Thomcord
Encyclopedia
Thomcord is a seedless
table grape
variety and a hybrid of the popular Thompson Seedless or Sultanina
grape (a Vitis vinifera
variety) and Concord grape (a Vitis labrusca
variety). Thomcord was developed in 1983 by Californian grape breeders working for the Agricultural Research Service
(ARS), an agency of the United States Department of Agriculture
(USDA), as part of a test to better understand a new seedless grape breeding procedure.
Its aromatic, "labrusca
" flavor is similar to that of Concord, but mellowed by the mild, sweet taste from Thompson Seedless. Thomcord grows well in hot, dry climates, ripens between late July and mid-August, and tolerates powdery mildew
. It is a productive variety, yielding an average of 15.1 kg (33.3 lb) of grapes per vine, but has produced as much as 30 to 32 kg (66.1 to 70.5 lb) per vine in grower trials. The berries weigh between 2.72 and 3.38 g (0.0959451769259045 and 0.119225991915278 oz) and have a medium-thick, blue-black skin that adheres to the fruit, unlike Concord, which has a thick skin that can slip off the pulp easily. The aborted seeds
in the fruit body are relatively small, but larger than those in Thompson Seedless.
The plant is not restricted
for propagation and distribution. Virus-free propagation material is available from the Foundation Plant Services (FPS) at the University of California, Davis
, and its genetic material is archived at the National Plant Germplasm System
. After 17 years of testing, it was declared ready for use in 2003. It is expected to appear in supermarkets, possibly as a specialty item.
, or Sultanina), which is popular in supermarkets during the summer, and seeded Concord grape (Vitis labrusca
), commonly used to make grape juice and jelly. It is a plump, juicy, seedless table grape
and is slightly firmer than Concord. Thomcord has a blue-black skin with medium thickness and a whitish bloom. Unlike Concord, whose tough skin separates easily from the fruit, Thomcord has a more edible skin that clings to the flesh, much like Thompson Seedless. It has an aromatic flavor, similar to the Concord in taste ("labrusca
"), though lighter due to the sweet, mild taste from Thompson Seedless.
Thomcord is suitable for hot, dry growing conditions, more so than Concord and other Concord seedless types. Its adaptability to hot dry climates was derived from Thompson Seedless. It grows well in California's vineyards, particularly the San Joaquin Valley
, just like Thompson Seedless. The plant is tolerant of (but not resistant to) powdery mildew
, and is less susceptible to the fungus
than Ruby Seedless, but more susceptible than Mars, Venus, Niabell, and Cayuga White
varieties. The fungus can affect its leaves
, stems
, rachis
(stem of the grape cluster), and berries
. The grape ripens in the summer (mid-season), between late July and mid-August.
and were comparable to the Venus variety, averaging 21.3 kg (47 lb) per vine. Unlike Thompson Seedless, which has its cluster size thinned as a normal production practice, Thomcord's is not thinned because of its smaller cluster size. The grape clusters range in weight between 259 and 534 g (0.570997259058833 and 1.2 lb) and average 340 g (0.749571691428584 lb), have medium to slightly loose tightness (or are "well-filled", meaning the individual pedicel
s are not easily visible), and have a conical shape with a small wing.
Compared with Thompson Seedless, the berry weight and diameter of Thomcord are larger, but cluster tightness is similar. The berry length ranged between 18.2 and 18.3 mm (0.716535433070866 and 0.720472440944882 in) and the diameter ranged from 16.7 to 17.2 mm (0.65748031496063 to 0.677165354330709 in) in tests between 2001 and 2002. The berries weigh between 2.72 and 3.38 g (0.0959451769259045 and 0.119225991915278 oz), averaging 2.85 g (0.100530791999569 oz) in 2002, which is on par with Venus, but heavier than Sovereign Coronation, and even more so than Thompson Seedless. The fruit's size has not been shown to increase appreciably by girdling
the vines or by applying gibberellic acid
when the berries set.
The aborted seeds of Thomcord are small, but in some years they can become sclerified (a thickening and lignification
of the walls of plant cells and the subsequent dying off of the protoplast
s), making them more noticeable inside the medium-soft flesh. There are usually two aborted seeds per berry, which averaged between 14 and 22.3 mg in 2001 and 2002. This varied in comparison to Venus depending on the year and location, was comparable to the Sovereign Coronation, and was significantly smaller than the Sovereign Rose and Saturn varieties. However, as with the other cultivar
s, it was consistently larger than Thompson Seedless, which had the smallest aborted seeds.
