even hits? At what stage should you spray? Is there too early of a time to spray, say if you already have rust? And is there a "you're in the clear" point, you know, if the bean pods are almost done growing?
Thank you,
Ryan H.
Indiana
A. Soybean rust is still found only hundreds of miles south of Indiana, so I don't recommend applying a fungicide at this time for rust control. If a grower applies a fungicide far in advance of rust infection (2 to 3 weeks or more), there won't be enough fungicide left in the plants when rust does arrive to provide any protection, so the spray is wasted. The lack of much rust development in the southern U.S. makes it unlikely that rust will arrive in Indiana this year in time to do any damage to our soybeans, if it even gets here at all.
The soybean plant can sustain damage from rust if it is infected any time before pods start to take on their mature color (tan or gray), but the later infection occurs, the less damage rust will cause. For now, you should continue to monitor the rust situation, and only apply a fungicide for rust control if the disease threatens Indiana's crop. You can hear regular updates on the soybean rust situation by calling Purdue's toll-free hotline, 866-458-RUST.
Regards,
Gregory Shaner, Professor
Department of Botany and Plant Pathology
Purdue University
Posted 8/7/2006:
Editor's note: Here's what Penn State plant pathologist Erick De Wolf is telling Pennsylvania growers about how the rust situation is shaping up this year, from his perspective:
"The risk of soybean rust continues to be very low in Pennsylvania. Monitoring for soybean rust has continued throughout most of the soybean producing states during recent weeks. This monitoring includes evaluation of soybean sentinel plots, commercial soybean fields and kudzu (another host of this fungus).
"Soybean rust remains limited to just a few states in the Deep South. We have seen some movement of the disease in these states during the past week, with disease reports in central Mississippi and Georgia. Rust is only being reported at low levels at most of these locations, and our colleagues in these states continue to indicate that the disease is being held in check by hot and dry weather.
"The low levels of disease are good news for soybean farmers throughout the country. Every week that passes with out significant increases of disease reduces the chance that soybean rust will cause damage to the U.S. soybean crop. At this time, it appears the risk of soybean rust in Pennsylvania is very low. Soybean farmers in the state should continue normal production practices, but should also keep an eye on the status of soybean rust in the Deep South.
"If the disease starts to increase in the Gulf Coast states, the potential for rust may increase. It seems unlikely that rust will arrive in time to cause any significant damage in Pennsylvania. At this point, our double-crop soybeans may still be at risk if the disease begins build in the South. We will continue to watch for soybean rust in our sentinel plots and send out warnings if we detect the disease in Pennsylvania.
"Pennsylvania is monitoring 10 soybean sentinel plots this year. These plots are located in Montgomery, Lehigh, Lancaster, Franklin, Cumberland, Lycoming, Bedford, Centre, Armstrong and Mercer counties. Sampling of the PA sentinel plots indicates that brown spot is becoming common in many fields. Brown spot is the most common disease to date in the plots. Trace levels of frogeye leaf spot and downy mildew continue to appear in the plots. These diseases are very common in PA and rarely result in yield reductions."
Source: Pennsylvania state commentary 8/7/2006 on www.sbrusa.net.
2005 Q & A
Posted 7/25/2005:
A. (Related to the part of the question immediately below re: risk of use of adjuvants with certain rust products)
Don Hershman today sent this Bayer CropScience presentation, "Asian Soybean Rust: 2005 ‘Azole’ Soybean Injury in Brazil 2005" (PDF) to his rust listserv. It addresses increases instances (although still rare) of injury to soybeans when treated with the "azole" family of fungicides in Brazil in 2005 compared to prior seasons. It discusses the triggers in Brazil, the lesser chance for that rate of injury in the United States, and gives specific guidelines for when to and not to use adjuvants with Folicur (tebuconazole) to lessen the risk of phytotoxicity. "Hot, drought-like conditions are the key factor driving potential injury." The slides also include photos of injury symptoms from treated fields in Brazil. (FYI: Tebuconazole is the co-pack ingredient that makes Headline from BASF into Headline SBR.)
Please view the whole presentation -- we've simply summarized a few of the key points above, and the information should be viewed in context, as it came from the manufacturer.
