Group Title: Berry/vegetable times.
Title: Berry/vegetable times. May 2002.
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Title: Berry/vegetable times. May 2002.
Uniform Title: Berry/vegetable times.
Physical Description: Newspaper
Creator: Gulf Coast Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Gulf Coast Research and Education Center, University of Florida
Gulf Coast Research and Education Center
Publication Date: May 2002
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Bibliographic ID: UF00087388
Volume ID: VID00005
Source Institution: University of Florida
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. U NV1\'EI lTY OF
A monthly newsletter of the University of Florida Institute of Food and Agricultural Sciences, Gulf Coast Research and Education Center, and Florida Cooperative Extension Service.
Gulf Coast Research and Education Center, 13138 Lewis Gallagher Road, Dover, FL 33527 (813) 744-6630 SC512-1160 Website: http//
Editors: Dan Legard (legard( & Craig Chandler I ,. !il .IIIi Design, Layout& Distribution: Christine Manley ., i,..l. .. !i I,, Director: Jack Rechcigl
May 2002

Water Movement in Raised Beds John
R. Duval and Eric Simmone

With increasing concern about water usage and
irrigation efficiency, a better understanding of water
movement through raised beds is needed. Where does water
go in the bed when the pump s are turned on? How long does
it take to get there? Many factors determine the answer to
these questions and need to be considered when choosing
irrigation supplies and run times for irrigation.
The major factor that determines water movement in
soil is macro- and micro- pore space. Pores in soil are simply
free space not occupied by soil particles. This can be
visualized as air filled spaces between soil particles. Macro-
pores are generally considered to be larger than 0.06
millimeter in diameter and anything smaller is considered a
micro -pore. Sandy soils usually have a porosity of 35-50%,
and finer textured soils have a porosity of 40-60%. With
larger soil constituents, sandy soils will have greater numbers
of macro pores. Water movement through macro-pores is
usually accomplished via mass flow, the movement of water
due to gravity, generally in a downward direction. In micro-
pores, water movement is more commonly a result of capillary
action, which can move water laterally. The distribution of
macro- and micro-pores depends on several factors: soil
compaction, aggregation and type. Soil compaction and
aggregation can be altered to some degree, while soil type is a
location specific factor that can only be changed by changing
location or by moving large quantities of soil.
Soil compaction may be the easiest factor to control
in a field setting. The use of deep tillage to break up
compacted layers in soil can improve the drainage of a field.
This is because macro -pore volume of the compacted layer is
increased, thus allowing water to move downward more
freely. If this is true, then the reverse should also be true to
improve the lateral movement of water in a planting bed. A
more compacted bed will have fewer macro -pores and more
micro -

pores, due to the forcing of soil particles together, improving
movement to the sides or shoulders of the bed. In a "loose"
bed, water from a drip tape will preferentially move
downward, whereas in a "tight" bed water movement will still
move downward, but not at as great a rate, with more water
being moved towards the side of the bed through capillary
action of the micro -pores.
Soil aggregation is the binding or flocculation of soil
particles to one another. Soil aggregates are naturally
occurring clumps of soil and help increase the numbers of
micro -pores present in the soil. There are four factors that
control soil aggregation: physical movements of soil particles,
organic matter content of the soil, cation concentrations in the
soil, and tillage. Organic matter in the soil is the major factor
contributing to aggregate formation. As organic materials
break down, bacteria and fungi will produce gels and other
products which bind soil particles together. Physical
movement of soil particles can be accomplished through
natural freeze thaw and wetting drying cycles, action of soil
organism, and root growth. These actions force soil particles
together promoting aggregation. Some cations (positively
charged ions) such as calcium and magnesium (which both
have a +2 charge) can help bind negatively charged soil
particles together in a process called flocculation. However,
cations such as sodium (+1 charge) can cause the dispersal of
soil particles. Tillage can have both a positive and negative
impact on soil aggregation. Incorporation of organic materials
uniformly in the soil (from crop residues or cover crops)
enhances soil aggregation in the short term. However, in the
long term, repeated tillage operations speed up the break down
of organic matter in the soil reducing aggregation, and
movement of machinery through the field can break stable soil
What does this mean to a strawberry grower? If the
physical properties of a soil are known, determinations can be
made on the amount of water needed to irrigate to a certain
depth or to wet a given volume of the bed. In the sandy soils
surrounding Plant City, lateral movement of water in the soil

