Cooperative Extension Service 

Institute of Food and Agricultural Sciences

Hendry County Cooperative Extension Office
PO Box 68
Labelle, Florida 33975

             Southwest Florida Vegetable Newsletter

September/October 2000


      Note from Gene
      Telone and Weed Control Options - Post Methyl Bromide
      New Federal Rule on Pesticide Residue May Cause Disruption of Food Supply
      Scouting For Diseases in Florida Vegetable Fields
      Disease Control
      Receipts From Florida
      Biotech foods pose no risk
      Microbes in Transplant Mix Boost Yields
      Health and the Environment
      New Organic Rules Released
      Pesticide Potpourri
      Environmental Concerns
      Fertilizer Costs May Rise
      Rely Receives EPA Registration
      Ag Chem Labels on Computer CD and Web Too
      The Lighter Side


November 5-8         46th Annual Meeting of the Southern Crop Protection Association
                                Amelia Island, Florida
                                Contact:  912-995-2125

November 6-9         International Methyl Bromide Alternatives Conference
                                Orlando, Florida
                                Contact 863-956-1151.

November 10-11    The 17th Hydroponic Grower's Conference, “The Farm of the Future - Today,”
                                Orlando, FL.
                                Contact CropKing at (800)321-5656 or visit

November 16         Vegetable Growers Meeting - Weed Control in the Post-Methyl Bromide Era.
                                SWFREC Immokalee, Florida.
                                Contact 863-674-4092

December 9            Suwannee Valley Field & Greenhouse Growers Short Course and Trade Show
                                Suwannee County Agricultural Coliseum, Live Oak. Florida 8:00 am - 5:00 PM.
                                For more information, call 904-362-1725
Return to Index
Note from Gene

Gene McAvoy 
Vegetable Extension Agent II 
Hendry County Extension Office 
PO Box 68 
LaBelle, Florida, 33975 

Hope this finds you all well as we enter a brand new growing season.  To me, one of the great things about working with agriculture and vegetables, in particular, is the fresh promise and renewed hope at the beginning of every season as ground is prepared and young plants are set in the ground and begin to grow and flourish.  This sense of optimism  is certainly one of the non monetary rewards enjoyed by vegetable growers.

Acreage appears to be down from last season, perhaps this will help out in the marketing arena and will bring growers some better prices than those they endured throughout the 1999 - 2000 season.

As we all know price is linked with demand, according to Dr John Van Sickle, economist with the University of Florida, the long term trend indicates a greater demand for vegetable and vegetable products, which is a good sign  for the future.  Americans are becoming increasingly health conscious and are exploring dietary improvements as a means of achieving a more healthy lifestyle.

It is widely acknowledged that there are naturally occurring compounds found in plants, especially fruits and vegetables,  which support specific bodily health functions.  While there has been a wide range of claims and benefits attributed to the use and consumption of  vegetables some of which "stretch" science to the absolutely ridiculous, there is a growing body of scientific evidence that supports the role of  diet in a healthy lifestyle.

Diet including the increased consumption of vegetables could play a role in the prevention and treatment of at least four of the leading causes of death in the United States, namely cancer, diabetes, cardiovascular disease and hypertension.  The National Cancer Institute estimates that one in three cancer deaths is related to diet and that eight out of ten  cancers have a nutrition/diet component.

The Harvard Medical School has demonstrated a strong  correlation between the consumption of tomato products and the reduced risk of prostate cancer, leading to further research  on lycopene.  Lycopene - the carotenoid found in tomatoes that gives them their red color, has been shown to have potent anti-oxidant properties, which plays a role in cancer prevention.

It seems that your mom was right - did you eat your vegetables today?  Maybe vegetable growers need to lead by example and take a more active role in cultivating this demand. Eat more veggies - you will look and feel better.
Return to Index
Telone and Weed Control Options - Post Methyl Bromide
The loss of methyl bromide in the very near future will represent a time of change for most vegetable growers.  Soilborne pest control always has been a challenge for growers, but the loss of methyl bromide may force some growers to make drastic changes in the way they farm.  Most of us have forgotten how to apply herbicides and which herbicides to select for weed control in the bed.  Some of us never knew because we entered farming after methyl bromide became the industry standard.  There are few farms with the proper application equipment readily available and gearing up to meet the demands of an age without methyl bromide will be demanding.  While growers have several options for control of nematodes and soilborne diseases, there are few options for weed control in the bed.

The most significant pest for growers will be weeds.  We have few options for them and they are the most visible pests.  A grower does not see nematodes and he may not see the manifestation of some soilborne diseases until late in the season, but he generally sees weed problems early in the season.  When growers complain of fumigant failure, it is usually due to the appearance of nutsedge or other tough weeds growing through the mulch film or out of the plant holes.  As a result, you, as growers, need to start learning how to use the replacements now, while you still have time.

In January 2001, there will be a 50% reduction in the availability of methyl bromide.  No one knows what the price will be, nor do they know what concentration will be available.  Rumor has it that it will be offered as a 50/50 mixture with chloropicrin.  That would represent 175 lbs of methyl bromide per treated acre, if a grower were using the standard  rate of 350 lbs of 67/33 formulated product.  This rate of methyl bromide is probably at or below the minimum quantity necessary for good weed control, especially for nutsedge, under ideal conditions.  Few of us ever have ideal conditions, so this means that nutsedge will become more widely distributed and more prevalent with time.  Even with methyl bromide, we have seen nutsedge spread and the seriousness of it as a weed increase.  Without methyl bromide, there is a chance that nutsedge will become an even greater problem.

