Cooperative Extension Service 

  Institute of Food and Agricultural Sciences

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

Southwest Florida Vegetable Newsletter

March/April 2000



April 26, 2000           Getting Paid for Fresh Produce Sales     7:30 –8:30 PM
                                  Lee County Cooperative Extension
                                  406 Palm Beach Boulevard
                                  Fort Myers, FL 33916
                                  For more information, contact Shannon Ruby at 941-338-3232

May 4, 2000            Summer Chemical Fallow Techniques using Roundup     5:30 – 7:30 PM
                                 Southwest Florida Research & Education Center, Immokalee
                                 For more information, contact Gene McAvoy at 863-674-4092

May 10, 2000         Spring Vegetable Field Day and Vegetable Growers Meeting  10 AM - 2:30 PM
                                Southwest Florida Research & Education Center, Immokalee
                                For more information, contact Gene McAvoy at 863-674-4092

May 11, 2000          Organizational Meeting  SW FL Vegetable Research and Investment Fund      5:30 PM
                                 Southwest Florida Research & Education Center, Immokalee
                                 For more information, contact Gene McAvoy at 863-674-4092

May 17, 2000          Methyl Bromide Update         5:30 – 7:30 PM
                                 Impact of Restrictions and Proposed Ban of Methyl Bromide on Cropping Practices
                                 and Practical Considerations for Vegetable Growers Regarding Methyl Bromide
                                Southwest Florida Research & Education Center, Immokalee
                                For more information, contact Gene McAvoy at 863-674-4092

May 15 –19, 2000  Aquatic Weed Control Short Course – earn up to 26 CEU’s
                                Fort Lauderdale Research and Education Center
                                3205 College Ave.
                                Fort Lauderdale, FL 33314
                                For more information, contact Dr Vernon VanDiver at 954-475-4125 or
                                Beth Miller-Tipton at (352)392-5930,   fax (352)392-9734 or e-mail:
                                Visit the workshop web site at:

June 3, 2000          Farm Safety Field Day    8 AM to 2 PM
                               Southwest Florida Research and Development Center Immokalee,
                               Contact:Barbara Hyman at (941)658-3400
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Note from Gene

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

Vegetable farming has never been an easy proposition and in recent years survival in this dynamic environment has not been easy.   The Southwest Florida Vegetable Advisory Committee has been pondering this situation for the past few months and has considered ways to alleviate the plight of area growers and help shift the competitive balance in their favor.  With this goal in mind, the committee has decided to launch the  “SW Florida Vegetable Research Investment Fund.” The fund is envisioned as a strategic partnership of growers and others in the vegetable industry who come together to pool their resources to address research needs of common concern.

The SW Florida Vegetable Research Investment Fund is set up to be managed by the contributor-members who will prioritize and fund research projects through a democratically elected advisory committee.  Membership will be based on contributions of one dollar per cropped acre per year or flat fee for non-growers.  Contributors will hold the purse strings and will be free to choose from public or private research groups and hold researchers accountable for performance.  An organizational meeting will be held in Immokalee in May 11th, 2000 at the SW Florida Research and Education Center at 5:30 PM.

Everyone involved with the vegetable industry is strongly urged to come out and hear more about the fund and how it will help you.  Government support for agricultural research is waning and often devoted to projects of little immediate importance to commercial growers.  By participating in the SW Florida Vegetable Research Investment Fund, you will be helping to
ensure the future of practical research that addresses the needs of local vegetable growers will be supported.  The strength and ultimately the future survival of not only the vegetable industry in southwest Florida but also every vegetable grower will depend on cooperation and unity within the industry.

I hope you will consider this proposal favorably - your future may depend on it!

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No-Till Transplanting 
Into Cover Crops
'New Generation' cropping systems have helped this producer build healthy soil, smother weeds and beat pests.

South-central Pennsylvania vegetable grower Steve Groff is pioneering what he calls “New Generation Cropping Systems,” which emphasize no-till transplanting vegetables with a customized Holland transplanter into cover crops, killed with a Buffalo rolling stalk chopper. With his father, Groff grows corn, alfalfa, tomatoes, pumpkins, soybeans, small grains and a few other vegetables on 175 acres of hilly land in southern Lancaster County.

Conservation has always been a concern of theirs.  The farm's slopes have been contoured for more than 40 years, and Steve started no-tilling in the early '80s.  “We had some erosion problems and I didn't like having to fill in gullies before harvesting corn,” says Steve, a board member of the Pennsylvania Association for Sustainable Agriculture.

The Groffs have held field days at Cedar Meadow Farm every July since 1994.  The crowds ask plenty of questions.  But with cooperating researchers Aref Abdul-Baki and Dr. Ron Morse also attending, “it's been hard to stump us,” says Groff. “I want to showcase what we're doing: Soil conservation, pesticide reduction and improved water quality --we have some hard results that you can't argue against.

“The demonstrations have proved to me that no-till transplanting truly has a place in vegetable production.  I'm not doing any economic comparisons anymore: I'm committed to it.  It's proved itself here and is proving itself to others who visit.”

More Information:

Cedar Meadow Farm - Visit Groff s website for information about Field Days, his video No-Till Vegetables -A Sustainable Way to Increase Profits, Save Soil and Reduce Pesticides and more.

Visit the sustainable farming connection Cover Crops Website and learn more about cover crops in vegetable production.  You can even watch a video showing no till tomatoes being planted in cover crops http://helios/
Email Groff at:

Email USDA cover crop researcher Aref Abdul-Baki at or Virginia Polytech’s transplanter developer Dr. Ron Morse at

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Food Quality Protection Act
There are always two sides to every debate; perhaps FQPA implementation is bad for human health.

According to a Harvard University study, a ban on organophosphates and carbamates could result in 1,000 premature deaths in the U.S. each year.  The Harvard study (and others) point out that food risks associated with organophosphate/carbamate residues on food are small to nonexistent.  The deaths would be associated with increased food costs and the concomitant reduction in fruits and vegetables.

American Farm Bureau News Release, 11-22-99

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Pesticide Information and Up-Dates

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Cultural Control for Management of Vegetable Pests in Florida
Integrated pest management (IPM) was a term coined in the 1950's to mean optimal combinations of chemical, biological and cultural control.  The concept of cultural control rests on the assumption that any agricultural practice may tip the balance between crop and pest one way or the other.  Unfortunately, the relationships are complex and it is not always clear which way the balance will tip.  Nevertheless, investigation and/or grower experience has led us to some general conclusions about a number of common practices.