Cross sections of the beds after 1, 2 and 3 hours of irrigation with drip tape that has a 4 inch emitter spacing
and a flow rate of 32 gal/100 ft/hr.

is poor. Recently, Dr. Eric Simmone and I performed tests
using dyes to determine water movement in raised beds. We
used different drip tapes with different flow rates and emitter
spacing. On a commercial farm, two tapes with 12 inch
emitter spacing and flow rates of 24 and 27 gal/100 ft/hour
were tested. At the GCREC-Dover a tape with 4 inch emitter
spacing and a 32 gal/100 ft/hour flow rate was tested. Both
test areas contained living strawberry plants spaced 15 inches
apart, and had received no irrigation for a month. All beds in
this study were "tight" beds, formed with 3 passes of bedding
equipment. Treatments consisted of irrigation run times of 1,
2, 3, 4, 6, and 8 hours. During the first 20 minutes of each
irrigation treatment, a blue indicator dye was injected to
follow the path of water in the soil. At the end of each
irrigation treatment, beds were dissected both length and cross
wise to determine where water had moved. The distance that
the dye moved downward, lengthwise, and crosswise across
the bed was measured (Table 1.) Lengthwise movement
would be the horizontal distance water has traveled along an
imaginary vertical plant that is parallel to the direction of the

bed and intersects the drip tape.
There is not much difference between the 24 or 27
gal/100 ft/hour tapes. It takes both of these tapes 6 hours for
the wetting pattern of two adjacent emitters to converge.
However, the wetting pattern of the 32 gal/100 ft/hour tape
with 4 inch emitter spacing converges after only an hour. This
tape also allowed for deeper penetration of water and provided
less water movement to the sides of the beds than the other
two tapes. This is due to the fact that on the commercial farm
a very distinguishable compacted layer existed at a depth of 17
inches. No irrigation with any of these tapes was successful in
wetting all the way to the shoulders of the bed (figures 1-6).
In future studies at GCREC-Dover, the effect of pulsing
irrigation through the drip system will be explored as a means
of moving water to the edges of the bed and getting more
uniform coverage for fertilizeror any other chemicals supplied
through the irrigation system.
More pictures of these tests can be found at

Cross sections of the beds after 4, 6 and 8 hours of irrigation with drip tape that has a 4 inch emitter spacing
and a flow rate of 32 gal/100 ft/hr.

Table 1. Downward (D), lengthwise (L), and crosswise (C) movement of water (in inches) in a raised bed planted with strawberries
after 1, 2, 3, 4, 6, and 8 hours of irrigation.

Flow rate (gal/100 ft/hour)

Hours of 24 27 32
Irrigation D L C D L C D L C

1 10.3 10.0 9.0 9.2 10.5 10.5 7.2 4.0 11.6

2 11.0 11.0 14.5 11.9 11.5 15.0 9.2 4.0 11.6

3 15.8 11.3 15.5 14.0 11.3 16.0 10.2 4.0 14.8

4 14.5 11.3 18.5 13.1 11.3 16.5 12.7 4.0 16.0

6 16.5 11.3 19.5 16.9 11.8 19.5 17.5 4.0 18.5

8 16.3 11.8 23.0 16.5 11.8 22.3 21.5 4.0 20.1

USDA / IR-4 Methyl Bromide
Alternatives Program for Strawberry
2002 Jim Gilreath, Joe Noling and Erin