For some time we have been trying to address the personal protective equipment (PPE) issue with Telone products.  For most growers, this is the biggest hurdle to the adoption of Telone (II, C-17, and C-35) as an alternative to methyl bromide, outside of the nutsedge control issue.  The approach of most scientists has been to shift from in-bed application to broadcast application of Telone products.  This eliminates PPE for all but one worker: the tractor driver making the application.  Results of this type of application are less than conclusive.  Most of the research has been conducted on commercial farms where methyl bromide has been used in the past.  Seldom do we encounter populations of rootknot nematodes or high incidences of soilborne disease.  We have obtained some results with the control of purple nutsedge; however, these results have been varied.  In several trials on tomato, application of Tillam preplant incorporated and broadcast application of Telone C-35 have produced tomato yields equivalent to methyl bromide or Telone C-35 in the bed with Tillam.  We even have observed residual weed control in the row middles from our broadcast application of Tillam, but not every time.  We also have seen what appears to be improvement in rootknot nematode control with broadcast application in at least one trial.  What we do not feel comfortable with, at this time, is control of soilborne diseases with broadcast applications of Telone combined with chloropicrin (Telone C-17 or C-35).  More research is needed.

Some of the research has focused on identification of the best applicator for broadcast and based on limited data, it appears that the Yetter coulter rig is doing the best job, in most situations.  However, there have been some problems even with this rig.  One of the big pluses for coulters is their ability to slice through trash in the field.  We do not drag tying twine and plastic mulch as we do with sweeps, knives, or other equipment.  One of the objectives of this applicator is to put the Telone deeper in the soil so more nematodes are killed.  If the soil is too wet, this can result in a longer residual life for Telone and an increased incidence of crop damage or a longer waiting period from application to planting.

Regardless of what fumigant we are using, weed control will be the greatest challenge. Each vegetable crop has a short list of herbicides labeled for use in them.  Tomato growers are perhaps the luckiest for they have Tillam which does provide some control of nutsedge.  However, even Tillam requires a certain amount of attention to detail to achieve any level of success.  Most growers will find that they will have to shift their thinking from weed control to weed management.  Weed management will dictate that those fields with heavy infestations of nutsedge should be the primary recipients of any available methyl bromide.  This is an investment for the future of those fields.  Growers also should do more to manage weeds in the off-season.  Practices like cover cropping can impact nutsedge populations with the selection of crop often being the most important aspect.  For example, nutsedge populations actually have been higher where millet was grown than where no cover crop was planted.  Iron clay pea and some other broad-leaved cover crops have reduced populations.  Remember one thing, though: these changes in populations are only temporary.  Thus, my emphasis on management rather than control.  Even methyl bromide does not completely eradicate nutsedge.  If it did, a grower would not have to retreat fields so often.  Double cropping encourages soilborne pest resurgence, even resurgence of nutsedge.  Cultural programs combining the application of herbicides, such as Roundup, during the offseason with cultivation can help with nutsedge management, but they will not eliminate it.  They reduce it to a manageable level for a short time and if the program is abandoned for any length of time, nutsedge quickly returns.

Along with selection of herbicides based on label for a specific crop growers will need to know something about their specific weed pests in each field in order to choose the right herbicide.  No one herbicide controls all weeds.  Growers also will have to consider plant back restrictions of various labeled products (Table 1).  If you are going to use Devrinol on pepper and will be following it with double cropped cucumbers, you may have a problem because the plant back restriction on Devrinol is 12 months and cucurbits are not listed on the Devrinol label.

Whatever herbicide you use, you will have to learn how to apply it.  You need a sprayer dedicated to herbicides to minimize the potential for accidental application of residues to other crops and you need to know how to calibrate the sprayer and operate it properly.  Most problems with herbicides are due to mistakes made during calibration and application errors, like excessive overlap between nozzles.  These may seem like very basic issues, but it is usually the little details that cost you money.  Many of these herbicides need to be incorporated into the soil and your choice of implement can influence results.  Each herbicide has its advantages and limitations.  I could tell ten people how to calibrate, apply and incorporate Tillam, along with all the little tricks I have learned, and I bet at least one person would have either crop damage or poor control.  Yet, when quizzed about what the grower did, I bet I would hear that they did everything just the way I instructed.  Sometimes you never figure out what went wrong, but most times I hear something weeks later that confirms what I suspected; someone did not follow ALL of the instructions closely.  In order to help you get up to speed on the principal herbicides with which you will be working in the near future, I want to spend the rest of my time discussing them and what I think you need to know, as briefly as possible.  I do not have time to cover all of the vegetable crops nor do I have enough experience with each of them to discuss them, so I will limit my comments to those crops and herbicides with which I am familiar.

Table 2 lists the principal mulched vegetable crops and the herbicides registered for use on them.  Since some herbicides, such as Devrinol, are labeled on more than one crop, I will focus on the herbicide rather than specific crops.


Alanap controls mostly grass weeds.  It is usually used in combination with Prefar on cucurbits.  Incorporation is not required, but a shallow incorporation is allowed and can improve performance somewhat.  The residual life of Alanap is fairly short and the label lists no plant back restrictions.


Soil incorporation is recommended with Prefar, but only shallow incorporation.  Prefar controls predominately broadleaf weeds and has a 120 day plant back restriction for non-registered crops.  This should not pose problems unless a cucurbit crop is abandoned and a grower attempts to plant a different crop.


Curbit is the same thing, as Sonalan which was labeled on cucurbits for about one season.  It is effective against many grass and broadleaf weeds, but tends to be a bit “hot”.  Under cold or wet soil conditions it can cause crop injury.  Crop damage in a cold spring was responsible for the manufacturer removing cucurbits from the Sonalan label.  It should not be incorporated; it only should be used as a surface spray.  It should never be used under polyethylene film mulch.  Use under mulch may result in crop damage.  The plant back interval varies, depending upon crop, but ranges from 8 to 13 months for non-labeled crops.


