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DANGLING CUCURBITS
The term cucurbit,
short for the botanical plant family cucurbitaceae,
includes many varieties of cultivated and wild cucumbers, gourds, melons, and
squash. Cucurbits are vine plants that produce fruit that are consumed as
vegetables.
As far back as 13,000 years ago, from either wild species or
cultivated varieties, humans have consumed cucurbit flesh for the starch and
seeds for the protein and oil they contain. There is more than one way to
grow cucurbits and this article looks at the advantages of using a trellis,
gives a brief overview of cucurbit pests and diseases in
Annually, the vining growth of
members of the cucurbitaceae family quickly takes
over many square yards of precious garden soil. In the face of this
unchecked, expansive habit, gardeners with small plots have turned to raising
compact bush varieties and building trellises. They’ve discovered that
growing cucurbits above ground frees up lots of garden space that can be used
for other plant varieties. Not only is this a space saving practice, it
facilitates the tasks of caring for the fruit, discourages pests and diseases
and offers the gardener significant other benefits.
The overhead trellis system is recommended over the vertical
one because the plant’s leaves are on top, facing the sun while the fruit hangs
down below. The strength and materials used to build it will depend on the
estimated weight of the fruit. For example, luffa
(Luffa acutangula) can
yield ten to twenty three fruit per plant in a season, reach 15 feet or more in
vine length, and produce a gourd which is 24 to 30 inches long. Each
fruit can weigh over two pounds. Nylon mesh slings can be used to support the
weight of very heavy fruit, thus preventing premature drop. The rule of
thumb regarding which vining cucurbits can be
trellised is whatever the weight the trellis will bear. The method of
construction and materials used, along with the height and width of the trellis
need to be proportionate with the weight of the many vine fruit that will rely
on it for support. It just isn’t practical to have weighty watermelons (Citrullus lanatus), Chinese
winter melon (Benincasa hispida)
or pumpkins (Cucurbita pepo
var. pepo) stressing the trellis structure with the
eventual crash and possible injury to the gardener, not to mention the
fruit. It is important to set up the trellis before planting or
transplanting to avoid root, leaf and stem injury.
URL http://www.ahs.cqu.edu.au
for
Because it is suspended, trellis-trained cucurbit fruit is
more visible. The foliar canopy shields the fruit, protecting it from
sunburn, yet does not hide it as is the case with fruit raised in rows.
Fruit stays clean and tending it is easier. For example, cucurbits need
plenty of water applied to the base of the plant, not the leaves above.
The base is easy to find on trellised plants. Adequate water goes to the
root system while the leaves and fruit remain high and dry. With fruit
being readily accessible, harvesting it frequently, while it is still small, is
easy. This causes the plant to produce more, sweeter fruit. In
fact, bitter melon (Momordica charantia)
also known as bitter gourd, snake gourd (Trichosanthes
anguina) and hairy melon (Benincasa
hispida var. chiegua) are
picked when they are immature because they are less bitter in their earlier
stages of development. In bitter melon, bitterness is caused by the
alkaloid momordicine, whereas in cucumbers (Cucumis sativus), it is caused by
the presence of two cucurbitacins (turpenoid compounds) concentrated near the stem and under
the skin. Zucchini, a summer squash (Cucurbita pepo) is picked before the rind hardens. Though
trellis-trained vines are generally higher yielding, up to forty percent in
some cases, it takes only one old fruit to slow the yield down
considerably. Thanks to gravity, trellised cucurbits grow straight and
down. In the case of the snake gourd, a small stone is sometimes
suspended from its apex to keep it aimed at the ground. When harvesting
cucurbits, best practice is to cut the stem with a sharp utensil, not rip,
pull, or twist off the fruit.
Trellised cucurbits are less vulnerable to attack by pests
and disease than those in contact with wet, soggy soil. This is due to
the increase in air circulation around the suspended fruit which reduces the incidence of mildew and rot. Gardeners can
routinely monitor and detect evidence of insect activity, i.e. eggs laid on the
underside of stems, leaves or at the base of plants or puncture marks on fruit
and can avert or control problems. The California Master Gardener
Handbook includes charts with disease and pest problem diagnosis for many
cucurbits including a list of symptoms, the probable cause and suggested
treatment. Integrated pest management is one of the many topics discussed
and available as free downloads from the
Diseases of cucurbits can be soil-borne, air-borne and
vectored by insects. To lessen the incidence of soil-borne diseases such
as fusarium and verticillium
wilt and anthracnose, cucurbits should not be planted in the same spot two
years consecutively but rather be part of a crop rotation program. As
fungus can survive for years in the soil, on old plant residue and on seed,
using clean seed is also an important cultural control. Anthracnose and
other rot organisms are often related to wet conditions as fruit ripens,
especially if fruit is touches the soil. Irrigation and rain water can
also carry the angular leafspot bacterium and infect
healthy plants.
Though gardeners may follow disease preventative cultural
practices, many of which are listed at the end of the article, powdery mildew
can appear when conditions are right. The fungus overwinters
in field debris, its primary spore source being wild and cultivated cucurbits
and some weeds. Spores are wind blown for long distances, land on vines
and germinate. The white powder is found on the upper surface of leaves
which die and collapse before fruit reaches maturity. The use of fungicides may protect uninfected leaves and
stems as prevention is the only control
In
Whether mallow fruits (another name for cucurbits) are
trellis-raised or grown in rows, one of the best ways to avoid pest and disease
problems is to select cultivars resistant to at least one or more diseases or
pests. Following the disease key below are lists of recommended
disease-resistant varieties.
