Prior to July 1996, the Delaney Clause of the Federal Food Drug and Cosmetic Act prohibited use of pesticides suspected
as potential carcinogens on processed foods if detectable residues could be found in those products. This clause disallowed use of EBDC fungicides and other pesticides on processed foods because minute residues could be detected in
the finished product. On July 23, 1996, Congress re-examined and reformed the stringent Delaney Clause. They chose to set a new standard of tolerance based on "reasonable certainty of no harm" broadly interpreted as meaning that pesticides on food should pose no reasonable risk of harm, including aggregate exposures from food, water, and other non-occupational exposures. This new standard is the Food Quality Protection Act (FQPA) and allows for a wider spectrum of approved pesticides to be used on processed foods.
The former Delaney Clause posed many constraints on the processing tomato industry. Since TOMCAST, a predictive
disease model, was also developed under these same constraints, exposure to fungicide programs outside of
Chlorothalonil (Bravo, Terranil, Echo) has been limited. Consequently, most research concerning appropriate TOMCAST
Disease Severity Values (DSV) spray thresholds by location or fruit quality are based on observations of
Chlorothalonil. With recent passage of FQPA, the number fungicides legally labeled on processing tomatoes in 1997
has increased. To help growers transition from Chlorothalonil to other products and spray regimes, some DSV
guidelines have been developed.
It should be understood that Ohio State University is only offering suggestions to modify current DSV spray intervals. It is incumbent upon growers to decide if these suggestions are worthwhile to their operation and acceptable to processors.
In general, spray thresholds should be shortened 3 DSV, from 18 to 15, for products such as Dithane, Mancozeb, and Ziram
as compared to Chlorothalonil. For growers who intend to use Quadris, a fungicide awaiting label later this spring,
DSV spray intervals should remain the same as a Chlorothalonil program. Quadris is a new class of chemical.
It has broad spectrum activity on tomato. It has given very good control of Early Blight, Septoria Leaf Blight, and
Pythium ground rot in our tests. Quadris gives good control of Anthracnose and Late Blight on tomato, and gives control
of Powdery Mildew on other crops, the latter has not been tested in Ohio. Quadris also has low toxicity to mammals.
On a calendar schedule Quadris will likely be applied on a 10-14 day schedule. At no time apply more than four
consecutive Quadris treatments.
Since Quadris is a new material growers, should familiarize themselves with the fungicide by applying it to a small
portion of their acreage to compare its efficacy and effects on quality with their traditional disease control program.
Supplies of Quadris in Ohio will be limited this year.
Some suggested programs might be the following.
- Dithane (Mancozeb) and Copper for the first two sprays or until fruit is 1/2", then finish the season with Chlorothalonil (Bravo) alone or in copper to control bacterial diseases;
- Chlorothalonil season long;
- Dithane in the first two sprays (or until fruit is 1/2") followed by four sprays of Quadris and finish the season
with Chlorothalonil. Quadris sprays applied in July will control Septoria Blight without the addition of Benomyl to spray program.
Ziram can be substituted for Dithane as an early season fungicide. The above fungicide programs are only suggestions
and by no means inclusive of all possible spray programs. Select a program that best fits the needs of your farming
operation.
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Problem: Poor germination.
- A. Improper temperature.
Remedy: Check the soil temperature. Be sure it agrees with the recommended germination temperature for that variety or kind of plant.
- B. Improper moisture.
Remedy: Correct improper watering practices. Improve cultural practices, e.g. type of growing medium, drainage, etc.
- C. Lack of light.
Remedy: Some species require light to germinate, sow this seed very shallowly.
- D. Damping-off
Remedy: Use steamed or chemically fumigated soil for germination, or else use a soiless growing medium that is pathogen free. Improve air circulation. Avoid contamination from unsterile soil, tools, pots, etc. Treat seed with fungicides, such as captan, or thiram, or apply fungicide drenches.
- E. High Salts.
Remedy: Don't use soils that have been heavily fertilized. Leached with water to remove excess soluble salts.
- F. Soil fumigant damage.
Remedy: Make sure chemically fumigated soil is well aerated. Plant a few seeds of radish or lettuce in a sample of treated soil to check for residues.
Problem: Distorted growth.
- A. Gas damage.
- Remedy: Clean all burners and ensure that the furnace has adequate outside air intake. Burners should be vented. Check gas lines to be sure there are not leaks.
- B. Herbicide Residues.
Remedy: Check for herbicide spills in or near the greenhouse. Do not use sprayers that have contained herbicides for applying other pesticides. Bioassay soil for possible contamination. Activated charcoal can be added to potting mixes to absorb trace amounts of most herbicides.
- C. Insect/mite damage.
Remedy: Control aphids, cyclamen mites and other foliar feeding pests.
- D. Guttation Injury.
Remedy: Increase air circulation. Reduce watering.
- E. Viruses.
Remedy: Discard infected plants.
Problem: Weak spindly growth.