(spaces between the lobes) of medium depth. The main vein is slightly longer than the petiole
(stalk attaching the leaf blade to the stem), and the petiole sinus opens widely. Between the veins on the underside of both the mature and young leaf there are dense hairs that lie flat against the surface. The teeth on the edge of the leaf blade are convex on both sides, medium in size, and short relative to their width. Young leaf blades are dark copper red on the upper surface.
The shoot
s have at least three consecutive tendril
s. Young shoots are fully open and have very dense hairs of medium anthocyanin
coloration that lie flat against the tip. The internode
of the young shoot is green with red stripes on the front (dorsal) side and solid green on the back (ventral) side.
s (removal of male flower parts to control pollination) of Thompson Seedless, the researchers produced 130 ovule
s using embryo rescue procedures. From these, 40 embryo
s developed and three seedling
s were planted. The original seedling of Thomcord was planted in 1984 in plots in cooperation with California State University, Fresno
. It was later selected in 1986 by Ramming and Tarailo and tested in the San Joaquin Valley under the name A29-67, and was introduced as "Thomcord."
The new hybrid was tested and scrutinized for 17 years before it was declared ready for growers and gardeners and was released on . Around 2008, trials outside of California were just beginning. Thomcord quickly became a hit at farmers' market
s while it was being tested, and it is expected to appear in the fresh-fruit section at supermarkets in the coming years. This continued the long-standing success of the ARS' grape-breeding research in California, which has developed some of the most popular seedless grapes on the market as well as red, white, and black grapes varieties for hobbyists and professional growers since 1923.
Although it has been called a "sentimental favorite" at farmers' markets, it is not expected to become a major commercial variety because its flavor is not as neutral as more popular grapes, such as Thompson Seedless, Crimson Seedless, or Flame Seedless. However, Ramming predicted that it would become a specialty item, much like the Muscat varieties
, due to its distinctive, Concord-like flavor. Because of its strong reception at farmers' markets, it could compete with Concord and Niabell varieties in eastern markets, according to Ramming.
indexed Thomcord and found it to be free of known viruses. The FPS offers certified virus-free propagation material. The FPS also deposited genetic material in the National Plant Germplasm System
, which offers material for research, including development and commercialization of new cultivars. The ARS does not offer Thomcord plants for distribution.
Thomcord is a public variety and is not restricted
in its propagation and distribution.
Seedless fruit
A seedless fruit is a fruit developed to possess no mature seeds. As consumption of seedless fruits is generally easier and more convenient, they are considered commercially valuable....
table grape
Table grape
Table grapes are grapes intended for consumption while they are fresh, as opposed to grapes grown for wine production, juice production, or for drying into raisins....
variety and a hybrid of the popular Thompson Seedless or Sultanina
Sultana (grape)
The sultana is a type of white, seedless grape assumed to originate from the Turkish, Greek, or Iranian area...
grape (a Vitis vinifera
Vitis vinifera
Vitis vinifera is a species of Vitis, native to the Mediterranean region, central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran....
variety) and Concord grape (a Vitis labrusca
Vitis labrusca
Vitis labrusca is a species of grapevines belonging to the Vitis genus in the flowering plant family Vitaceae. The vines are native to the eastern United States and are the source of many grape cultivars, including Catawba and Concord grapes, and many hybrid grape varieties such as Agawam,...
variety). Thomcord was developed in 1983 by Californian grape breeders working for the Agricultural Research Service
Agricultural Research Service
The Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...
(ARS), an agency of the United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
(USDA), as part of a test to better understand a new seedless grape breeding procedure.
Its aromatic, "labrusca
Vitis labrusca
Vitis labrusca is a species of grapevines belonging to the Vitis genus in the flowering plant family Vitaceae. The vines are native to the eastern United States and are the source of many grape cultivars, including Catawba and Concord grapes, and many hybrid grape varieties such as Agawam,...
