SUNIVERSITY OF Cooperative Extension Service
FLORIDA Institute of Food and Agricultural Sciences
A Vegetable Crops Extension Publication
l ^Ilorticultural &cicnccs Department P.O. 110690 Gaincevi(le, FL 32611 Telephone 904/392-2134
July 17, 1994
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
II. COMMERCIAL VEGETABLES
A. Fall Temperatures Under Plastic.
B. Nitrogen BMP Bill Senate Bill 2420.
C. Update on Carrot Yields and P Fertilization.
III. VEGETABLE GARDENING
A. Book Review: Plant Nutrient Disorders 3 Vegetable
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.
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.
-r.i --tt W Aftflwl f'tr ntntri TVr-tfnt A If TI T lt P r r ?ILT/ 1 L'IT r ?.t' P Ti rr11TTk TI A T TTr r ITlCe V fE CTElDITM A
I. NOTES OF INTEREST
A. Vegetable Crops Calendar.
August 14-16, 1994. National Pepper
Conference. Las Cruces (NM) Hilton. Contact
P. W. Bosland, Dept. of Agronomy and
Horticulture, NM State Univ., Box 30003, Dept.
3P, Las Cruces, NM 88003.
September 7, 1994. Tomato Institute,
Ritz Carlton Hotel. Contact Charlie Vavrina,
SW Fla REC, Immokalee.
November 1-4, 1994. Cucurbitaccae 94.
Radison Resort, South Padre Island, TX.
Contact James R. Dunlap, TAES, 2415 East
Hwy 83, Weslaco, TX 78596-8399.
II. COMMERCIAL VEGETABLES
A. Fall Temperatures Under Plastic.
Last fall (1993) Sonoco Products Co.
funded a study to compare soil temperatures
under various colored plastic mulches at the SW
FL Research & Education Center. The mulches
tested included white on black (Sonoco 1.0
mil), white on black (1.41 mil), white on white
(1.5 mil), black (0.75 mil), silver on black
(painted 1/2 gal. per 150 ft.), and red (0.8 mil).
All mulches were applied without methyl
bromide or fertilizer to beds on September 7,
1993. Seepage irrigation was supplied as if a
crop were in place to keep the beds moist
throughout the study. It should be noted that the
coating of silver paint used here would be
considered excessive by industry standards. Also
without methyl bromide treatment, grass weeds
were not controlled under white on white mulch.
Soil temperatures were monitored using
standard soil thermometers at a depth of 4 inches
on sunny days from early September through late
December. Each colored plastic treatment was
replicated 4 times and these data represent the
mean of those four measurements.
Soil temperatures beneath the black and
red plastic mulches ran hotter than those
measured under silver, white, or white on black
mulches throughout the late summer, fall, and
early winter (Fig. 1). Generally, soil
temperatures under silver, white, and white on
black fell within a few degrees of each other
during the study.
Soil temperatures dropped as fall
progressed toward winter. However, under all
mulches in September and under black and red
mulches in October, soil temperatures
approached or exceeded 100 degrees in the
afternoon. The optimum temperature for tomato
root growth is 68-91F, root growth slows in
temperatures of 95-104F and practically ceases at
temperatures greater than 104F (White, P1. Phys.
12:771-776, 1937). High soil temperatures may
be alleviated as the tomato canopy shades the
root zone, but transplants might find root
development impaired by such temperatures.
These data should not be taken as "gospel", but
should aid you in making intelligent decisions on
your choice of plastics for fall production.
(Vavrina, Vegetarian 94-07)
TEMP 4 INCH DEPTH, Sept. 10, 1993
TEMP 4 INCH DEPTH, Oct 12, 1993
8:30 9:30 10:30 11:30 12:30
TEMP 4 INCH DEPTH, Nov. 12, 1993
1:30 2:30 3:30 4:30
TEMP 4 INCH DEPTH, Dec 27, 1993
9:30 10:30 11:30 12:30
B. Nitrogen BMP Bill Senate Bill
The following is a synopsis of Senate
Bill 2420, the Nitrogen BMP bill. This bill will
open up numerous challenges and opportunities
for Extension personnel with regard to
fertilization of vegetables. The opportunities
involve some possibilities for funding the
development and demonstration of IFAS
fertilization recommendations. The challenges of
course are going to revolve around the area of
litigation. IFAS currently has individuals
studying that aspect. If you would like a copy
of the Bill, call me. The following was provided
at a recent meeting of the Fertilizer Technical
This bill authorizes DACS to develop
fertilizer BMPs designed to meet nitrate
ground water standards with due
consideration to economic and
The BMPs are not mandatory.
Two primary benefits are available to
growers who elect to implement the
BMPs specified by DACS. These
benefits take the form of relief from
existing water quality standards.
The bill authorizes DACS to impose
supplemental fees to fund the program.
Fees will increase for fertilizer
distribution licenses, product
registrations, and for the sale of all
nitrogen containing fertilizers.
2. BMP Development
DACS is authorized to contract with
IFAS, FAMU, etc. to develop BMPs for
nitrogen containing materials.
DACS will develop rules containing
commodity specific BMPs based on the
DEP is authorized to conduct field
monitoring to verify the effectiveness of
the implemented BMPs on representative
sites for each commodity group.
During the research stage of BMP
development, DACS may adopt interim
measures by rule to be implemented
prior to adoption of BMPs.
