Prepared: August, 2000
Revised: September, 2003
Avena sativa L. (Poaceae)
| 1997 | 1998 | 1999 | 2000 | 2001 | |
| Acres in Colorado: | 25,000 | 25,000 | 20,000 | 35,000 | 32,000 |
| Percent U.S. Acreage: | 0.9% | 0.9% | 0.8% | 1.5% | 1.7% |
| National Ranking: | 20th | 19th | 24th | 15th | 18th |
| Per Acre Value: | $54.40 | $119.00 | $104.00 | $119.71 | $126.00 |
| Value of Production in Colorado: | $3,808,000 | $2,975,000 | $2,080,000 | $4,190,000 | $4,032,000 |
Data from 1997-2001 Colorado Agricultural Statistics Services
Description of Crop
Oat is an annual grain crop used for seed production, livestock feed, breakfast cereals, oatmeal, flour, cosmetics, and as a cover crop for alfalfa.
Cropping System
Oats grow best in the cooler regions of Colorado, such as the San Luis Valley, but can be grown in warmer areas if irrigation is available. It is a spring seeded crop, and should be planted as early as possible. In southeastern Colorado, oats should be planted by March 1, northeastern Colorado planting should be by March 15, and oats should be planted after April 1 in the San Luis Valley. The optimal soil temperature for planting is 40 F. Seed should be placed 1 - 2" into the soil. Some growers use 6" row widths, while others use 10 - 14" row widths.
Conventional tillage is used. Oats are mostly furrow irrigated, but some pivot irrigation and dryland production does occur.
Oats that are being planted as a cover crop for alfalfa are planted at 20 - 30 lb of seed per acre, whereas oats for grain production are planted at a density of 100,000 plants per acre.
The fertilizer requirement for oats is one pound of nitrogen per bushel of grain. Fertilizer is usually applied pre plant or prior to boot stage. Manure is also used. Too much nitrogen can cause severe lodging.
Oat hay is harvested in late June. Oat grains are harvested in late July to August. In the San Luis Valley, oat hay is harvested in late July to August and grain crops are harvested from early August to early September. When the grain crop is harvested, it is usually swathed first, then combined. However, if the crop is free of weeds, the standing crop can be directly combined.
Store oat hay at 13% moisture.
Location of Production
Northwest
Boulder, Larimer, Moffat, Routt
Northeast
Adams, Kit Carson, Logan, Morgan, Phillips, Sedgwick, Weld, Washington, Yuma
Southeast
Baca, Bent, Cheyenne, Crowley, Elbert, El Paso, Las Animas, Otero, Prowers, Pueblo
Southwest
Alamosa, Consejos, Costilla, Delta, Dolores, Douglas, Garfield, La Plata, Mesa, Montezuma, Montrose, Ouray, Rio Grande, Saguache, San Miguel
Note: Shaded boxes indicate counties where the crop is grown. Regions have been delineated by Interstates I-70 and I-25.
Bird Cherry Oat Aphid, Rhopalosiphum padi
Bird cherry oat aphids are olive-green with a reddish-orange area on their rear end. They are medium sized aphids, 0.05 - 0.10" with long antennae, long dark tube-shaped cornicles, and dark colored legs. The aphids feed on wheat by sucking plant sap. Bird cherry oat aphids vector barley yellow dwarf virus.
Russian Wheat Aphid, Diuraphis noxia
Russian wheat aphid (RWA) is one of the most destructive insect pest in Colorado. RWA damages small grains by injecting saliva into and sucking sap from plants. Yield losses due to Russian wheat aphid damage are 50% or more if economic infestations are left untreated. RWA are yellow-green or gray-green and are often covered with wax. RWA are small, less than 0.09" in length, and are convex and elongate. The two forms of RWA are found in Colorado during the year are wingless and winged females. In Colorado, most severe spring infestations are caused by wingless aphids. Winged aphids begin to appear in Colorado in April and May and flights peak in July. At this time winged aphids include both local aphids and immigrants from the south. Winged aphids infest late maturing winter wheat and spring grains. Grasses serve as alternate hosts for RWA during the period between grain harvest. Weather conditions that favor cool season grasses and volunteers will increase the number of aphid infestations. Aphid feeding prevents young leaves from unrolling. RWA colonies are found within the tubes formed by these tightly curled leaves. This not only makes it difficult to achieve good insecticide coverage, but also interferes with the ability of predaceous and parasitic insects to reach and attack aphids. Leaves infested by RWA have long white, purple or yellowish streaks. Heavily infested plants are stunted and some may appear prostrate or flattened.
