Cooperative Extension Service 
                                                   ________________________________________________

Institute of Food and Agricultural Sciences

Hendry County Cooperative Extension Office
PO Box 68
Labelle, Florida 33975
863-674-4092

      Southwest Florida Vegetable Newsletter

September — October  2001

Index:

Calendar

November 7, 2001              Vegetable Growers Meeting - Sandea Herbicide Control of Nutsedge
                                             and Certain Broadleaf Weeds in Florida Vegetables – 6:00 to 8:00 P.M,
                                             SW Florida Research and Education Center
                                             Hwy 29, Immokalee.
                                             Contact 674-4092 for more information.

November 8, 2001              WPS -Handler Training
                                            Dallas Townsend Agricultural Center
                                            1085 Pratt Blvd.
                                            LaBelle, Florida
                                            Spanish and English classes available.
                                            Contact Sheila at 863-674-4092 to register or for more information.
 

November 8-9, 2001          17th Annual Tomato Disease Workshop
                                            West Palm Beach, Florida.
                                            Presentations and discussions on the occurrence and management of tomato diseases.
                                            Both processing and fresh market tomato problems will be addressed.
                                            For additional information visit: http://erec.ifas.ufl.edu/TDW.htm

November 13, 2001           Weather seminar - Short term forecasts - 10:00 AM - 12:00 Noon
                                            Weather by the Seat of Your Pants with Jim Clarke, meteorologist, WBC-WBBH TV
                                            SW Florida Research and Education Center
                                            Hwy 29 N
                                            Immokalee, FL
                                            Contact Sheila at 863-674-4092 to register.

November 20, 2001          Sub-surface Drip Irrigation  -  9 AM
                                          Pacific Tomato Growers
                                          Myakka City, Florida
                                          Use Wauchula Road entrance approximately 1 ¼ mi north of SR 70

November 28-29, 2001     The IV Americas Food and Beverage Show
                                            The largest in the Western Hemisphere will take place on in Miami Florida
                                            featuring more than 600 exhibits from 24 countries. This is a great opportunity
                                            for ag-products (fresh and processed) for export to Latin America, Europe, and Asia.
                                            For more information contact (305) 871-7910.

December 8-12, 2002      Cucurbitaceae 2002
                                          Naples Beach and Golf Club
                                          Naples, Florida
                                          Contact Don Maynard at 941-751-7636 ext 239 or dnma@mail.ifas.ufl.edu
 
 
Note from Gene

Gene McAvoy 
Vegetable Extension Agent II 
Hendry County Extension Office 
PO Box 68 
LaBelle, Florida, 33975 
863-674-4092 

GMcAvoy@mail.ifas.ufl.edu
Are you a vegetable ambassador? It has struck me many times in attending various vegetable industry functions how few vegetables are served at luncheons and dinners.  As growers and others involved in the industry, you would think we could  do more to stimulate the supply side of the supply and demand equation and promote our products.

In other ways, growers can promote the industry by speaking with school groups,  host tours of their operations and other wise actively promote the vegetable industry.  In my position as an extension agent, I am involved in many such activities on an annual basis and can not begin to describe the interest and downright fascination people of all ages have with the vegetable industry and agriculture in general.  With most Americans now far removed from agricultural , there is a yearning to rediscover their rural roots.

Although there has been a lot of negative press about agriculture and it’s impact on the environment, there has been little attention focused on the positive aspects of our industry.  Certainly the economic returns from various agricultural enterprises based in Florida has allowed the preservation of large tracts of land in their natural state as opposed to more intense forms of development which would most likely occur if the income from agriculture was denied landowners.

With Florida just suffered through on of the most severe droughts in the last century, the importance of agricultural lands as aquifer recharge areas has become more apparent.

On other fronts new research underscores the importance of a healthy diet particularly the consumption of fruits and vegetables in preventing many chronic illnesses.

While many critics of the industry are stuck in a “Silent Spring” mentality that may have had some validity four decades ago,  agriculture has made tremendous strides during this time in reducing pesticide usage and the development of a range of reduced risk “green chemistry”  to ensure bountiful harvests of high quality food  for the American public.

Scientific advances in the production of crops and the  management of pests and diseases through the development and use of what is literally in many instances space age technology is nothing short of fantastic.  Think about it—applications of computer technology, biological engineering, microbiology, and many other cutting edge technologies to agriculture would have seemed like the stuff of a Buck Rodgers novel just a few short years ago.

We have an important and powerful story to tell and it is up to all of us to communicate it to the public.  There are many ways to do this.  Offer to talk with a public school class– your child or grandchild would surely be proud to have you speak with his or her class.  Open up your operation on occasion to a farm tour or local garden club or civic group like Rotary.  Participate in one of the periodic legislative tours held by Farm Bureau and others to make sure that our elected officials don’t lose sight of the valuable contributions of our industry.  There are many ways in which you can be a vegetable ambassador.
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Terrorist Attacks in New York City and Washington, D.C.

Implications for the Florida Vegetable Industry
The tragedy inflicted on the American people when the World Trade Center and the Pentagon were attacked on September 11, 2001, created havoc in much of the world, extending beyond the borders of the United States.  The crisis that followed created great uncertainty and shook the confidence of many people throughout the world.  This type of uncertainty impacts markets as normal economic activity and decisions made by market “actors”, ranging from the producer to the consumer, will be influenced by the actions on that day.

The vegetable industry, however, will likely see only minor impacts in its markets.  On the demand side, consumers are not likely to change their purchasing practices for fresh vegetables over the next few months.  The tragedy will weigh on the minds of people and may influence investment decisions made by consumers, but food such as fresh vegetables will still need to be consumed to nourish the body and will continue to be seen as vital to the American diet.  The international demand for U.S. fresh vegetables will likely suffer from the uncertainty of situations resulting from the tragedy, but the international demand for fresh vegetables is small relative to the domestic demand.  The largest foreign market for U.S. grown vegetables is Canada, and there should be only a minor, if any, impact in that market.

The supply side of the market in the United States should also remain strong.  There have been few disruptions in the supply of inputs necessary for producing vegetables.  The cost of inputs may decline as interest rates decline to help the other parts of a floundering economy.