Crop-Free Periods  The annual cropping system creates a simplified environment dominated by a single plant species that often makes an easy target for pests.  Insecticidal control may provide temporary relief, but can make things worse in the long run by eliminating beneficial insects that could help maintain control.  The result is a race with the pest to the harvest.  Given this scenario, the size of the initial pest population can be critical and an infested field next door may spell disaster.  Most pests are mobile in at least one growth stage and can move in huge numbers from old crops into new plantings.  After 1 or 2 crop
cycles the pest pressure becomes too great to deal with.  Its time for a break!

Silverleaf whitefly gave us a good lesson in Southwest Florida of the importance of crop-free periods.  The pest first appeared in 1986 on poinsettias but quickly jumped to a broad range of vegetable crops.  Less than 2 years passed before clouds of whiteflies were seen in tomatoes and squash and with them a new plant disorder, irregular ripening caused by feeding of the nymphs.  Then in the fall of 1989 a whitefly-borne tomato mottle geminivirus (ToMoV) devasted many fields, only to "miraculously" disappear in the spring crop after a Christmas freeze.  The hard-earned lesson was taken to heart and growers
responded to the call for rapid clean-up after the spring harvest.  The result was almost a complete elimination of ToMoV in the next fall crop although there was still enough there to damage the spring (1991) crop.  Another crop-free window was needed between the fall and spring, although this requirement has largely been eliminated by new systemic insecticides.  However, at least one break a year is still needed.

Crop-free period is also considered a necessity for a number of other important vegetable pests such as pepper weevil, tomato pinworm, and Thrips palmi and is recommended for management of all vegetable pests.  Crop-free periods are most effective when practiced areawide, so cooperation among growers is important.

Crop Rotation Most growers would rather not grow a single crop on the same piece of ground year after year, although they might think it necessary for economic reasons.  Pest and disease problems build up over time, especially if the same chemical regimes are used season after season.  The ideal rotation crop is one that is most distantly related to the previous crop and would therefore share the fewest pests and diseases.  An example might be sweet corn and almost any other vegetable.  However, pest and disease organisms often evolve host-specific strains that may be less virulent on even closely related crops, so any rotation is better than none.  Host range can often be used as a guide to using rotation to manage some specific pest problems.  For instance, Thrips palmi is a pest on most fruiting vegetables as well as potatoes but not on tomato.  Tomato pinworm also attacks eggplant and potato but not pepper.   Pepper weevil has no other crop hosts of any significance.  Fall armyworm is essentially a pest of grasses and therefore corn although they will occasionally attack other crops such as pepper.  Beet armyworm has a wide host range that includes most broad leaf crops but prefers pepper to tomato while preferences of the southern armyworm are reversed on these two crops.  Again, an areawide approach is most affective for managing
mobile pests through rotation.

Companion Crops  Sometimes two or more crops may be grown together to derive some benefit for one or both.  A companion crop would hopefully be managed in a similar way as the main crop and would produce a salable product.  However, management of two crops simultaneously in the same field can be a daunting task.  Companion crops may have various purposes: (1) as refuges for natural enemies, (2) to repel pests, or (3) to act as a trap by attracting pests away from a more valuable or vulnerable crop.   An ideal refuge crop would provide resources for beneficial insects such as nectar or alternative prey without itself becoming a source of pests for the main crop.  Potential pests should be closely enough
related to share key natural enemies but not the same host plant.  Therefore, the correct choice for a refuge crop may require either a lot of knowledge of predator prey relationships or a lot of luck.

Marigolds have often been used as pest repellents although their effectiveness may be a matter of opinion.

A good trap crop would presumably be more long lived and attractive to the target pest than the main crop.  By these criteria, eggplant might be a good choice to serve as a trap crop to attract whiteflies away from tomato.  However, we have consistently seen whiteflies increase on tomatoes next to eggplant compared to tomatoes next to tomatoes unless the eggplant has been protected with imidacloprid (Admire®).  Of course the grower's resources would be better spent treating the tomato itself rather than the trap so that the use of attractive trap crops appears not to be a viable management option for silverleaf

Dr. Phil Stansly
UF/IFAS, Immokalee

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Irrigation Scheduling and Management
Irrigation scheduling is used to apply the proper amount of water to a crop at the proper time.  The characteristics of the irrigation system, crop needs, soil properties and atmospheric conditions must all be considered to properly schedule irrigations.  Poor timing can result in crop stress and reduced yields from inappropriate amounts of available water and/or nutrients.

Crop water requirements depend on crop type, stage of growth and evaporative demand.  Evaporative demand is termed evapotranspiration (ET) and may be estimated using current weather data or historical data.  Generally, reference evapotranspiration (ETo) is determined for use as a base level.  ETo represents the water use from a uniform green-cover surface, actively growing and well watered.  Crop water use is related to ETo by a crop coefficient (kc) which is the ratio of crop water use (ETc) to the reference value ETo.  Because different methods exist for estimating ETo, it is very important to use crop coefficients which were derived using the same ETo estimation method as will be used to determine the crop water requirements.

                                                                                         Figure 1

Crop coefficients (Fig 1) for vegetable production vary for different soil and cultural conditions such as when plastic mulch is used, when the crop is staked, when wide rows exist, or if the soil is light vs. dark or wet vs. dry.  For general estimating purposes, crop growth can be divided into four stages:

Stage 1 -Early-season growth (the first 10 to 25 percent of the season);
Stage 2 -Rapid growth and development (the second 25 to 30 percent of the season);
Stage 3 -Peak growth and fruit sizing with full-crop cover (the third 25 to 40 percent of the season), and
Stage 4 -Late-season growth (from the end of Stage 3 until full maturity or final harvest).

The actual length of each growth stage varies with crop and seasonal characteristics.  Crop ET (ETcrop) can be estimated using the ETo data from Table I and the crop coefficient (kc) where:  ETcrop (kc) x (M).

Table 2 lists estimates of crop coefficients for many of the vegetable crops produced in Florida.