Here is Hershman's note regarding the Bayer presentation, which was sent to him and a few other University plant pathologists by the company:
"Here is some information I got from Bayer on Azole injury to soybean, with an emphasis on Folicur. It is interesting and worth looking at. On a side note, I applied two formulations of tebuconazole two weeks ago, with and without additives. I did not see any phyto, but I did have cloud cover and moderate temps during application and for the week immediately following application. Basically, I had the perfect conditions to AVOID phytotoxicity." -- Don Hershman
-- Marilyn Cummins, Editor
Posted 7/24/2005:
Q-1. I was encouraged today (7/20) to begin spraying Headline SBR for “plant health” reasons. I just happened to find the info on this site about the cautions being given by University people about their concerns with this and the lower rate of Headline at the Headline SBR rate. I had just talked to two landlords for their opinion. After reading the article my mind is made up, I wait.
But my question is: What is the rate of each co-pack product for Headline SBR. Each is different by volume in the co-pack and the rate is 7.8 oz, so how much of each? The labels on the two jugs don't help for this situation, and the info I received from BASF has no instructions on the measurements of quantities for tank mixing. They also said I should use a non-ionic surfactant such as “Preference.” Please answer ASAP -- I may spray some test strips tomorrow.
Thanks for your help and the web site!!
Gary H.
Central Ohio
A-1. BASF Ag Product Communications Manager/Corn Belt, Catherine Iftner, sent this Headline SBR conversion chart today (7/24):
She said that additional questions could be directed to:
Gary Fellows, BASF Technical Marketing Manager
26 Davis Drive, Research Triangle Park, NC 27709
(919) 547-2656; (919) 547-2428 fax; (919) 624-7559 mobile
Fellowg@BASF.com
A-2. Because the grower, Gary H., had asked for help ASAP, we e-mailed back on 7/20, directing him to technical information publicly available on the BASF Web site in case it would help:
Technical Information Bulletin: Asian Soybean Rust Headline Preventative + Tankmix Curative Options (with rates and active ingredient amounts)
Headline SBR Technical Information Bulletin, with co-pack component information
We gave no advice regarding any of this information, nor did we comment on the topic of using adjuvants or not with Headline SBR. He'd already read the article quoting University experts on that issue.
Marilyn Cummins, Editor
Grower's response 7/22/2005: Thanks for your help! I learned a lot through this, and the rates you found are what I had figured up also doing the math. I think some more education about what a “Section 18” label is would be great. We have heard the term, but don’t understand the risks with it. If I understand it right, we are using the product and for all intent and purposes we are “on our own.”
I am now very concerned about what some of the co-ops are doing spraying so many acres for this so-called "soybean health" reason. Remember I am in OHIO, no rust here yet. But fungicide is being used for the health reason. Maybe the product they are using is fully labeled.
Right now, before I asked the question last night, I had treated 24 acres with Headline SBR with an adjuvant, as they say to do, I guess I will find out what happens. Because of the info I found here, I have stopped spraying and will keep the product in case rust does get here. Thanks a lot!!!
Gary H.
Central Ohio
P.S. I have told several people about your Web site. Great site -- keep up the good job.
[Thank you, Gary. MC]
Posted 7/21/2005:
Letter to the Editor:
Dear Editor,
It doesn't matter how many rust spores or where they are found!
Look at what is happening to the price of soybeans. Many farmers I've talked
to say they won't spray because the board of trade isn't giving any price
incentive to spray. Why spend the money to increase final bushels when no
one wants farmers to raise a crop anyway.
Thank you!
David K.
Central Nebraska
Posted 7/21/2005:
Q. I have been unable to access the web site sbrusa.net since the site underwent "a few changes." All the site will do is show "map is loading." No other feature on that page will work either.
I can utilize the stopsoybeanrust.com page articles just fine. This is good information. I am able to keep up-to-date by using this page, but the map on sbrusa.net was a good feature also. I know two fellow producers on two different service providers unable to receive this page also. I have Windows 6.0. Would appreciate any advice help you may have! Thanks!
Leo M.
Kentucky (7/11/2005)
A. One of Leo M.'s peers hit on the answer after several days of trial and error by both men. We're sharing it in case it might help anyone else having trouble getting the USDA Public Soybean Rust site to load and operate properly.
"In the Norton antispam features and settings, I had to turn off both ad blocking and pop-up blocking to make the site work. Sounds simple now," Leo said.
If this doesn't work for you, or you've found other solutions, let us know.
-- Marilyn Cummins, Editor
Posted 7/9/2005; updated 7/11/2005:
Q. Several of our farmers are concerned about the hurricanes and the wind patterns associated with them. I was wondering if there was a chance of rust making its way here.
Rick A.
Northwest Missouri
A-1. The answer may be obvious by now (7/11/2005) -- anything is possible. We don't know
if "Dennis" will make it that far west or not - but again it seems that
anything is possible. If not this year, then maybe the next.