Imports may suffer the greatest impact in the vegetable industry.  Any continuation of the uncertainty in the international arena will increase the cost of moving products throughout the world.  This may be especially true in the cost of moving products across the border as the United States moves to increase the security of its borders. Delays at the borders increase the cost and uncertainty of providing a quality product in the U.S. market.  This may cause a small decline in the supply of foreign produce that competes with U.S. produce in U.S. markets.

On balance, little impact of the tragedies in New York City and Washington, D.C. is expected to trickle down to the domestic vegetable industry.  Any impact is likely to be positive for Florida producers as it becomes more difficult to bring in imports that compete with Florida produce in the domestic market.  Inputs are also likely to decline in cost to reflect the lower cost of capital.  The fresh vegetable industry in Florida should not suffer any significant consequences from the September 11th tragedy and should see a normal year of operation.

John VanSickle
Department of Food and Resource Economics,
Florida Cooperative Extension Service
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Tornado Rips US Department of 
Agriculture Beltsville Station
A tornado that ripped through Maryland may have done as much as $41 million in damage to the government's top ag. research center, destroying several greenhouses and ruining years of plant research.  Fifteen buildings at the 7,000-acre Beltsville Ag. Research Center were damaged in the rare F3 tornado.

Officials are calculating the exact cost of the damage but know that “it's going to be high,” spokeswoman Sandy Miller Hays told the Washington Post.  With a staff of 1,400, the Beltsville center is considered the flagship research center for USDA.
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Report from Phil 

WHITEFLY CONTROL IN SPAIN
Dr Phil Stansly – Entomologist with the UF/IFAS Southwest Florida Research and Education Center is in Spain on sabbatical.  He is working with Koppert Biological Systems – one of the world foremost suppliers of Biological Controls.  Koppert is a Dutch company with subsidiaries in numerous countries including the US, Mexico and Spain.  In Spain, they are headquartered in Aguilas.  This location serves the vegetable industry on the southern coast of Spain and in the Canary Islands, over 120,000 acres of greenhouse production.

One of the areas served is the “Campo de Cartegena” region north of Aguilas where 4,500 acres of greenhouse pepper are grown.   Last year biological control was used in 2750 of these acres.  Little if any insecticidal control was necessary.  The main pest western flower thrips controlled by a predaceous mite, Amblysieus cucumeris, and a predaceous bug, Orius laevigatus.

The whitefly here is Bemisia tabaci biotype “Q”, and it loves pepper.  Fortunately it carries no viruses to pepper here, yet anyway.  Whitefly was controlled with a combination of parasites (Eretmocerus eremicus), soap and growth regulators (Knack and Applaud).

Tomato is a different matter.  Most of the tomato-growing areas are intensively cropped year round.  TYLCV is the big problem, and there is often very little that can be done against it.  Admire seems to have little effect.  Hard chemicals like Lannate and Thiodan are used extensively, sometimes daily, but with little result.  Resistant tomato varieties are available, but do not have the quality most growers want.

Furthermore, the resistance seems to be breaking down.  In many cases, so-called resistant plants express TYLCV symptoms ranging from slight to severe.  It seems the virus is evolving to get past the resistance mechanisms now available.

The challenge here is to try and develop effective biocontrols under such a grim scenario.  Currently there is no biological control to offer the grower against adult whitefly.  Nevertheless, Phil’s project is to develop and evaluate a biological control program here in tomato.  It’s clear that this will be impossible unless some way to stop virus movement can be found.

Many growers are screening in their greenhouses.  Most new structures going up have sophisticated systems of screens on vents and doors.  It’s not easy when they're trying to grow in 85-degree weather, but there's really no other option.  Then there are the resistant varieties, which still offer some protection.  Finally, late plantings avoid most of the whiteflies coming off the last season's crops.  So, there are some situations where growers can take advantage of biological control techniques.

A parasitic wasp, Eretmocerus eremicus is one of the main biological tools against whitefly.  It is originally from North America and is produced by Koppert’s Biological in Holland using greenhouse whitefly as a host.  One of the interesting results from previous seasons was that although E. eremicus was readily established in greenhouses where the insecticidal regime was not prohibitive, it was steadily replaced by a native parasite, E. mundus, coming in from the outside.

So switch to E. mundus, right?  Not so easy.  Its almost impossible to rear on greenhouse whitefly and regulations in Holland prohibit mass rearing on Bemisia.  So, if Koppert wants mundus, they have to rear it in Spain, which is what is being done.

Phil is working to evaluate the critter, from the petri dish all the way to the greenhouse.  At the commercial level, they have about 10 pairs of identical or nearly identical greenhouses set up with growers all along the southern coast of Spain and in the Canary Islands.  One greenhouse of each pair is under conventional (chemical control), and the other is employing an integrated system developed by Koppert that utilizes biological control and compatible chemicals when necessary.  Both greenhouses are divided into 4 sections and evaluated weekly by an experienced scout for pest and disease incidence, focusing on whiteflies.  Two of the 4 sections in the “IPM” greenhouses receive E. mundus and two E. eremicus when the scout thinks a release is warranted.

Phil indicates that they are massing a “mountain” of data and promises regular updates.  Hopefully, they will have some good (and convincing) results that will help the Spanish grower and that could have possible applications to our industry.  Stay tuned for future updates from Phil.
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NATURAL AREA WEED MANAGEMENT MANUAL
NOW AVAILABLE
To learn how to control weeds in natural areas, turn to the University of Florida's new training manual, Natural Area Weed Management.

The 46-page, full-color publication, now available from UF's Institute of Food and Agricultural Sciences, is designed for those who apply herbicides to control invasive vegetation in natural areas of Florida.

The manual contains information on herbicide application and safety in natural areas, said Kenneth Langeland, professor of agronomy and author of the publication.  He said the manual is one of two publications recommended for those seeking certification and licensing by the Florida Department of Agriculture and Consumer Services. Priced at $12, the manual contains valuable information, photographs, tables and charts.

“The second manual, Identification and Biology of Non-Native Plants Found in Florida's Natural Areas, is recommended for identifying invasive plants,” Langeland said. “ The two manuals, developed as study guides for those seeking state certification, also are useful resources for land managers and others with an interest in identifying and managing invasive plants.”

Both publications are available through the UF/IFAS-Extension bookstore, PO Box 110011, Gainesville, Fla. 32611-0011.  Call (352) 392-1764 to order the book. Make checks payable to the University of Florida. School purchase orders are also accepted. For credit card orders, call (800) 226-1764.