Additional Insects
Army Cutworm, Euxoa auxiliaris
Army cutworm is one of several species of caterpillars that attack small grains in Colorado. Adult moths are brown with light brown or black markings on the forewings and have a wingspan of about 2". Larvae vary in color from dull green to brown with faint stripes on the back and have brown heads. Army cutworms produce one generation per year. Eggs hatch in the fall with sufficient moisture. Army cutworm larvae spend the winter as partially grown caterpillars. They feed only on warm days in the winter; feeding is more frequent in the spring. Army cutworms alway feed above ground during the night and/or on cloudy days. They are found under soil clods and other debris during the day. Cutworm larvae build small pupation chambers several inches below the soil surface. Moths emerge in May and June and migrate to higher elevations in the Rocky Mountains to escape high summertime temperatures. In late summer and early fall the moths return to the plains to lay their eggs in wheat fields and in other cultivated areas. With adequate moisture, eggs hatch and larvae of the next generation begin feeding as weather conditions permit. Army cutworm caterpillars feed on plant foliage. Their feeding has the most effect on yield when there is relatively little foliage for them to feed on, which increases the likelihood of damage to the crown.
Armyworm, Pseudaletia unipuncta
In Colorado, the armyworm is mainly a pest of spring grains. Armyworms occur in eastern Colorado and in the San Luis Valley. Mature larvae are about 1.5" long, smooth-bodied, and dark gray to greenish-black. They are characterized by five stripes running the length of the body, three on the back and two on the sides. Stripes on the back vary in color, whereas the stripes on the sides are pale orange with a white outline. The head capsule is remarkable for its "honeycomb" of black markings. The armyworm is unable to survive Colorado winters. Instead, armyworm moths migrate into Colorado in early summer. They lay their eggs in rows or clusters on the lower leaves of various grass crops. Dense grassy vegetation is preferred for oviposition. Newly hatched larvae move with a looping (inchworm) action. Larvae feed at night and on cloudy days, and hide under crop debris during sunny periods. One or more generations may occur each year. Armyworms feed on leaves, kernels, and beards of small grain heads. Their most obvious damage to small grains is by clipping the heads.
Banks Grass Mite, Oligonychus pratensis
Banks grass mite is an important pest of oats in Colorado. Mites are microscopic arthropods that feed on the sap of host plants. They have eight legs (six in the first stage). Banks grass mites are extremely small, 0.001", and yellow to cream colored. Heavy populations of Banks grass mite can kill small plants and reduce kernel size in larger plants. They produce heavy webbing to protect colonies consisting of eggs, larvae and adults. Damaged leaves first become yellow, then brown and finally necrotic. The overwintering form of the mite is bright orange. With the onset of winter, the mites move to wheat plant crowns where they feed until spring when they travel to corn plants either by walking short distances or by "ballooning" - becoming windborne on web spun silk threads over longer distances. Small pearly white eggs are laid which eventually give rise to pale to bright green male and female adults. Banks grass mites are most likely to infest water- stressed plants, so irrigation can be an important cultural control mechanism. Factors that encourage Banks grass mite infestations include host drought stress, high temperatures, low rainfall, low humidity, absence of two-spotted spider mites (Tetranychus urticae), lack of natural enemies, insecticide use on other target pests, and adequate moisture for alternate hosts during the previous growing season. Most Banks grass mite problems occur in the drier growing areas of Colorado and are always associated with grasses.
Brown Wheat Mite, Petrobia latens
Brown wheat mite is an important pest of small grains - namely oats - in Colorado. Mites are microscopic arthropods that feed on the sap of host plants. They have eight legs (six in the first stage). Brown wheat mites are about 0.025" long, oval shaped and dark red or brown. They spend the summer in the soil as white eggs resisting hot, dry conditions. In the fall, as temperature and moisture increase, eggs develop and hatch after 10 days of incubation. Females follow in about two weeks. These females lay round, red eggs which give rise to further fall (1 or 2) and spring (2 or 3) generations. As summer conditions return, a generation of females is produced which lay only white, over-summering eggs. Both egg types are placed in the soil near the plant base. Brown wheat mites feed during the day and spend the night in the soil. Their activity peaks at about mid-afternoon on warm, calm days. This mite is not affected by cold temperatures, but populations are quickly reduced by driving rains of 0.33" or more.