This is an old compound which has never found much favor with growers.  Frequently it does not work very well and the residual life appears to be rather short; however, there are some things you can do to improve performance.  A lot of the problem with Devrinol in the past was due to how it was applied.  Devrinol breaks down quickly in sunlight and without overhead irrigation we have no way to move it into the soil surface to protect it from photo destruction.  Because it is considered to be completely degraded after 24 hours of exposure to bright sunlight, mechanical incorporation greatly improves its performance.  It is effective against a wide range of grass and broadleaf weeds, but it is very weak on nutsedge, especially at the current labeled rates for tomato and pepper.  Strawberry allows a 2x increase in use rate over that registered for tomato and it makes a big difference in weed control.  If you are going after small seeded annual weeds, then a surface application just prior to laying plastic mulch will probably do.  You may want to improve upon that by shallowly incorporating it in the bed surface, but if you are going after nutsedge, you should incorporate to the full depth of the bed because nutsedge will emerge from throughout the bed profile.  The equipment used for incorporation is important and will be discussed under Tillam.  How effective is Devrinol against nutsedge?  I have observed a range of control from no control to about 60 to 70%, but lower is more the norm.


Tillam is another old compound, having been around about 30 years now.  It is labeled only for tomato, tobacco, and sugar beets.  Until last fall there was a label restriction against using it in hand transplanted tomatoes.  That restriction has been lifted for about 3 years to give the manufacturer time to generate the data necessary for a permanent label amendment.  Tillam is fairly effective against nutsedge and many other weeds, but its best attribute is the capacity to provide some control of nutsedge.  Tillam is very volatile and must be mechanically incorporated as soon as it is applied.  The best way to do this is to mount your spray boom on the front of your incorporation implement.  Occasionally I observe a failure with Tillam, but it usually can be explained.  The incorporation method for Tillam can be quite important, not only for good weed control, but also for minimization of phytotoxicity or yield effects.  Field research has demonstrated that Tillam, if not applied and incorporated properly, can be quite phytotoxic to tomato.  Incorporation with a grove disk (a shallow cultivating disk) or a field cultivator (S-tine harrow with crumbler bars) appeared to provide sufficient mixing of Tillam for good weed control and no crop injury.  Thorough incorporation with a light disk or a field cultivator is the preferred method and can provide results comparable to methyl bromide when combined with Telone C-17 or Telone C-35.

Tillam must be applied at the full label rate of 2/3 gallon (86 oz.) per treated acre to be effective.  Reducing the rate will reduce efficacy greatly.  Rates in excess of 2/3 gallon per acre may cause crop injury and reduce tomato fruit production.  Small discrepancies in rate generally are not a problem.  Typical damage consists of stunting and may include malformed leaves.  Foliar chlorosis is not normally observed and would suggest some other causal agent.  Good agitation in the tank is important and spray pressure should be maintained below about 40 psi to minimize spray drift and assure that all product is going where you want it - on the soil.

Tillam should be applied uniformly to the entire field from ditch to ditch so there is no chance that non treated soil can be pulled into the bed.  Not only should the sprayer be checked for uniformity and accuracy of application rate, but Tillam also must be incorporated properly.  Research has demonstrated that Tillam must be mixed thoroughly into the soil to the depth of the bed to provide good nutsedge control.  Since bedders pull soil from about 6 to 8 inches deep, Tillam must be incorporated to at least this depth.  Deeper mixing also may be advantageous for broadcast field applications.  For example, nutsedge control has been achieved even in the row middles when the broadcast, pre-bed application of Tillam was deeply incorporated and all of the Tillam treated soil was not moved into the finished bed.  If nutsedge is not the target weed,  Tillam can be applied more shallowly, but movement of too much nontreated soil into the bed can reduce efficacy.  A shallow incorporation on the bed surface would provide control of small seeded annual weeds, such as crabgrass, but would not provide good nutsedge control since nutsedge easily can emerge from deeper in the bed.

Method of incorporation for Tillam can be quite important, not only for good weed control, but also for minimizing phytotoxicity or negative plant growth and yield effects.  For example, in one experiment plant stunting was observed when Tillam was incorporated with bedding disks.  Bedding disks tend to fold soil and layer surface applied materials rather mixing them thoroughly.  A concentrated layer of Tillam in the soil can cause delays in plant development, early season phytotoxicity, and restriction of root growth until the herbicide degrades to a point where it no longer impedes root development.  In the study in question, tomato fruit production was reduced to about 2/3 of what it should have been and maturity was delayed by approximately 2 weeks.  Application of Tillam in the throat of a bedder, expecting the bedder to properly mix it into the soil, is a recipe for disaster similar to the use of bedding disks or disk/hillers.  The mixing is not thorough enough with this equipment and poor weed control and crop injury are almost certain to follow.  Thorough incorporation with a disk, rototiller, or a field cultivator is the preferred method and can provide results comparable to methyl bromide when combined with Telone C-17 or C-35.  Incorporation with a disk may require two passes to thoroughly mix Tillam, whereas under good soil conditions a field cultivator (s-tine harrow) usually can achieve the desired extent of mixing in one pass.  A rototiller is the best incorporation implement, but they are slower than a disk or cultivator, require more horsepower to operate and are not as readily available as a disk or cultivator.

Speed of incorporation can be important for good mixing.  Generally when using a disk or a field cultivator, ground speed should be at least 6 mph in order to throw the soil more and assure complete working of the soil.  At slower speeds soil mixing is not as good because of less action.  With disks, the amount of set can be a factor in mixing.  Maximum set is to be discouraged because it tends to bury the herbicide more than desired and disking at this stage is strictly for herbicide incorporation, not for land preparation where maximum set to the gangs is more commonly practiced.  The extent of set should be enough to mix the soil to the desired depth without leaving the soil surface in a less than acceptable condition, such as deep troughs or ridges, and not so much that the ground speed can not be maintained above 6 mph.