Source: Kenneth Langland UF/IFAS Gainesville, FL. (352) 392-9614
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Irrigation Scheduling and Water Conservation with Tensiometers
Irrigation is an important component of vegetable production in Florida.  The amount of water applied to the crop during the growing season and proper timing of irrigation events play a significant role in achieving high crop yields.  Traditional approaches to irrigation are often based on field history, visible symptoms of plant stress, or visual estimation of soil moisture.  This often leads to under- or over- irrigation of the crop.  Shortages of water in the early stages of plant development may lead to plant stress, delay crop maturity and lower yields.

Water shortages later in the growing season often result in reduced quality even if total yields are not effected.  Over-irrigation causes leaching of fertilizers from the root zone, possibly into ground or surface water.  Plants receiving excessive irrigation during the growing season are also prone to developing root diseases and ultimately yield reduction.

The tensiometer is a simple and valuable tool that can be used for scheduling irrigation.  Tensiometers continuously measure soil water potential or tension.  This is expressed in centibars (cbar).  If the tension of the soil is high, plants have to use more energy to extract soilwater.

A typical tensiometer is a water-filled tube with a porous ceramic cup at the lower end.  After installation in the soil, water moves from the tensiometer through the cup into the unsaturated soil.  This process continues until the negative pressure inside the tensiometer equals the negative pressure in the surrounding soil.  The pressure inside the tensiometer is then in equilibrium with the pressure in the soil and can be measured by reading the vacuum gauge on the tensiometer.

Preparing tensiometers for installation:  The Fact sheet “Tensiometer Service, Testing and Calibration”(1) provides detailed instructions on calibrating and testing tensiometers before installation in the field.  Producers of tensiometers often provide instructions for tensiometer users as well (2).

Site Selection:

Sites selected for tensiometer installation should be representative of the soil type in the field.  If soil types vary within the field, each of the soil types present should have a separate set of tensiometers.

Tensiometers should be installed in the active root area in the wetting zone of the irrigation system.  For vegetables grown with the drip irrigation, the tensiometers should be located in the plant row, between plants in the wetting zone of the drip tape.  For very shallow rooted vegetable crops, only one tensiometer placed at least 4 to 6 inches below the surface may be required.  For moderately deeply rooted vegetables, such as drip irrigated tomatoes, two tensiometers (at 6 and 12 inches) should be installed in each field.

Installation:

Before installation of new tensiometers and reinstallation of used ones, the ceramic cups should be soaked in water for several hours to overnight to ensure that the ceramic is throughly saturated.  Tensiometers should be tested and calibrated before installation using a hand vacuum test pump, or tensiometer calibration chamber.  Proper installation is critical to assure effective contact between the ceramic cup and the surrounding soil.  In very loose soils 6 inch tensiometers can simply be pushed into the ground.  For other soils it may be necessary to prepare hole using a pointed a 7/8 inch steel rod or galvanized pipe.  The diameter of the hole should be the same as diameter of the tensiometer.

In very coarse soils, like the rocky soils of southern Florida, installation requires the use of heavy hammer and 7/8 or 1 inch diameter steel rod to drill a hole deep enough to accommodate the tensiometer.  Prepare a thick slurry by mixing screened soil (< 2 mm) collected from the surrounding area with water.  After placing some of the slurry in the bottom of the hole and carefully placing the tensiometer in the hole, the rest of the slurry should be added around the ceramic cup and the plastic tube of the tensiometer.  Then the tensiometer should be rocked gently back and forth a few times to ensure good contact with the soil (3).

Taking and recording tensiometer readings:

In light soils the readings should be taken at the same time each day, ideally in the early morning before irrigation. The readings should be recorded in a notebook along with the rainfall and irrigation amounts and dates.  The location of each tensiometer station should be identified by recording the site number, the depth of the tensiometer being read, and the date and time of the reading.

Irrigation scheduling with tensiometers:

In general the following guidelines should be used to schedule vegetable irrigation in gravelly or sandy soils.

Tensiometer Readings 0-5 cbar: Soils are saturated or nearly saturated as a result of irrigation or a rain events. Discontinue irrigation to prevent wasting water and leaching nutrients from the root zone.

Tensiometer Readings 10-20 cbar:  Crops should be irrigated as soon as possible.

Tensiometer Readings 30 cbar and higher:  Plants probably show symptoms of water stress. Irrigate immediately!

The duration of irrigation can be determined by using longer (12-18 inch) tensiometers in addition to 6 inch tensiometers.  If the readings from the longer tensiometer drops 1-2 cbar after irrigation, then shorten the time of the irrigation event until the irrigation not longer registers on the gauge of the longer tensiometer.  If the readings obtained from the longer tensiometer are persistently higher than 25 cbar, increase the length of the irrigation period.

Maintenance of tensiometers:

Tensiometers are simple instruments, but they require regular maintenance to provide proper readings of soil water status. During the growing season, all tensiometers should be refilled with water periodically (especially after long periods without irrigation or rain) to prevent losing suction due to a low water level in the plastic tube. All tensiometers should be removed from the soil every 3-4 months or at the end of the growing season and washed to remove soil, algae, bacteria and other debris from inside and outside the ceramic cup and the plastic tube.  A mild household detergent and a small bottle brush can be used for cleaning.  The ceramic cup should be soaked in a chlorine solution (1/4 cup of household bleach in a gallon of water) to kill bacterial growth.

After cleaning, fill the instrument with clean water and add a mild biocide to prevent algae growth. A hand-held vacuum pump should be used to remove excess air before reinstallation in the field.

Trouble shooting:

Tensiometer gauge always reads zero.   If correct, a zero reading means that soil is saturated from irrigation, heavy  rainfall or very poor drainage.

 Possible problems:

A) No water in the tensiometer, or lost suction due to a low water level.

    Solution:  Service the tensiometer   and refill with water

B)  The gauge is faulty:

     Solution:  Check and replace the   gauge.

C)  A connection is leaking:

    Solution: Check the general assembly including ceramic cup and O-ring seals.

2. Tensiometer does not seem to record  the true soil moisture content.

Possible problems:

A)  Poor contact between the ceramic cup   and the surrounding soil.

    Solution: Reinstall correctly.

B)  The gauge is faulty.

    Solution: Check and replace the   gauge.