Glen Hartman
Research Plant Pathologist
USDA Agricultural Research Service
University of Illinois
A-2. Rick, how big a chance is something only the experts can -- or can't yet -- say (see A-1 above).
Earlier this year, Pat Guinan, Extension climatologist with the MU Commercial Agriculture Program, said that in Missouri, prevailing winds during March are generally from the west and southwest. "Then, as the growing season begins, winds will predominantly come out of the south from April through October," he said. "That's when soybean farmers will want to pay very close attention to what's going on to the south."
See the daily updates in our Soybean Rust Tracking Center for the very latest in what the USDA and the North American Plant Disease Forecast Center are saying about the possibility of spore movement. On 7/11/2005, the USDA model is still predicting possible spore deposition as far north as southeast Missouri and southern Illinois this week.
Marilyn Cummins
Editor
Posted 6/29/2005:
Q. Can I use Quadris, Quilt or Headline through my center pivot irrigation system for soybean rust? Sales reps and tech reps don't agree on subject.
Thanks,
Dave B.
Northwest Missouri
A-1. The labels for Quilt and Quadris allow chemigation. Quilt may be applied by chemigation only to the crops specified on the label. Soybeans are not on the Quilt master label, and there is no reference to chemigation with Quilt on the Section 18 label for soybean rust. It is specifically stated on the Quadris label that it can be applied by chemigation on soybeans for soybean rust control.
The Headline label does not specify application by chemigation, therefore it may not be applied in that manner since it would be in conflict with the specifications for how Headline should be applied (ground and aerial).
Martin A. (Marty) Draper
Extension Plant Pathologist
South Dakota State University
A-2. Quadris may be applied by either ground, air or chemigation as indicated on our label. However, the preferred method of application for Quadris on soybeans is by ground or air. Quilt may be applied by either ground or air, but cannot be applied by chemigation.
Dr. Jennifer Yocum
Technical Fungicide Specialist
Syngenta Crop Protection
Posted 4/03/2005:
Q. I am going to spray preventively for rust. In the March 05 Farm Industry News, Folicur is listed on p. 74 as a preventative/curative. This is the first time I have seen this. The Folicur label does not list it that way. This could be a benefit if you were planning to spray when the rust is found in Kentucky (we farm in Illinois), and you had a lot of rain preventing spraying. By the time you could get in the field, you may have an infestation. Then a purely preventative spray will be the wrong fungicide to have. Do you have any answer for this?
Elmer N.
Eastern Illinois
A. All the Section 3 fungicides registered and labeled for soybean rust control as well as and all the fungicides listed in the Section 18 Emergency Exemption request are effective when applied before infection occurs. Thus, all the products can be applied protectively, so all are “protectant.” Only a few of the triazoles on the list of available products are effective when applied after infection and are described as curative. These products can be used in both protectant and curative applications. When used at recommended rates, Folicur is one of the products that is both protectant and curative. Domark and Laredo also fit into this group.
The terms protective and curative were used to separate the fungicides that could be used shortly after infection (curative) from those that HAVE to be used before infection (protectant). It is important to remember that NONE of the fungicides are eradicates, and once the disease is established in the field, even the best curative fungicides will not kill all the infection sites. Protective applications have been the best control strategy in South America and Southern Africa.
Monte Miles
Research Plant Pathologist
USDA Agricultural Research Service
University of Illinois
A. The triazoles can be used either way – preventative or curative.
Glen Hartman
Research Plant Pathologist
USDA Agricultural Research Service
University of Illinois
Editor’s note: Relative to the questioner’s comments about the Folicur label, the current Asian soybean rust technical bulletin from Bayer CropScience about Folicur (and Stratego) includes this statement:
“Numerous field trials in Brazil have shown that STRATEGO is most effective when applied preventively. FOLICUR is effective when applied preventively and provides some curative activity.”
Posted 4/03/2005:
Q. What is going to happen to red clover with this rust? I raise clover to bale hay for a brood cow herd. Will I need to spray the clover to protect it from rust?
Thanks,
Ed
A. Based on all the available lists of known and suspected alternate hosts for Asian soybean rust, red clover (Trifolium pratense L.) is NOT considered a host for the fungus. (Neither is alfalfa, FYI, per X.B. Yang and others.)
Not only do you not have to spray your hay clover, but you should not. None of the fungicides labeled (Sec. 3 or Sec. 18) are labeled for use on clover. Most, if not all, of those that will be used on soybeans have label restrictions forbidding the feeding of treated forage to livestock.
Several other clovers present in the United States have been shown to be susceptible to the pathogen when inoculated in a greenhouse setting, but as yet have not been observed to host the disease in nature. No doubt they will be scouted if rust spreads this spring or summer.
