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Buckwheat

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Summary

Common Name
Buckwheat (Bugg, pers. comm.).

Scientific Name
Fagopyrum esculentum Moench (Marks and Townsend, 1973) or also Fagopyrum sagittatum Gilib (Munz, 1973).

Cultivar
Old cultivars of buckwheat are 'Tempest' and 'Tokyo,' which are small seeded and mature during midseason. The large-seeded varieties 'Mancan' and 'Manor' are now prevalent, and mature similarly but have larger stems and leaves (Gubbels et al., 1990).

New large-seeded buckwheat varieties 'Mancan' and 'Manor' developed in Canada feature large leaves and stems and vigorous growth. Experiments are also being conducted using semi-dwarf types of buckwheat, for resistance to lodging (Gubbels and Campbell, 1986).

Seed Description
The seed of buckwheat is a three-sided achene that is smooth, shining, and 5 mm long (Munz, 1973).

Seedling Description
No information is available in this database on this topic.

Mature Plant Description
Buckwheat is a fast-growing, frost-sensitive dicotyledonous (broad-leafed) plant used as a summer green manure (Johnny's Selected Seeds, 1983).

Temperature
Buckwheat is very frost sensitive (Johnny's Selected Seeds, 1983; Pears et al., 1989; Gubbels et al., 1990), so sowing is governed by frosts (Pears et al., 1989). Seeding in Manitoba is delayed until early June (Gubbels et al., 1990).

Geographic Range
Buckwheat is subject to plant breakage and seed shattering due to high winds; wind also interferes with pollination by flying insects. However, benefits from windbreaks of corn were not consistent (Gubbels, 1985). Buckwheat is grown as an economic crop in the northern Great Plains and as a cover crop in much of the United States, including the northeastern U.S. and California. It has been regarded as a "poor man's crop" because it can do well on poor soil (Bugg, pers. comm.).

Water
Germination occurs about 4 days after seeding (Bugg, pers. comm.).

Nutrients
There is some evidence that buckwheat concentrates calcium and makes it more available to succeeding crops (Johnny's Selected Seeds, 1983).

Soil pH
Buckwheat apparently tolerates a wide range of soil pH (Bugg, pers. comm.).

Soil Type
This species will tolerate poor soils (Pears et al., 1989).

Shade Tolerance
Buckwheat appears intolerant of shade (Bugg and Dutcher, 1989).

Salinity Tolerance
No information is available on salinity tolerance of buckwheat.

Herbicide Sensitivity
No information is available on herbicide sensitivity of buckwheat.

Life Cycle
The following account is from Bugg (pers. comm.), except where otherwise noted. Buckwheat is a quick-germinating, warm season annual broadleafed plant. Germination occurs within 4 days after seeding, flowering occurs about 30 days after seeding, and insect visitation to the flowers is profuse. Seed maturation can occur about 14 days after flowering begins, and flowering may last 45 days or more (Bugg and Dutcher, 1989). Even with adequate soil moisture, the shallow-rooted buckwheat shows mid-day wilting if weather is warm. Insect visitation typically ceases when wilting occurs (Pellett, 1976). Recovery typically occurs at night, and insect visitation resumes the following morning.

Seeding Rate
Seeding rate is 60 lb/acre (Johnny's Selected Seeds, 1983), presumably for the older varieties. Gubbels and Campbell (1986) reported that seeding rates of 30-45 kg/ha for the new large-seeded varieties 'Mancan' and 'Manor' and semi-dwarf types of buckwheat led to near-maximum yields of seed. The usually-recommended seeding rate is 40-55 kg/ha.

Seeding Depth
Seed should be sown at a depth of about 0.5 inches (Bugg, pers. comm.).

Seeding Method
Broadcast seed and incorporate with light disking, or use a grain drill. Seed should be sown at a depth of 0.5 inches (Bugg, pers. comm.). Two crops of buckwheat can be grown successively, the second sown immediately after tilling in the first (Johnny's Selected Seeds, 1983).

Seeding Dates
Buckwheat is very sensitive to frost; therefore, seeding in Manitoba is delayed until early June (Gubbels et al., 1990). In Manitoba, seed production is greatest with early June seedings; delay leads to declining yield; infection by downy mildew was greater with delayed seedings of buckwheat (Gubbels et al., 1990).