English Grain Aphid, Sitobion avenae
English grain aphids are yellow green to reddish brown, medium sized aphid with antennae greater than half the body length. Their cornicles are medium sized and black. Antennae and leg joints are dark colored. This aphid overwinters mainly in the mature and nymphal stages, but a few individuals may overwinter in the egg stage. Only females overwinter, and with warm spring temperatures they begin giving birth to live young. Males appear during the fall and mate with true females. English grain aphid colonies often develop on leaves and then move to heads in the boot stage. Aphids may cluster around the bracts of wheat heads or other grains. Wheat kernals may shrivel as a result of aphid feeding. This aphid is a vector of barley yellow dwarf virus.
Grasshoppers
Grasshoppers follow roughly a 22-year cycle in Colorado, with the last major outbreak occurring in the late 1970s and early 1980s. Grasshoppers vary considerably depending on the species. Grasshopper nymphs have a similar appearance to adults but are smaller in size. Grasshoppers lay eggs in undisturbed areas, usually in late summer and early fall. Small nymphs or "hoppers" hatch the following spring. Winged adults will appear 5 - 6 weeks after hatch. A few Colorado grasshopper species have eggs that hatch in late summer and overwinter as nymphs. Winged adults of these species usually appear early in the following summer, often causing undue alarm about unusually early grasshopper activity. Some of these species are important on rangeland, but none are considered a threat to field crops. The usual pattern of grasshopper damage in field crops is for early development to occur in weedy areas of roadsides, fence rows, irrigation ditches, and other non-crop areas. As these food sources are exhausted or begin to dry down, the grasshoppers leave in search of other food - often an irrigated crop. Here they will first feed in the field margins and subsequently spread throughout the field. Most field crop damage is caused by the differential, red-legged, two-striped, and migratory grasshoppers.
Greenbugs, Schizaphis graminum
Greenbugs are light green aphids; their legs are also green, but their feet are black. The cornicles (small pipes near the rear end) are green with black tips. Adult aphids have a dark green stripe down the back and may be winged or wingless. All wingless greenbugs are female and they give birth to females. During the summer, females begin to reproduce within a week and may produce as many as 80 female offspring during their 25 day adult life span. Generally, greenbugs are found in colonies on the underside of the lower leaves. They may also be found in the whorl of the plant until the head emerges. Greenbugs migrate north from Texas and Oklahoma on weather fronts. This migration generally occurs in late May or early June but usually does not reach economic levels until late June or July. In the process of feeding, greenbugs inject toxins into the plant, which apparently break down cell walls to facilitate their feeding. The toxins cause a red leaf discoloration which, in conjunction with cell content removal, will cause leaf death if enough greenbugs are feeding. Greenbug frass, called honeydew, remains on the leaves, interfering with leaf transpiration, and further affecting plants.
Key Insect Management Strategies
Cultural Controls
Accurate timing and application of irrigation water, in addition to accurately timed planting will reduce pest pressures on the oat crop.
Insecticides-
Pesticide: Bacillus thuringiensis (DiPel ES)
Pesticide: carbofuran (Furadan 4F)
Pesticide: endosulfan (Endosulfan 50WP, Endosulfan 50WPS)
Pesticide: malathion (Malathion 5EC);
Pesticide: methyl parathion (Penncap-M)
Key Weeds
Common Lambsquarters, Chenopodium album
Common Lambsquarters, a member of the Goosefoot family, was introduced from Europe. It reproduces by seed. The stem is erect, stout, smooth, grooved, often striped with pink or purple, branched and grows 1 - 6' high. Lower leaves are alternate and ovate. Upper leaves are also alternate, but are more narrow. The flowers are small, green, and crowded in the axils and at the tips of the stems and branches. Common lambsquarters is a succulent, fast growing plant which rapidly removes moisture from the soil.