" flavor is similar to that of Concord, but mellowed by the mild, sweet taste from Thompson Seedless. Thomcord grows well in hot, dry climates, ripens between late July and mid-August, and tolerates powdery mildew
Uncinula necator
Uncinula necator is a fungus that causes powdery mildew of grape. It is a common pathogen of Vitis species, including the wine grape, Vitis vinifera. The fungus is believed to have originated in North America. European varieties of Vitis vinifera are more or less susceptible to this fungus...
. It is a productive variety, yielding an average of 15.1 kg (33.3 lb) of grapes per vine, but has produced as much as 30 to 32 kg (66.1 to 70.5 lb) per vine in grower trials. The berries weigh between 2.72 and 3.38 g (0.0959451769259045 and 0.119225991915278 oz) and have a medium-thick, blue-black skin that adheres to the fruit, unlike Concord, which has a thick skin that can slip off the pulp easily. The aborted seeds
Seedless fruit
A seedless fruit is a fruit developed to possess no mature seeds. As consumption of seedless fruits is generally easier and more convenient, they are considered commercially valuable....
in the fruit body are relatively small, but larger than those in Thompson Seedless.
The plant is not restricted
Plant quarantine
Plant quarantine is a technique for insuring disease- and pest-free plants by isolating them during a period while performing tests for the presence of these problems....
for propagation and distribution. Virus-free propagation material is available from the Foundation Plant Services (FPS) at the University of California, Davis
University of California, Davis
The University of California, Davis is a public teaching and research university established in 1905 and located in Davis, California, USA. Spanning over , the campus is the largest within the University of California system and third largest by enrollment...
, and its genetic material is archived at the National Plant Germplasm System
National Plant Germplasm System
The U.S. National Plant Germplasm System is a cooperative effort by U.S. state and federal government and private organizations to preserve the genetic diversity of plants....
. After 17 years of testing, it was declared ready for use in 2003. It is expected to appear in supermarkets, possibly as a specialty item.
Description
Thomcord grape is a hybrid of Thompson Seedless grape (Vitis viniferaVitis vinifera
Vitis vinifera is a species of Vitis, native to the Mediterranean region, central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran....
, or Sultanina), which is popular in supermarkets during the summer, and seeded Concord grape (Vitis labrusca
Vitis labrusca
Vitis labrusca is a species of grapevines belonging to the Vitis genus in the flowering plant family Vitaceae. The vines are native to the eastern United States and are the source of many grape cultivars, including Catawba and Concord grapes, and many hybrid grape varieties such as Agawam,...
), commonly used to make grape juice and jelly. It is a plump, juicy, seedless table grape
Table grape
Table grapes are grapes intended for consumption while they are fresh, as opposed to grapes grown for wine production, juice production, or for drying into raisins....
and is slightly firmer than Concord. Thomcord has a blue-black skin with medium thickness and a whitish bloom. Unlike Concord, whose tough skin separates easily from the fruit, Thomcord has a more edible skin that clings to the flesh, much like Thompson Seedless. It has an aromatic flavor, similar to the Concord in taste ("labrusca
Vitis labrusca
Vitis labrusca is a species of grapevines belonging to the Vitis genus in the flowering plant family Vitaceae. The vines are native to the eastern United States and are the source of many grape cultivars, including Catawba and Concord grapes, and many hybrid grape varieties such as Agawam,...
"), though lighter due to the sweet, mild taste from Thompson Seedless.
Thomcord is suitable for hot, dry growing conditions, more so than Concord and other Concord seedless types. Its adaptability to hot dry climates was derived from Thompson Seedless. It grows well in California's vineyards, particularly the San Joaquin Valley
San Joaquin Valley
The San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...
, just like Thompson Seedless. The plant is tolerant of (but not resistant to) powdery mildew
Uncinula necator
Uncinula necator is a fungus that causes powdery mildew of grape. It is a common pathogen of Vitis species, including the wine grape, Vitis vinifera. The fungus is believed to have originated in North America. European varieties of Vitis vinifera are more or less susceptible to this fungus...