As an example, consider drip irrigated tomatoes grown in the Tampa Bay area.  For plants in growth Stage 3, the crop coefficient is 0.90 (Table 2).  If this period of growth occurred in April, the ETo value is 5160 gal/acre/day (Table 1).  Crop water use would be estimated as: ETcrop = (0.90) x (5160 gal/acre/day/) = 4640 gal/acre/day.

If the drip irrigation system can apply water to the root zone of the crop with an application efficiency of 85 percent, the irrigation requirements would be:  Irrigation Requirement = (4640 gal/acre/day)/(0.85) = 5460 gal/acre/day.

This amount of water would be a good estimate for scheduling purposes under average growth and average April climatic conditions.  However, field moisture and plant status should be monitored or determine if irrigation levels need to be increased or reduced.  While deficit irrigation will reduce fruit size and plant growth, excessive irrigation may leach nutrients from the active root system.  This may also reduce plant growth.

Note: A. G. Smajstrala, Ph. D., was a professor of water management, UFs Agricultural and Biological Engineering Dept., Gainesville. Smajstrala passed away last year after a lengthy illness.

A. G. Smajstrla
Citrus and Vegetable Magazine

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A Business Gone Sour
I like milk. I like it with my Cheerios in the morning and my cookies at night. With two kids, and another on the way, milk is important in my household. So while that predator Microsoft gets all the attention, we're focused on a monopolist you have probably never heard of. At what point do we worry about one player dominating a market? A 50 percent market share? Sixty percent?

Try 80 percent. That's the share of the Massachusetts milk market regulators say Suiza Foods Corp., the nation's largest milk processor, will have when it completes its newest step in cornering the market here. When you go to the store you largely have three choices buying milk: H.P. Hood, Garelick Farms, and the store brand. But, in fact, you have just two choices. Suiza owns Garelick and supplies, or soon will, nearly all the milk sold under such store brands as Star and Demoulas.

Almost without notice Dallas based Suiza has since 1998 been buying up the milk-processing competition throughout the Northeast -and shutting much of it down. Garelick Farms in Franklin, West Lynn Creamery in Lynn, Nature's Best Dairy in Rhode Island, and Cumberland Farms' milk-processing units were all acquired by Suiza.

Next: Stop & Shop has decided to close its Readville processing plant, New England's second-largest facility, and will buy its store-brand milk from Suiza. At the same time, Suiza's partner, Dairy Farmers of America, the nation's largest dairy farmer cooperative, has been pursuing a similar consolidation strategy among farmers. The giant co-op's pitch to farmers is not subtle, say those in the business: Join us or lose giant Suiza as a customer.''Suiza and Dairy Farmers of America must be considered
a pair,'' says Peter Hardin, editor of the Milkweed, an industry publication.

Regulators and industry watchers estimate Suiza now controls 70 percent of the milk business in New England, the greatest concentration of any region in the country. Suiza disputes those numbers but will not discuss its share. Jonathan Healy, Massachusetts' Commissioner of Food and Agriculture, says five companies not long ago controlled 80 percent of the state's milk market; now one company, Suiza, controls that same 80 percent. ''Suiza's activities tend to substantially lessen competition and appear to be attempts to monopolize,'' he says.

The heat is finally, if belatedly, gettingturned up on Suiza. The attorney generals in Massachusetts, Connecticut, and Vermont have begun an inquiry, including looking at the Suiza-Stop & Shop deal. US Senator Patrick J. Leahy, Democrat of Vermont, has pressed the Justice Department to investigate. And Leahy and Senator Thomas Daschle, Democrat of South Dakota, next week will introduce legislation to level the playing field between farmers and the giant agribusiness concerns.

Finding the right balance won't be easy. Consolidation is changing the face of agriculture across-the-board from livestock to soybeans to milk. Just protecting farmers or manufacturers or anything else at the expense of consumers is a losing strategy in the world today. The kind of price fixing for milk we now have on the federal and regional level offends my free-market bones. Why should dairy farmers be guaranteed a set price for their milk when tomato farmers aren't?  But agriculture does present some special antitrust problems. Antitrust enforcement is geared to situations where you have few producers Microsoft,
for instance and millions of consumers.

Agriculture faces the opposite situation: few and fewer buyers -Suiza, for instance -and many,  increasingly powerless sellers. When we arrive at a place where one company has 70 percent of the New England market, or anything close, it's time to worry. If the Justice Department is willing to allow Suiza to control 70 percent of New England's milk market, why then can't some other giant control 70 percent of the orange juice market? This isn't good for farmers or consumers. Sooner or later, all of us are going to pay for it over our Cheerios.

Steve Bailey
Boston Globe  4/7/2000

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Could food prices go the way of gas prices?
THIS MORNING (MARCH 15)  saw regular unleaded gasoline being advertised at $1.66 a gallon in Gainesville.  That's up eight cents in just eight days and is a record high price.  Government officials are predicting that Americans will be paying two dollars per gallon before the end of summer.

Public discontent is starting to manifest itself.  Truckers are demonstrating today in Washington, demanding the removal of the excise tax on diesel fuel.  Members of Congress are calling for an investigation of petroleum prices.  Messages posted on the Internet beg the public not to buy gas for three days in April. Incidents of gas stealing are increasing.

The price of gas and diesel is just a symptom.  The basic issue is the cost of petroleum and its effect on our total economy.  The situation is serious and needs to be a concern to every American.

Our economy is based on petroleum.  The dependence of our transportation system with its cars, trucks, planes and trains, is obvious.  That system has been a major contributor to the quality of life and the economy of this nation and the world.  The things we take for granted like plastics, wrapping materials, clothing, toys, tools, boats, insulation and a lot more, are products of a developed petroleum industry.  Any increase in oil prices causes increased costs for many products and will lead to spiraling inflation.

Americans are committed to using autos for their work, shopping, school and pleasure.  Some people think we should be a nation of bike riders, walkers and mass transportation enthusiasts.  I don't foresee that happening quickly or easily.  Meanwhile, people will be spending more of their income for transportation, and reducing their spending on other items due to a general price increase for all products.  The lower a person's income, the more he or she will be hurt.  Inflation is especially cruel to people with low or fixed incomes.

Certainly as a group, no segment will be hurt as much as agriculture.  Farmers and ranchers will have significantly higher fuel costs than in recent years.   Supplies and delivery of products to market will cost more due to increased transportation cost.  Increased costs for fertilizer, crop protection products, lubrication products and irrigation are almost a certainty.  Historically, farmers have not been able to pass on increases in costs of operation.  With agriculture in general having experienced a series of difficult years, the financial outlook for agriculture is worrisome with increased cost.

