NEWARK, Del. Watermelons
are a high value crop in Delaware,
but they require extensive
management for profit. University
of Delaware extension vegetable
specialist Ed Kee estimates about
2,000 acres of this popular fruit are
grown annually in the state. He’s
been working closely with
producers over the past few years
in an effort to help them grow and
market their melons more ef
fectively.
"Most growers feel that if they
can get good early fruit set, they’ll
stand a better chance for
profitable returns,” the specialist
says. "When you analyze your
yield per acre and relate this to the
number of melons produced per
plant, the need for good fruit set
becomes even more obvious.”
Because watermelon vines run
together and overlap, it’s hard to
get a handle on just how many
melons per plant are harvested in
a commercial field. Estimates
range from one per plant to three
or four. "By setting up a
hypothetical example on paper,”
Kee says, "you can start to zero in
on the yield per plant in your own
operation.”
A spacing of 6 feet by 3 feet gives
2,420 plants per acre. If one 20-
pound melon is harvested from
each plant, that means a yield of
48,000 pounds an acre. At 8- by 4-
foot spacing, or 1,361 plants per
acre, the yield with one 20-pounder
per plant is 27,220 pounds per acre.
The above illustration shows two
things: first, that spacing can
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Good fruit set vital in watermelons
affect yield, and second, that even
one full-grown melon per plant can
result in good yields at the
closer spacing. “The hard question
growers must ask themselves is
whether it’s realistic to expect one
melon per plant, or one large and
one smaller melon-or some other
combination-at the various
possible spacmgs,” Kee says.
Understanding the factors which
affect fruit set in watermelons will
make such production decisions
easier.
During the 1930 s and 1940 s
researchers at several
agricultural experiment stations
across the country studied the
factors affecting fruit set in this
crop.
One thing they discovered was
that fruit set depends on the
number of leaves the plant is
carrying. "Because the dry matter
content of each watermelon is
made up largely of carbohydrates,
the plant needs a lot of leaves to
develop fruit properly,” the
specialist explains. “Thus, one
step toward good yields is to en
courage rapid early growth. Of
course, there’s a danger of ap
plying too much fertilizer and
delaying flowering. But, all things
being equal, it appears that the
plant with the most leaves will set
fruit soonest and grow out that
fruit best ”
In a related study, researchers
showed that removing defective
melons increased final yield. A
growing melon tends to inhibit
setting of other female flowers on
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the vine. This means dial it a
misshapen fruit is present, setting
of a subsequent normal one many
be delayed for several weeks.
Another study showed that when
the number of melons per plant
was limited to two, the greatest
returns were realized from the
standpoint of earliness and total
yield, Kee reports. When fruit
production was limited to one
melon per plant, the increased size
did not compensate for decreased
yield. “This doesn’t mean that
Delmarva growers need to control
the number of melons per plant,”
he says. "But it does indicate how
a watermelon vine sets, grows and
compensates for developing fruit."
Scientists also found that more
fruit is set during cooler weather
or during the cooler parts of the
day. Temperatures in the high 90s
and over 100 degrees F are
detrimental to fruit set. "This is
somewhat academic because we
can’t control the weather, but with
irrigation and other good growing
practices we can help plants cope
better with weather extremes,”
Kee says
A more important factor in
fluencing fruit set is competition
for food material. This will affect
set and development even more
than environmental conditions.
This competition probably exists
between fruit and flowers already
set,’’ the specialist says. "It’s also
known that developing melons pull
the bulk of their food from the
leaves closest to them. This is
important in terms of fertility
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piogiams and other factors af
fecting the movement of nutrients
within the vine. An obvious
example is blossom end rot, or
shriveled melons, a condition
usually associated with dry soil
and calcium deficiency.”
Irrigating to maintain even soil
moisture will help avoid this
problem, as will proper liming to
provide calcium in the soil. This
nutrient is immobile inside the
plant, so it won’t move from
distant leaves into those closest to
developing fruit. A sidedressing of
FFA’ers visit Trenton
NEW BRUNSWICK, N.J. - FFA
Chapter Presidents and their
advisors throughout New Jersey
participated in the Chapter
Presidents’ Tour of Trenton on
Feb. 23. This event was part of
National FFA Week celebrated by
nearly 450,000 FFA members
nationwide from Feb. 18-25.
The tour consisted of visits to the
Department of Agriculture
Laboratories, the Farm Bureau
and the State House. Students had
the opportunity to speak with
entomologists, chemists, seed and
animal health specialists while
viewing the practices and
operations of the staff.
President Walter Ellis of the
Farm Bureau and the *sprrptarv of
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calcium nitrate may be useful to
prevent blossom end rot, Kee says.
Pruning may also help if large
numbers of shriveled melons
occur.
For further recommendations on
a fertility program for water
melons, he suggests growers
consult the 1984 edition of the
extension bulletin, "Commercial
Vegetable Production Recom
mendations.” Copies are available
from county extension offices in
Newark (451-2506), Dover (736-
1448) and Georgetown (856-5250).
Agriculture, Arthur Brown,
discussed issues of New Jersey
agriculture with the student
leaders.
Gov. Thomas H. Kean met with
the group and presented the signed
Proclamation to the State FFA
President, Steven Gruenberg, and
his fellow State Officers. The
Governor then answered questions
raised by the FFA members.
This opportunity to thur Trenton
and meet with state leaders was a
unique and educational experience
for vocational agriculture and
FFA students who are preparing
for careers and leadership
positions in New Jersey
agriculture