Clovers infected in greenhouse research are: alyce or oneleaf clover (Alysicarpus vaginalis); crimson clover (Trifolium incarnatum); white clover (Trifolium repens); Japanese clover ( Kummerowia striata); and Korean clover (Kummerowia stipulacea). The government lists of these hosts and other suspected hosts state: “Inclusion of a crop in this list is not an indication of a need to spray fungicides.” Growers are advised to contact local or state Extension specialists for disease-management information.
Information gathered from published sources by Marilyn Cummins, Editor.
Answered and posted 3/21/2005
Q. My question concerns spray nozzles and gpa (gallons per acre) for soybean rust
control/protection. If you are spraying at 20 gpa with 04-air-induction nozzles, I understand this leads to larger droplets than regular 04-flat fan nozzles, but wouldn't it be the same amount of coverage or better and therefore give the same protection since the gpa is the same and more infiltration into the canopy since the droplets
are bigger? It seems to me that the real question is how many gallons
per acre you are using, since coverage is the real issue.
Thanks for your help.
Josh B.
Lincoln County, N.C.
A. In theory, you are right about having more potential for getting the bigger droplets deeper into the canopy. However, many of those droplets will probably not hit the plant or if they do, will not provide the coverage needed for effective rust control. Having larger droplets means many less droplets also.
When you cut the size of the droplet in half, you are actually increasing the number of droplets by eight times. An example would be changing from 500 to 250, which is what we are talking here. With fewer, larger droplets, you may even end up with quite a bit of the product on the ground, where it is not useful.
I am not as concerned about the nozzle type as I am about the droplet size being achieved. We are thinking that droplets in the 200-300 micron size are going to be best for the good coverage. Therefore, selecting the correct pressure to match the nozzle type and orifice size is critical. A chart will be needed to work this out. All the nozzle manufacturers provide this information. If you are going to choose a venturi (air-induction) nozzle, then pressures will need to be considerably higher to get the droplets atomized properly.
Robert Wolf
Assistant Professor & Extension Specialist, Application Technology
Kansas State University
Erdal Ozkan, Ohio State University Extension agricultural engineer, adds:
A. Because Asian soybean tust disease starts from the bottom of the plant and moves up, it's important to get excellent coverage at the bottom. We have a much better chance to get the pesticide active material to lower parts of the plant by using smaller droplets.
For more information on this topic from Wolf, see:
Tips for Ground Application of Fungicides for Asian Rust Control
Rebroadcast of March 16 Asian Soybean Rust Web Seminar featuring Wolf discussing sprayer technology for improved application (audio with slides) and answering questions in detail on the topic.
Web resources for nozzle charts, other company information.
Answered and posted 3/17/2005
Q. A question for Dr. Jim Dunphy of North Carolina State University: Have we had enough cold weather this winter for kudzu not to be able to be a host for Asian rust? What are our chances of a breakout?
Thanks,
Joel P.
Sampson County, N.C.
A. Joel: We've had enough cold weather in North Carolina that I do not expect soybean rust to overwinter on kudzu in the state, or for that matter, anywhere north of central Florida.
Jim Dunphy
Crop science Extension specialist (soybean)
North Carolina State University
A. I agree with Jim's statement. Kudzu is now breaking dormancy along the Gulf Coast and thus far, no rust has been sighted except around Tampa that I know of.
Steve Koenning
Research assistant professor and Extension specialist
Department of Plant Pathology
North Carolina State University
Posted 3/17/2005
Q. I have been reading that spraying by plane for rust is better than by ground. Some reasons are ground rigs release spores that could affect other fields and even the sprayer itself could bring spores to other fields. Also, what percent of damage would a ground rig cause in 30-inch rows? (Yes 30" rows). I'm hearing 3 percent to 5 percent. On an average of just 30 bushel beans, that would be 1 to 1.5 bushels, which would be more than the cost of a plane. The National Agricultural Aviation Association says planes will be available by being able to travel to areas that they are needed. Should a person still have a ground rig on standby just in case?
J.C.
Louisiana
A.
[Here are answers to part of the question. Responses regarding damage from a ground rig are still pending.]
Regarding spreading spores by moving ground application equipment from an infected field, I understand that if the disease comes our way, it will not select one field here and one field there. It will sweep the area with the same wind that blows across the region.
Should a person still have a ground rig on standby just in case?
Yes. If there are enough aerial applicators to do the job in a timely manner, then I would not worry too much about having a back-up plan. But what if there are not enough aircraft, and everyone wants to hire them? Then it would be nice to have a back-up plan.
