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WEED CONTROL > Identifing Weeds

Noxious weeds are present in the San Luis Valley in subdivisions on ranches, along roadways and waterways, in high mountains meadows, in center pivot corners, and on topsoil piles next to gravel pits. Wherever land is or has been disturbed noxious weeds are likely to appear. Weed seed is transported by water, birds, livestock, elk, deer, automobiles, and construction equipment. Some noxious weeds are very resilient and one treatment or one year's treatment will not eradicate them or control them.

Citizens Assistance
The best way to prevent weeds from spreading is to first recognize what species it is. There is a weed brochure available at your county conservation district (CD) office, and Cooperative Extension (CE) office in Del Norte. If you do not know what the plant is ask personnel at the CD office and or CE office. In the counties of Conejos, Rio Grande, Alamosa, Saguache you can talk with the County Weed Supervisors.

When you see land being disturbed, report this to your county weed supervisor. Make sure you give specific location information, so that the weed supervisor can make contact with the appropriate people.

Weed Images

Field Bindweed, Convolvulus arvensis, L. Creeping perennial

Biological Control: Grazing

Cultural Control: None available

Chemical Control:

Roundup Ultra: 4-5 qt/ac or 80 cc/gal water in fall prior to killing frost.
Weedmaster: 4-6 pt/ac or 30 cc/gal water at flowering stage.
Banvel: 2 qt/ac or 19 cc/gal water at early flowering stage.
Clarity: 2 qt/ac or 19 cc/gal water at early flowering stage.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal, water at flower.
2,4D (4# product): 4-6 pt/ac or 19-29 cc/gal water at flowering and repeat.

Integrated management: Grazing combined with chemical application and reseeding to competitive grasses will help control this weed species.

Canada Thistle, Cirsiu arvense, L. Creeping perennial

Biological Control: Weevils-LarinusPlanus, Ceutorhynchus litura; Beetle – Cassida rubiginosa; Gall fly – Urophora cardui.

Cultural Control: Mowing is effective if done once a month Prescribed burning in spring slows spread by reducing number of mature plants, decreasing seed production, and stimulating native grass growth.

Chemical Control: with good soil moisture and active plant growth.

Curtail: 2-3 qt/ac or 44-66 cc/gal. Water at rosette to bud.
Stinger: 1/3-2/3 pt/ac or 3.5-7.3 cc/gal water at rosette to bud.
Clarity: 2 qt/ac or 19 cc/gal water at rosette.
Roundup ultra: 2-3 qt/ac or 80 cc/gal of water at bud.
Redeem R&P: 3-4 pt/ac or 33-44 cc/gal water at rosette or fall regrowth.
2,4-D (4#product): 4-6 pt/ac or 19-29 cc/gal water at rosette.

Integrated Management: A combination of repeated mowing and chemical ap-plication before the first hard freeze in the fall.

Black Henbane, Hysoscymas niger, L. Biennial

Biological Control: None available

Cultural control: Mowing before seed production.

Chemical Control:

Banvel: 1 qt/ac or 10 cc/gal water at rosette.
Clarity: 1 qt/ac or 10 cc/gal water at bud.
2,4-D (4#product): 2-4 pt/ac or 10-19 cc/gal water at rosette.
Stinger: -1/2 pt/ac or 3-5.5 cc/gal water at 5 leaf stage or less.

Integrated Management: Chemical treatment and reseeding to grasses will control Black Henbane.

Hoary Cress, Short Whitetop, Cardaria drava L. Creeping perennial

Biological Control: Graze with sheep/goats.

Cultural Control: Mowing during bud stage in spring and continue when plants rebud. Planting competitive grass/.maintaining maximum native vegetation.

Chemical Control:

Weed Master: 4-6pt/ac or 30 cc/gal. Water at early bud stage.
Plateau: 8-12 oz/ac or 2.5-3.5 cc gal. Water at bud.
Roundup Ultra: 3 pt/ac or 15 cc/gal water at flower.
2,4-D Amine (4# product): 4-6 pt/ac or 19-29 cc/gal. water at bud growth stage and repeat on regrowth.

Integrated management: Mow 2-3 times at bud stage, apply chemicals in fall before first hard freeze and reseed to competitive grasses the next spring.

Houndstounge, Cynoglossum offcinale, L. Biennial

Biological Control: None available

Cultural control: Mowing second year plants during flowering.