Soil temperature and moisture conditions can be very important in determining the level of weed control achieved with Tillam.  For example, soil which is too dry promotes volatilization of Tillam into the atmosphere.  A dry sand also tends to be warmer than a moist one and volatilization losses can be rapid.  Some of the worst performance observed in research occurred when Tillam was applied to a soil that was on the dry side and the cultivator fluffed the soil, allowing the soil to dry even more.
 In addition to volatilization, performance can be lost due to poor mixing.  Soil moisture can play a significant role in this.  A soil which is very dry does not “flow” as well through a disk or cultivator as does one with optimum moisture content.  Good mixing is dependent upon the soil particles having some adhesion to one another so that the soil is more easily turned and blended rather than moving more like a liquid as it does when it is too wet or dry.  If the soil is wet, it becomes sticky and will not break apart as it is disturbed, moving around field cultivator sweeps or points much like butter would.  This can result in uneven distribution of Tillam in the bed when the bed is formed which, in turn, can mean areas where weeds germinate and emerge.  It  is very difficult to mix dry soil; the soil tends to fall out of the disk blades prematurely and does not “turn over” when a field cultivator moves through it.  Soil moisture should be adequate for good seed germination so that it mixes well when Tillam is incorporated and so the weed seed and tubers germinate quickly.  Since about one half the Tillam is present in the soil after 2 weeks, it is important that weed seed germinate and tubers sprout soon after application when the maximum amount of Tillam is present.

Nutsedge often becomes a problem on bed shoulders, even with the use of methyl bromide.  This is because the shoulder gets hotter than most of the rest of the bed and pesticide loss is greater under higher temperatures.  Tillam can exhibit the same behavior, presumably due to volatilization and faster degradation on shoulders.

Soil should be free of weeds and debris should be well decomposed, as it should be when applying methyl bromide.  Some growers allow some weed growth to be disked into the soil at time of fumigation and expect good efficacy.  While this often works with methyl bromide, it is a poor practice in which to engage when using any of the other fumigants and herbicides.  Tillam will not control weeds once they have emerged from the soil and it is important that it be applied prior to germination and emergence.  This is especially important with nutsedge.  Fields should be clean cultivated for several weeks prior to Tillam application and all plant debris should have decomposed enough so that it is no longer recognizable.

Lastly, you should not expect Tillam to control ALL weeds.  If you do not have nutsedge in your field, you may wish to select another herbicide.   Herbicide selection should be based on weeds expected to be a problem.  Thus, knowing the field history is important.


Many of the same comments made for Tillam apply to Treflan.  Just like Tillam, Treflan is a very volatile product and must be incorporated thoroughly immediately after application.  Immediately means within seconds.  The use rate must be closely adhered to or you may experience crop injury.  Although it does not control nutsedge, Treflan has an advantage in that it is labeled on quite a few vegetable crops.  It is especially effective against grass weeds. The plant back restrictions vary by crop, but in general average 5 months for non-labeled crops.  Proper incorporation is a must with Treflan.  The same equipment as is used with Tillam can be used with Treflan.  Refer to the comments under Tillam for more information on this.

Growers will be facing challenges in the post methyl bromide era.  Perhaps their greatest challenge will be effective weed control, especially nutsedges.  Attention to details can make a big difference in how effective your herbicide program is. Knowing field histories will become increasingly important in the future because growers will be targeting specific weeds within fields.  Greater emphasis will need to be placed on year round weed management rather than seasonal weed control.  Yes, life without methyl bromide will be a challenge, but that is what farming is all about: challenges.

FACTS Proceedings 2000
James. P. Gilreath, Associate Professor, Gulf Coast
Research and Education Center, University of Florida,
Institute of Food and Agricultural Sciences, Bradenton, Fla.

Table 1.
  Principal herbicides for use in vegetable crop beds and use considerations
Herbicide  Incorporation required  Plant back restriction
Devrinol no, but aids nutsedge control   12 months for nonlabeled crops
Alanap no, but shallow incorporation is allowed None listed on label
Curbit no, do not use under mulch varies 8 to 13 months for nonlabeled crops
Prefar  yes, shallow  120 days
Tillam yes, immediately  none listed on label
Treflan/Trilin yes, immediately  5 months on average

Table 2
Some of the major vegetable crops grown in Florida which are dependent upon methyl bromide as a soil fumigant and the principle herbicides labeled for use on them and the efficacy of those herbicides against nutsedge weeds
Nutsedge Control
Tomato Tillam yes, but not consistent
Sencor/Lexone not in bed, no
Treflan/Trilin no
Devrinol fair to no control, erratic
Pepper Devrinol fair to no control, erratic
Treflan/Trilin  no
Strawberry Devrinol fair to no control, erratic
Cucumber, squash, melons Prefar no mostly broadleaf weeds
Alanap no, mostly grasses
Curbit  not under mulch, no, grass and broadleaf
Tillam, Devrinol, Prefar, Alanap and Curbit are older herbicides with limited markets and therefore less potential for market development.  Additional new registrations are unlikely with these products.
Return to Index
New Federal Rule on Pesticide Residue May Cause Disruption of Food Supply
A new approach to the way the federal government handles pesticide residues in food already in the distribution chain is signaling alarm bells in the produce industry.

The new policy, triggered by the Food Quality Protection Act (FQPA), has been proposed by the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) to cover the insecticide methyl parathion.  This material was effectively banned in August of 1999.   This policy for methyl parathion would set a precedent and would apply to all crop protection materials that are voluntarily canceled.

In the past, EPA recognized that such a cancellation leaves inventories of foods that had residues of pesticides that were legal at the time the food entered the pipeline.  These foods were then allowed to clear the food distribution system.  The time needed for such foods to clear the system range from days (fresh produce) to years (frozen foods).  Only then would the residue tolerances be revoked.