Higher oil prices may well lead to higher food costs for consumers.  This increase will be due, not to farmers, but to a handful of people in other countries who control the amount of oil available and its price.  A Reuters news story today reports that the oil minister from Venezuela and his counterpart from Saudi Arabia will meet to "reach common ground on additional OPEC oil supplies."  That means they are going to set the world price.

Currently, the United States is importing about 54 percent of its petroleum needs.  There has not been a major refinery built in this country for nearly 25 years.  Consequently, there is little ability for supply to get ahead of demand.  Refineries are not being started because of governmental regulations dealing with environmental issues and the uncertainty of future regulations.  As a result, facilities are becoming obsolete or too expensive to operate.

It is ironic that there has been little attention given to new and existing research for alternative sources of energy.  Ethanol is utilized as a gasoline replacement, but not to the extent it could be.  The development of technology which would utilize biomass as a renewable source of fuel promises great rewards.  It would make us less dependent on foreign oil, be good for agriculture and good for the environment.

When I hear of people getting upset with the current price of gas, I point out that much of our problem is because our leaders have allowed our nation to become dependent on other countries for petroleum.  They have allowed us to base our economy on the assumption that other countries would be willing to sell oil to us at a reasonable price.  Today we are experiencing the fallacy of that assumption.  I then ask people: "Are you ready to become dependent on other counties for this nation's food supply like we have done for oil?"  So far, no one has said "yes".

Carl B. Loop Jr.,
FFBF President
FloridAgriculture  April 2000

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Let a Dog Be Your Teacher

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The Critical Period of Nutsedge Interference in Tomato
Purple and yellow nutsedges (Cyperus rotundus L. and Cyperus esculentus L.) are considered among the worst weeds in the world. Both species are found as weeds in vegetable crops in Florida. Nutsedges are problematic because of their difficulty of control, and their high capacity for reproduction and spread. The high rate of methyl bromide use in tomatoes is solely due to nutsedge control. Nutsedges also can emerge and penetrate through the polyethylene mulch when not controlled in a mulched bed situation. The reduction of methyl bromide use and pending loss of use causes concern in nutsedge control in tomato production. Due to the lack of information on the negative impact of purple and yellow nutsedge on yield and quality of the crop, several studies were undertaken. The information presented here is part of the results obtained from studies carried out over three years at three locations.

Materials and Methods

Depending on the study, either the Solar Set or the Solemar cultivar was used and grown on mulched beds 32 inches on top, with an in-row spacing of 18 inches. To standardize the studies overhead irrigation was used, and monitored with irrometers. The crop was harvested three times and graded toTomato Committee standards.

Beds were fumigated with MC-33 to control all pests. Tomato and sprouted nutsedge tubers were planted into the bed seven days after fumigation.

Additive Studies

The extent of weed interference with crops is density-dependent. No systematic data is available regarding the relationship between season-long interference of different nutsedge densities on yield losses. Such knowledge is vital in order to determine nutsedge density thresholds, below which suppressive (control) actions would be unnecessary, based on allowable yield losses due to weed interference.

Yellow nutsedge was planted in the beds at the same time as tomato at the populations of 0, 10, 20, 25, 30, 40, 50, and 100 plants per square meter. Purple nutsedge tubers were planted at 0, 25, 60, 75, 90, 100 and 150 per square meter.

 Tomato yield losses increased sharply as nutsedge densities increased from 0 to 50 plants/m2 (4.6/ft2) and 0-100 purple nutsedge plants/m2 (9.3/ft2). Season long interference by yellow nutsedge reduced total marketable yield of tomato by 50%. Total marketable yield loss of tomatoes was as high as 81% with purple nutsedge. Marketable yield loss of 10% was seen at season long interference with the population of 25 plants/m2 (2.3/ft2) for both the yellow and purple nutsedges.

The percent of yield loss was most dramatic in the medium sized tomato fruit from interference by both species. Purple nutsedge interference caused yield losses of 43% for extra-large fruit, 52% for large sized fruit and 98% for medium sized fruit. Yellow nutsedge interference caused losses of 40% for extra-large sized fruit, 50% for large and 75% for medium sized fruit. The yield losses were slightly less from interference from yellow nutsedge than purple nutsedge, but the interference was from only half as many plants per area.

Interference Influenced by Nitrogen Fertilization

Recommended N, P and K rates for tomato are relatively well established in Florida’s production areas. However, recommendations are generally based on weed-tree nutrient rate studies, which may not be adequate when troublesome weeds are present in the field. Competition for nutrients has been recognized as an important factor in weed-crop interference relationships in other crop-weed studies. There has been no experimental data regarding the effects of N rates on interference of nutsedges in tomato.

In these trials, N fertilizer was applied at 50, 100, 150, 200, 250, 300 and 350 kg/ha which is equivalent to 45, 90, 134, 180, 224, 268 and 312 lb/A. P and K was applied at soil test recommended rates. Interference with yellow nutsedge was at 50 plants/m2 and purple nutsedge at 100 plants/m2.  The best tomato yields were obtained at N rates of 200 to 250 kg/ha (180-224 lb/A) coinciding
with the recommended rates for Florida. Above these N rates, the number of X-Large and Large size fruit declined while the number of medium sized fruit increased.

When the tomatoes were grown with either yellow or purple nutsedge interference, the percent marketable yield loss was less influenced by the nutsedges at the recommended N rates of 200-250 kg/ha (180-225 lb/A). Tomato was less competitive at N rates under 200 kg/h and the nutsedges were more competitive at the higher N rates.

Manipulating N rates does not seem to be an option. Using the recommended N rates for optimum tomato yield is also the optimum N rate even if nutsedges are present.