Chemical control:

Banvel: 1 qt/ac or 10 cc/gal water rosette.
Clarity: 1 qt/ac or 10 cc/gal water at rosette.
2,4 – D (4# product): 2-4 pt/ac or 10-19 cc/gal water at rosette.
Stinger: 4-8 oz/ac or 3-5.4 cc/gal water at rosette.

Integrated management: Use a combination of mowing and chemical treatments for effective control.

Leafy Spurge, Euphorbia esula L. –Creeping perennial

Biological control: Flea beetles – aphthona nigricuitis, A. flaca, A.cyparissiae, A. czwalinae; Long horned beetle – Oberea erythrocephala; Gall midge – Spurgia esulae. Grazing with sheep and goats planned to maintain healthy native vegetation.

Cultural control: Prescribed burn in spring.

Chemical control:

Campaign: 40-54 oz/ac or 12-16 cc/gal water at bud. Banvel: 2 qt/ac or 19 cc/gal water at bud.
Clarity: 2 qt/ac or 19 cc/gal water at bud.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at late summer.

Integrated Management: Grazing/burning in spring, spraying, and planting w/mixture of early, mid & late season grasses with shallow, intermediate and deep roots.

Musk Thistle, Carduus nutans, L. Biennial

Biological control: Weevils-Rhinocyllus conicus, Trichosirocalus horridus

Cultural control: repeated mowing after flowering before seed sets.

Chemical control:

Weed master: 2 pt/.ac or 30 cc/gal water at rosette.
Campaign: 40-54 oz/ac or 12-16 cc/gal water at rosette.
Stinger: 4-8 oz/ac or 2.7-5.4 cc/gal water at rosette.
Banvel: 1-2 pt/ac or 5-10 cc/gal water at rosette.
Clarity: 1-2 qt./ac. Or 10-19 cc/gal. Water at bud.
Curtail: 2-3 qt/ac or 44-66 cc/gal water at rosette.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at rosette.
Redeem R& P: 16-24 oz/.ac or 17-22 cc/gal water at rosette.
2,4 –D (4# product): 2-4 pt/ac or 10-19 cc/gal water at rosette.

Integrated management: Use a combination of mowing and chemical treatments for effective control.

Russian Knapweed, Acroptilon repens L. Creeping perennial

Biological Control: Nematode – Subanguina picridis. Grazing with goats. Poisonous to horses.

Cultural control: Prescribed brning/mowing to remove old growth, mowing again prior to flower. Reseeding to competitive grass.

Chemical control:

Curtail: 3-4 qt/ac or 66-88 cc/gal of water at early bud or fall regrowth.
Redeem R&P: 3-4 pt/ac or 33-44 cc/gal water at bud or fall regrowth.
Clarity: 1-2 qt/ac or 10-19 cc/gal water at bud.
Banvel: 2 qt./ac. Or 19 cc/gal. Water at bud.
Roundup Ultra: 4 qt/ac or 80 cc/gal water at bud.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at fall regrowth.

Integrated Management: Prescribed burning/mowing/grazing with goats in spring, mowing/spraying at flower stage on regrowth, and spraying prior to first hard frost in fall. Reseed infested area to competitive grasses.

Tall Whitetop, Perennial Pepperweed, Lepidium latiflium L. Creeping perennial

Biological: Cattle, sheep and goat grazing of early spring growth and regrowth will significantly reduce density and seed production. Planned grazing facilitates the maintenance of grass health and vigor.

Cultural: Spring mowing and/or burning offers limited control,.
Chemical:

Campaign: 40-54 oz/ac or 12-16 cc/gal waer at early bud to flower.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water before bud.
Roundup Ultra: 3 pt/ac or 15 cc/gal water at bud or fall prior to first hard freeze.
2,4 –D (4# product): 4-6 pt/ac or 19-29 cc/gal water applied in early spring growth then followed by 4-6 pt/ac or 19-29 cc/gal water regrowth.

Integrated Management: Grazing spring growth, repeated mowing and fall chemical application, along with reseeding competitive grasses for the following spring, are the most effective ways to control Tall Whitetop.

Yellow Starthistle, Centaurea solstitalis L. Biennial

Biological control: Weevils – Eustenopus villosuis, Bangasternus orientalis. Cattle, sheep and goats will graze before spines appear. Poisonous to horses.

Cultural control: Mowing/burning at bud stage, tillage is effective combined with reseeding. Burning at early flower stage.