3. Tensiometer needs frequent refilling  with water.

Possible problems:

A)  Ceramic cup or seal is leaking

Solution. Replace the seal or cup.   Check other seals for leaks.

4. Tensiometer responds too slowly to irrigation.

 Possible problems:

A)  Water is slow to infiltrate between the ceramic cup and the soil.  The ceramic cup may be clogged by salts or algae.

    Solution: Clean or replace the cup.

B)  The gauge sticks from minor damage.

    Solution: Tap to test, and replace the   gauge if faulty (from Gillet J. 2000)

Summary:

With proper calibration, installation and maintenance, tensiometers are useful instruments for scheduling irrigation. They are not affected by the amount of salts in the soil.  They can measure soil water potential with good accuracy in the wet range before plant water stress occurs.

A recent tomato field trial conducted in 1999-2000 in Miami-Dade County using tensiometers to schedule irrigation, proved that reducing irrigation by 27% (scheduled according to the tensiometer readings) did not significantly influence total and marketable yields of tomatoes (5).  Tensiometers can be used successfully to schedule irrigation according to crop needs and reduce the total amount of irrigation water used during the growing season.

References:

Smajstra A. G. and D.J. Pitts. 1997. Tensiometer service, testing and calibration, Fla. Coop. Ext. Serv. Bul. 319, IFAS, Univ. of Fla., Gainesville, Fla.

Irrometer Company. 1998. Moisture indicator reference book. Riverside, Calif.

Li YC. 2000. Using tensiometers for irrigation scheduling in tropical fruit groves. Fla. Coop. Ext. Serv. IFAS. Univ.of Fla., Gainesville, Fla. http://edis.ifas.ufl.edu/BODY_TRO02

Gillet J. 2000. Tensiometers need periodic maintenance. http://www.agric.nsw.gov.au/reader/3901

Olczyk T., R. Regalado, Y. Li, and R. Jordan. 2000. Usefulness of tensiometers for scheduling irrigation for tomatoes grown on rocky, calcareous soils in Southern Florida. Proc. Fla. State Hort. Soc. 113:239-242.

Teresa Olczyk
FACTS Proceedings 2001
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WORKER PROTECTION 
STANDARD
A pesticide handler is anyone who is employed (including self-employed) for any type of compensation by an agricultural establishment or a commercial pesticide handling establishment that uses pesticides in the production of agricultural plants on a farm, forest, nursery, or greenhouse AND is doing any of these activities.

 A person is not a handler if he or she only handles pesticide containers that have been properly emptied or cleaned. A person is not a handler if he or she is only handling pesticide containers that are unopened.  However, a person who is not a handler may not load unopened, water soluble pesticide packets into a mixing tank.

You can find a WPS check list at our web site. http://www.ces.uga.edu/Agriculture/PesticideApplicator/pest-home.html

You can find out everything about WPS at the EPA website. www.epa.gov/pesticides/safety

Do you need to ask some questions about WPS or other regulations that affect agriculture? Call the National Agriculture Compliance Center at 1-888-663-2155 or visit them on the web at www. epa. gov/oeca/ag

The Georgia Pest Management Newsletter
September 2001
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Irrigation Evaluation
A statewide network of mobile irrigation labs offers growers a free, confidential source for evaluating their irrigation systems' efficiency.

Ever wonder if your irrigation system could be running more efficiently?  That's what Tom Jones, Jim  Cloughley, and Tom Dryden asked themselves about their operations.

All three southwest Florida growers called on a team of experts from Florida's network of mobile irrigation labs (MILs).  At no cost, a team of trained technicians methodically evaluated the growers' existing systems from top to bottom.

The service, says Barron Collier's Jones, “is a good check to make sure you're operating where you think you're operating.”  After all, he points out, much of the system runs underground.  “You drive by, you see water coming out.  It looks like it's working right.”  But the mobile lab technician's “second set of eyes” can spot problems that may be easy to fix.

Like Barron Collier, managers at nearby Berry Citrus didn't think they had any serious problems, but called on the lab anyway.  The evaluation turned up “a few surprises,” recalls Cloughley.  He knew he had some clogged emitters, but only after the water-quality test was completed did the magnitude of the problem become apparent:  In some spots, the system was running at only 36% efficiency.  “That opened my eyes,” says Cloughley.  Berry Citrus has made some changes over the last couple of years, and now that block is producing more fruit.

At Gargiulo Farms, lab technicians didn't come up with any surprises for Dryden, who was confident his farm had a well-designed drip system running through his tomato fields.  “We didn't cut corners like a lot of people do,” he says.  Still, he wanted to make sure he was getting what he paid for, particularly since uniform fertilization is so critical.

With an evaluation rating his system at 93% to 95% efficient, Dryden now has one less thing to worry about.

Complimentary And Confidential

Such free evaluations have been available since the 1980s, when the first MIL sprung up in Naples.  There are now 13 MILS scattered across the state, and MIL Team Leader Robert Beck expects others to be started.  All services are publicly funded by various government agency partnerships interested in seeing all kinds of irrigation systems - both urban and rural - be the best they can be.

The program is not just free; it is entirely voluntary and confidential.  As a federal program associated with the USDA's Natural Resources Conservation Service (NRCS), the reports are not filed with the water management district, stresses Beck. If they weren't kept private, “We would have been out of business the first year.”  Local NRCS staff can sometimes help growers pay for improvements by steering them toward available cost-share or other financial sources.

Beck's Naples lab ordinarily covers Collier, Lee, Hendry, Glades and Charlotte counties, and serves commercial agricultural and nursery operations as well as residential, commercial, and public-turf irrigation systems.  Other labs have their own territories, but not all cover farms.

In-Depth Analysis

Agricultural producers stand to save money on pumping and to gain assurance that their applied water is going where it needs to go - and no further.  Technicians collect a range of information, including crops, soils, water sources, and current operating practices.  They measure water flows, pressures, wetted areas, spacing, root depth, and other relevant parameters.  They then calculate what kinds of flow, uniformity, and application rates growers are actually getting.

Typically, technicians begin their irrigation analysis by interviewing the operator.  Technicians outline the system design and components, as well as its management and use.  They start up the system and record pressure readings at the pump, downstream of the filter, and at the lateral inlets of each submain.  They then measure the output of each zone, taking flow rates directly from a sampling of 16 emitters, and recording pressures at the end of selected laterals.  Readings are then calculated to help identify any potential problems.