The Critical Period of Interference

The duration of weed interference is of great importance in the outcome of the crop-weed interaction. The season-long data reflects the maximum interference effects of nutsedges. The quantification of the impact of nutsedge interference during periods of the crop growth would determine the period of weed suppression necessary to avoid yield reductions above predetermined acceptable losses. To determine the period of weed suppression necessary to avoid yield reductions (Critical Period of
Interference), two separate studies are necessary.   In these studies, the yellow nutsedge population was 50 plants/m2 and the purple nutsedge population used was 100 plants/m2. In the first study, the nutsedge was planted at the same time the tomato was transplanted. The nutsedges were then removed at either 1, 3, 5, 7, 9 or 11 weeks after transplanting. The yield from each removal date was then compared to no nutsedge interference to determine the period of time that the nutsedges can compete with the crop before yield reduction occurs. In the second trial nutsedges are planted 1, 3, 5, 7, 9 or 11 weeks after tomato establishment. In many instances, weeds may emerge later during the season and not be competitive or cause yield losses. This study would define that period. The time between the initial period where the weed does not cause yield reduction above a specified percentage and late in the season when the weed will no longer reduce yield if it emerges, is the time when the weed must be controlled and is
called the critical period.

The results of these studies show that in order to avoid tomato yield losses above 5%, the crop must  be kept purple nutsedge-free during the period of 2-10 weeks after transplanting. To avoid tomato yield losses above 10%, purple nutsedge must be suppressed during the period of 3-6 weeks after transplanting.

For yellow nutsedge interference, tomato yield losses above 5% can be prevented by suppressing the weed during the period of 2 to 10 weeks after transplanting, whereas yield losses above 10% can be avoided by yellow nutsedge suppression during the period of 4 to 9 weeks after transplanting.


The studies conducted indicate that to reduce yield losses of tomatoes due to interference by yellow and purple nutsedges, the grower should:

1.  Reduce the population of nutsedge in the field to less than 25/m2, 20/yd2 or 2.3/ft2. Below this population less than 10% yield loss will be expected.

 2.  Grow the tomatoes under the optimum recommended nitrogen fertilizer rate. Overfertilization will enhance the nutsedge competition while underfertilization will reduce the tomato plants competitive ability.

3.  Control the nutsedge in the bed, when possible, from 2 to 10 weeks after tomato transplanting.

W.M. Stall and J. Pablo Morales-Payan, UF/IFAS

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1999 Fall Tomato Variety Evaluation
Twenty-eight fresh market tomato varieties or advanced experimental hybrids were evaluated in a replicated yield trial at the Gulf Coast Research and Education Center-Bradenton in west-central Florida in the fall 1999 season.

Production Practices

Seeds were sown on 12-14 July into planter flats (1.5 x 1.5 x 2.5-inch cells) containing a commercial mix of vermiculite, Canadian sphagnum peat and poly beads and then covered with a layer of coarse vermiculite and germinated in a greenhouse.  Plants were conditioned before transplanting by limiting water and nutrients in the final phase of production.

The EauGallie fine sand was prepared in early August. Beds were formed and fumigated with methylbromide:chloropicrin, 67:33 at 2.3 lb/100 lbf. Banded fertilizer was applied in shallow grooves on the bed shoulders at 2.34-0-3.25 lb N-P2O5-K2O/100 lbf after the beds were pressed and before the white on black polyethylene mulch was applied. The total fertilizer applied was equivalent to 203-0-283 lb N-P2O5-K2O/A. The final beds were 32 in. wide and 8 in. high, and were spaced on 5 ft centers with six beds between seepage irrigation/drainage ditches which were on 41 ft centers.

Transplants were set in the field on 23 August and spaced 24 in. apart in single rows down the center of each bed. Transplants were immediately drenched with water containing the recommended rate of imidacloprid for silverleaf whitefly control. Four replications of 10 plants per entry were arranged in a randomized complete block design. Plants were lightly pruned, staked and tied.

Plants were scouted for pests throughout the season. Lepidopterous larvae, leafminers and silverleaf whitefly were the primary insects found. Bacillus thuringiensis, methomyl, spinosad, buprofezin, endosulfan, and pyriproxyfen were used according to label instructions to control insect pest populations during the season. A preventative spray program using maneb, copper hydroxide, and chlorothalonil was followed for control of plant pathogens. Tomato yellow leaf curl virus affected plants were removed and
disposed of early in the season, but were allowed to remain after the second tie. Fruit were harvested at or beyond the mature-green stage on 17 and 30 November and 14 December. Tomatoes were graded as cull or marketable by U.S. Standards for Grades of Fresh Tomatoes and marketable fruit were sized by machine. Both cull and marketable fruit were counted and weighed.


Seasonal yields from three harvests ranged from 1294 cartons/acre for SBT 5011 to 2648 cartons/acre for Fla. 7885 (Table 1). Nine other entries had similar yields to those of Fla. 7885. All entries produced yields exceeding the 1106 cartons/acre state average yield for fall 1997-98 and exceeded yields obtained at this location in recent fall seasons.

Yields of extra large fruit varied from 629 cartons/acre for SBT 5011 to 1835 cartons/acre for Fla. 7816. Eight other entries had extra large fruit yields similar to those of Fla. 7816. Large fruit yields of fresh market types ranged from 405 cartons/acre for ‘BHN 190' to 872 cartons/acre for HA-3048. Average fruit weight for fresh market types varied from 5.4 oz for HA-3017 A to 6.9 oz for Fla. 7816. Cull fruit by weight ranged from a low of 12% for Fla. 7816 to 32% for HA-3044. The incidence of plants infected with tomato yellow leaf curl virus varied from 0 for HA-3017 B, HA-3048, ‘Sanibel,’ HA-3017 A, and HA-3044 to 40%
for SBT 6682.

Overall, total marketable yields surpassed those obtained at this location in recent fall seasons. In fall 1999, yields ranged from about 1300 cartons/acre to more than 2600 cartons/acre. The proportion of extra-large fruit varied from less than 50% to over 75% for the entire season.

The University of Florida experimental hybrids Fla. 7885, Fla. 7921, Fla. 7816; and ‘BHN 273,’ and HA 3017 B were outstanding performers in the fall 1999 replicated trial. Those readers needing more information can request a detailed report from the author at

Don Maynard
Vegetarian 4/2000

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Do Nematodes Move in Soil?
Believe it or not just a few years ago we would have answered the question about whether nematodes move by saying that nematodes that feed on plant roots are capable of moving only a few inches in their short life span.  But during the past 25 years we have come to realize that nematodes are capable of fairly rapid movement and of moving relatively long distances.  Their ability to move through a hostile soil environment is remarkable.

