Southeastern U.S. Vegetable Crop Handbook - 2023 - 13

TRITICALE: Triticale is a small grain resulting from a cross
between wheat and rye. Triticale has similar characteristics to
wheat, while the plant has the overall vigor and winter-hardiness
of rye. Fall planting of triticale should follow similar recommendations
as wheat, sowing 60 to 120 lbs/A. Triticale biomass can
exceed wheat, thus plowing under or killing for no-till culture
should occur at an earlier time in the spring.
NOTES on SMALL GRAINS: Determine small grain fertilizer
and lime needs based on soil test results. Successful stand establishment
generally can be obtained with planting dates later
than those of legumes, even as late as early December in coastal
plain regions. This permits establishment of the cover crop after
late-fall-harvested crops such as sweetpotatoes. Remember, that
some soil erosion protection may be sacrificed with late seeding
dates. For sandier coastal plain soils, rye is the preferred small
grain cover crop. As previously discussed, seeding depth varies
from ½ to 1½ inches, depending on soil texture. Planting methods
are the same as described for legumes.
TYPES OF WINTER COVER CROPS: LEGUMES
A wide range in planting dates exists for most legumes, though
best results are obtained with early plantings. Early seeding
dates are easy to meet with legume cover crops following spring
vegetables. Because Cahaba White Vetch possesses little winter
hardiness, it is not adapted to western NC and the northern
regions of other southeastern states. Freeze damage has also
occurred with Austrian Winter Pea in higher elevations (above
2,500 feet). Avoid planting late otherwise you increase the risk
of winter kill. For state specific recommendations for planting
dates, seeding dates and management for legume cover crops,
consult your local Extension office.
Seeding Rates and Depths
REGAL GRAZE LADINO CLOVER: broadcast 15 to 20 lbs/A
(seeding depth: 1/4 in.). Can be bedder-disked for bare
ground or plasticulture forming a between row mulch useful
for conventional or bare ground production. Inhibits yellow
nutsedge and can survive year-round with moisture.
CRIMSON CLOVER: broadcast 20 to 25 lbs/A;
drill 15 to 20 lbs/A (seeding depth: ¼ - ½ in.)
HAIRY VETCH: broadcast 20 to 30 lbs/A;
drill 15 to 20 lbs/A (seeding depth: ½ - 1½ in.)
CAHABA WHITE VETCH: broadcast 20 to 30 lbs/A;
drill 15 to 20 lbs/A (seeding depth: ½ - 1½ in.)
AUSTRIAN WINTER PEA: broadcast 25 to 35 lbs/A;
drill 20 to 25 lbs/A (seeding depth: ¾ - 1½ in.)
When seeding, use shallow planting depths for finer-textured,
clayey soils and deeper depths for coarse-textured, sandy soils.
Drilling into a conventional seedbed is the most reliable way to
obtain a uniform stand. A no-till grain drill can be used successfully,
provided residue from the previous crop is not excessive
and soil moisture is sufficient to allow the drill to penetrate to
the desired planting depth. Seeds can be broadcast if the soil has
been disked and partially smoothed. Cultipacking after broad2023
Vegetable Crop Handbook for Southeastern United States
casting will encourage good soil/seed contact. Crimson clover
responds favorably to cultipacking.
MIXING GRASS AND LEGUMES: Planting a single grass or
legume may be necessary but combining a grass and legume together
may prove better than either one alone. Grasses provide
soil protection during the winter and produce great forage or
plow-down organic matter. Legumes do not grow well during
the winter, but late spring growth is abundant and produces high
protein forage and nitrogen for the following crop. Crimson clover
is a legume to grow in combination with a grass. Crimson
clover's height matches well with barley, wheat, and oats, but
may be shaded and outcompeted by rye. Hairy vetch has been
sown with grass cover crops for many years, using the grass/
vetch combination as a hay or plowdown.
BIOFUMIGATION AND COVER CROPS:
Biofumigation refers to the suppression of soilborne pathogens
and pests (such as plant-parasitic nematodes and weeds) using
naturally occurring biocidal compounds or allelochemicals, particularly
isothiocyanates. These compounds, which are chemically
similar to the active ingredient of the chemical fumigant
metam sodium, are released from bioactive cover crops. The
biofumigant process is initiated by cellular disruption (chopping
up crop tissue), incorporating the crop tissue into the soil, and
irrigating the soil with the incorporated tissue. This activates a
chemical reaction of naturally occurring plant compounds called
glucosinolates. The chemical reaction releases gases into soil
pores that are generally toxic to microbes.
Most biofumigant cover crops are in the Brassicaceae family
(also known as Crucifers or Cole crops) and mustards are the
commonly utilized biofumigant crop. However, not all mustards
are well-suited as biofumigants since concentrations of the bioactive
compounds vary by species and cultivar.
Brassica crops have been used extensively as winter cover
crops and as " break crops " where the residues are tilled into the
soil for their biofumigation effect. They have also been used in
rotations, where the Brassica crop is harvested for sale and then
the remaining residue is tilled-in for the biofumigation effect.
There are several commercially available cover crops that have
been used for biofumigation. " Caliente 119 " (a mixture of oilseed
radish and mustard), oilseed radish, " Florida Broadleaf Mustard " ,
garden cress, penny cress, " Dwarf Essex " rape, and several canola
varieties have been reported to have biofumigation potential.
In much of the southeast region of the U.S., these crops can
be seeded in fall and over-wintered, or direct seeded in early
spring. In either case, the crop should be chopped and tilled-in
when it is in the early flowering stage to achieve the maximum
biofumigation potential. The early flowering stage is the point at
which the allelochemical concentrations are their highest. Seeding
rates range from 4 to 20 lbs/A and will vary with location
and seed size (generally, the smaller the seed size, the lower the
rate).
These crops respond and produce more biomass and more
bio fumigation potential when provided with 30 to 90 lbs/A N
fertilizer at planting. These crops grow rapidly and can normally
be plowed down in 6 to 10 weeks. In areas where the average
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