A Vegetable Crops Extension Publication
University of Florida
Institute of Food and Agricultural Sciences
Cooperative Extension Service
Adobe Acrobat .pdf
VEGETABLE CROPS CALENDAR
Suwannee Valley REC Website Promo
Fuel for the Fire on the Organic Debate
Color Plastic Mulch
(Note: Anyone is free to use the information in this newsletter. Whenever possible, please give credit to the
authors. The purpose of trade names in this publication is solely for the purpose of providing information and
does not necessarily constitute a recommendation of the product.)
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Florida Fertilizer & Agrichemical Association Convention- July 19-21, Ritz Carlton, Amelia
Island. Contact Mary Hartney at 863-293-4827.
FSHS and ASHS Meetings July 23-25. Disney Coronado Springs Resort, Lake Buena Vista.
Contact Kathy Murphy at 407-673-7595 or go to the FSHS 2000 Annual Meeting site at
Tomato Institute -Sept 6, 2000. For more information, contactCharlie Vavrina at 941-658-3400.
Florida Agricultural Conference and Trade Show (FACTS) -September 26-27. Civic Center,
Lakeland, FL. Contact Elizabeth Lamb at 561-468-3922.
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Suwannee Valley REC Website Promo
The Website for the North Florida REC-Suwannee Valley is designed to provide information on a
diverse range of topics for farmers in the Suwannee Valley region of North Florida. There are
several horticultural topics of interest at the site including: greenhouse vegetables & hydroponics,
fruit and nut crops, organic production, postharvest information, and marketing. Farms in the
region tend to be diversified with several crops or enterprises. The USDA classifies over 90% of
the 4,500 farms in the region as small farms. Farmers throughout the region are seeking
information on alternative crops; new technologies; efficient use of farm inputs, such as water
and fertilizer; and marketing. This site has up to date information on the topics listed below and
also can be used to access weather information, upcoming meetings, pesticide labels, and more.
Many of these topics include several links to other sites across the country. Visit the site at:
http://nfrec-sv.ifas.ufl.edu or http://liveoak.ifas.ufl.edu
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:NFREC-SV Field Trials
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'Universityof Florida (UF)
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'UF Online Extension Publications
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'Florida Depatment of Agriculture & Corsuner
'United States Depu-rtent of Agriculture (USDA)
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7580 County Road 136, Live DCk, FL 32060, Plnne: (904 362-1725; Fax: (904) 362-3067;
Suncom: 821-3050/3051; e-mail: rec-sv.@mail.ifas.l.edu
(Bob Hochmuth, County Agt. IV, Suwannee Valley REC, Vegetarian, 00-06)
Fuel for the Fire on the Organic Debate
There has been a recent spate of articles in the popular press on the benefits of organic foods
prompted by the increase in consumption and production of organic products. In March 1999,
Consumer Reports issued a comparison of the pesticide residues in a variety of organic and
conventional fruits and vegetables. The ABC news program 20/20 presented a report on the
cleanliness and nutritional value of organic foods on February 4, 2000. The New York Times put
organic farming on the front page of the Sunday Business section with an article entitled 'Organic
Farming Seeking the Mainstream'. The perception of organic foods as being safer, cleaner,
healthier, tastier, better for the environment and more sustainable translates into a price premium
for producers. A dramatic example of this is the success of companies that will send you
everything from organic produce to organic beer and wine overnight from orders placed on the
However, is there data to support the perceptions? This lack of scientific research to support the
claims made by proponents of organic production encouraged a discussion on a sustainable
agriculture list-serve which is based at the University of Minnesota (firstname.lastname@example.org).
Among the 20 or so who responded, few had scientific studies to cite. So, although the resulting
comments don't provide any hard and fast conclusions, they do provide some material for
Pesticide residues: The Consumer Reports study found lower levels of pesticides on
commercially available organic tomatoes, peaches, apples and green peppers compared to
those produced conventionally. This may be particularly important for children who have a lower
susceptibility to the residues and for whom safe levels have not been identified. However, the
20/20 study found no residues on either organic or conventional products. A consumer
organization in New Zealand suggested that crops can't be guaranteed free of residues unless
they are tested as some pesticides are accepted for use on organic products and there are
potentially other sources of residues
Cleanliness: Although pesticide residues may be lower, bacterial counts were higher in the
organic products as reported by 20/20, particularly on sprouts and pre-cut salad greens. This was
said to be due to the use of manure for fertilizer although sprouts aren't usually in contact with
any type of fertilizer. Are pesticide residues more dangerous than bacteria? Do they have a
greater effect than not eating fruits and vegetables? According to David Klurfeld, a Scientific
Advisor to the American Council on Science and Health and Chair of the Department of Nutrition
and Food Science at Wayne State University, the answer is a definite no
Nutrition and taste: The New Zealand article discusses, but does not cite, the results of a large
number of tests on nutritional value of organic products. The general conclusion is that the
results vary, although there is a tendency for increased nutritional quality. However, the soil may
have as large an effect on nutrition as the methods of production. They also cite Consumer
Reports (issue not given) as finding no differences in the taste of organic and conventional
carrots, apples and tomatoes purchased at a Farmers' Market. It is fairly easy to find those who
will disagree, however. Some sources for data on nutritional differences are:
Pither & Hall, 1990, Analytical survey of the nutritional composition of organically grown fruit and
vegetables. Tech. Memo., Campden Food & Drink Res. Assoc. No. 597, 99 pp.
Hornick, 1992, Factors affecting nutritional quality of crops. Amer. J. Alter. Agric. 7:63-68.