The USDA/IR-4 Methyl Bromide Alternatives
Program for strawberry began approximately three years ago
and has worked to identify possible alternatives to methyl
bromide for fruiting berries in Florida and California. The
program is managed on a national level by Dr. Jack Norton
and is funded by the IR-f project and participating
manufacturers. The program has grown to include 18
different treatments during the past strawberry season at two
sites in Florida. Some of these treatments represent new
chemistry, while others are comprised of older products, and
combinations of products. The Florida experiment focused
primarily on sting nematodes and soilborne pathogens. A
second experiment is being conducted at the Gulf Coast
Research and Education Center Bradenton and has sting
nematodes and weeds as the principal pests.
Although the primary objective of the program was
to identify
alternatives to
methyl bromide
as a soil
fumigant, data
being generated
will be of
value to growers
Fumigation process in the event the
industry attempts
to obtain a critical use exemption for methyl bromide on
strawberry. Not only will these data demonstrate the efficacy
of methyl bromide in scientific assessments, but the IR-4
program will go a long way toward satisfying two of the
requirements of the critical use exemption process: 1)
demonstration of the efficacy of products relative to methyl
bromide to determine if any is a viable alternative in unbiased
research and 2) an on going research program to continue
evaluation of new and existing alternatives in support of
industry critical-use exemption requests.
A key focus of the IR-4 program is outreach. In a
recent tour, participants clearly saw the effect of sting
nematodes and soilborne pathogens on fruiting plants at
Dover. Results were quite dramatic when treatments were
viewed against nontreated control plots where strawberry
plants were either dead or close to it. Interestingly, even
methyl bromide treated plots suffered some damage from sting
nematodes and crown rot in this trial. One of the more
successful treatments was a combination of chloropicrin and
metam sodium. Telone C-35 provided good results in most
plots in this experiment. Iodomethane, formerly referred to as
methyl iodide, was among the better treatments. A significant
population of Carolina geranium (a weed) was observed at
Bradenton. At that location even methyl bromide treated plots
suffered from poor winter annual weed control. Some new

products provided some control of winter annuals and a few
treatments controlled nutsedge.
New chemistry is constantly being sought for
inclusion in these trials. Products identified as successful
candidates have the advantage of access to and support by the
IR-4 registration program and award of methyl bromide
alternative status in the EPA registration process. Recognition
of a pesticide as a methyl bromide alternative advances a
product in the time frame of the registration process.
Hopefully, this valuable program will continue in Florida and
growers will benefit from it.

Strawberry Production in Spain Dan
During my recent trip to Europe I had the opportunity
to visit the Spanish
strawberry production
region near Huelva in
southern Spain. .
Currently, Spain is the ..
second largest
producer of
strawberries in the
world after the USA.

same two-row raised bed culture system used in Florida).
However, the Spanish are currently fumigating their beds with
Jos 50:50 methyl
Small tunnels in Spain

chloropicrin. The
citing felds ( hectfrres)uitin ing season in the
are produced in plastic tunnels in Spain (80% inside of single

bed tunnels an nde ulple be nHuelva area runs

same twoow aised ed clressem id-May, anda

primary cultivar
being grown (95% of
the plantings).

Jose Manuel Aranda, Breeder, During my
in large Spanish tunnel trip I had the
opportunity to visit
with several excellent researchers working in Spain. The
strawberry breeders showed me several promising new
strawberry selections being developed by a joint Spanish
government / private sector program. Two of these selections
will soon be named and released for commercial use. Spanish
strawberry producers have many of the same disease problems
we have in Florida, although the drier climate and tunnels
helps to reduce disease problems. Every year they have
epidemics of Botrytis fruit rot and this season they had
problems with Colletotrichum acutatum (Colletotrichum root
rot and anthracnose fruit rot).