Chemical control:

Weed Master: 4-6 pt/ac or 30 cc/gal water at flower.
Roundup Ultra: 2 qt/ac or 80 cc/gal water at flower.
Campaign: 40-54 oz/ac or 12-16 cc/gal water at rosette.
Banvel: 1-2 pt/ac or 5-10 cc/.gal water at rosette.
Clarity: 8-32 oz/ac or 2.5-9.5 cc/gal water at rosette.
Curtail: 2-3 qt/ac or 44-66 cc/gal water at rosette.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at rosette.
Stinger: -1/2 pt/ac or 2.7-5.4 cc/gal water at rosette.
2,4 –D (4# product): 2-4 pt/ac or 10-19 cc/.gal water at rosette.
Redeem R&P: 1.5-2 pt/ac or 17-22 cc/gal water at rosette.

Integrated Management: Grazing/mowing/burning combined with chemical application and reseeding/maintaining native grasses.

Yellow Toadsflax, Linaria vulgaris, L. Creeping perennial

Biological Control: beetle – Brachypterolus pulicarius; Moth – Calophasia lunula

Cultural control: Repeated mowing before seed sets. In cropland, two years of intensive clean cultivation, 8-10 times the first year and 4-5 times the second year.

Chemical control:

Banvel: 1-2 pt/ac or 5-10 cc/gal water at flower.
Campaign: 40-54 oz/ac or 12-16 cc/gal water at flower.
Roundup Ultra: 2-3 pt/ac or 15 cc/gal water at flower.

Integrated Management: Mowing combined with chemical application.

WEED CONTROL > Identifing Weeds

When you see land being disturbed, report this to your county weed supervisor. Make sure you give specific location information, so that the weed supervisor can make contact with the appropriate people.

Weed Images

Field Bindweed, Convolvulus arvensis, L. Creeping perennial

Biological Control: Grazing

Cultural Control: None available

Chemical Control:

Integrated management: Grazing combined with chemical application and reseeding to competitive grasses will help control this weed species.

Canada Thistle, Cirsiu arvense, L. Creeping perennial

Biological Control: Weevils-LarinusPlanus, Ceutorhynchus litura; Beetle – Cassida rubiginosa; Gall fly – Urophora cardui.

Cultural Control: Mowing is effective if done once a month Prescribed burning in spring slows spread by reducing number of mature plants, decreasing seed production, and stimulating native grass growth.

Chemical Control: with good soil moisture and active plant growth.

Integrated Management: A combination of repeated mowing and chemical ap-plication before the first hard freeze in the fall.

Black Henbane, Hysoscymas niger, L. Biennial

Biological Control: None available

Cultural control: Mowing before seed production.

Chemical Control:

Banvel: 1 qt/ac or 10 cc/gal water at rosette. Clarity: 1 qt/ac or 10 cc/gal water at bud. 2,4-D (4#product): 2-4 pt/ac or 10-19 cc/gal water at rosette. Stinger: -1/2 pt/ac or 3-5.5 cc/gal water at 5 leaf stage or less.

Integrated Management: Chemical treatment and reseeding to grasses will control Black Henbane.

Hoary Cress, Short Whitetop, Cardaria drava L. Creeping perennial

Biological Control: Graze with sheep/goats.

Cultural Control: Mowing during bud stage in spring and continue when plants rebud. Planting competitive grass/.maintaining maximum native vegetation.

Chemical Control:

Weed Master: 4-6pt/ac or 30 cc/gal. Water at early bud stage. Plateau: 8-12 oz/ac or 2.5-3.5 cc gal. Water at bud. Roundup Ultra: 3 pt/ac or 15 cc/gal water at flower. 2,4-D Amine (4# product): 4-6 pt/ac or 19-29 cc/gal. water at bud growth stage and repeat on regrowth.

Integrated management: Mow 2-3 times at bud stage, apply chemicals in fall before first hard freeze and reseed to competitive grasses the next spring.

Houndstounge, Cynoglossum offcinale, L. Biennial

Biological Control: None available

Cultural control: Mowing second year plants during flowering.

Chemical control:

Banvel: 1 qt/ac or 10 cc/gal water rosette. Clarity: 1 qt/ac or 10 cc/gal water at rosette. 2,4 – D (4# product): 2-4 pt/ac or 10-19 cc/gal water at rosette. Stinger: 4-8 oz/ac or 3-5.4 cc/gal water at rosette.

Integrated management: Use a combination of mowing and chemical treatments for effective control.

Leafy Spurge, Euphorbia esula L. –Creeping perennial

Biological control: Flea beetles – aphthona nigricuitis, A. flaca, A.cyparissiae, A. czwalinae; Long horned beetle – Oberea erythrocephala; Gall midge – Spurgia esulae. Grazing with sheep and goats planned to maintain healthy native vegetation.

