Tomatoes and Squash
Do you know the basics of blooming? If not,
you are probably very distressed by now that your bloomers
may be dropping! That's right, friends, blooms are falling
from plants and it’s really not your fault. Some vegetable
crops just naturally need their sexual parts manipulated before
production will occur in early spring. The vegetables that
cause the most problems are vine crops such as squash, cantaloupe,
cucumber and watermelon, as well as such garden favorites
as tomato, pepper and eggplant.
The vine crops mentioned are monecious plants.
That means that both male and female organs exist on the same
plant. The problem is that the flowers with the male parts
are separate from the flowers with the female parts. To complicate
matters even further, at this time of the year, both male
and female flowers may not be on the plant at the same time.
Since it "takes 2 to tango", if the female appears
first, the fruit will fall off the plant because it lacks
pollination by the male. And, if that were not enough, many
times when the male and female are both present, the male
is impotent! The pollen that is produced is sticky and not
readily adaptable to wind pollination. Pollen transferal from
flower to flower relies principally on honeybees. Without
good bee activity, the fruit set will be dramatically reduced.
Each fruit of the vine crop produced from a
female flower contains several hundred seeds which required
a transfer of several hundred pollen grains. The female flower
is only open for 1 day and is most receptive between the hours
of 9 am and 4pm. During this time, the flower must receive
about 15 bee visits for maximum pollination. Unfertilized
or poorly fertilized flowers abort and fall from the vine
within 1 or 2 days. Fortunately, the vine crops have some
100 female flowers produced during a life cycle.
Each flower could potentially become a harvested
fruit. Fruits formed near the crown (stem area) of the plant
are the most desirable, as they usually are larger, mature
earlier and contain more sugar. For this reason, it is important
to have bees present at first bloom. Usually, male flowers
are formed first and the bees can gather pollen from these
flowers and establish regular feeding and watering patterns
before the female flowers are developed. This creates the
best opportunity for the crop to produce crown- set fruits.
As mentioned earlier, the male bloom appears
first. "How does one distinguish a female from a male
bloom?" you ask (with some hesitation). The female bloom
has a small fruit attached to the base of the flower. The
male bloom is just a plain flower attached to the plant by
a green stem.
If you, the gardener, lacks a source of such
pollinating insects, or you continually kill them by spraying
insecticides during flight periods, inadequate pollination
and fruit drop will occur. During seasons of peak pollination,
spray insecticides late in the afternoon to avoid problems.
If you do not have bees, you can hand pollinate
blooms. This involves taking a male bloom and rubbing it in
a female bloom early in the morning. This will effectively
transfer the male pollen to the female bloom.
The bloom time of squash also signals the beginning
of another squash-growing, task-squash vine-borer control
period. Just as blooming begins, the reddish, wasp-like moths
visit plants and deposit eggs which hatch into the white borer.
In the spring, plants will be in the bloom stage before eggs
are deposited. So, you can enjoy some harvest before the enlarging
borer larvae can devastate the inside of the vine until it
dies. In the fall, seedlings are small when they are attacked,
so feeding vine-borers will kill plants faster. Many times,
a fall planting of squash will be killed even before seedlings
are 6 inches tall.
A protective dome cover made of screen can
be placed over squash seedlings to physically keep the moth
from depositing eggs until plants are larger. However, plants
soon outgrow such devices. Dusting or spraying main stalks
with Sevin every 3 days (which has also been recommended)
can stimulate spider mite populations. Products containing
the active ingredient endosulfan, commonly referred to as
Thiodan, are more effective. Endosulfan is sold as Garden
Bug Killer and Thiodan Garden Dust.
Since endosulfan is effective for a longer
period of time, it is more successful in combating the destructive
trio—vine-borers, squash bugs and stink bugs—with
weekly applications. Endosulfan can be used on squash, potatoes,
peas, tomatoes, peppers, eggplant, beans, celery, cabbage,
broccoli, carrots, Brussels sprouts, cauliflower, lettuce,
spinach, collards, mustard greens and kale. No pesticide is
perfect. All should be used as label instructions direct.
But the exciting thing about endosulfan is that it offers
an opportunity to rid the most damaging of the garden insects
without stimulating spider mites. Simply dust the main squash
stem—not the entire plant—weekly to eliminate
vine=borer devastation. Tomato, pepper and eggplant blooms
drop off plants because of another type of pollination problem.
The tomato is hermaphroditic which means that both male and
female parts exist in the same flower. So how could it have
a pollination problem?
The pollination problem of these crops exists
because the female part of the flower (pistil), which must
be pollinated, is located above the male flower parts which
produce pollen. If this pollen is inactivate because of hot
temperatures, or made sticky by cool, cloudy conditions, the
female flower part will not be pollinated, and the entire
flower and potential tomato will drop off.
Tomato, peppers and eggplant flowers are wind
or mechanically pollinated, so gardeners don't have to rely
on bees. The flowers can be artificially set, or made to stay
on the plants, by use of blossom-set hormones sold in local
nurseries. These hormones are effective fruit-setters only
during early spring when cool, cloudy temperatures are the
villains. Tomatoes that are artificially set with hormone
sprays will have fewer seed. These are not test tube babies
but can certainly claim conception by artificial means.
So don't become alarmed if your bloomers are
dropping—do something about it, now that you know the
basics of blooming.