In addition, at each pump the technicians test the water for quality by checking the following criteria: pH, temperature, calcium, magnesium, total hardness, total and phenolphthalein alkalinity, iron, sulfides, and total dissolved solids.  After the evaluation, the technicians provide growers with written reports containing  recommendations for improvements and suggest operating schedules that should improve system efficiency.  All reports also include soil maps, manufacturers' specifications for the equipment used, and maintenance guidelines. Technicians then discuss their findings with the operator - being sure to highlight how improvements can offer grower savings in terms of lower pumping costs, reduced fertilizer and pesticide leaching, and optimal use of applied water.

Significant Savings

The reports also estimate the volume of irrigation water that could be saved if recommendations are followed.  In follow-up visits, the program tries to track actual water savings based on improvements growers make.

In just the Gulf Coast region of southwest Florida - which Beck oversees - the program's 2000 figures show that from the 110 evaluations performed (70 were agricultural systems), corrected deficiencies and new schedules could be saving an estimated 5.41 billion gallons - or 16,616 acre feet - of water.

Follow-up evaluations showed that many of the recommended changes were indeed made.  “Actual” water savings estimated from the Gulf Coast region added up to 890.7 million gallons of water (2733 acre feet).  That's 16.4% of the calculated “potential” water savings.

The program also offers periodic workshops, demonstrations, and displays for the benefit of the general public.

Florida Grower
September 2001
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Biorational Insecticides in Vegetable Integrated Pest Management
IPM and Biorational Insecticides.  Integrated pest management (IPM) can be defined as the use of all available means to maintain pest populations below economic levels while minimally impacting the environment.  The tactics utilized in IPM programs include chemical, cultural, physical and biological control.  Most management programs rely heavily upon the use of insecticides applied when periodic scouting indicates that pests have exceeded a pre-determined threshold.  Insecticides provide quick control of pests but often require repeated applications to provide long term management.  It has long been recognized by researchers and, more recently, by IPM practitioners that the integration of biological control (mortality induced by natural enemies including parasites, predators and pathogens) into IPM programs is essential for long term, stable management of pests.  Repeated applications of insecticides can lead to the development of resistance in the target pest and can reduce the natural enemy populations, leading to resurgence of the target pest(s) and outbreaks of secondary pests, i.e. those normally kept under control by their natural enemies.  Therefore, knowledge not only of the effect of an insecticide on the target pest but also on non-target natural enemies is essential.  Although this information has been collected for at least the last 50 years for some insecticides, the term “biorational” has only recently been proposed to describe those insecticides that are efficacious against the target pest but are less detrimental to natural enemies.  The term at times has been used to describe only those products derived from natural sources, i.e. plant extracts, insect pathogens, etc.  However, we choose to define a biorational pesticide as “any type of insecticide active against pest populations, but relatively innocuous to non-target organisms, and therefore, non-disruptive to biological control” (Stansly et al.  1996).  An insecticide can be “innocuous” by having low or no direct toxicity, or by having systemic or rapid translaminar activity or short field residual, thereby minimizing exposure of natural enemies to the insecticide.

As will be seen in the present discussion, the “biorationality” of an insecticide is almost always relative, i.e. the toxicity of one insecticide is compared to that of other insecticides, or is almost never broad spectrum, i.e. an insecticide can be innocuous to one natural enemy or even some life stages of one natural enemy but can be toxic to another natural enemy or other life stages.  Traditionally, soaps/detergents, oils and botanicals, i.e.neem products (products made with azadirachtin extracted from neem tree seeds), have been termed biorational; however, in the present discussion, systemic insecticides, insect growth regulators and products containing Bacillus thuringiensis or its components will be included.  In addition, the “biorationality” of several new products that are available, or will soon be available, also will be discussed.

Tomato Pests in Florida.

It is always necessary to consider the entire pest complex when designing an IPM system for a particular crop because actions taken to control one pest may impact another pest or its natural enemies.  The present discussion will focus on tomatoes, although many vegetable crops have the pests and pesticides in common with tomatoes.  The silverleaf whitefly, Bemisia argentifolii Bellows & Perring [a,k.a., the B strain of the sweetpotato whitefly, B. tabaci (Genn.)], is the key and most damaging insect pest of tomatoes in Florida.  Adults, eggs and the four, scale-like nymphal life stages all occur on the undersides of the leaves, making control with contact insecticides more difficult.  Adults can transmit plant viruses, particularly geminiviruses, that are extremely damaging, especially tomato yellow leaf curl virus (TYLCV), and feeding by nymphs induces a systemic disorder of fruit call irregular ripening.

The southern armyworm, Spodoptera eridania (Cramer), is the most abundant armyworm species on tomatoes in south Florida and the yellow-stripped armyworm, S. ornithogalli (GuenÈe), is the most abundant species in north Florida.  The beet armyworm, S. exigua (Hubner), is a more difficult species to control that may be damaging to tomato but generally is more abundant on other vegetable crops such as pepper.  All three species deposit eggs in hair-covered masses on the undersides of leaves where hatching larvae feed gregariously.  Older larvae disperse and may cause significant defoliation but cause most economic damage when they feed on fruit.  The tomato fruitworm, Helicoverpa zea (Boddie), lays eggs singly on foliage or flowers and hatching larvae, unlike those of armyworms, seek out developing fruit into which they bore.

 Leafminers, principally Liriomyza trifolii (Burgess), and the tomato pinworm, Keiferia lycopersicella (Wals.), were the key pests of Florida tomatoes in the 1970’s and early 1980’s, but efficacious, and to some extent, selective insecticides and the appearance of the silverleaf whitefly have reduced their pest status.  Leafminers lay their eggs in the upper surface of leaves where hatching larvae form characteristic serpentine mines.  High levels of defoliation can result, particularly when secondary micro-organisms invade the mine causing the mines to coalesce and leaflets to become necrotic.  The tomato pinworm deposits eggs singly on the undersides of leaves where hatching larvae immediately bore into the leaves and form blotch mines.  Older larvae may roll and tie leaflets together but inflict most damage when they bore into fruit, usually unseen under the calyx.

