Vegetarian Newsletter

A Vegetable Crops Extension Publication
University of Florida
Institute of Food and Agricultural Sciences
Cooperative Extension Service

Vegetarian 00-06
June 2000
WB01645_.gif (935 bytes)Index Page

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WB01647_.gif (256 bytes) VEGETABLE CROPS CALENDAR

WB01647a.gif (256 bytes)COMMERCIAL VEGETABLES

WB01647b.gif (256 bytes) VEGETABLE GARDENING

(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, contact Charlie 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: or

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(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 Internet, i.e. .

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 ( 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 consideration.

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 factor (

For more articles on organic production, is a good, if definitely pro-organic source. The USDA site on organic production is And if you just like to surf the web on sustainable/organic agriculture, is 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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Bitter Cucumbers

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 of bitterness.

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 called cucurbitacin. 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 fruiting structure.

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 compound(s) 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 fruit.

Therefore, one practical measure the consumer can take to reduce the bitter taste is to peel the fruit a certain way each time. Starting 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 disorder. Fruits 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 conclusive.

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 Department
Mark A. Ritenour
Assistant Professor, postharvest

Timothy E. Crocker
Professor, deciduous fruits and nuts, strawberry

Ronald W. Rice
Assistant Professor, nutrition
John Duvall
Assistant Professor, strawberry
Steven A. Sargent
Professor, postharvest
Chad Hutchinson
Assistant Professor, vegetable production
William M. Stall
Professor, weed control
Elizabeth M. Lamb
Assistant Professor, production
James M. Stephens
Professor and Editor, vegetable gardening
Yuncong Li
Assistant Professor, soils
Charles S. Vavrina
Associate Professor, transplants
Donald N. Maynard
Professor, varieties
James M. White
Associate Professor, organic farming
Stephen M. Olson
Professor, small farms

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