Under the new policy, EPA says it will begin revoking tolerances of foods within 180 days of voluntary cancellation.  The job of enforcing the revocations would be up to the FDA.  Unless a food handler can prove that residue present is the result of a legal application, the food would be out of tolerance - or “adulterated” - and would then need to be removed from the distribution chain.

Food industry organizations have expressed their concerns to EPA and FDA officials without result.  A comment period on the new rule has just closed.  Now officials are attempting to find a legislative remedy to the problem.  They stress the argument is not about ends, but about means.

 “The goal for both EPA and us is the same - moving food that has been treated on a product that has been canceled through the pipeline,” said Jerry Hill, Washington D.C. representative for the National Potato Council.  “Their way would create problems in the marketplace.  Our way is to say ‘you’ve already canceled us.  Let whatever’s been treated move through the marketplace and then revoke the tolerance at that point.”

At any time over the next several weeks or months, the two agencies can come out with the new rule.  Hill does not expect the comments received to change the stance of the agencies. Thus, the only realistic opportunity to stop the rules from being implemented is by legislation, which would almost certainly take the form of an attachment to one of the appropriations bills now under consideration.

 The Minor Crop Farmer Alliance (MCFA) filed comments in opposition to the regulations.  MCFA is concerned the new rule has the potential to cause serious disruptions in both the domestic and international marketplaces.  Processors and other food handlers may be reluctant to purchase foods that have been treated with the affected pesticides at all.

A company may conclude it doesn't want to get involved in the thicket of paperwork required to prove when a material was actually applied, said Hill.  So, the company could just tell a grower it will take no more raw product after the date of a tolerance cancellation, and move what product is in the pipeline without extensive record keeping.

The safety of the nation's food supply is not an issue; the issue revolves around how treated food will be distributed and not whether it should be distributed.  Yet, some food industry leaders are concerned that actions arising from the change in policy may be construed as a food safety issue.

“If you have documentation that you treated a crop such as spinach when the use was still legal and in place, there is no problem under the new rule,” said Cindy Baker of Gowan Company, a member of EPA's Committee to Advise on Reassessment and Transition.  “But activists can make the charge that the tolerance was changed, so that anything that has residue is adulterated.”

What happens if a food product is the result of a mixture of raw products, such as a blended fruit juice or bag of mixed frozen vegetables?  The FDA gives the example of a blended frozen pear and apple juice concentrate product.  The food processor has records to show that the pear concentrate was purchased before the cancellation of the pesticide.  However, because the product is a blend, the company would also have to prove the apple concentrate also met the provisions of the law.

How would the food company do this?  FDA says the firm would have to have documentation advising its suppliers to not provide apples treated with the pesticide in question, documentation from the supplier indicating it has not provided apples treated with the pesticide, and additional documentation proving the supplier had tested the apples for residue.

This example demonstrates the burden on the food marketing system the new regulation would create, according to MCFA.  In its comment on the rule, MCFA noted the added cost of establishing such a pesticide residue testing program, a cost that is difficult to pass on to the consumer.

“The net result of the FDA’s policy is counter to the orderly marketing of foods,” according to the MCFA comment.  The buyer is actually encouraged to include a specification that the food it is purchasing has not been treated with canceled pesticides.  If such advice is followed, what happens to the inventory of foods which cannot meet this specification?

Lee Dean
The Vegetable Growers News
September 2000
Return to Index
Scouting For Diseases in Florida 
Vegetable Fields
Scouting for diseases is a fundamental component of any integrated pest management program for vegetable crops in Florida.  The sampling unit is the same as that for insect assessment; e.g., a 6 row/ft. sample for every 2.5 acres of tomato, a 1 m row sample every 2.5 acres of snap bean, etc.  Foliar disease incidence is evaluated using the Horsfall-Barratt rating system.  Diseases that cause whole plant loss are recorded as percent plants infected per sample.  A detailed description of the scouting techniques can be found in the latest edition of the Florida Tomato Scouting Guide.

The relationship between pest levels and treatment protocols is fundamentally different for disease and insects.  Since most disease prevention chemicals must be applied before pathogen propagules arrive, scouting and application of pesticide at action thresholds do not work well for disease management.  Dangerous levels of disease have been shown to develop when scout and spray regimens are used for high r-value diseases.  Therefore the emphasis on disease scouting is correct identification of problems and correct selection of control options.  Additional emphasis is placed on detection and proper identification of signs of the pathogen, as opposed to heavy dependence on symptomatology alone.  Signs include sclerotia; mold and mildew growth; fruiting bodies, such as pycnidia; and bacterial streaming.  Scouts are also encouraged to perform simple tests to detect pathogen signs.  These include bacterial streaming and construction of simple moisture chambers to enhance fungal growth.

FACTS Proceedings 2000
Return to Index
Disease Control
Agricultural Research Service scientists and cooperators are searching for environmentally friendly ways to control plant diseases.  In the case of Fusarium wilt, beneficial strains of Fusarium are being used to control plant pathogenic strains.  In tests so far, some of the beneficial Fusarium are winning, and that's good news for tomato growers who need an alternative to the chemical fumigant methyl bromide.

The scientists’ enemy is a pathogenic strain of Fusarium oxysporum that causes Fusarium wilt.  This affects many vegetables, melons and other crops such as basil, causing severe losses.  Fusarium wilt, however, is a particular problem for tomatoes since there is a new race of the pathogen that attacks tomatoes.  For now, methyl bromide is used to keep this pathogen at bay.  But by 2005, methyl bromide will be phased out.  So scientists are studying alternatives that are environmentally safe while still effective against the pathogen.