Flower thrips in the genus Frankliniella are small, featherwinged insects that inhabit flowers where feeding and egg laying may cause dimples on fruit at the blossom end or “zippering” “catfacing” on the sides of fruit.  Some species can transmit tomato spotted wilt virus which is more prevalent in north Florida than south Florida.  Green and brown species of stink bugs, particularly the southern green stink bug [Nezara viridula (L.)], and leaffooted bugs, especially Leptoglossus phyllopus (L.) and Phtia picta (Drury), deposit egg masses on the undersides of leaves where hatching nymphs may feed gregariously.  Older nymphs and adults cause most damage by feeding on fruit with their piercing-sucking mouthparts.  Stink bugs cause a lightened blotch beneath the fruit surface.  Leaffooted bug punctures usually are deeper, often causing distortion of fruit as the fruit grow and expand.  Discolored zones may develop around punctures, especially with leaffooted bugs, due to the introduction of secondary microorganisms which may lead to fruit rot.

Soap, Oil and Neem

Insecticidal soap (and detergents), horticultural mineral oil (HMO) and neem products containing azadirachtin have been investigated for their effects on the silverleaf whitefly (Price et al. 1990; Price and Schuster 1991’ Butler et al. 1993; Liu and Stansly 1995a, 1995b; Stansly, unpublished data) and selected natural enemies (Price and Schuster 1991, Liu and Stansly 1996, Stansly and Liu 1997, Schuster and Stansly 2000).  These studies showed that soap, neem and oil were all toxic to whitefly nymphs, although coverage was particularly important for oil.  Oil was also repellent to whitefly adults but reduced yields of tomato in the field when applied at a concentration higher than 2%.  Oil was relatively non-toxic to adults of two species of lacewings [Chrysoperla rufilabris (Burmeister) and Ceraochrysa cubana (Hagen)] or to adults of a small, lady beetle species [Nephaspis oculatus (Blatchley)], and was moderately toxic to larvae of a major whitefly parasite species [Encarsia pergandiella (Howard)] and to larvae of non-trash bearing species of lacewing (C. rufilabris).  Oil was highly toxic to adults of the parasite species, to eggs of both lacewing species and, to a lesser extent, to lady beetle eggs.  Toxicity was again mitigated by coverage.  Soap was highly toxic to whitefly adults, but only when wet.  Soap caused only slight effects on the parasite species and was moderately toxic to adults of both lacewing species and to larvae of the non-trash bearing lacewing species.  Conversely, soap was highly toxic to young lady beetle larvae.  Neem is reportedly antifeedant to whitefly adults and is practically non-toxic to both species of lacewings and to the parasite.  In general, trash bearing lacewing larvae were less susceptible to all three biorational pesticides than non-trash bearing larvae, even when considering the broad-spectrum pyrethroid bifenthrin.

The potential of a liquid dish detergent and HMO (Sunspray Ultrafine™) to cause phytotoxicity on tomato also was investigated.  It was found that applications of 0.5% or more detergent applied twice weekly delayed production (Vavrina et al. 1995).  Weekly applications were less damaging.  On the other hand, no effect was seen from weekly applications to pepper of concentrations of HMO up to 2% applied with or without mancozeb plus copper (Vavrina et al. 1996).

Bacillus thuringiensis Products

The non– or low toxic effects of products based upon the bacterium, Bacillus thuringiensis Berliner, are documented for numerous species of natural enemies of numerous pests (as summarized for leafminer parasites in Schuster et al.  1996).  Products for control of lepidopterous larvae are based upon two subspecies of B. thuringiensis: kurstaki (i.e. DipelTM, JavelinTM) and aizawai (i.e. XenTariTM) or a combination of the two (i.e. AgreeTM).  As with insecticidal products, there is a time line of product evolution.  The first generation products are based on wild-type isolates collected directly from nature (i.e. Dipel, Javelin, XenTari).  Second generation products are based upon conjugation of the two subspecies (i.e. Agree).  Third generation products are based upon the so-called Psuedomonas-based delivery system (insertion of B. thruingiensis genes into Psuedomonas bacteria for the purpose of increasing field persistence, i.e. MattchTM).  Fourth generation products are based upon new B. thuringiensis strains constructed using recombinant DNA technology (i.e. CrymaxTM, LepinoxTM).

Bacillus thuringiensis is a bacterium that is pathogenic to larvae of certain insects, particularly lepidopterous insects, and as such, can induce mortality through infection; however, the resting stage, or endospore, of the bacterium contains endotoxins which are capable of paralyzing and lysing the insect gut, there-by causing mortality through starvation.  The endotoxins are not equally toxic to all species of Lepidoptera; therefore, wild strain selection, conjugation or recombinant DNA techniques have been used to develop B. thuringiensis products that have different arrays of endotoxins to alter or broaden the spectrum of activity of the product .  Numerous studies have been conducted  on the efficacy of B. thuringiensis products on lepidopterous pest of tomatoes.  In general, the products are effective against armyworm and fruitworm larvae (Kund et al. 1999).  From the standpoint of resistance management, products with different arrays of endotoxins should be alternated; however, many products contain endotoxins in common.  Nevertheless, it would be prudent to rotate wild-type B. thuringiensis var. kurstaki products (i.e. Dipel, Javelin) with either wild-type B. thuringiensis var. aizawai products (i.e. XenTari) or with genetically modified B. thuringiensis products (i.e. Agree, Crymax, Lepinox, Mattch).

New Insecticides

The biorational status of older insecticides in the organophosphate, carbamate, pyrethroid and avermectin classes has been studied and reported previously, at least for parasites of leafminers and the tomato pinworm (as summarized in Schuster et al. 1996, Schuster 2000).  A number of new insecticides in new chemical classes have recently become available or will likely become available in the near future.  Unfortunately, little or nothing is known about the relative toxicity of these compounds to the natural enemies of interest to Florida vegetable growers; however, the biorational nature of the compounds can be predicted by the spectrum of activity and other characteristics of the compounds.

The nicotinoids are a relatively new class of compounds, although imidacloprid has been available for use on tomatoes since 1994.  Thiamethoxam received approval by the EPA in 2001.  All of the nicotinoids are highly systemic (i.e. they are distributed through the plant, primarily to new growth, when applied to the roots) and are translaminar (i.e. readily absorbed into the leaf through the leaf surface).  Soil-applied imidacloprid and thiamethoxam have provided control of the silverleaf whitefly for 3 months on tomato (Stansly and Connor 1998b).  Foliar applications of imidacloprid, thiamethoxam and acetamiprid controlled whitefly nymphs, but not as well as soil applications.  Foliar applications of thiamethoxam and acetamiprid also controlled whitefly adults.  Not only are soil applications of nicotinoids more effective than foliar applications in controlling whiteflies, the impact of soil applications on natural enemies would be expected to be less than that of foliar applications because most natural enemies would not be exposed directly to the compounds.