Spotlight on Diagnosis- Jim

The Strawberry Diagnostic Lab is now entering its
usual summer dormancy period. Only a few strawberry
samples fromBradford County have been processed recently.
This time of year, strawberry growers occasionally bring in
vegetable or melon samples for diagnosis. This practice is
discouraged since our lab is neither equipped nor authorized to
handle such samples. Growers experiencing problems with
crops other than strawberry should contact Erin Rayfield at the
Hillsborough County Extension Office (813) 744-5519 Ext.
105. She may help with the problem directly or refer a sample
to the appropriate clinic at the University of Florida in
Gainesville. Drs. Bob McGovern and David Schuster are
other sources of assistance at the Gulf Coast Research and
Education Center in Bradenton. Dr. McGovern (914) 751-
7636 Ext. 299 is a plant pathologist specializing in ornamental
and vegetable crops. Dr. Schuster, Ext. 247, is an
entomologist who works with insect pests of vegetables.

Additional Ways to Earn CEUs Erin

The Hillsborough County Extension Office has
recently acquired computer disks that will allow growers to
earn CEUs in the Core and Private applicator categories.
Growers can earn 2 core CEUs and/or 4 private applicator
CEUs. The disks are loaded on a computer in the Extension
office. Please contact Dave Palmer if you are interested in
using the disks (813)744-5519 x103.

'Carmine' Strawberry Craig
Dan Legard

Chandler and

On April 9th the
University of Florida's cultivar All
release committee
unanimously approved the
release of FL 95-256
strawberry as 'Carmine'
(pronounced Kar-men, a word for deep red or crimson). There
is a need in west central Florida and other winter strawberry
production areas for an early ripening cultivar to replace or be
an alternative to 'Sweet Charlie'. 'Sweet Charlie' has
benefited the Florida strawberry industry through its high
production of fruit early in the season, when market prices are
typically high. But the texture of 'Sweet Charlie' fruit is
relatively soft, making its shipment and shelf life problematic.
'Carmine' has produced high early-season (Dec. through Feb.)
yields of firm, deep red fruit at GCREC-Dover and in several
commercial fields in west-central Florida. It is recommended
for trial in areas with mild winter climates.

Overview of Spring 2002 Strawberry
Entomology Field Research in Dover
- Jim Price

Entomological fieldwork at Dover emphasized two
main areas of interest: Pesticide development and integration
of biological control of spider mites into common strawberry
In the area of pesticide development, we performed
three large experiments to learn the best patterns of use for
two newly registered miticides, Acramite' (bifenazate) and
Savey? (hexythiazox). In addition, we performed extensive
work on two emerging miticides, Mesa' (milbemectin) and
acequinocyl (no trade name yet). Each of these four
compounds performed very well and offers growers reasons
for confidence in mite control success for some years to come.
Mesa' likely will be registered for use in strawberry
fields this fall, but it possesses a mode of action similar to that
of Agri-Mek'. We shall recommend that growers choose only
one of them.
In the second area of emphasis, we studied the
compatibility of Mesa Danitol? (fenpropathrin), Switch'
(cyprodinil/fludioxonil) fungicide and experimental
formulations of thiram fungicide with Phytoseiulus persimilis
predators. Mesa appears to reduce motile form predators to
about the degree we are accustomed to with Agri-Mek' We
were pleased to discover that the pyrethroid, Danitol may
not be as hazardous to the predators we used as it had been in
the past. Apparently, the biological control products industry
is beginning to select and propagate mites that possess some
tolerance to certain pyrethroid insecticides. Switch? and the
experimental formulations of thiram appear to be compatible
with our biological mite control.
Additional details of results from this season of work
will be published in future issues of the Berry Times

Congratulations to Dr. Craig
Chandler on his recent promotion to full
professor as well as on the release of the
nevl cultiva r C('ai mine'. il

The use of trade names in this publication is solelyfor the purpose of providing specific information It is
not a guarantee or warranty of the products named, and does not signify that they are approved to the
exclusion ofothers ofsuitable composition Use pesticides safely Read andfollow directions on the
manufacturer's label
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