Inoculation
Buckwheat is not a legume and requires no inoculation.

Seed Cost
No information is available in this database on this topic.

Seed Availability
Buckwheat is readily available from many seed dealers.

Days to Flowering
Buckwheat sown on May 7 entered flower on June 13 and was in full flower by June 20. The second crop of buckwheat was sown July 7, began flowering by July 29, and attained full flower during the first week of August. The third crop was sown August 5 and attained full flower during the last week of August (coastal Massachusetts) (Bugg and Ellis, 1990). In southern Georgia, buckwheat sown on July 3 and 4 had begun flowering by August 1, was in full flower by August 10, and continued flowering until at least September 29 (Bugg and Dutcher, 1989).

Days to Maturity
Old cultivars of buckwheat are 'Tempest' and 'Tokyo,' which are small seeded and mature during midseason. The large-seeded varieties 'Mancan' and 'Manor' are now prevalent and mature similarly but have larger stems and leaves (Gubbels et al., 1990). Maturation of some seeds occurs within about 50 days of sowing; some flowering can continue for an additional 70 days (Bugg, pers. comm.).

Seed Production
Buckwheat seed should be harvested at the time when flowering has almost ceased and 75% of the seed have turned brown (Gubbels and Campbell, 1985). This crop is subject to plant breakage and seed shattering due to high winds; wind also interferes with pollination by flying insects; however, benefits from windbreaks of corn were not consistent (Gubbels, 1985). Application of fungicide (metalaxyl, 25% wp) to control downy mildew (Peronospora ducometi) did not increase seed yield of buckwheat (Gubbels et al., 1990).

Seed Storage
No information is available in this database on this topic.

Growth Habit
Buckwheat normally shows an erect growth habit (Munz, 1973), but under some conditions may appear decumbent (Bugg,.pers. comm.).

Maximum Height
Maximum height attained was 0.50-0.55 m (19.7-21.7 inches) (Bugg and Ellis, 1990).

Root System
Buckwheat is termed a deep rooter by Pears et al. (1989), but this is apparently an error (Bugg, pers. obs.). Rooting system is superficial but does show a high root volume in the upper soil stratum (0.0-0.25 m in depth) (Bugg, pers. comm.).

The ability of buckwheat to acquire phosphorus was characterized by investigating P uptake, morphological features, and chemical changes in the rhizosphere. Root weight and length, and frequency of root hairs were higher when plants were grown under P-deficiency. P uptake rates were only moderate, concentrations of P in the shoot were high (1.8% of dry weight). Release of Mn from MnO2- and P from FePO4- and glucose-6-phosphate was not due to a buildup of organic acids in the rhizosphere, but P release was due to high activities of acid phosphatase for plants grown with low P. The following parameters in which buckwheat is outstanding were regarded as important for its P efficiency: (1) a finely divided root system of considerable length with a high ratio of root surface to root or shoot length; (2) a high storage capacity for inorganic P; (3) an increased release of protons and FePO4- or MnO2- solubilizing substances by P-deficient plants; (4) a favorable ratio of P uptake to root mass increase, especially at low P supply; and (5) a high acitivity of acid phosphatase in the rhizosphere and the capability to use P from organic sources. (Annan and Amberger, 1989).

Establishment
Buckwheat is fast growing (Johnny's Selected Seeds, 1983).

Maintenance
Growers observing the mid-day wilting of a buckwheat cover crop may be tempted to irrigate excessively. This should be avoided, because buckwheat actually needs little water (Cantisano, pers. comm.).

Mowing
No information is available in this database on this topic.

Incorporation
When used as a green manure, buckwheat is typically ploughed down after 7 to ten days of flowering (Bugg and Ellis, 1990), or before seed is set (Johnny's Selected Seeds, 1983.). Residue breaks down rapidly after incorporation (Johnny's Selected Seeds, 1983).

Harvesting
No information is available in this database on this topic.

Equipment
No information is available in this database on this topic.

Uses
Buckwheat is a fast-growing, frost-sensitive dicotyledonous (broad-leafed) plant used as a summer green manure, and it is sometimes grown immediately after an area is cleared for agriculture (Johnny's Selected Seeds, 1983.). Fast-growing annuals such as buckwheat or oat may be used during the growing season to prepare for transplants or to protect soil during short periods when it would otherwise be bare (Gershuny and Smillie, 1986).

