Southeastern U.S. Vegetable Crop Handbook - 2023 - 23

appropriate width of plastic on the bed so that no more than
6 " of plastic is buried on both sides of the bed reduces the
soil and debris.
* Proper retrieval equipment: Adjustments to removal
equipment might be required to optimize debris removal as
well as tightness of bundles.
Row covers
Row covers are used to hasten the maturity of the crop, exclude
certain insect pests, and provide a small degree of frost protection.
There are two main types of row covers: vented clear or
translucent polyethylene and floating row covers. Polyethylene
types are supported by wire hoops placed at regular (5 to 6 ft) intervals.
In addition, plastic can be placed loosely over the plants
with or without wire supports. Floating row covers are porous,
lightweight spunbonded materials placed loosely over the plants.
Floating covers are more applicable to the low-growing
vine crops. Upright plants like tomatoes and peppers have been
injured by abrasion when the floating row cover rubs against
the plants or excess temperatures build-up. Erratic spring temperatures
require intensive management of row covers to avoid
blossom shed and other high-temperature injuries. In particular,
clear plastic can greatly increase air temperatures under the cover
on warm sunny days, resulting in a danger of heat injury to crop
plants. Therefore, vented materials are recommended. Even with
vents, clear plastic has produced heat injury, especially when the
plants have filled a large portion of the air space in the tunnel.
This has not been observed with the translucent materials. Usually,
row covers are combined with plastic mulch.
High Tunnels
High tunnels are unheated, polyethylene-covered structures
that provide a larger degree of frost protection than row covers.
A properly built high tunnel with one or two layers of plastic,
should afford 5-8 °F of frost protection. As with row covers,
high tunnels require intensive management to ensure that they
are vented properly when warm spring temperatures can cause
excessive heat to build up in tunnels, resulting in damage to the
crop. Tomatoes are commonly produced in high tunnels as well
as a variety of leafy greens crops, due to the premium prices
obtained. Row covers are often combined with the use of high
tunnels and plastic mulch.
High tunnels can provide 3-4 weeks or more of season
extension for spring and fall crops such as tomatoes as well as
year-round production of Cole crops and lettuce. High tunnels
can reduce the incidence of certain diseases and insects due to
protection from rain and changes in light interception, respectively,
inside the tunnel; however, traditional greenhouse pests,
such as leaf mold, aphids, spider mites, and whiteflies may be
more prevalent in high tunnels. In many states, high tunnels are
considered a greenhouse structure for the application of pesticides,
which may reduce the number of chemicals available
compared to field production. Be sure to determine if the pesticides
you are applying are acceptable for use in high tunnels in
your state.
Extensive information regarding construction, specifics of
crop production, soil management, and economics of production
2023 Vegetable Crop Handbook for Southeastern United States
for many fruits, vegetable, and cut flowers grown in high tunnels
can be found at https://www.sare.org/resources/hightunnels-and-other-season-extension-techniques/.
Considerations
for Using Mulch, Drip Irrigation,
and Row Covers
Each grower considering mulches, drip irrigation, and/or row
covers must weigh the economics involved. The long-term versus
short-term opportunities must be considered.
* Does the potential increase in return justify the additional
costs?
* Are the odds in favor of the grower getting the most benefit
in terms of earliness and yield from the mulch, drip irrigation,
and/or row covers?
* Does the market usually offer price incentives for early produce?
Will harvesting early allow competition against produce
from other regions?
Depending on the row spacing and bed width, polyethylene
mulch can cost $350 to $700 per acre, including installation and
removal. Biodegradable mulches can cost twice as much as
polyethylene mulches. Additionally when using these mulches,
drip irrigation must also be installed ($400 to $1,200/acre).
Growers must determine costs for their situation and calculate
their potential returns. For more help in determining exact costs
for your operation, use the Mulch Calculator:
https://biodegradablemulch.tennessee.edu/wp-content/
uploads/sites/214/2020/12/Chen-Mulch-calculcatorintroduction.pdf
POLLINATION
Honeybees
or other pollinating insects are essential for commercial
production of cucurbit vine crops and may also improve the yield
and quality of fruit in beans, eggplants, peas, and peppers. In other
fruiting vegetables, such as okra and some legumes, pollination
does not require insect visits. Lack of adequate pollination usually
results in small or misshapen fruit in addition to low yields. The
size and shape of the mature fruit is related to the number of seeds
produced and each seed requires one or more pollen grains for normal
development. Cucumbers, squash, pumpkins, and watermelons
have separate male and female flowers, while cantaloupes and other
specialty melons have male and hermaphroditic (perfect or bisexual)
flowers. Adequate amount of the sticky pollen of the male flowers
must be transferred to the female flowers to achieve fruit set.
Cucurbit flowers are usually open and attractive to bees for no more
than one day. Flower opening, release of pollen, and commencement
of nectar secretion normally precede bee activity. Pumpkin,
squash, cantaloupe, and watermelon flowers normally open around
daybreak and close by or before noon; whereas, cucumbers and
melons generally remain open the entire day. Pollination must take
place on the day the flowers open because pollen viability, stigmatic
receptivity, and attractiveness to bees lasts only that day.
European honeybees and various native wild bees may visit
the flowers of flowering vegetables. However, successful pollination
requires that these insects visit male and female flowers
frequently for pollen transfer to occur. Some insects present in
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https://www.fda.gov/food/food-safety-modernization-act-fsma/fsma-proposed-rule-agricultural-water https://www.fda.gov/food/food-safety-modernization-act-fsma/fsma-proposed-rule-agricultural-water https://biodegradablemulch.tennessee.edu/wp-content/uploads/sites/214/2020/12/Chen-Mulch-calculcator-introduction.pdf https://biodegradablemulch.tennessee.edu/wp-content/uploads/sites/214/2020/12/Chen-Mulch-calculcator-introduction.pdf https://biodegradablemulch.tennessee.edu/wp-content/uploads/sites/214/2020/12/Chen-Mulch-calculcator-introduction.pdf

Southeastern U.S. Vegetable Crop Handbook - 2023

Table of Contents for the Digital Edition of Southeastern U.S. Vegetable Crop Handbook - 2023