- A. Low Light Intensity.
Remedy: Don't keep plants in poor light conditions.
- B. High Temperature.
Remedy: Reduce air temperature by forced ventilation, shading, etc.
Problem: Leaf Burn (edges of mature leaves).
- A. Gradual Salt Buildup.
Remedy: Review fertilization program and reduce the amount if possible.
- B. Specific element toxicity.
Remedy: Have soil and water tests done to pinpoint the source and identity of toxic elements.
- C. Drought.
Remedy: Water more frequently. Increase relative humidity. Provide shade. Reduce air temperature.
Problem: Leaf Burn (edges of immature leaves).
- A. High or Extreme Temperatures.
Remedy: Adjust temperatures to optimum levels.
- B. Guttation Injury.
Remedy: Increase air circulation. Reduce watering.
- C. Drought.
Remedy: Water more frequently. Increase relative humidity. Provide shade. Reduce air temperature.
- D. Pesticide Injury.
Remedy: Review application procedures and check equipment. Use less phytotoxic chemicals.
Problem: Leaf Burn (scattered spots).
- A. Foliar Disease.
Remedy: Remove and destroy badly infected plants. Ask a specialist to diagnose the specific cause & to provide control recommendations.
- B. Copper or phosphorus deficiency; sodium toxicity. Remedy: Have soil and water tests done to pinpoint the source and identify the deficient or toxic element.
- C. Pesticide Injury.
Remedy: Review application procedures and check equipment. Use less phytotoxic chemicals.
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This reprint is a completely revised and updated from the former edition.
New features and updated chapters include:
- Areas of Production,
- Table 1. Product From Fifty Plants Male and Female,
- Table 2. Yield of Asparagus Varieties Across the U.S.,
- California Hybrids,
- Open-Pollinated Varieties,
- Mineral Nutrient Composition of Green and White Asparagus Spears,
- Direct Marketing,
- Pick Your Own Marketing,
- Wholesale Marketing,
- Table 4. Estimated Costs and Returns of Asparagus Production (1996).
See below on how to view the on-line version.
To order, ask for Bulletin 826 through you local OH county extension office, or
Contact: Janis Cripe,
Office of Information,
216 Kottman Hall,
2021 Coffey Rd.,
Columbus, OH 43210-1044.
PH: 614-292-1607
fax: 614-292-2270
e-mail: cripe.2@osu.edu
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"The 1997 Ohio Vegetable Production Guide" and "Asparagus Production, Management and Marketing" Bulletins are now available as online editions from Ohioline. Go to the "It's New" section.
Also, they will probably be included in the next edition of the Ohioline CD-ROM.
The address for Ohioline is....
http://www.ag.ohio-state.edu/~ohioline/
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 NEW Reprint of: "Asparagus Production, Management & Marketing Guide"
New Features, The Online Edition, and How To Order Bulletin # 826, Click Here:
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 1997 Ohio Vegetable Production Guide, Now Available
The Online Edition plus How To Order Bulletin #672, Click Here (Price:$6.25 plus tax & postage)
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What's New At The VegNet Web Site
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 "The 1997 Ohio Vegetable Production Guide" and "Asparagus Production, Management and Marketing" Bulletins OnLine.
I have provided direct links to these publications from the VegNet homepage, (or see above), plus a list of new features in the Asparagus bulletin and Ordering information.
The Library. Come see our new library page which just opened. We have a few pictures and research reports currently available and hope to expand rapidly in the near future.
The Potato Late Blight Workshop Continues Through Apr. 18.
Review papers and join in discussion groups. Get the latest on Late Blight. See the last VegNet newsletter for details.
From the American Phytopathological Society. At the Potato Late Blight Workshop, you are invited to review papers from a recent workshop on this important disease. You can be just a visitor and review papers and you can register and participate in discussion groups. New information was uploaded last week. The on-line workshop dates are February 17 — April 18, 1997.
Come visit Ohio State Extension Vegetable Crops on the
Internet at...
http://www.ag.ohio-state.edu/~vegnet/
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Return to Vegetable Crops Homepage
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We appreciate very much the financial support for this
series of vegetable reports which we have received from the
board of growers responsible for the Ohio Vegetable and
Small Fruit research and Development Program. This is an
example of use of Funds from the "Assessment Program".
Where trade names are used, no discrimination is intended
and no endorsement by Ohio State University Extension is
implied.
Although every attempt is made to produce
information that is complete, timely and accurate, the
pesticide user bears the responsibility of consulting the
pesticide label and adhering to those directions.
Issued in furtherance of Cooperative Extension work, Acts of
May 8 and June 30, 1914, in cooperation with the U.S.
Department of Agriculture, Keith L. Smith, Director, Ohio
State University Extension.
All educational programs and activities conducted by Ohio
State University Extension are available to all potential
clientele on a nondiscriminatory basis without regard to
race, color, creed, religion, sexual orientation, national
origin, sex, age, handicap or Vietnam-era veteran status.
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