October 2019 - 9

CONTROLLED ENVIRONMENT
How plasticulture prospered for vegetable growers
By William J. Lamont Jr.
Penn State Professor Emeritus
VGN Correspondent
Ask a vegetable grower to define the
term plasticulture, and they will most
likely give you a bewildered look and
say in a questioning tone, " The growing
of plastics? " They did catch the plastics
component part but missed the rest of
the word. With the development of the
polyethylene polymer during World War
II and of other petroleum-based polymers
in succeeding years, growers, university
researchers and Extension specialists, and
industry personnel have been developing
and refining cropping systems that utilize
many different plastic components.
Plasticulture is simply defined as systems
for the production of horticultural crops,
especially vegetables, that utilize plastics.
The plastics may be mulch films, drip
irrigation tapes and tubing, row covers, low
and high tunnels covered with clear plastic
sheeting, or more permanent greenhouse
structures for the production of vegetable
transplants and greenhouse vegetables,
such as tomatoes, cucumbers, eggplants
and peppers.
The development of plastics
completely revolutionized growing
systems for many horticultural crops in
some geographical areas and, certainly,
several major vegetable crops, such as
tomatoes, cucumbers and lettuce grown
in the greenhouse or tomatoes, peppers,
muskmelons, watermelons, eggplant
and squash grown in the field. The
production of strawberries was changed
radically from the conventional mattedrow
system to the plastic-mulched
annual hill system of production.
How it started
What were the origins of this
revolution, the major current uses
of plastics in vegetable production
systems, and what might be the future
of plasticulture in the area of vegetable
crop production?
In 1960, George Marlowe of the
University of Kentucky invited 55
industry and university colleagues,
whom he knew to be interested in the
applications of plastics to agriculture, to
Lexington, Kentucky, for a conference on
the subject. This first annual conference
(forerunner of the National Agricultural
Plastics Association (NAPA) and then the
American Society for Plasticulture (ASP)
congresses) on " Use of Plastic Film in the
Production of Horticultural Crops " was
dedicated to E. M. Emmert, University of
Kentucky, for his pioneering work in the
horticultural use of plastic films. Many
consider Emmert the " Father of Modern
Plasticulture. "
Much of the early work in plasticulture
of vegetable crops centered on developing
efficient uses for clear plastic sheeting
to cover greenhouse structures for
the production of tomatoes and on
field applications of plastic mulches,
drip irrigation tape/tubing and solid
polyethylene row covers. Different
colored plastic mulches, primarily clear
and black, were evaluated for their effect
on the microclimate around crops, such
as tomatoes, peppers, or muskmelons,
and their subsequent growth and yield.
Early experiments and testing on use
of plastic mulches and drip irrigation
were conducted at several locations
around the country. As the benefits of
clear plastic films became apparent,
researchers began focusing on using
narrow clear polyethylene sheets as row
covers over such vegetables as tomatoes
and cucumbers to promote earliness and
eliminate the use of individual hot caps.
New plastic materials continued to be
developed and tested around the country
on a variety of vegetable crops.
It was during this period of time that
plastic mulches with highly reflective
surfaces (silver or aluminized) were
evaluated for their ability to repel
aphids and, thus, delay the onset of
virus symptoms in summer squash.
Even during this early period in the
development of plasticulture, work was
being directed toward the use of paper
mulches or paper impregnated with
a plastic compound as alternatives to
pure polyethylene mulches and toward
degradable plastic mulches.
At the third conference, Marlowe,
first president of NAPA, the immediate
forerunner of ASP, said " One of the
significant recent developments in
horticulture has been the use of plastic
films for crop production. " Today, we
can appreciate fully the significance of
his observation. Currently, well over
125 million pounds of plastic films
are used annually in the U.S. in crop
applications such as mulches, row
covers and greenhouse covers. Many
more pounds are utilized in drip and
field irrigation pipes, tubing, flowerpots,
seed flats and packaging.
Many pioneering studies on the
development and uses of greenhouse
films, plastic-covered greenhouse
structures, nondegradable and degradable
plastic mulching materials, drip
irrigation, fertigation, soil fumigation,
plastic containers and packaging, soil
solarization, hydrophilic polymers,
transplant containers, row covers and
high-tunnel culture were published
over the years in the 35 Proceedings
of the National Agricultural Plastics
Association and the American Society for
Plasticulture Congresses.
Use continues to grow
The use of plasticulture in the
production of selected vegetable crops
continues to expand throughout the
United States and the world. Systems
of production currently utilize various
plastic mulching materials; drip irrigation;
fertigation; row covers; container-grown
vegetable transplants; and unheated,
plastic-covered, high tunnels that increase
the early harvest, total yields and overall
quality of vegetables produced.
Photos: William Lamont Jr.
Plastic mulches currently in use are
either nondegradable/conventional,
wavelength-selective, or biodegradable.
The nondegradable/conventional
mulches can be further subdivided into
either smooth or embossed surfaces and
into three major colors, black, whiteon-black,
metalized silver reflective and
some limited additional colors such as
red and blue. The degradable mulches
such a photodegradable disintegrate,
depending on their formulation, in the
presence of sunlight at various intervals
but have been replaced by a newer
family of biodegradable that have been
more consistent.
Biodegradable, especially the plantbased
polymer mulches have created
considerable interest because of the
continuing disposal problems associated
with the non-degradable/conventional
mulches. One main concern is that the
biodegradable mulches perform to the
same standards of performance of the
conventional non-degradable mulches.
The use of drip irrigation or microirrigation
has allowed vegetable growers
to increase the application efficiency
of water applied and reduce the total
amount of water used by as much as
half when compared to other methods
of irrigation, such as overhead sprinkler
or furrow irrigation. Allocation of water
resources and preservation of water
quality are becoming critical issues
in many leading vegetable-producing
areas. The utilization of drip irrigation
has also allowed vegetable producers
to practice fertigation (injection
of fertilizer into the drip irrigation
system), resulting in efficient feeding
programs that greatly reduce the
See PLASTIC, page 10
VGN | OCTOBER 2019 | 9
October 2019

Table of Contents for the Digital Edition of October 2019