Although you didn’t ask this, a popular related question is:
Is aerial application as effective against soybean rust as the ground applications?
To answer that question, I refer to a study done by my colleague Prof. Ulisses Antuniassi and his colleagues in Brazil. (UNESP, Botucatu). They compared the fungicide coverage on the leaves and efficacy levels from two ground applications (with cone and XR Flat fan nozzles at 13 gallons per acre), and aerial applications done at 4 different application rates (0.5, 0.9, 1.25 and 3.2 gpa).
They concluded that "soybean rust was controlled by all treatments."
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
More on ground vs. aerial:
In the March 16, 2005, Asian Soybean Rust Web Seminar on sprayer and application technology, Bob Wolf of Kansas State University said:
In fact, it probably doesn’t matter which system you use – we may need a combination of all sources! There are a lot of scenarios where a ground rig is not even usable – wet, muddy conditions or if there is a concern of transporting spores field-to-field.
We’re going to have to use both air and ground applications if we have a large outbreak. Either system alone can’t do it all.
Robert Wolf
Assistant Professor & Extension Specialist, Application Technology
Kansas State University
Posted 3/03/2005
Q. Can you help me understand the "Section 18" labeling? I understand that this is a special "emergency" label, and only applies to certain states that have applied for this exemption. My question lies within application of section 18 labeled products and when they can be applied.
Does the Asian Rust have to be found and confirmed within the state it is to be applied? Or since the discovery of living Asian rust in Florida, does this allow the Section 18 products to be applied in any of the states that have applied for the Federal Exemption?
Thanks for your time,
Doug K.
Illinois
A. Part 1: First of all, there are enough differences in what is labeled how in each state, that experts say a grower, adviser, retailer or applicator should start by checking with his or her state Extension plant pathologist. (See Web resources for soybean rust sample collection and plant diagnostic facilities for several contact lists for Extension, university and state officals.) Another reason for checking with the expert(s) in your state is to see if there is a state label which may have requirements in addition to the federal label and to learn the recommended application timing and practices for your state. Applicators are required to have the physical Sec. 18 label in their possession at the time of application.
That being said, there are some more specific answers for your general question.
This response is from R. Allen Straw, assistant professor, Plant Sciences -- Commercial Vegetables and Strawberries, UT Institute of Agriculture (Tennessee):
"Since Section 18s are generally applied for on a state-by-state or occasionally a regional basis, the pest has usually been observed to be a problem in that state or region. The Section 18s that are being applied for to control Asian soybean rust are known as Section 18 “Quarantine Exemptions.” There was originally concern that meant the disease had to be found in the state before treatment could occur. However, since it was identified in Louisiana (and later eight other states) this past fall, anyone can use the treatments in any state that has an approved Section 18 petition."
This official word from EPA Section 18 staffer Andrew Ertman:
"The way the authorizations are now worded is as follows:
'On November 10, 2004, U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA/APHIS) confirmed the presence of Phakopsora pachyrhizi, the pathogen that causes soybean rust, on soybean leaf samples taken from two plots associated with a Louisiana State University research farm. Because P. pachyrhizi has now been found in the continental United States, all existing EPA-approved section 18s for soybean rust, including this one, are released for implementation in [state name] as the [state regulatory agency] feels is appropriate.'
So basically, all approved section 18s are available for use in all states, regardless of whether soybean rust has been found in that state, as long as the state regulatory agency says it's okay. In this case it would be Illinois Department of Agriculture."
A. Part 2: Here is a USDA document that includes a lengthy Q&A on your Sec. 18 questions and more, from a national perspective:
Common Questions and Answers.
Topics in this PDF document break down as:
A. Section 18 Fungicides Requested by South Dakota and Minnesota
B. Section 18 Status
C. Section 18 Guidance
D. Fungicide availability
E. Fungicide products that do not require Section 18 approval – Full Registrations
F. To contact specific pesticide manufacturers
Here are ones that apply, in general and in principle, to your query:
D. Fungicide Availability
QUESTION: Will the states who received Sec 18s be allowed to immediately use the fungicides so granted once SBR (soybean rust) is found in the continental United States, even though SBR has not yet been found in their state?
ANSWER: Yes. It is noted in the EPA Section 18 approval letter, once USDA/APHIS has confirmed that P. pachyrhizi is present, all existing EPA approved Section 18s for soybean rust will be automatically released for implementation as the state departments of agriculture feel is appropriate.
QUESTION: Will the state where SBR was first detected be able to immediately apply the Sec 18 granted fungicide?
ANSWER: Yes.