According to Schonbeck (1988), in the Northeast, buckwheat is commonly used for summer cover and weed control; buckwheat was used for weed control by 16 of 51 farms using cover crops in the Northeast. Buckwheat can also be used to make P and other nutrients more available and to improve soil structure. Buckwheat crops or residues can inhibit weed germination, and several growers and researchers suspect that allelopathy may be involved. Decomposing buckwheat roots can inhibit weed germination, and a buckwheat intercrop can save weeding in squash. Some growers have reported inadequate control of quackgrass and other stubborn weeds by buckwheat. Buckwheat produces much less biomass than do other summer cover crops, such as sudangrass (Schonbeck, 1988).

Mixtures
Buckwheat can grow in mixture with cowpea and sesbania (Bugg, pers. comm.).

Biomass
Buckwheat produces much less biomass than do other summer cover crops such as sudangrass (Schonbeck, 1988).

N Contribution
Buckwheat is not a legume makes no net contribution of N (Bugg, pers comm.).

Non-N Nutrient Contribution
Buckwheat can be used to make P and other nutrients more available (Schonbeck, 1988).

The ability of buckwheat to acquire phosphorus was characterized by investigating P uptake, morphological features, and chemical changes in the rhizosphere. Root weight and length, and frequency of root hairs were higher when plants were grown under P-deficiency. P uptake rates were only moderate and concentrations of P in the shoot were high (1.8% of dry weight). Release of Mn from MnO2- and P from FePO4- and glucose-6-phosphate were not due to a buildup of organic acids in the rhizosphere, but P release was due to high activities of acid phosphatase for plants grown with low P. The following parameters in which buckwheat is outstanding were regarded as important for its P efficiency: (1) a finely divided root system of considerable length, with a high ratio of root surface to root or shoot length; (2) a high storage capacity for inorganic P; (3) an increased release of protons and FePO4- or MnO2- solubilizing substances by P-deficient plants; (4) a favorable ratio of P uptake to root mass increase, especially at low P supply; and (5) a high acitivity of acid phosphatase in the rhizosphere and the capability to use P from organic sources (Annan and Amberger, 1989).

Effects on Water
No information is available in this database on this topic.

Effects on Microclimate
No information is available in this database on this topic.

Effects on Soil
Buckwheat can be used to improve soil structure (Schonbeck, 1988) and to enhance soil life (Johnny's Selected Seeds, 1983).

Effects on Livestock
No information is available in this database on this topic.

Effects on Workers
No information is available in this database on this topic.

Pest Effects, Insects
Flowers are attractive to hoverflies (Syrphidae) (Pears et al., 1989): in southern Georgia, Bugg and Dutcher (1989) found adults of the following hoverfly (Syrphidae) species visiting buckwheat flowers: Allograpta obliqua (Say), Pseudodoros clavatus (Fabricius), Ocyptamus fuscipennis (Say), Ocyptamus costatus (Say), Toxomerus boscii Macquart, and Toxomerus marginatus (Say); these are aphid predators as larvae. The following predatory wasps were also observed feeding at the flowers, family and genus or species are given, with known prey items in parentheses: Sphecidae: Ammophila sp. (lepidopterous larvae), Bicyrtes quadrifasciatus (Say) (Hemiptera), Cerceris sp. (Coleoptera), Isodontia apicalis (Smith) (Orthoptera: mainly Gryllidae and Tettigoniidae), Philanthus gibbosus (Fabricius) (Hymenoptera: Mainly Apoidea), Prionyx parkeri Bohart and Menke (Orthoptera: Acrididae, Pseudoplisus phaleratus (Say) (Homoptera?), Synnevrus plagiatus (Cresson) (Unknown), Tachytes guatemalensis Cameron (Orthoptera: Acrididae); Eumenidae: Zethus spinipes variegatus Saussure, Rhyacionia frustrana (Comstock), Nantucket pine tip moth (Lepidoptera: Tortricidae), Stenodynerus sp. (lepidopterous or coleopterous larvae), Vespidae: Polistes exclamans Vier. (Mainly lepidopterous larvae). Also observed were two species of Scoliidae, parasites of Scarabaeidae (Coleoptera), were also observed: Scolia dubia dubia Say and Scolia (Scolia) nobilitata nobilitata Fab.

