Southeastern U.S. Vegetable Crop Handbook - 2021 - 122

VARIETIES1
AL
WATERMELONS (cont'd)
Triploid Mini/Seedless Mini
Mielheart S
Ocelot S
Paragon S
Proxima S
Sirius IR
Sweet Bite S
1
Abbreviations for state where recommended.
2 Yellow flesh fruit.
3
Orange flesh fruit.
4 Local markets only.
A
A
A
MS
IR
S
G
G
Anthracnose tolerance/resistance.
Moderately susceptible to Fusarium wilt race 1.
Intermediate resistance to Fusarium wilt race 1.
Susceptible to Fusarium wilt race 1.
R
PM
N
AR
GA
KY
LA
MS
NC
OK
SC
TN
A
G
N
N
S
S
S
T
Resistant to Fusarium wilt race 1.
Powdery mildew tolerance/resistance.
Seed Treatment. Check with seed supplier to determine if seed
has been treated with an insecticide or fungicide. Be sure that
seeds have been assayed for bacterial fruit blotch. Further information
on seed treatments can be found under SEED TREATMENTS
in the disease management section of the handbook.
Direct Seeding & Transplant Production.
Direct seeding for Diploids Only: Seed when the soil temperature
at the 4-inch depth is 60-65 °F. The recommended spacing for watermelons,
both direct seeded and transplant, is 6 - 12 feet between
rows providing 24 - 30 square feet per plant. Typically, a wider
row spacing will produce a larger-sized watermelon.
Transplant Production for Triploids: For seedless watermelons,
transplants should be grown in containers that provide a space of
at least 1.5 inches by 1.5 inches for each plant. Smaller pots or
cells will restrict root growth and provide less protection to the
newly set transplants. If the seed is of good quality with high germination,
one seed per pot is sufficient. The seed coat of seedless
watermelons tends to adhere to the seedling as it emerges, at times
slowing growth, or reducing stand.
For maximum germination, seedless watermelon seed should
be planted with the point of the seed facing up (root end). However,
this is not possible for any large-scale operation. Growing media
should be pre-watered and allowed to drain before seeding and
no additional moisture applied for at least 48 hours. Place trays in
a germination chamber at 85-90°F for 48 hours. Next, place the
trays in a greenhouse with day temperatures 70-80 °F and night
temperatures 65-70°F.
The required amount of seed for direct seeding and transplant
production, the number of required seed can be estimated using
Table 6.
Planting. Transplants: Ideally, transplant container-grown plants
into plastic mulch after the last killing frost.
This is difficult to
predict and planting dates vary, so consult the following table for
your area. Plantings should be protected from winds with row covers,
rye strips, or windbreaks.
Grafting and Diseases. In recent years, grafted watermelon plants
have emerged as a strategy to combat soilborne diseases. Grafting
is used against Fusarium wilt. Grafted plants are more expensive
per transplant. For more information, see the section Grafting in
Vegetable Crops in this handbook.
122
POLLINATION AND PLANTING ARRANGEMENT
WITH TRIPLOIDS
Fruit set and enlargement in watermelon is dependent upon growth
regulators from pollen grains and from embryos in the developing
seeds within the fruit. Inadequate pollination results in triploid
watermelon fruit that are triangular in shape and of inferior quality.
Additionally, inadequate pollination increases the incidence of
hollow heart. Triploid watermelon flowers do not produce viable
pollen, which is required to induce fruit set and development.
Therefore, pollen from a " normal " (i.e., diploid/seeded) or a special
pollinizer watermelon variety must be present.
Several seed companies have developed new varieties for use
solely as a pollinizer, non-edible special pollinizers. These pollinizers
can be interplanted into a field totally devoted towards the
production of triploid watermelons. Unique, compact growth habits
prevent these pollinizers from competing for space with triploid
plants.
Fields should be interplanted with pollinizer plants or diploid
watermelon plants in order to provide sufficient, viable pollen for
fruit set and development.
The arrangement for incorporating pollinizer plants in a field
of seedless watermelons has changed over the years. Currently
most growers plant the pollinizer plant between every third and
fourth plant within each row without changing the plant spacing
of the seedless/triploid watermelon. Due to the less competitive
nature of the special pollinizer plants mentioned above, they often
work best with this seedless/pollinizer arrangement. However,
growers can use a normal diploid/seeded watermelon as a pollinizer.
The diploid/seeded watermelon must be marketable and have a
fruit rind pattern and/or shape easily distinguished from the seedless
fruit. Not all diploid/seeded watermelons are suitable for use
as pollinizers due to excessive plant vigor, reduced pollen production,
and lack of disease resistance. (See recommendations below
for Edible Diploids). It is also advisable that the grower reach an
agreement with his harvesting crew as to how both type watermelons
will be handled at harvest.
Many growers prefer special pollinizers because they do not
have markets for seeded watermelons. In addition, using a special
pollinizer makes harvesting easier for crews who can more easily
distinguish between fruit produced from the seeded, special pollinizer
and fruit from the seedless watermelon varieties. Most fruit
of the special pollinizer is much smaller (< 10 lbs) than fruit pro2021
Vegetable Crop Handbook for Southeastern United States
Southeastern U.S. Vegetable Crop Handbook - 2021

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