Bashev, 1992, Comparison of taste and quality between organically and conventionally grown
fruits and vegetables. Amer. J. Alter. Agric. 7:129-136.
Environmental effects, sustainability of production: Although many organic farms use fewer
pesticides, have more diversity in their production and may do a better job at building the soil, it
may be more related to farm size and the philosophy of the growers than to their organic nature
per se. However, more large scale operations are turning to organic production practices for at
least a portion of their acreage so it may be possible to measure the effects without the farm size
For more articles on organic production,www.purefood.org is a good, if definitely pro-organic
source. The USDA site on organic production is www.ers.usdagov/whatsnew/issues/organic/
And if you just like to surf the web on sustainable/organic agriculture,
www.floridaplants.com/abstracts.htmis for you.
(Lamb, Asst. Prof., IRREC-Ft. Pierce, Vegetarian 00-06)
Color Plastic Mulch
Fourteen color plastic mulches are being evaluated for growth, yield, and weatherability at Penn
State, MREC-Apopka, FL, Costa Rica, and Canada. There are 1 black, 1 red, 1 olive, 1 green
thermic, 1 brown thermic, 2 blue, 2 white, 2 black on white, and 3 silver plastics in the trial. The
experiment at MREC was replicated four times and transplanted to 'cv' Brigadier pepper on
March 21, 2000. Drip tubing with 12-inch spacing and a flow rate of 0.37 GPH @ 10 psi was
placed under the plastic mulch for fertigation.
Plant growth was interrupted by a hot dry wind and sand blasting one week after transplanting.
No visible plant growth differences were observed due to plastic mulch color. The first harvest
was on May 22, 2000. Yields ranged from 373 to 677 bu/acre of marketable fruit with one blue
and the brown thermic being lower in yield than the 65% black on white. For fancy yields, the
silver 12239 mulch out yielded seven of the 14 mulches (355 vs. 201-293 bu/acre).
The weatherability is being measured by taking a 6-inch square each month from each of the
plastic mulches and having them evaluated in a private lab. More data and the final results will be
available after harvest is completed. If anyone has questions or would like additional information
contact J. M. White at (407) 884-2034 (X 127), SunCom 354-2034 (X 127, or
(White professor, CFREC-Sanford, Vegetarian 00-06)
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Anyone who has ever eaten a cucumber without first peeling it should be aware that sometimes
this vegetable can be a bit on the bitter side. Even a peeled cucumber may have a slight amount
Bitterness can be a serious problem if, for example, a buyer refuses to buy your cucumbers
because too much bitter taste is detected. Why are some cucumbers more bitter at certain times
than at others? What causes this bitterness? These are questions asked every year.
The bitter taste is due to a natural organic compound calledcucurbitacin. It is prevalent in
relatively high concentrations in wild cucumbers, causing them to be highly bitter. Both in wild
and cultivated cucumbers, cucurbitacin occurs in varying amounts mainly in the vegetative parts
of the plant like leaves, stems, and roots. On occasion and to a lesser degree, it spreads to the
Even when this bitter principle occurs in the fruit, it does not accumulate uniformly. Its
concentration varies from one fruit to another and from one portion of the fruit to another part.
The compounds) is likely to be more concentrated in the stem end than in the blossom end of
the cucumber fruit. It is associated with the peel and is located both in the green peel and in
the light green area just beneath the peel. It is not likely to be found in the deeper interior of the
Therefore, one practical measure the consumer can take to reduce the bitter taste is to
peel the fruit a certain way each timeStarting at the blossom end, slice away one strip of the
green peel toward the stem end, and stop about one inch from the stem. Wash the knife blade,
then repeat peeling in the same manner until the fruit is peeled. Wash the knife and cut up the
fruit as needed. This prevents spreading the bitter taste.
From a growers standpoint, why there is more bitterness at certain times and with certain crops
than others is difficult to say. Several theories have been advanced, but not much proven.
The malady is best categorized as a climatically induced physiological disorderFruits
picked from vines growing during periods of stress are often observed to be somewhat bitter.
However, since stress to plant growth and development covers so much territory, this does not
define the cause of the malady too precisely. "Nubbins", "cooter-tails", and other misshapen
fruits are more likely to be bitter than are the well-shaped fruits. This suggests some sort of
relationship between poorly pollinated fruits and bitterness.
Temperature during the growing period seems to be a factor, since there are more complaints
during cool periods than the warm times. Some research data on bitterness have been collected
during trials on fertilizers, plant spacing, and irrigation frequency, but the results were never too
Bitterness does seem to vary with the cultivar, but some degree of bitterness should be expected
from time to time in most any variety of cucumber commonly grown in Florida. For the most part,
bitterness is only an occasional problem and not of overwhelming proportions.
(Stephens, Vegetarian 00-06)
Extension Vegetable Crops Specialists
Daniel J. Cantliffe
Professor and Chairman, Horticultural Sciences
Timothy E. Crocker
Professor, deciduous fruits and nuts, strawberry
Assistant Professor, strawberry
Assistant Professor, vegetable production
Elizabeth M. Lamb
Assistant Professor, production
Assistant Professor, soils
Donald N. Maynard
Stephen M. Olson
Mark A. Ritenour
Assistant Professor, postharvest
Ronald W. Rice
Assistant Professor, nutrition
Steven A. Sargent
William M. Stall
Professor, weed control
James M. Stephens
Professor and Editor, vegetable gardening
Charles S. Vavrina
Associate Professor, transplants
James M. White
Associate Professor, organic farming
Professor, small farms
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