A grower may say, so what.  After reviewing the data presented here the “so what” will become a little more clear.  The fact that nematodes have mobility in soil has important implications to growers.  Before we begin discussion about movement we need to think about the vertical distribution of nematodes in soil and how this affects survival.

Distribution in soil.

In the early 1970's we began researching the distribution of root-knot nematodes in Florida's sandy soils.  To do this we chose to monitor the distribution of this nematode in a naturally infested peanut field located near Williston, Florida.  The soil was a deep sand with 92% to 94% sand and less than 1% organic matter.  Soil samples were collected monthly with a soil auger in 6 inch
increments down to 3 feet for a period that extended over 2 years, but for simplicity in this article we only show a 5 month period.  Following the harvest of the peanut crop we found that the nematode numbers reached very high densities at all depths tested, but that these numbers dropped considerably in the upper depth during the winter months (Table 1).  This drop was probably due to mortality caused by cooler soil temperatures, and probably more importantly to natural antagonist of the nematode.  Notice, however, that the numbers of infective juveniles remain high throughout the autumn and winter monts at the deeper soil

It must be pointed out that soils in Florida are variable, ranging from deep sands, to sands stratified over layers of heavy clay, and over high water tables.  We would not expect root-knot nematodes in heavy clay soils, or in free water in high water table soils.


In the early 60's a researcher at the University of California, Dr. Glenn Bergeson, reported that the best survival of root-knot nematodes was obtained at 500F.  Our work confirmed these findings.  Root-knot nematode infective juveniles placed at 500F survived for longer periods of time then at any other temperatures tested.  This fact is interesting in that we know that while Florida soil temperatures at deeper depths change overall to near the same lows and highs as in the upper depths, the changes are more gradual, especially deeper in the soil.  This provides nematodes at the deeper depths a more favorable temperature for survival.


Jean Claude Prot, a Frenchmen working on his doctorate at the University of California discovered that root-knot nematodes when placed in soil cylinders in the laboratory moved up to 2 feet in a short period of time.  This report in the mid-1970's opened the door for others to look again at nematode movement.

With our knowledge about root-knot nematode distribution in soil we asked the question, if there are infective second-stage juveniles at these deep soil depths do they move into the root zone and infect susceptible plant roots?  We set up experiments to answer this question. Preliminary results were surprising in that we set up a system to measure movement through a 2 foot span of soil over a 30 day period.  The surprise was that the tomato root systems were heavily galled by the end of the 30 day period.  We only expected a few galls, if any.

Determining the mobility of nematodes in soil is a very difficult task, which probably explains why we know so little about the distances most plant-parasitic nematodes move.  Root-knot infective juveniles actually live in a film of water surrounding soil particles.  These juveniles measure only a mere fraction of an inch, thus they are microscopic.  In order for them to move in soil they must swim through the film of water surrounding soil particles.  Their swimming motion is similar to that of a snake moving on land, however the nematode's movement is made while laying on its side (dorsal-ventral contraction and relaxation of muscles).

Because of the nematodes small size and the physical structure of soil, scientists originally believed nematodes were limited in their ability to move.

We devised a system to measure the vertical and horizontal movement of a natural population of root-knot nematodes, Six inch (inside diameter) PVC tubing was cut to lengths of 12, 18, 24, 36, and 48 inches.  These tubes formed what we called migration chambers.  The top end of each tube was capped with a plant root growing chamber, which formed the root chamber.  The root chamber was 6 inches long and the bottom was covered with a nylon mesh cloth with openings that allowed for free movement of infective juveniles, but small enough to prevent roots from penetrating into the migration chamber.  Both the migration and root chambers were cemented together and then each was filled with steam pasteurized soil.  A healthy tomato seedling was ransplanted into each root chamber and the top of these cylinders was capped with a Plexiglas plate designed with stem and watering holes.  The watering hole was capped with a cork and the tomato stem was covered in aluminum foil in a manner to prevent soil splashing into the root chamber.  These precautions were taken to ensure that no nematodes moved into the root chamber from the top side.  The design worked well.  Control tubes that had their bottom sealed did not have any galling on
the tomato roots.  The design was modified to include a horizontal migration tube so we could measure horizontal as well as vertical movement.  Movement was determined by observing the roots in the root chamber for galls formed (gall index) on the tomato root by infective juveniles.  For the mobile nematodes to reach the plant roots they had to move through the pasteurized soil column.

The infective juveniles moved into all of the migration chambers (Table 2).  They moved through the 18 inch long migration cylinder and induced galls on plant roots inside the root chamber within 13 days.  Galls formed within 23 days for the 24-inch and 36-inch-long cylinders, and 29 days for 48-inch-long cylinders.  The juveniles were capable of traversing through the soil packed cylinders at a distances of approximately 1.3 to 1.6 inches per day.  We also determined that the juveniles could move a distance of 12 inches horizontally to induce galls on roots within 19 days.  In some cases the nematodes infected the plant roots, developed to the adult stage and laid eggs in a mass (Table 2).  These egg masses, which generally form on the outside of roots, can be observed with the naked eye on the galled tissue.


Distribution, survival, and movement all have important implications in management of these tiny parasites.  In our vegetable industry root-knot nematodes are always a serious threat to production.  Nearly all the vegetables grown in Florida are susceptible to injury from root-knot nematodes.  In many cases the damage is limiting to production.  For vegetables, fumigation is our first line of defense against root-knot disease.  Injection of a fumigant nematicide into soil, if done properly, provides a zone of control 6 to 8 inches in diameter from the point of injection.  One could visualize this treated zone as being a 12-to 15-inch diameter cylinder placed horizontally in the soil.  For example, if one treated a 3 foot wide bed with a fumigant applicator rigged with three chisels spaced 12 inches apart, one would fumigate a 3 foot wide zone approximately 12 to 15 inches deep.  This zone would be approximately 98% to 99% free of infective juveniles.  With this scenario what happens to all the infective juveniles that may lie below this treated zone?  While we have demonstrated that these nematodes are capable of moving upwards there is no way to
know how many will move into the fumigated zone or even how many are capable of movement.  Many of the nematodes may already have depleted their energy reserves, some may be sick with diseases, infected with parasites, or gobbled up by predators.  When we placed healthy nematodes at the bottom of our migration chambers we recorded greater movement then occurred with the field population of nematodes.  This is to be expected in that the healthy nematodes had plenty of food reserves thus enabing them to move quickly.  Mobility of nematodes that tie deep in the soil obviously provide nematodes a means of survival,
thus ensuring that the population survives.  To maximize the benefits of soil fumigants growers must become aware of root-knot nematodes distribution, survivability, and movement.  They must ensure proper placement and sealing of any soil fumigants they use for management.