Deborah R. Fravel, a plant pathologist at the USDA/ARS' Biocontrol of Plant Diseases Laboratory in Beltsville, Md., and George Lazarovits, research scientist and team leader with Agriculture and Agri-Food Canada in Ontario, Canada, are working in a cooperative study to find methyl bromide alternatives.  In their studies, they're pitting harmless Fusarium species and other “good guy” biocontrol organisms against the wilt-causing F. oxysporum.  The researchers tested several beneficial strains of F. oxysporum against the wilt-causing strain.  They found one strain, CS-20, reduced wilt by 49.6%.  They also mixed beneficial strains of a fungus (Trichoderma virens strain G1-3) and a bacterium (Burkholderia vietnamiensis strain Bc-F).  The fungus/bacterium treatment reduced wilt incidence by 41.6%.  Also, CS-20 and the fungus/bacterium combination treatment significantly increased both the weight and number of tomatoes on the plant.

Now, researchers must figure out how the biocontrol mechanisms work.  Some biocontrol agents work by competing with the pathogenic strains for nutrients and space.  CS-20 seems to pump up the plants’ natural defenses against pathogens, a reaction called “induced systemic resistance,” according to Fravel.

Deborah Fravel can be reached at the ARS Biocontrol of Plant Disease Laboratory, Beltsville, Md., 301-504-5080,
fax 301-504-5968,

Citrus & Vegetable Magazine
September 2000
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Receipts From Florida
Receipts from Florida agricultural products totaled nearly $7.1 billion in 1999, according to the Florida Agricultural Statistics Service.  The 1999 tally was 1.5% higher than the 1998 figure.

Sales of citrus fruits amounted to $1.92 billion, or 14.4% gain compared to the previous year.

The total receipts for vegetable and melon crops was 11.6% lower than in 1998.  Tomatoes and green peppers accounted for most of the loss in sale value.

Field crops registered a modest gain of 2.5% with cash receipts worth more than $686 million.  Sugar cane and hay were the biggest winners, each garnering increases of more than 8%.

Total cash sales of livestock and livestock products slipped by 1.9%.  Milk receipts suffered the largest single losses in this category, showing a decrease from $424 million to $411 million.

Sales of ornamental horticultural products increased by nearly $58 million or 4.1%.

“These results are testimony to the tenacity and ingenuity of Florida farmers to find a way to cut costs and increase production in the face of adverse weather and falling farm prices,” Florida Agriculture Commissioner Bob Crawford said.  “Our growers have every right to be proud of their achievements.

“It's unfortunate that drought and suppressed vegetable prices prevented a segment of our agriculture community from sharing in the full bounty of our progress,” Crawford added.

October 2000
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EPA Ruling Questioned
An EPA announcement calling for changes in the use of the insecticide chlorpyrifos is not likely to enhance the health and safety of Americans, said officials of two organizations representing the pesticide industry.

“For more than 30 years, chlorpyrifos and other products have successfully and safely kept cockroaches out of our kitchens, termites from undermining our houses, and disease carrying ticks and fleas from biting our children,” said Allen James, executive director of Responsible Industry for a Sound Environment (RISE).  “By reducing pest control options, this move could reduce certain health and property protection.”

Chlorprifos was reviewed by EPA under the Food Quality Protection Act (FQPA), which established new standards for pesticides.  Under the 1996 law, EPA must review all pesticides by 2006.

“We are disappointed with the process followed to evaluate chlorpyrifos,” said Jay Vroom, president of the American Crop Protection Association.  For its evaluation of the chemical, EPA was provided with extensive information documenting the wide margins of safety provided by the registered uses of chlorpyrifos.  More than 3,600 scientific studies and reports that have examined every facet of the product as it relates to health and safety.

Citrus & Vegetable Magazine
September 2000
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Bio Tech Foods Pose No Risk
The spotlight has again been turned on the issue of the safety and oversight of agricultural biotechnology.  We like the clarity of this statement by Ambassador David L. Aaron, under secretary of commerce for trade:

“Thirteen years of experience with biotech products in the U.S. have shown us that biotech foods developed and used in the U.S. present no food safety risks beyond those of their “natural” counterparts not a single ailment has been attributed to biotech foods.  Not one!  Not a sneeze, not a rash, not a headache.”

To help assure the public of the safety of biotechnology, the American Crop Protection Association (ACPA) recently issued a white paper titled “Plant Biotechnology Regulation: Science Based and Consumer Accessible From Plow to Plant.”  In this report, the ACPA clarifies some misconceptions that have been raised over the past few weeks.

The safety of agricultural biotechnology has already gained unequivocal endorsements from the following organizations: World Health Organization, the National Research Council, Food and Agriculture Organization of the United Nations, Organization for Economic, Cooperation and Development, the American Medical Association, the American Dietetic Association and the American Council on Science and Health.

In addition, the US National Academy of Science, in conjunction with the National Academies of Sciences of Brazil, China, India, Mexico, the Third World, and the Royal Society of the U.K., recently released a report outlining biotechnology’s role in helping to alleviate world hunger and improve safety in farming.

In July, the Organization for Economic Cooperation and Development (OECD) endorsed agricultural biotechnology after conducting an assessment to determine if food produced through biotechnology is as safe as other foods.  The study was presented at the Group of Eight's (G8) summit in Okinawa, Japan and was the culmination of a year-long effort to determine the health and environmental benefits of biotechnology.  According to Peter Kearns, the OECD's principal administrator for biotechnology, “Those countries that have conducted assessments are confident that those GM foods they have approved are as safe as other foods.”

In outlining the procedure of biotech regulation, the ACPA has described the 10 steps to evaluate the environmental and heath impacts of agricultural biotechnology.  As the ACPA notes, the National Institute of Health (NIH), the United States Department of Agriculture (USDA), the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) all take a pro-active approach in evaluating the effects of biotechnology.

A stringent approval process

Biotechnology products are subject to considerably more FDA and USDA testing than their conventional counterparts.  It can take up to 10 years to bring plants produced through biotechnology to market.