Pymetrozine is another insecticide in a new class of compounds that is active against both aphids and whiteflies.  It is active against both nymphs and adults and has long residual activity because it is absorbed translaminarly and apparently is translocated to new foliage (Nicholson et al. 1996).  Because the compound is translaminar and systemic and because it is highly specific to Homoptera (aphids and whiteflies), it should have minimal impact on natural enemies.

Pyriproxyfen and buprofezin are two new products for controlling whiteflies.  Although both are insect growth regulators (IGRs) and both negatively impact development of immature life stages of whiteflies, they are in different chemical classes and affect whiteflies differently.  Neither kills adults, but treated adults lay infertile eggs;  Furthermore, eggs treated with pyriproxyfen fail to hatch while those treated with buprofezin tend to hatch normally.  Pyriproxyfen interferes with the final molt of the whitefly from pupa to adult while buprofezin interferes with all nymphal molts.  Both products are recommended for application to tomatoes as the effects of soil-applied imidacloprid diminishes.  A threshold of 5 nymphs or pupae/10 leaflets has been established to time the applications (Schuster 1999).  Because the IGRs affect development, control of whiteflies is not rapid.  Although both of the IGRs would be expected to have minimal impact on natural enemies, pyriproxyfen has been shown to be highly toxic to pupae and moderately toxic to larvae of the whitefly parasite E. formosa Gahan, but not to the whitefly parasites E. pergandiella and E. transvena (Timberlake) (Liu and Stansly 1997).  Buprofezn was toxic to larvae but not pupae of the whitefly parasite Eretmocerous tejanus Rose & Zolnerowich and was relatively non-toxic to larvae and adults of the parasite E. mundus Mercet (Jones et al. 1995, 1998).

Tebufenozide, indoxacarb, spinosad and emamectin benzoate are new insecticides that have indicated good control of the southern armyworm (Schuster 2001) and the tomato pinworm (Stansly and Connor 1998a, Stansly et al. 2000), although control of the latter with tebufenozide has not been as good as with the other products (Stansly and Connor 1998a, Schuster 1998, Schuster 2000).  Spinosad and emamectin benzoate also have activity against leafminers (Stansly and Connor 1998a) while spinosad is active against thrips (Eger et al 1998).  Indoxacarb has been inconsistent in leafminer and stink bug control (Stansly and Connor 1998a).  While much is known regarding the spectrum of activity of these new compounds against pest insects, less is known regarding their effects on natural enemies of interest in Florida vegetables.  Spinosad has been shown to have short-term toxicity to the mite Phytoseiulus persimilus Athias-Henriot, a predator of spider mites (Price, unpublished data); however, spinosad was much safer than the pyrethroid cypermethrin for this predator as well as for E. formosa; and generalist predators, including the insidious flower bug [Orius insidiosus (Say)], a lacewing (C. rufilabris), and the convergent lady beetle (Hippodamia convergens GuÈrinMÈneville) (Schoonover and Larson 1995).  In another trial, indoxacarb slightly reduced survival of O. insidiosus adults but did not affect survival of C. rufilabris larvae, while spinosad had no negative impact on survival of either species (Ruberson and Tillman, unpublished data).

Conclusion

From the preceding discussion it is clear that pesticides are available that are effective against most of the life stages of most of the important insect pests of tomatoes and other vegetables, and that these pesticides can be less detrimental to certain natural enemies of these pests.  It is also clear that no single pesticide is completely safe to all life stages of  all natural enemies.  Thus, the biorational nature of pesticides depends upon the time, pest and crop upon which they are used.  Therefore, in order to maximize the effectiveness of these biorational products in managing pests and to more fully integrate biological control into IPM programs, it is essential to have a thorough knowledge of the life stages of the pests and natural enemies that are present.  Only periodic, thorough scouting that includes an assessment of natural enemies can provide this information.

David Schuster and Phillip Stansly
FACTS Proceedings 2001
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Eden Honored
 The presidential Green Chemistry Challenge Award was presented to Eden BioScience for its technical innovation in the development of harpin technology in the small business category.  The awards are given annually through the Environmental Protection Agency Office of Pollution Prevention and Toxics to recognize organizations and individuals that are successfully researching, developing and implementing outstanding green chemical technologies.  These technologies are defined as chemical products and manufacturing processes that reduce or eliminate the use or generation of hazardous substances.

The awards were presented at the National Academy of Sciences during the fifth National Green Chemistry and Engineering Conference.  This is only the third time an agricultural products company has won the award.

 Eden researchers say the harpin protein activates a defense mechanism that stimulates growth without harming the plant.

Citrus & Vegetable Magazine
September 2001
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Genetically engineered tomato plants may provide answer to salty problem
Research on a genetically engineered tomato plant offers hope that genetically modified plants could grow in areas of the world affected by salty irrigation water and salt-damaged soils.

An estimated 24.7 million acres worldwide of once-agriculturally productive land are being lost annually because of irrigation-induced salinity, according to the U.S. Department of Agriculture.

 To alleviate the problem, plant biologists at the University of California, Davis, and the University of Toronto have developed a genetically engineered tomato plant that thrives in salty irrigation water.  With proper funding, it would be possible to develop commercially useful salt-tolerant tomato plants within three years, says Eduardo Blumwald, who led the research team that discovered the salt-tolerance gene.

Irrigation increases the salinity of soils and water by depositing soluble salts, such as sodium, calcium, magnesium, potassium, sulfate and chloride, in the field. Salty irrigation water then upsets the plants' abilities to take in water through their root cells.

To counter the effect, the genetically engineered tomato plants produce higher levels of a naturally occurring protein called “transport protein.”  The gene that controls the increased production was taken from Arabidopsis, a relative of the cabbage.

The transport protein uses energy in the cells to move salt into compartments within the cells called vacuoles.  Once inside the vacuoles, the salt is isolated from the rest of the cell and unable to interfere with the plant's normal biochemical activity.