Key to disease abbreviations:
AAS: all-America selection, hardy in most areas, resists
most diseases
ALS: angular leaf spot
AN: anthracnose
CMV:
cucumber mosaic virus
DM: downy mildew
F: fusarium
diseases
M: mosaic virus
PM: powdery mildew
S: scab
Cantaloupes (muskmelon) and Honeydew (Cucumis melo):
Orangeflesh: Samson (AAS, F,
PM); Ambrosia (DM, PM); Saticoy Hybrid (F, M, PM); Topmark
(PM); Bush Star (AAS, F, PM); Honeybush (bush plant)
(F); Crenshaw; Casaba; Galia: Rocky Sweet.
Honeydew: Tam Dew (DM, PM); Fruit Punch; Limelight
(F).
Cucumber:
Pickling: Liberty Hybrid (AAS, ALS, DM, M, PM, S);
Saladin (AAS, DM, CMV, PM); County Fair 83 (AN, DM, M, PM, S); Pickle
Bush (OK for containers) (CMV, PM); Pot Luck (OK for containers) (CMV).
Slicing: Dasher II (CMV), DM, PM, S); Sweet Success
(AAS, AN, ALS, CMV, DM, PM, S); Sweet Slice, burpless
(AN, CMV, DM, S, PM); Burpee Hybrid (DM, M); Bush
Champion (OK for containers) (M); Parks Bush Whopper (OK for containers);
Pot Luck (OK for containers) (CMV); Salad Bush (OK for containers); Spacemaster (bush plant, OK for containers) (M); Slice Nice
(AN, DM, S); Slice Master Hybrid (ALS, AN, DM, M, PM, S).
Pumpkin:
Spirit (semi-bush) (AAS); Autumn Gold (AAS); Jack O’Lantern; Big Max; Bushkin
(compact vine OK for large container); Cinderella.
Winter Squash: (Cucurbita pepo var. melopepo)
Acorn: Table King (bush) (AAS); Table Ace (semibush); Jersey Golden (semibush)
(AAS); Sweet Mama (AAS, F).
Butternut:
Summer Squash: (Cucurbita pepo var. melopepo) (grows on
non-vining bushes)
Scallop (patty pan): Peter Pan Hybrid (bush) (AAS);
Sunburst (AAS); Scallopini (bush) (AAS); Early White
Bush; Trombocini or Zucchetta
rampicante.
Yellow: Early Prolific Straightneck
(AAS); Sundance; Early Golden Summer Crookneck;
Zucchini: Aristocrat (AAS); Greyzini
(AAS); Ambassador (PM), Golden Rush (AAS); Burpee Fordhook (AAS).
Watermelon:
Bush vine: Garden Baby; Bush Charleston Gray (F); Bush
Jubilee (AN, F); Bush Sugar Baby.
Large vine: Calsweet (F); Crimson
Sweet (AN, F); Sugar Baby; Sweet Baby (F); Charleston Gray (AN, F); Prince
Charles (F).
Seedless: Triple Sweet Hybrid; Tri X-313 Hybrid;
Firecracker.
Yellow-fleshed fruit: Yellow Baby (AAS); Yellow Doll.
Japanese and other Asian varieties of cucurbits are
available to gardeners worldwide via online seed companies. Some sources
are listed below:
http://www.evergreenseeds.com; Vendor states that most seeds (over 300 varieties) are imported
from
http://www.futurefoods.com;
Site includes narrative on origin, fruit description, preparation and growth
habits of a selection of cucurbits.
http://www.johnnyseed.com;
This site provides a plant illustration, days to
maturity, disease resistance, cultivation notes, and other useful information.
http://www.kitazawaseed.com;
Specializes in Asian vegetable seeds from
http://www.sakata.com; Features illustrations and written description
containing disease resistance information, fruit size and shape, rind
characteristics, plant habits, weight and flesh color of fruit.
There are many names to denote Asian cucurbits and although
a few seed catalogs refer to the botanical name, that information isn’t always
helpful to everyone. The website http://www.nre.vic.gov.au/trade/asiaveg/thes-00.htm
provides an Asian vegetable thesaurus. Each vegetable is illustrated,
given one of its names in English, the botanical name, and what it is called in
at least twelve languages.
Gardeners who follow good cultural and sanitation practices can
help control the persistence and spread of diseases caused by soil organisms,
airborne spores and insects.
These practices include:
1. Planting
a disease resistant variety. Pathogen cannot infect and if it does, it is
not able to reproduce or cause damage. Resistance can be used to avoid
problems with powdery mildew, certain viruses, and vascular wilts.
2. Selecting
certified and disease-free planting material. The best way to prevent
disease is to keep it out of the garden from the beginning.
3. Selecting
a suitable planting site for the plant and spacing it properly. Avoiding
planting susceptible plants near fields that may harbor pests and
diseases. Not overcrowding plants. Arranging plants according to
their watering requirements.
4. Irrigating
plants regularly and early in the day. Fertilizing adequately.
5. Removing
diseased plants and discarding them. Pruning out diseased foliage from
trees.
6. Keeping
garden implements clean to avoid spreading contaminated soil or disease
organisms from infected plants. Sterilizating
tools with household bleach diluted in water (one part bleach to nine parts
water). Cleaning off shoes, washing hands well after handling diseased
plants.
7. Rotating
crops keeps diseases from building up. Allowing parts of garden to go
fallow.
8. Controlling
weeds which can harbor disease-causing fungi and viruses in garden and in
adjacent areas.
9. Composting
aerobically to allow plant material to decay.
10. Solarizing the soil with clear plastic for two months
during midsummer.
11. Allowing
biological control of disease organisms and pests by organisms found in nature.
12. Carefully
timing application of pesticides to control plant pathogens.
For more information about growing cucurbits and other
vegetables, pests and diseases of cucurbits or of other plants in
References
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