The FDA, EPA and USDA work together through a coordinated framework, along with several state governments, to make sure biotechnology products are safe to eat and safe for the environment.

The NIH conducts a “Biosafety Committee Review,” which calls upon scientists, company employees and citizens to evaluate products for potential health and environmental risks.

Throughout the biotech review process, the public is always notified and comments are invited through publication in the Federal Register.

After a product is introduced, the FDA, EPA and USDA each have the legal authority to demand immediate removal of products that do not meet all government safety standards.

There is no evidence that biotechnology poses a risk to the environment or human health.  Source: Council for Biotechnology Information. A PDF file of ACPA's Plant Biotechnology Regulation can be found at:

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Microbes in Transplant Mix 
Boost Yields
By adding two naturally occurring soil microorganisms – Paenobacillus macerans and Bacillus amyloliquefacien -to a transplant mix called BioYield 213, scientists are reducing yield losses caused by soilborne pathogens.  The mix gives the beneficial microorganisms the environment they need to grow on seedling roots.  The microbes then stimulate vigorous growth and improve the health of transplanted seedlings by triggering the plants’ resistance mechanisms.

Greenhouse producers can expect to grow seedlings in less time, and farmers can anticipate 5 to 20% yield increases in tomatoes, bell peppers, and even strawberries.  When the beneficial microorganisms are combined with other alternative soil treatments, such as Telone H and Plantpro 45, levels of crop productivity approach those achieved with methyl bromide.  This research is part of the ongoing ARS effort to provide farmers with alternatives to the soil fumigant methyl bromide, which is slated for phaseout by 2005.

Nancy K. Burelle, USDA/ARS U.S. Horticultural Research Laboratory
Fort Pierce, Florida;
phone (561) 462-5861,

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Health and the Environment
The June issue of the American Journal of Public Health reported a study that assessed acute hazards of pesticides to young children.  The study used information from a database maintained by the American Assoc. of Poison Control Centers.  From 1993-95, about 7,500 children younger than six years were exposed to Toxicity Category I or II pesticides.  More than 98% of the children had minor or no clinical effects resulting from their exposure; health care professionals treated 14% of the children.

Before you start to criticize farmers or pest control operators, you need to hear the whole story.  Disinfectants (primarily bathroom and kitchen cleaners) accounted for 93% of the exposures.  Insecticides were identified in 6% of the cases.  Three fourths of the cases were children one or two years old.  (Agromedicine Program Update, 8/15/00)

I think we can conclude from this report that we parents are responsible for most of the pesticide risks our children face.  Many times we do not think of familiar chemicals as pesticides, and we ignore the risks associated with them.  Check around the house now for household cleaners and other pesticides.  Please lock them away from children.  Store the chemicals securely even if your children are older.  Many times, children are poisoned at the home of a friend or relative.

The EPA Scientific Advisory Panel (SAP) is trying to sort out the ongoing cancer risk assessment for malathion.  Malathion is a widely used organophosphate insecticide, and its use around the home may increase dramatically as a result of the recent actions against chlorpyrifos and diazinon.  The Agency determination about carcinogenicity carries broad implications.  Before the EPA released the preliminary risk assessment, the Agency classified malathion as a ‘likely’ carcinogen.  In the assessment, malathion is called a ‘suggestive’ carcinogen.  The change of this single word greatly changes the way that people will view the risks of malathion.

The plot thickens with an accusation from the National Treasury Employees' Union (a federal union that represents some EPA employees).  The union claims that the Agency refused to send anyone to a Pathology Working Group that was reviewing tissue slides from a malathion bioassay.  Upon reviewing the slides, the working group reportedly concluded that some of the slides were not carcinomas as previously thought.

(Pesticide & Environmental News, 8/17/00)
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New Organic Rules Released
In December 1997, the USDA released a new rule to regulate organic production that infuriated many stakeholders; a revised rule is now available.  The original rule caused an outcry because it permitted the use of sewage sludge, ionizing radiation, and genetically engineered organisms in organic production.  The new rule excluding genetically modified organisms (GMO) or GMO products may create some new headaches for organic producers.  To be certified organic, the producer would have to ensure that any compost or manures used in production are free from any GMO products.  For example, you may not be able to use manure from source animals that have fed upon any GMO product.  Keep in mind that a large portion of U.S. soybeans, corn, and cotton are planted to GMO.

IPM Practitioner, May/une 2000
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Pesticide Potpourri
Protein As A Pesticide

An alternative to chemical pesticides has been found in a protein product that switches on a plant's natural defense mechanisms.  Field tests have shown an increase in crop yields for tomatoes and peppers by 22%.  The protein, called Messenger (harpin, Eden Bioscience) is produced from genetically engineered bacteria and makes plants more tolerant of drought.  Messenger is one of many biopesticides that can trigger or strengthen a plant's natural defenses.  It is the first natural product that can turn on crops’ own immune systems.

New Paraquat Herbicide

Griffin L.L.C. will be selling Boa, its own brand of paraquat herbicide.  The recent EPA registration for Boa covers all paraquat crop markets, all application, and all tank mix partners.  The new product is formulated at 2.5 pounds active paraquat per gallon.  Boa will be added to the line of Griffin residual herbicides.

Melon And Brassica Protection

Growers now can use Danitol 2.4 EC Spray (fenpropathrin, Valent) to control insects and mites on melons and head and stem brassicas.  The new formulation reduces the risk of eye irritation, putting the product's danger label at a warning level.  Apply Danitol as directed when pest populations are just starting to build.

Gramoxone Not Approved

The EPA has ruled that Gramoxone (paraquat) cannot be used as a burndown agent on tomato vines at the end of the growing season.  Diquat (diquat dibromide) has been approved as the alternative.  The product is more expensive gallon for gallon, but it kills faster than Gramoxone and has a lower application rate.  Zeneca, the owner of both products, is working to get a full EPA label approved for burndown use of Gramoxone, but the approval process will take at least a year.