In Massachusetts, Bugg and Ellis (1990) assessed insects associated with buckwheat and four other cover crops: (1) hairy vetch/cereal rye, (2) sorghum, (3) annual white sweetclover, and (4) bell bean. Those workers observed 2 types of Tachinidae at the flowers: Trichopoda pennipes (F.) (a parasite of true bugs) and an unidentified species near Archytas (a parasite of caterpillars). Adults of the following aphidophagous syrphids were also seen: Allograpta obliqua (Say), Sphaerophoria spp., Syrphus spp., Toxomerus spp.; and the following non-aphidophagous syrphids Eristalis tenax (L.) and Eristalis spp.). The following species of predatory wasps also fed at the flowers (family and genus or species are given, with known prey items in parentheses): Sphecidae: Sphex ichneumoneus (L.) (Orthoptera: Gryllidae; Gryllacrididae; Tettigoniidae), Cerceris fumipennis Say (Coleoptera), Cerceris sp. (Coleoptera), Eremnophila aureonotata (Cameron) (Lepidoptera: Notodontidae), Isodontia harrisi (Fernald) (Orthoptera), Tachytes pennsylvanicus Banks (Orthoptera), Philanthus gibbosus (Fabricius) (Hymenoptera: Mainly Apoidea), Philanthus lepidus Cresson (Hymenoptera: Mainly Apoidea), Ectemnius lapidarius (Panzer) (Adult Diptera), Oxybelus uniglumis (L.) (Adult Diptera), Bicyrtes quadrifasciata (Say) (Nymphal Hemiptera: mainly Pentatomidae and Coreidae); Eumenidae: Eumenes fraternus Say (lepidopteran larvae), Monobia quadridens (L.) (lepidopteran larvae), Ancistrocerus antilope (Panzer) (lepidopteran larvae); Vespidae: Polistes fuscatus pallipes Lepeletier (mainly lepidopteran larvae), Vespula maculata (L.); Pompilidae: 2 unidentified spp. (Araneae). No Ichneumonoidea were observed imbibing at the flowers of white sweetclover, and few were observed at blooms of buckwheat. This is consistent with observations by Ozols (1964). Insidious flower bug (Orius insidiosus), a beneficial predator, and tarnished plant bug (Lygus lineolaris), a pest, were relatively abundant on buckwheat on several sampling dates. Also abundant were adult aphidophagous Syrphidae and pooled adult Sphecidae (predatory wasps).

Bugg and Ellis (1990) noted that insect visitation to buckwheat was low during afternoons, whereas insects continued to visit white sweetclover. This is consistent with Pellett's (1976) statement that buckwheat often stops producing nectar during the afternoon.

Pest Effects, Nematodes
Buckwheat harbored particularly high densities of root lesion nematode (Pratylynchus penetrans) (Marks and Townsend, 1973).

Pest Effects, Diseases
Infection by downy mildew (Peronospora ducometi) was greater with delayed seedings of buckwheat. Application of fungicide (metalaxyl, 25% wp) to control this pathogen did not increase seed yield of buckwheat (Gubbels et al., 1990).

Pest Effects, Weeds
Buckwheat is grown for weed suppression (Johnny's Selected Seeds, 1983).

As reported by Schonbeck (1988), in the Northeast, buckwheat is commonly used for summer cover and weed control; some growers use sudangrass or millet. Buckwheat was used for weed weed control by 16 of 51 farms using cover crops in the Northeast. This crops or its residues can inhibit weed germination, and several growers and researchers suspect that allelopathy may be involved. Decomposing buckwheat roots can inhibit weed germination, and a buckwheat intercrop can save weeding in squash. Some growers have reported inadequate control of quackgrass and other stubborn weeds by buckwheat.

Of 8 warm-season cover crops assessed in a pecan orchard in southern Georgia, cowpea, alyceclover, and a sorghum-sudangrass hybrid reduced weed vegetational cover better than did buckwheat (Bugg and Dutcher, 1989).

Pest Effects, Vertebrates
No information is available in this database on this topic.

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