3. Liability Waiver
If a grower notifies DACS of his or her intent to
implement commodity-specific interim measures
and/or BMPs as described in future DACS rules,
the landowner or leasee will not be liable under
s. 376.307 (5) F.S. for any costs or damages
associated with the remediation of drinking water
wells contaminated with nitrate from the
application of materials containing nitrogen. In
order to maintain this waiver once specific
interim measures or BMPs are adopted in rule
form, the grower must implement the BMPs
according to the schedule specified and comply
with recordkeeping requirements.
If the grower implements BMPs which have
been verified to be effective by DEP and
complies with the requirements listed above, the
landowner or leasee will not be subject to
administrative penalties if nitrate ground water
standards are violated.
Two hundred dollars for each license to
Two hundred dollars for each of the first five
specialty fertilizer registrations and fifty dollars
for each additional registration.
An additional fifty cents per ton (in addition to
the existing 75 cent inspection fee) for all
fertilizer containing nitrogen sold in the state.
5. Time Line
DACS implements new fee schedule by July 1,
DACS publishes by rule the Notice of Intent To
Comply with Interim Measures of or BMPs.
Growers submitting the "Notice" will not be
liable for nitrate remediation costs associated
with contaminated drinking water wells.
DACS contracts with the appropriate institution
to begin BMP research on prioritized
commodities and regions where nitrate
contamination of groundwater is a documented
Interim nitrate measures are specified in DACS
rules for implementation prior to formal adoption
BMPs and recordkeeping requirements are
formally adopted by DACS and published in
Published BMPs are implemented by growers
according to the schedule in DACS rules.
DEP verifies the effectiveness of adopted and
implemented BMPs at representative sites.
(Hochmuth, Vegetarian 94-07)
Update on Carrot Yields and P
As a part of the Lake Apopka
Hydrologic Unit Project (LAHUAP), five carrot
demonstration trials with various rates of
phosphorus (P) fertilizer were conducted from
1992-1994. Three grower sites were involved,
with repeated crops of carrots grown on two
sights. The objectives of the demonstrations
were to use predictive soil testing for managing
P fertilization and to determine if a starter
application of nitrogen (N) and P would result in
a yield benefit. Soil samples were taken from
each site before planting and P rates were based
upon the results as well as the P rate the grower
used in the remainder of the field. The variety
"Apache" was grown in each demonstration trial.
Total amounts of applied N ranged from 0 to 51;
P2O, from 0 to 225; and K20 from 0 to 120
lb/acre. A liquid starter fertilizer was applied at
either 8.8-30-0 or 51-75-0 lb/acre of N-P20,-
K20. In four of the five tests, there were no
significant differences in marketable yield among
any of the fertilizer rates. The liquid starter
treatment did not demonstrate a marketable yield
benefit over no fertilizer applied when the soil
test indicated adequate nutrients (P205 and K20).
In one test, an application rate of 0-0-60 lb/acre
of N-P205-K20 resulted in a significantly lower
marketable yield than treatments of 0-0-0; 8.8-
30-0; and 15-30-60 lb/acre. At harvest, this site
had more culls due to disease, more weeds than
the average field, and had been in the ground
longer than a normal carrot crop. These factors
may account for the yield difference.
Overall, soil tests results indicated there
was no need for P fertilization on carrots for the
five demonstration sites selected. Yield results
verified that adding P when soil tests indicated
none was required did not increase yields. The
liquid starter fertilizer did not improve carrot
yields when the soil test indicated no additional
P or K was needed.
This is a brief summary of cooperative
work by C. A. Neal, E. A. Hanlon, G. S. Crnko,
J. M. White, A. Ferrer, and personnel from Soil
Conservation Service (S. Cox) and Agricultural
Stabilization and Conservation Service (P.
Salminan) conducted in the Zellwood drainage
(White, Vegetarian, 94-07)
II. VEGETABLE GARDENING
A. Book Review: Plant Nutrient
Disorders 3 Vegetable Crops.
Because it has been such a long time
since I've seen forthcoming a text on nutritional
disorders of vegetables similar to the old
classical "Hunger Signs in Crops", I was struck
by a recent notice of such a book.
Allen Barker, Dept. of Plant and Soil
Science, University of Massachusetts, reviewed
the book in Hort Science, Vol. 28(11), Nov.
1993, pg 1135. The authors are R. G. Weir and
G. C. Cresswell, 1993. Inkata Press, Melbourne,
According to Barker's review, the fact
that the text was written in Australia rather than
on this continent detracts little if any from its
authoritative nature. Of course references to
Australian conditions are a bit distracting, but
only to a limited extent.
The book is a short course in plant
nutrition, summarizing the nutritional needs of
vegetables and what the plants look like when
Techniques for distinguishing nutritional
disorders from disorders caused by infectious
diseases, environmental stresses, mechanical
injury, and chemical injury are described.
Stepwise procedures for identifying a
disorder and its underlying cause are outlined.
These steps involve gathering background facts
about contributing factors, assessing visible
symptoms, confirming the diagnosis, correcting
the problems, and following up on the overall
process. The book contains several tables and
insets for quick reference and guides to these
procedures. This book will be valuable to
Extension agents and Master Gardeners. It is
105 pages, 170 color illustrations, and sells for
around $35.00. Distributor: Florida Science
Source, PO Box 927, Lake Alfred, FL 33850-
(Stephens, Vegetarian 94-07)
Prepared by Extension Vegetable Crops Specialists
Dr. D.J. Cantliffe
Dr. S.M. Olson
Mr. J. M. Stephens
Dr. G.J. Hochmuth Dr. D. N. Maynard
Profesor & Editor Professor
Dr. S.A. Sargent Dr. W.M. Stall
Assoc. Professor Professor
Dr. C. S. Vavrina Dr. J. M. White
Asst. Professor Assoc. Professor