, and is less susceptible to the fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
than Ruby Seedless, but more susceptible than Mars, Venus, Niabell, and Cayuga White
Cayuga White
Cayuga White is a wine grape was developed from crosses of the hybrids Schuyler and Seyval Blanc done at Cornell University's New York State Agricultural Experiment Station in Geneva, New York. It is a hardy vine with some bunch-rot disease resistance. It should be picked at low sugars to avoid...
varieties. The fungus can affect its leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
, rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
(stem of the grape cluster), and berries
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
. The grape ripens in the summer (mid-season), between late July and mid-August.
| Color | Skin type | Seed type | Aborted seed size | Growing conditions | Flavor profile | |
|---|---|---|---|---|---|---|
| Thompson Seedless | White | Adhering, thin | Aborted | Very small | Hot, dry climate | Mild & sweet |
| Concord | Blue | Separable, thick & tough | Viable | High humidity | "Foxy" | |
| Thomcord | Blue-black | Adhering, medium thickness | Aborted | Small | Hot, dry climate | "labrusca", but mild & sweet |
Production details
Thomcord is a productive variety, with a yield comparable to Thompson Seedless. When two cordons (arms) of the vines are trained horizontally on wires ("bilateral-trained") and are pruned to remove most of the previous year's growth ("spur-pruned") during the winter, it can produce up to 13–16 kg (28.7–35.3 lb) per vine, or an average of 15.1 kg (33.3 lb). In 2002, cane-pruned vines of Thomcord were significantly more productive than Sovereign CoronationCoronation (grape)
Coronation grapes are a "virtually seedless" hybrid variety of table grape developed in Canada. Coronation grapes are popular throughout Canada, and are available during a short period in late summer and early fall...
and were comparable to the Venus variety, averaging 21.3 kg (47 lb) per vine. Unlike Thompson Seedless, which has its cluster size thinned as a normal production practice, Thomcord's is not thinned because of its smaller cluster size. The grape clusters range in weight between 259 and 534 g (0.570997259058833 and 1.2 lb) and average 340 g (0.749571691428584 lb), have medium to slightly loose tightness (or are "well-filled", meaning the individual pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
s are not easily visible), and have a conical shape with a small wing.
Compared with Thompson Seedless, the berry weight and diameter of Thomcord are larger, but cluster tightness is similar. The berry length ranged between 18.2 and 18.3 mm (0.716535433070866 and 0.720472440944882 in) and the diameter ranged from 16.7 to 17.2 mm (0.65748031496063 to 0.677165354330709 in) in tests between 2001 and 2002. The berries weigh between 2.72 and 3.38 g (0.0959451769259045 and 0.119225991915278 oz), averaging 2.85 g (0.100530791999569 oz) in 2002, which is on par with Venus, but heavier than Sovereign Coronation, and even more so than Thompson Seedless. The fruit's size has not been shown to increase appreciably by girdling
Girdling
Girdling, also called ring barking or ring-barking, is the complete removal of a strip of bark from around the entire circumference of either a branch or trunk of a woody plant. Girdling results in the death of wood tissues beyond the damage...
the vines or by applying gibberellic acid
Gibberellic acid
Gibberellic acid Gibberellic acid Gibberellic acid (also called Gibberellin A3, GA, and (GA3) is a hormone found in plants. Its chemical formula is C19H22O6. When purified, it is a white-to-pale-yellow solid....
when the berries set.
The aborted seeds of Thomcord are small, but in some years they can become sclerified (a thickening and lignification
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
of the walls of plant cells and the subsequent dying off of the protoplast
Protoplast
Protoplast, from the ancient Greek πρῶτον + verb πλάθω or πλάττω , initially referred to the first organized body of a species.Protoplast has several biological definitions:...
s), making them more noticeable inside the medium-soft flesh. There are usually two aborted seeds per berry, which averaged between 14 and 22.3 mg in 2001 and 2002. This varied in comparison to Venus depending on the year and location, was comparable to the Sovereign Coronation, and was significantly smaller than the Sovereign Rose and Saturn varieties. However, as with the other cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s, it was consistently larger than Thompson Seedless, which had the smallest aborted seeds.
Vegetative description
The mature leaves on the vine have three lobes with open upper lateral sinusesSinus (botany)
In botany, a sinus is a space or indentation, usually on a leaf, between two lobes or teeth that does not break the continuity of the structure....
(spaces between the lobes) of medium depth. The main vein is slightly longer than the petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
(stalk attaching the leaf blade to the stem), and the petiole sinus opens widely. Between the veins on the underside of both the mature and young leaf there are dense hairs that lie flat against the surface. The teeth on the edge of the leaf blade are convex on both sides, medium in size, and short relative to their width. Young leaf blades are dark copper red on the upper surface.