QUESTION: Does each state need to provide any additional evidence to EPA beyond the official
USDA/APHIS confirmation, to allow the use of each state’s approved Section 18 fungicides for soybean rust?
ANSWER: No.
QUESTION: Will the States who did not receive Sec 18s be allowed to immediately use the fungicides
granted Sec 18s in other States, even though SBR has not yet been found in their States?
ANSWER: Use of any authorized chemical under a section 18 quarantine will be allowed nationwide at the time the fungal species, P. pachyrhizi, has been confirmed to be present in the continental U.S. or Puerto Rico by USDA/APHIS, at the discretion of the state lead agencies. As noted above, the state lead agency would need to make a crisis declaration in order for applications to begin in a situation where the state had not yet applied for or received approval by EPA for the quarantine exemptions.
[Note:This USDA Q&A was drafted with content/status “as of Nov. 10, 2004,” when 25 states had applied for Sec. 18 exemptions for several fungicides for use on soybean rust, but not all had yet been approved.]
For more:
C. Section 18 Guidance
This link to the IPM Centers Web site leads to a list of states with approved Section 18s and their EPA approval
letters. Each state's official for Section 18s is identified in the state's approval letter, if you should need to check with them about product status in your state in addition to the plant pathology specialists. Look under “Quarantine Exemptions,” then the
fungicide approval letters for your state.
Current EPA-approved labels may be found at www.Greenbook.net, the CDMS Web site, or the EPA Web site. As stated earlier, because some states have state labels in addition to the federally approved labels and because the status is changing frequently, you should check with your state experts to learn that status and see if there is a state label which may have requirements in addition to the federal label. Applicators are required to have the physical Sec. 18 label in their possession at the time of application.
The expert listed on the Integrated Pest Management (IPM) Centers soybean rust home page where this Q&A is linked is:
Kent Smith
Plant Pathologist
Office of Pest Plant Management Policy
USDA Agricultural Research Service
Compiled by Marilyn Cummins, Editor
Posted 3/1/2005
Q. I have probably missed this point, but I still would like to have the answer. Does the rust fungus need a living host plant, or will it survive on a non-living plant (over wintering)?
Dennis
A. Good question that’s not always spelled out when you read about Asian soybean rust. The bottom line is: The fungus has to have living plant tissue in order to survive, winter or not.
“Spores can’t reproduce without green tissue,” says Glen Hartman, plant pathologist at USDA-ARS and the National Soybean Research Center at the University of Illinois. “So in the temperate North, the spores are all going to die. But in Southern areas where you might have some green tissue, they could overwinter on those hosts. As long as alternative hosts are green, the fungus will continue to sporulate.” (From the new Soybean Asian Rust Research Update just published by the North Central Soybean Research Program, the United Soybean Board and the Plant Health Initiative. Order a print copy from NCSRP by calling 1-800-383-1423.)
Put another way, “Rust pathogens are considered to be obligate parasites in that they survive on living plant material. Although the soybean rust fungus may not be able to overwinter in central or northern soybean-production areas of the United States, it may be able to survive the winter months on hosts such as kudzu in the southern United States.”(From the Univ. of Missouri Soybean rust guide).
So that’s why freezing temperatures are said to help stop overwintering of soybean rust -– not because the spores freeze, but because the plant tissue upon which soybean rust depends for survival does.
Compiled by Marilyn Cummins
Editor
Posted 2/28/2005
Q. Can you tell me where to purchase a 20x magnifying glass? What diameter would I be looking for? Should I get a plastic or glass lens? What cost should I expect?
Thanks,
Joe R., CCA
A. Expert recommendations for a hand lens to use to distinguish symptoms of Asian soybean rust on plant leaves in the field range from 10X to 30X, with the majority recommending at least 20X magnification. Most do not mention a preference for glass over plastic, but we’ve been told glass is worth the added cost if only to avoid the lens being scratched as easily in the field. Costs appear to vary from about $23 to $40 and up, depending on whether you purchase a single lens, or, as this University of Wisconsin “Using a hand lens” guide says,
“Some scouts equip themselves with a range of magnifiers - lower magnifications (2x to 10x) to scan larger areas, and higher magnification (20x to 50x) to observe disease symptoms and signs in more detail.” Other guide sheets mention the same thing – because the depth of field and field of view both go down with higher magnification (such as 20X).
None of the guides we read mentioned an optimum or suggested diameter -- they said to chose the style of lens you feel most comfortable using. Your area agronomist or county Extension agent may have additional recommendations.