D. W. Dickson, professor, Department of Entomology and Nermtology, University of Florida,
University of Florida, Institute of Food & Agricultural Sciences, Gainesville

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Cultural Methods for Management of Nematodes in Florida
Plant-parasitic nematodes can cause serious damage to many vegetable, fruit, agronomic, and ornamental crops (Barker et al., 1998; Luc et al., 1990).  Warm temperatures and a year-round growing season are particularly favorable for nematodes, and these conditions contribute to the severity of nematode problems in Florida.  In addition, a number of particularly serious nematode pests occur in Florida.

Root-knot nematodes (Meloidogyne spp.) are probably the most frequently encountered nematode pests in the state.  Meloidogyne incognita is widely distributed in Florida, especially on susceptible vegetable crops like tomato, pepper, eggplant, bean, cucumber, watermelon, and squash.  Meloidogyne arenaria is an important pest of peanuts in north Florida.  The reniform nematode, Rotylenchulus reniformis, attacks a variety of crops in Dade County, and is becoming an increasing problem on cotton and other crops in the Panhandle.  Stubby-root nematodes (Paratrichodorus spp., Trichodorus spp.) carry virus diseases to potatoes in northeast Florida.  The sting nematode, Belonolaimus longicaudatus, damages a variety of crops grown on sandy soils.  Sting nematodes and lance nematodes (Hoplolaimus spp.) damage turf throughout the state.

A variety of cultural practices are available for managing plant-parasitic nematodes. Cultural practices include most nonchemical methods. Some authorities include biological control with cultural practices while others do not.  Many different predators and parasites have been shown to affect nematodes under laboratory conditions (Stirling, 1991).  These organisms may provide some degree of naturally-occurring biological control, although this has not been accurately measured.  With few exceptions, commercial use of biological control agents for nematode management has generally been unsuccessful.

Site-Specific Pests.

The most important step in managing nematodes is an accurate identification of the problem.  As mentioned, many different kinds of plant-parasitic nematodes occur in Florida, and each of these cause different types of problems and react to management attempts in different ways.  Although the root-knot nematodes produce galling symptoms on plant roots, diagnosis of most kinds of nematodes requires a soil sample.  Nematodes tend to be a site-specific problem because their mobility and ability to migrate are limited.  Once present in a site, they are very difficult, if not impossible, to eradicate.  Their numbers, then, will depend on how the site is managed.


The first line of defense is sanitation, to avoid introducing nematodes into uninfested sites.  While nematodes may not move far on their own, they are transported to new locations on infected seedlings and planting material, or in contaminated soil that is moved by equipment, water, or other means.

Resistant cultivars.

Once a nematode species has invaded a site, the rise or fall of its population will often depend on the plant species grown.  For example, populations of Meloidogyne incognita usually decline following sorghum-sudangrass, which is a poor host, but increase rapidly following most cultivars of tomato, which is a highly susceptible host.  For this reason, double-cropping susceptible vegetable crops is extremely difficult in an infested site.  On the other hand, nematode-resistant plants are probably the most
important method for reducing nematode populations and minimizing problems.  Local extension and advisory services can provide information on crop varieties resistant to nematode pests in a particular area.  The response of different cultivars of the same crop can vary greatly.  In tests conducted in north-central Florida, for example, ‘Mississippi Silver’ cowpea was fairly resistant to Meloidogyne incognita, but ‘Whippoorwill’ cowpea was highly susceptible (Gallaher and McSorley, 1993).  A crop resistant to one
nematode species may be susceptible to another.  For instance, the sorghurn-sudangrass resistant to M. incognita is a preferred host of the sting nematode.  In these difficult cases where multiple species of nematodes are present, it is important to focus on the most serious pest for the crop(s) to be grown.  In some cases, the responses of particular plant cultivars to local nematode populations may be unknown, so local testing may be necessary to find the crops and cultivars most effective for nematode management.

Rotation and Cover Crops.

Rotation crops and cover crops can be helpful in manipulating nematode populations during those times of the year when cash crops cannot be successfully grown.  In north Florida, winter cover crops of rye or oats are better than vetch or clover for managing M. incognita.  In central or south Florida summer cover crops such as  sorghum-sudangrass, nematode-resistant cowpea, marigold, velvetbean, castor, jointvetch, or sunn hemp may be used against this nematode.  Weeds growing on uncultivated land impact nematode populations and act as a cover “crop”.  While some weeds, like hairy indigo, may suppress populations of M. incognita, many other weeds can be nematode hosts.  Absence of growing plants, achieved by clean fallow or flooding, can reduce nematode populations.  However, flooding for two to three months may be impractical, and clean fallow may result in soil erosion.

Organic Amendments.

It is difficult to predict how organic amendments, such as compost, crop residues, yard waste, manure, or other biosolids, might affect nematode populations.  Although some decomposition products have been shown to affect nematodes in the laboratory, performance under field conditions has been inconsistent.  Any organic amendment is a potential source of nitrogen that can
stimulate plant growth.  In some cases, increased root growth may even result in increased nematode populations.  Interpretation of results from organic amendment applications can be difficult, since the fertilizer effect may stimulate plant growth, while effects on nematode populations may be unclear or unknown.


igh temperatures will kill nematodes, and so steam sterilization or other forms of heat treatment are often used for sterilizing soil used in greenhouses or nurseries.  Soil solarization is receiving increased attention for the management of nematodes and other soilborne pests.  In this method, a thin sheet or tarp of clear plastic is placed over the soil surface, allowing the sun to heat the uppermost layers of soil. Performance has been variable, depending on application technique and season (McGovern and McSorley, 1997).  Plant material infected with nematodes can be treated in hot water, provided that a suitable temperature range can be found (high enough to kill nematodes but not lethal to the plant).

Additional Information.

Additional information and details on the nematode management methods introduced here can be found in a variety of sources (Barker et al., 1998; Luc et al., 1990; McSorley, 1994; 1996a, b; 1998; 1999; McSorley and Gallaher, 1992; Roberts, 1993; Stansly et al., 1999).