The plants actually remove salt from the soil.  Because the salt is stored in the leaves, the tomato maintains its quality.

Research has shown the tomato plants grow and produce fruit in irrigation water that is about 50 times saltier than normal.  The plants were irrigated with water having a salt concentration of 200 millimolar (mM) sodium chloride, which is more than one-third as salty as seawater.

The Natural Sciences and Engineering Research Council of Canada and the Will W. Lester Endowment from the University of California funded the research.
The Grower
October 2001
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Buried irrigation system helps boost water management, nutrient savings
A buried irrigation system designed to save trees has agricultural benefits as well.  Those using the system in Florida have found it can cut water use by up to a third.

It is hoped that the price of the system, which can be more than $1,000 per acre, will come down and prove cost-effective.

The irrigation system took root in 1998. Environmentalists and Florida water managers at the time suspected water runoff from farms was causing high rates of tree deaths in Manatee County's Flatford Swamp.  The excess irrigation water was keeping the swamp from drying out normally in the winter, they say.

University of Florida researchers came up with a solution, a buried irrigation system that reduces runoff and keeps the water in swamps at normal levels.  The system, known as enclosed seepage or subsurface drip irrigation, uses a series of tubes buried 16 inches underground that carry water into the fields.

Besides allowing trees to have enough water, the system also reduces the amount of nitrates and other nutrients in surface water by encouraging growers to use less fertilizer, says Craig Stanley, a researcher at the UF's Gulf Coast Research and Education Center where the system was developed.

 “This system can provide better control of water table level, meaning farmers can get by applying less fertilizer to their fields,” Stanley says.

Pacific Tomato Growers has installed the system on 80 acres it owns that drain water into Flatford Swamp.  Because of success there, the company may extend the system's use in Florida, California, Georgia and Maryland, says Gary Bethune, engineering director for Pacific Tomato.

The system's use of buried microirrigation tubing eliminates surface runoff, making it more efficient, Stanley says.

“The system still requires as much maintenance and cleaning as above-ground microirrigation systems, but it's a lot more forgiving system if a problem develops,” he says.

Bethune says the system saves Pacific Tomato Growers money in fertilizer and other areas.  The savings does not offset the costs of the system itself, which he estimates at about $1,100 per acre.

Bethune expects the price to come down.  He says the system is permanent, unlike conventional drip where drip tape is replaced annually.

 “We're hoping that in the long term the system will prove cost-effective,” Bethune says.

THE GROWER
OCTOBER 2001
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Status of Vegetable Crop Best Management Practices (BMP) Manual Development
Given that the row crop agricultural sector comprises approximately 15% of the agricultural acreage in Florida and includes many of the more intensive agricultural operations statewide, the Florida Department of Agriculture and Consumer Services recently embarked on a mission to develop a BMP manual for this important industry group.

Organizational efforts to date include the development and formatio of a Steering Committee, various technical Working Groups, and a core group charged with editorial oversight of the manual itself.  One of the manual’s cornerstones, as envisioned, will be its ability to encompass environmental issues dealing with water resources, nutrient management, technical performance standards, and other industry specific nuances such as plasticulture effects.

Under consideration are future ramifications for field and vegetable crops water supply issues relative to the Governor’s Drought Action Plan, particularly regarding the Water Conservation Initiative work product/recommendations.  The Florida Department of Agriculture and Consumer Services is now under a new legislative mandate for agricultural water conservation under Section 570.080, Florida Statues.

Bill Bartnick
FDAC
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Pesticide Potpourri

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The cancellation of benomyl raises some unexpected health concerns. 
A few months ago, DuPont announced the cancellation of its popular fungicide, benomyl.  Their decision was driven by their business plan, not by any health risk.

 Thiophanate-methyl (TPM) is expected to take a substantial part of the benomyl market.  TPM is already registered for a wide variety of food and residential applications.  TPM breaks down into carbendazim; TPM and carbendazim have a similar toxic endpoint.  Additionally, carbendazim is registered for use as a paint preservative.  Suddenly, EPA was faced with an unforeseen scenario in which potential exposures were much greater than anticipated.

 TPM is classified as a ‘likely carcinogen’, and carbendazim is a ‘possible carcinogen’.  Both chemicals can affect developing fetuses.  These classifications do not mean that current or predicted exposures will result in human illness, but the EPA is taking a close look at the new scenario.

The Agency is seeking comments on their revised assessment of risks.  If you use benomyl or TPM, you should take the time to comment.  You can read the assessment and comment at http://www.epa.gov/pesticides/reregistration/tm/

The Georgia Pest Management Newsletter
September 2001
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The Lighter Side
Work Vs Prison

 IN PRISON you spend the majority of your time in an 8x10 cell.
  AT WORK you spend most of your time in a 6x8 cubicle.

 IN PRISON you get three meals a day.
 AT WORK you only get a break for 1 meal and you have to pay for it.

 IN PRISON you get time off for good behavior.
 AT WORK you get rewarded for good behavior with more work.

 IN PRISON a guard locks and unlocks all the doors for you.
 AT WORK you must carry around a security card and unlock and open all the  doors yourself.

 IN PRISON you can watch TV and play games.
 AT WORK you get fired for watching TV and playing games.

 IN PRISON you get your own toilet.
 AT WORK you have to share.

 IN PRISON they allow your family and friends to visit.
 AT WORK you cannot even speak to your family and friends.

 IN PRISON all expenses are paid by taxpayers with no work required.
 AT WORK you get to pay all the expenses to go to work and then they deduct taxes from your salary to pay for prisoners.

 IN PRISON you spend most of your life looking through bars from the inside wanting to get out.
 AT WORK you spend most of your time wanting to get out and inside bars.

 IN PRISON there are wardens who are often sadistic.
 AT WORK they are called managers.
 

“Quotable Quotes”

The only thing more overrated than natural childbirth is the joy of owning your own business.

"Advice is what we ask for when we already know the answer but wish we didn't." - Erica Jong

"My grandfather's a little forgetful, but he likes to give me advice. One day, he took me aside and left me there." - Ron Richards

People who make mistakes should take my dog's advice. "When you do something wrong, always take responsibility (as soon as you're dragged out from under the bed)."

Why are builders afraid to have a 13th floor but book publishers aren't afraid to have a Chapter 11?

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