The Florida Department of Agriculture and Consumer Services (FDACS) issued a Section 24(c) registration (SLN No. FL 200005) to Gowan Company for Imidan 70W for control of sweet potato weevil in sweet potatoes.

Bayer has added the control of aphids, cucumber beetles, thrips and whiteflies on Chinese okra, cucumbers and squash to their Admire label.

FMC has added cucurbits, eggplant, beans and sweet corn to their Capture 2EC (bifenthrin) label,

Bayer has added cucumbers, Chinese okra and squash to their Provado (imidacloprid) label.

Florida Grower /September 2000
Citrus & Vegetable Magazine/September 2000
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The microclimate within a crop canopy changes dramatically as rows in fields begin to  “close,” meaning that the plants in adjacent rows have just begun to touch.   From a disease management standpoint, this change has some pretty serious ramifications.

Plant pathologists like to use the “disease triangle” to illustrate the three elements that must be present before plant disease can develop.  These three elements are a susceptible host, a virulent pathogen and finally, the right environment.  If any of these three elements are not in the mix, you won’t get disease.

For most serious vegetable diseases, a cool, humid, and even wet environment is just what is needed.  Most fungal pathogens actually require droplets of water (often referred to as “free moisture”) for their spores to germinate, penetrate, and infect.  Bacterial pathogens often require free moisture for their cells to multiply.  Within the closed canopy of a field, conditions like these are far more likely to occur and persist than they are under a more open canopy.

Conducive Conditions

Naturally, prolonged conditions within the field that are conducive to disease can be a real problem during extended rainy periods in production areas that traditionally receive a fair amount of rainfall.  A full, lush canopy can trap and hold moisture long enough for many pathogens to get a toehold.  The cooler temperatures that occur during the night are especially favorable for disease development.  Important note:  You don’t have to experience rain or use irrigation to get good disease conditions within a field - dew can be a significant source of moisture.

Disease Management

Sometimes you can actually change the environment to make it less conducive to disease development.  You can schedule irrigation applications so that the dew period occurs in the middle of the watering cycle.  This practice can greatly shorten the length of time that foliage stays wet, and thus susceptible, to foliar diseases.

More often we monitor the environment and use the information to help with more effective and more economical disease management.  Weather monitoring has been particularly effective for management of some destructive diseases.  Forecasting models for both of these diseases are based on the occurrence and accumulation of time periods during which environmental factors such as temperature, relative humidity, and precipitation are favorable for disease development.  When enough of these favorable time periods are accumulated, disease management programs are either initiated or intensified.  Unfortunately, many of these models breakdown in south Florida, where temperature and humidity are almost always in critical ranges.

When it comes to the initiation and development of plant diseases, the proper environment is a major contributing factor.  So remember, when those rows begin to close, the conditions within your fields are probably getting a lot better for diseases to get started.  Row closure might be a good time to step up your scouting programs.

Adapted from American Vegetable Grower
September 2000
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Fertilizer Costs May Rise
 Prices of natural gas - which is used to make anhydrous ammonia, which in turn is used to make nitrogen fertilizer - more than doubled from February through June.  Most of the cost involved in producing nitrogen fertilizer comes from natural gas, prompting concerns that fertilizer costs will go through the roof this spring or sooner.  However, the large amount of offshore fertilizer production could temper rising fertilizer costs if imports are increased.

American Vegetable Grower
September 2000
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Rely Receives EPA Registration
Rely herbicide for potato vine desiccation is the latest product to be registered from the glufosinate ammonium chemistry being developed by Aventis CropScience.  The unique feature of Rely is that in most cases, the potato vines are completely dried down with a single pass over the field.  Rely provides a thorough termination of plant growth, allowing more time for the nutrient reserves contained in the upper portion of the plant to move down into the tuber.

The active ingredient, glufosinate ammonium, has a relatively short shelflife in the soil of 7 to 20 days.  It is rainfast and adheres to the leaf and stem within 4 hours of application.
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Ag Chem Labels on Computer CD and Web Too
Crop Data Management Systems, Inc.’s is a CD and Web-based solution for the distribution of AgChem labels and MSDSs.  The program allows each user to download exactly which MSDSs and/or labels they want to their PC hard drive.  Users can choose from a list of nearly 1300 products from over 75 manufacturers.  The products can be viewed out in the field on a laptop, on a desktop computer, or a customized printed label or MSDS book from a printer.  Information can be updated anytime by downloading the changes to the customized label “book”.

American Vegetable Grower
September 2000
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On the Lighter Side
You may be a farmer if....

Captain Bravado...
Long ago, there lived an officer of the Royal Navy named Captain Bravado. He was a manly man's man, who showed no fear when facing his enemies.

One day, while sailing the Seven Seas, his lookout spotted a pirate ship approaching, and the crew became frantic. Captain Bravado bellowed, "Bring me my red shirt!"

The first mate quickly retrieved the captain's red shirt, and while wearing the brightly colored frock, the Captain led his crew into battle and defeated the pirates.

That evening, all the men sat around on the deck recounting the day's triumph. One of them asked the Captain, "Sir, why did you call for your red shirt before battle?"

The captain replied, "If I were to be wounded in the attack, the shirt would not show my blood. Thus, you men would continue to fight,  unafraid." All of the men sat and marveled at the courage of such a manly man's man.

As dawn came the next morning, the lookout spotted not one, not two, but TEN pirate ships approaching. The crew stared in worshipful silence at the captain and waited for his usual orders. Captain Bravado gazed with steely eyes upon the vast armada arrayed against his ship, and without fear, turned and calmly shouted, "Get me my  brown pants!"

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