Almost any method will require some on-site testing to be sure that it will be effective for a particular nematode and crop combination.


Barker, K. R., G. A. Pederson, and G. L. Windham, eds. 1998. Plant and Nematode Interactions.  American Society of Agronomy, Madison, WI.

Gallaher, R. N., and R. McSorley. 1993. Population densities of Meloidogyne incognita and other nematodes following seven cultivars of cowpea. Nematropica 23:21-26.

Luc, M., R. A. Sikora, and J. Bridge. 1990. Plant Parasitic Nematodes in Subtropica and Tropical  Agriculture. CAB International, Wallingford, U.K.

McGovern, R. J., and R. McSorley. 1997.  Physical methods of soil sterilization for disease management including soil solarization. Pp. 283-313 in N. A. Rechcigi and J. E. Rechcigl, eds.  Environmentally Safe Approaches to Crop Disease Control.  CRC Lewis Publishers, Boca Raton, FL.

McSorley, R. 1994.  Alternatives for nematode management. Citrus and Vegetable Magazine  (September 1994): 50-51.

McSorley, R. 1996a. Impact of crop management practices on soil nematode populations.  Soil  and Crop Science Society of Florida Proceedings 55:63-66.

McSorley, R. 1996b. Cultural control of plant-parasitic nematodes.  Pp. 149-163 in D. Rosen, F. D.  Bennett, and J. Capinera, eds.  Pest Management in the Subtropics.  Intercept, Andover, U.K.

McSorley, R. 1998.  Alternative practices for managing plant-parasitic nematodes.  American Journal of Alternative Agriculture 13:98-104.

McSorley, R. 1999.  Nonchemical management of plant-parasitic nematodes.  The IPM Practitioner 21(2):1-7.

McSorley, R., and R. N. Gallaher. 1992.  Managing plant-parasitic nematodes in crop sequences. Soil and Crop Science Society of Florida Proceedings 51:42-45.

Roberts, P. A. 1993.  The future of nematology: Integration of new and improved management strategies. Journal of Nematology 25:383-394.

Stansly, P. A., R. McSorley, and M. Ozores-Hampton. 1999.  Management of root-knot nematodes in organic production. Citrus and Vegetable Magazine (March 1999): 11-12.

Stirling, G. R. 1991.  Biological Control of Plant Parasitic Nematodes.  CAB International, Wallingford, U.K.

Robert McSorley
Dept of Entomology and Nematology /University of Florida

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Dow Showcases New Telone Application Rig 
Dow Chemical Company recently unveiled a new application rig for broadcasting Telone with demonstrations in Gainesville, Palmetto, and Immokalee.  The rig itself is the brainchild of John Mirusso, who fabricated specially designed colters to place the Telone a full 12 inches below the ground.  This depth actually places the fumigant where no fumigant has gone before!  Additionally, this depth of placement so adequately seals the Telone and chloropicrin in, that it cannot be detected by the human nose.

The new rig uses a series of 30-inch vertical colters placed one foot apart to knife-in the Telone C-35 while simultaneously broadcasting Tillam.  The equipment offers several advantages, including:

Although the rig is designed for a once-over application including the Telone and Tillam, the consensus among the growers was that the Tillam might best be applied toward the end of the Telone re-entry period to help aerate the soil and provide the longest-lasting weed control.  It was also believed that a light disc would provide for a better incorporation of the Tillam than the S-tines on the rig.  Tillam is best used in conjunction with mechanical transplanting equipment.  If plants are to be set by hand, workers must be provided with waterproof, chemical-resistant gloves (Category A).  The REI on Tillam is 12 hours.  However, according to Zeneca's Tillam label, tomatoes should not be transplanted before 21 days.

Telone C 35 has surfaced as the best, readily available alternative to methyl bromide at the present time.  The 35% chloropicrin is included in the mixture for additional disease control.  Methyl bromide users are no strangers to chloropicrin.  It should be noted, however, that 35% chloropicrin will require more time (approximately 21 days) to vacate the soil than growers remember with the 2% product found in the old methyl bromide.

The rig impressed those in attendance and persuaded many attendees to think more seriously about the coming loss of methyl bromide.  Although projections are for a total phase out of methyl bromide by 2005, most growers feel it will be almost impossible to obtain by fall 2001.  For more information on Telone, contact Jerry Nance, Telone Specialist, Dow AgroSciences (863-293-4224); for specification on the application rig, contact John Mirusso (561-251-5187).

(Vavrina, McAvoy, Vegetarian 00-03)

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On The Lighter Side
This is the transcript of the ACTUAL radio conversation of a US naval ship with Canadian authorities off the coast of Newfoundland.

Canadians: Please divert your course 15 degrees the South to avoid a collision.

Americans: Recommend you divert your course 15 degrees the North to avoid a collision.

Canadians: Negative. You will have to divert your course 15 degrees  to the South to avoid a collision.

Americans: This is the Captain of a US Navy ship. I say again, divert YOUR course.

Canadians: No. I say again, you divert YOUR course.


Canadians: This is a lighthouse. Your call.

As a young man, Norton was an exceptional golfer. At the age of 26, however, he decided to become a priest, and joined a rather peculiar order. He took the usual vows of poverty, chastity, but his order also required that he quit golf and never play again. This was particularly difficult for Norton, but he agreed and was finally ordained a priest.

One Sunday morning, the Reverend Father Norton woke up and realizing  it was an exceptionally beautiful and sunny early spring day, decided he just had to play golf.

So... he told the Associate Pastor that he was feeling sick and convinced him to say Mass for him that day. As soon as the Associate Pastor left the room, Father Norton headed out of town to a golf course about forty miles away. This way he knew he wouldn't accidentally meet anyone he knew from his parish.

Setting up on the first tee, he was alone. After all, it was Sunday morning and everyone else was in church! At about this time, Saint  Peter leaned over to the Lord while looking down get away with this, are you?"  The Lord sighed, and said, "No, I guess not."

Just then Father Norton hit the ball and it shot straight towards the pin, dropping just short of it, rolled up and fell into the hole. It WAS A 420-YARD HOLE IN ONE!

St. Peter was astonished. He looked at the Lord and asked, "Why did  you let him do that?" The Lord smiled and replied, "Who is he going to tell?"
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