These sources for hand lens/magnifiers are from the Purdue University soybean rust site:
Gempler’s Tip Sheet: The best IPM tool to carry is a magnifier
Hand lens magnifiers: Kooter’s Geology Tools
Hands lenses and magnifiers: ASC Scientific
Hand lenses, loupes, magnifiers: Miners Inc.
Compiled by Marilyn Cummins
Editor
Posted 2/28/2005
Q. I have a question about Dr. Ozkan's response to a nozzle recommendation. He recommended not using air-induction nozzles because the droplets are too big. I have a Greenleaf Technologies brochure for a twin-fan arrangement that uses a venturi with different size exit tips that produce droplet sizes that range from fine to medium when used at boom pressures above 80 psi. If the droplets are the correct size, why wouldn't they work? And wouldn't the increased pressure greatly improve canopy penetration in later growth stages?
Rob
Iowa
A. Dear Rob,
Let me start answering your question with this general information that applies to all nozzle types and sizes when selecting the right nozzle for application of rust fungicides.
To help applicators select nozzles and use them at the most optimum droplet size range for a given situation, ASAE (American Society of Agricultural Engineers) has developed a classification system. According to this system, spray quality from a nozzle can be classified as: Very Fine, Fine, Medium, Course, Very Course, and Extremely Course.
Fine-to-medium spray quality (approximately 200-300 micron in size, which is two to three times the thickness of human hair) is recommended by nozzle manufacturers for application of fungicides for soybean rust. To achieve this spray quality, choose the right type and size of nozzles and operate them at the appropriate pressure. Nozzle catalogs have charts to help you find out at what pressure the nozzle you picked will produce Fine to Medium quality spray. When drift is a concern, choose the Medium spray quality.
I think you may find the answer to your question in the paragraph above, but let me answer your specific question: Can air induction nozzles be used for application of rust fungicides?
The answer is “Yes,” with some caution. You can use air-induction nozzles as long as the spray quality is fine-to-medium. Some air-induction nozzles give you this spray quality at medium to high pressures (70-80 psi), and some at pressures as high as 120 psi, depending on the size of the nozzle. When you operate a sprayer at very high pressures, you may need to consider operating ranges of the sprayer components. For example, the pump may not be suitable to be operated at such high pressures, or the pump may not be able to maintain the desired flow rate as the pressure is increased (as is the case with some centrifugal pumps).
In short, if a high pressure setting will not create any restrictions in your spray delivery system, you picked the right size air-induction nozzle, and you are able to produce fine-to-medium spray quality, then you should be able use the air-induction nozzles successfully for application of rust fungicides.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
Posted 2/22/2005
Q. I have purchased a used John Deere Hi-Cycle sprayer, and the nozzles are set up on 30-inch spaces. Is there any way I can use that spacing? I sprayed with it last year with 110 degree nozzles and had excellent results. Any help appreciated.
Paul
A. Twenty-inch spacing is more common than 30-inch spacing, but you can use it if you are paying careful attention to two things:
1. proper boom height and
2. spray drift.
I assume the nozzles you are referring to are flat-fan nozzles. All flat-fan nozzles require proper overlap of adjacent spray patterns to obtain a uniform coverage across the boom. The optimum boom height recommended by manufacturers for 110 degree nozzles at 30-inch spacing is 20 to 22 inches (about 4 inches higher than what is recommended for 20 inch spacing). As long as you maintain this boom height, you will be okay with a 30-inch spacing. However, the 20-spacing will give you better protection against spray drift, which is a major problem for many growers. Lowering the boom 4 inches by using a 20-inch spacing will provide you an added cushion against drift that you may like. Also, keep in mind that keeping the boom closer to the ground reduces the influence of turbulence around the boom to distort the spray pattern.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
Posted 2/22/2005
Q. I have row banders that I use when I spray herbicides on my crops. If I used these with TwinJet nozzles, would I be getting extensive-enough coverage to control soybean rust? The banders I use have the capabilities of three nozzles per row using an application kit like the one TeeJet sells. One nozzle is over the top, and the other two are directed on either side of the row. I can either use all three nozzles or can use only the two directed at the sides.
Thanks,
Al R.
Iowa
A. If I understand correctly, you are talking about using a directed application kit with three nozzles: one nozzle directly over the row, and the other nozzles are on both sides of the row, spraying toward the row crop. I believe more people use cone nozzles than even flat fan nozzles (such as TwinJet) with directed applications.
Directed application is such a good concept that regardless of which of the two types of nozzles you use, you are likely to get a much better coverage than using only one nozzle over the row. The concern I have using the TwinJet nozzles is that you may be running the risk of generating a spray made up of mostly fine droplets. With directed spraying, you are already dividing your total flow rate to three nozzles. This will require using small orifice nozzles such as size 2-3. If you further divide the spray to two by using TwinJet, you may actually be spraying with size 1 nozzles (0.1 gpm @40 psi). This will tremendously increase the number of small, drift-prone droplets. This is not what you want to do.