The shoot
Shoot
Shoots are new plant growth, they can include stems, flowering stems with flower buds, and leaves. The new growth from seed germination that grows upward is a shoot where leaves will develop...
s have at least three consecutive tendril
Tendril
In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support, attachment and cellular invasion by parasitic plants, generally by twining around suitable hosts. They do not have a lamina or blade, but they can photosynthesize...
s. Young shoots are fully open and have very dense hairs of medium anthocyanin
Anthocyanin
Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH...
coloration that lie flat against the tip. The internode
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
of the young shoot is green with red stripes on the front (dorsal) side and solid green on the back (ventral) side.
History
In 1983, research horticulturist David W. Ramming and technician Ronald L. Tarailo—Californian grape breeders working for the ARS, the chief scientific research agency of the USDA—crossed Thompson Seedless and Concord in order to answer a technical question about a newly developed procedure for breeding novel, superior seedless grapes. The researchers wanted to demonstrate that plants created from embryo culture were derived from fertilized eggs (zygotic) instead of the maternal tissue (somatic). From 1231 emasculationEmasculation
Emasculation is the removal of the genitalia of a male, notably the penis and/or the testicles.By extension, the word has also come to mean to render a male less of a man, or to make a male feel less of a man by humiliation. This metaphorical usage of the word is much more common than the...
s (removal of male flower parts to control pollination) of Thompson Seedless, the researchers produced 130 ovule
Ovule
Ovule means "small egg". In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center...
s using embryo rescue procedures. From these, 40 embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s developed and three seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...
s were planted. The original seedling of Thomcord was planted in 1984 in plots in cooperation with California State University, Fresno
California State University, Fresno
California State University, Fresno, often referred to as Fresno State University and synonymously known in athletics as Fresno State , is one of the leading campuses of the California State University system, located at the northeast edge of Fresno, California, USA.The campus sits at the foot of...
. It was later selected in 1986 by Ramming and Tarailo and tested in the San Joaquin Valley under the name A29-67, and was introduced as "Thomcord."
The new hybrid was tested and scrutinized for 17 years before it was declared ready for growers and gardeners and was released on . Around 2008, trials outside of California were just beginning. Thomcord quickly became a hit at farmers' market
Farmers' market
A farmers' market consists of individual vendors—mostly farmers—who set up booths, tables or stands, outdoors or indoors, to sell produce, meat products, fruits and sometimes prepared foods and beverages...
s while it was being tested, and it is expected to appear in the fresh-fruit section at supermarkets in the coming years. This continued the long-standing success of the ARS' grape-breeding research in California, which has developed some of the most popular seedless grapes on the market as well as red, white, and black grapes varieties for hobbyists and professional growers since 1923.
Although it has been called a "sentimental favorite" at farmers' markets, it is not expected to become a major commercial variety because its flavor is not as neutral as more popular grapes, such as Thompson Seedless, Crimson Seedless, or Flame Seedless. However, Ramming predicted that it would become a specialty item, much like the Muscat varieties
Muscat (grape and wine)
The Muscat variety of grapes of the species Vitis vinifera is widely grown for wine, raisins and table grapes. Their color ranges from white to near black. Muscat almost always has a pronounced sweet floral aroma. Muscat grapes are grown around the world...
, due to its distinctive, Concord-like flavor. Because of its strong reception at farmers' markets, it could compete with Concord and Niabell varieties in eastern markets, according to Ramming.
Availability
The Foundation Plant Services (FPS) at the University of California, DavisUniversity of California, Davis
The University of California, Davis is a public teaching and research university established in 1905 and located in Davis, California, USA. Spanning over , the campus is the largest within the University of California system and third largest by enrollment...
indexed Thomcord and found it to be free of known viruses. The FPS offers certified virus-free propagation material. The FPS also deposited genetic material in the National Plant Germplasm System
National Plant Germplasm System
The U.S. National Plant Germplasm System is a cooperative effort by U.S. state and federal government and private organizations to preserve the genetic diversity of plants....
, which offers material for research, including development and commercialization of new cultivars. The ARS does not offer Thomcord plants for distribution.
Thomcord is a public variety and is not restricted
Plant quarantine
Plant quarantine is a technique for insuring disease- and pest-free plants by isolating them during a period while performing tests for the presence of these problems....
in its propagation and distribution.