Cultural control: Prescribed burn in spring.

Chemical control:

Campaign: 40-54 oz/ac or 12-16 cc/gal water at bud. Banvel: 2 qt/ac or 19 cc/gal water at bud. Clarity: 2 qt/ac or 19 cc/gal water at bud. Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at late summer.

Integrated Management: Grazing/burning in spring, spraying, and planting w/mixture of early, mid & late season grasses with shallow, intermediate and deep roots.

Musk Thistle, Carduus nutans, L. Biennial

Biological control: Weevils-Rhinocyllus conicus, Trichosirocalus horridus

Cultural control: repeated mowing after flowering before seed sets.

Chemical control:

Integrated management: Use a combination of mowing and chemical treatments for effective control.

Russian Knapweed, Acroptilon repens L. Creeping perennial

Biological Control: Nematode – Subanguina picridis. Grazing with goats. Poisonous to horses.

Cultural control: Prescribed brning/mowing to remove old growth, mowing again prior to flower. Reseeding to competitive grass.

Chemical control:

Integrated Management: Prescribed burning/mowing/grazing with goats in spring, mowing/spraying at flower stage on regrowth, and spraying prior to first hard frost in fall. Reseed infested area to competitive grasses.

Tall Whitetop, Perennial Pepperweed, Lepidium latiflium L. Creeping perennial

Biological: Cattle, sheep and goat grazing of early spring growth and regrowth will significantly reduce density and seed production. Planned grazing facilitates the maintenance of grass health and vigor.

Cultural: Spring mowing and/or burning offers limited control,. Chemical:

Integrated Management: Grazing spring growth, repeated mowing and fall chemical application, along with reseeding competitive grasses for the following spring, are the most effective ways to control Tall Whitetop.

Yellow Starthistle, Centaurea solstitalis L. Biennial

Biological control: Weevils – Eustenopus villosuis, Bangasternus orientalis. Cattle, sheep and goats will graze before spines appear. Poisonous to horses.

Cultural control: Mowing/burning at bud stage, tillage is effective combined with reseeding. Burning at early flower stage.

Chemical control:

Integrated Management: Grazing/mowing/burning combined with chemical application and reseeding/maintaining native grasses.

Yellow Toadsflax, Linaria vulgaris, L. Creeping perennial

Biological Control: beetle – Brachypterolus pulicarius; Moth – Calophasia lunula

Cultural control: Repeated mowing before seed sets. In cropland, two years of intensive clean cultivation, 8-10 times the first year and 4-5 times the second year.

Chemical control:

Banvel: 1-2 pt/ac or 5-10 cc/gal water at flower. Campaign: 40-54 oz/ac or 12-16 cc/gal water at flower. Roundup Ultra: 2-3 pt/ac or 15 cc/gal water at flower.

Integrated Management: Mowing combined with chemical application.

Banvel: 1 qt/ac or 10 cc/gal water at rosette.
Clarity: 1 qt/ac or 10 cc/gal water at bud.
2,4-D (4#product): 2-4 pt/ac or 10-19 cc/gal water at rosette.
Stinger: -1/2 pt/ac or 3-5.5 cc/gal water at 5 leaf stage or less.

Weed Master: 4-6pt/ac or 30 cc/gal. Water at early bud stage.
Plateau: 8-12 oz/ac or 2.5-3.5 cc gal. Water at bud.
Roundup Ultra: 3 pt/ac or 15 cc/gal water at flower.
2,4-D Amine (4# product): 4-6 pt/ac or 19-29 cc/gal. water at bud growth stage and repeat on regrowth.

Banvel: 1 qt/ac or 10 cc/gal water rosette.
Clarity: 1 qt/ac or 10 cc/gal water at rosette.
2,4 – D (4# product): 2-4 pt/ac or 10-19 cc/gal water at rosette.
Stinger: 4-8 oz/ac or 3-5.4 cc/gal water at rosette.

Campaign: 40-54 oz/ac or 12-16 cc/gal water at bud. Banvel: 2 qt/ac or 19 cc/gal water at bud.
Clarity: 2 qt/ac or 19 cc/gal water at bud.
Plateau: 8-12 oz/ac or 2.5-3.5 cc/gal water at late summer.

Cultural: Spring mowing and/or burning offers limited control,.
Chemical:

Banvel: 1-2 pt/ac or 5-10 cc/gal water at flower.
Campaign: 40-54 oz/ac or 12-16 cc/gal water at flower.
Roundup Ultra: 2-3 pt/ac or 15 cc/gal water at flower.