So, stick with cone nozzles, or use single flat-fan nozzles with an even pattern. By the way, you must be one of few people growing soybean on 30-inch rows. Directed spraying may be a viable option for people like you if soybean rust arrives early in the season when there is still clearance between rows. Once the canopy closes when beans are fully developed, you will not be able to use directed spraying.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
Q. Ok, so kudzu hosts the darn stuff (Asian soybean rust). My question is, can I at least get some satisfaction that it KILLS the kudzu????
Bob B.
Indiana
A. Rust gets along very well on kudzu. Unfortunately, it doesn’t seem to hurt the weed real badly. Sorry, Bob.
Jim Dunphy
Crop science Extension specialist (soybean)
North Carolina State University.
Q. Could you please
tell me what style of tip, recommended pressure, tip spacing and any other
information you may have so that I can get my sprayer ready now to apply
fungicides?
I work full-time for a farm machinery dealership and also farm, so I need
to be ready this winter for anything that may happen this coming growing
season.
John
Indiana
A. Nozzles
with a flat-fan pattern, compared to cone pattern, seem to be better choices
for soybean rust. However, we are not recommending use of air-induction
nozzles to treat rust, even though they provide flat-fan patterns. These
nozzles produce relatively courser droplets, which do not provide the
desired coverage for fungicides in soybeans.
Set up your sprayer
so that the nozzle spacing is 20 inches, and then adjust the boom height
(above the target) so that proper overlap is achieved. Check the nozzle
catalog for the proper boom height depending on the spray pattern angle
of the nozzle.
A small size (size
2 or 3) Turbo Teejet Duo at 60-70 psi is a better choice than the same
size TwinJet. I would not recommend size 2 and 3 TwinJet nozzles being
operated at higher pressures, because they would create too many very
small droplets that will not penetrate into the canopy. If you will be
using TwinJet nozzles, the minimum size you should pick should be size
4 (TJ 8004).
Here are my overall
recommendations:
Choose the appropriate
size and type of nozzles and operate them at a pressure that will allow
them to produce small- to medium-size droplets. (Nozzle catalogs have
info on which nozzles at what pressure produce droplets that are categorized
as "small" or "medium.")
Calibrate the sprayer.
Keep spray volume (application rate) above 15 gpa for best results.
Try running the sprayer at slightly higher pressures than usual. Higher
spray pressures usually help the droplets penetrate into the canopy better.
If spray drift is a concern, you may use some of the “low-drift”
nozzles (other than air induction nozzles). These nozzles allow you to
increase the pressure without increasing the number of small, drift-prone
droplets. Operate these nozzles at slightly higher pressures (60-70 psi)
than usual.
To improve coverage, if applicable, use directed spraying.
Use twin nozzle/pattern technology. Two nozzles (or spray patterns) angled
(one forward one backward) work better than single nozzles spraying down.
Air–assisted spraying usually provides the best coverage and droplet
penetration into canopy when beans reach their full or near-full growth
stage.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
Q. What information
can you give me about the ESP series Spra-Coupe? This is an electronic
spray process that gives the spray an electronic charge so it is attracted
to the green foliage.
Troy
A. Several types of electrostatic sprayers exist. Some are coupled
with air assistance (such as the ESS system at http://www.maxcharge.com/home/default.asp
). Some others, like the one that you are talking about, do not use air
assistance. The electrostatic sprayers without the air assistance have
not consistently shown any benefit (in terms of drift) compared to conventional
spraying. I can probably say the same thing for coverage and penetration
of droplets. However, electrostatic nozzles with air assistance seem to
provide better drift control, coverage and penetration into the canopy.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
Q. I need information on air injection to be used on my 60-ft. three-point-hitch
boom for fungicide application on Asian soybean rust. Thank you.
John K.
A. Air-assisted
sprayers provide the best results for soybean rust control. There are
not too many manufacturers of air-assisted sprayers, however. The major
manufacturer is HARDI® Inc. Another manufacturer of air-assisted sprayers
is Spray-Air Technologies Ltd. The atomizer they use on their air-assisted
sprayers is called Shear Guard Plus. Here is a grower’s review of
his experiences using a Spray-Air system from the Manitoba - North Dakota
Zero Tillage Farmers Association Web site.
Dr. Erdal Ozkan
Extension Agricultural Engineer
Ohio State University Extension
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