Kochia, Kochia scoparia
Kochia, a member of the Goosefoot family, is native of Eurasia. It is an annual, reproducing solely by seed. It is on the Colorado noxious weed list. Flowering season is from July to October. Stems are erect, round, slender, pale green, branched, and 1 - 6' tall. Leaves are narrow, bright green, hairy, numerous and are attached directly to the stem. Upper leaves are more narrow than lower leaves. Flowers are inconspicuous in the upper leaf axils. Seed are about 0.063" long, wedge-shaped, dull brown, and slightly ribbed. Kochia can be found throughout Colorado up to 8,500' in elevation. It has become a major problem on roadsides, waste areas, and non-cultivated fields. In the fall, plants become red, later turning brown and breaking away from the root, causing them to tumble over the ground scattering large amounts of seed. Many kochia populations in Colorado are resistant to sulfonylurea, imidazilinone, triazine and benzoic acid herbicides, representing three very different modes of action. Therefore, care should be taken when using herbicides to control kochia. Some alternative herbicides include: fluroxypyr, bromoxynil, MCPA ester, isoxaflutole, pyridate, flufenacet, fomesafen, glyphosate, lactofen and clomazone. It is important to rotate herbicide modes of action to prevent future cases of herbicide resistance.
Russian Thistle, Salsola iberica and S. collina
Russian thistle, a member of the Goosefoot family, was introduced from Russia. It is an annual and reproduces by seed. It is on the Colorado noxious weed list. It is a round, bushy, branched plant growing 1 - 3.5' high. The branches are slender, succulent when young, and woody when mature. The first leaves to develop are alternate, dark green, soft, slender, and 1 - 2.5" long. These senesce early and new leaves form which are alternate, short, stiff, spiny, and not over 0.5" long, with two sharp-pointed bracts at the base. The flowers are small, inconspicuous, green-white or pink, and are usually solitary in the leaf axils. Seed are conical and 0.063" in diameter. Russian thistle grows in dry plains, cultivated fields, roadsides, and waste areas, primarily in grain-growing areas of the state. At maturity, the plant breaks off at the base. Its round shape allows it to tumble, scattering seed for long distances. It is widespread over Colorado in elevations up to 8,500'.
Sunflower, Helianthus annuus
Sunflower, a member of the Sunflower family, is a native weed. It is an annual, 1 - 10' tall. Stems are erect, simple to branched and rough. Leaves are alternate, simple, rough, and hairy. Ray flowers are yellow to orange-yellow and disk flowers are brown. Flowering is from July to September. Seed are the only source of reproduction.
Wild Buckwheat, Polygonum convolvulus
Wild Buckwheat, a member of the Buckwheat family, is an annual weed with arrowhead shaped leaves. It has trailing stems that wind around other plants and is often mistaken for field bindweed. Its leaves are heart shaped, alternate and more pointed than those of field bindweed. The leaves have an inconspicious papery sheath that encircles the stem at the base of each petiole. Stems can be 8 - 40" long. In contrast to field bindweed, wild buckwheat has small, green flowers in the leaf axils. Seed are triangular, black and slightly roughened. Seed are the sole source of reproduction.
Additional Weeds
Canada Thistle, Cirsium arvense
Canada Thistle, a member of the Sunflower family, was introduced from Europe. Canada thistle is on the Colorado noxious weed list as well as marked as one of the top ten most widespread weeds causing the greatest economic impact to the State of Colorado. It is a creeping perennial which reproduces by seed and fleshy, horizontal roots. Stems are erect, hollow, smooth and slightly hairy, 1 - 5' tall, simple, and branched at the top. The leaves are set close on the stem, slightly clasping, and dark green. Leaf shape varies widely from oblong to lance-shaped. There are numerous sharp spines on the outer edges of the leaves, branches and main stem. The flowers are small and compact, about 0.75" or less in diameter, and light pink to rose-purple in color, occasionally white. The seed are oblong, flattened, dark brown, and approximately 0.125" long. Canada thistle emerges in April or May in most parts of Colorado. It is one of the most widespread and economically damaging noxious weeds in Colorado. Infestations are found in cultivated fields, riparian areas, pastures, rangeland, forests, lawns, gardens, roadsides, and waste areas. Because of its seeding habits, vigorous growth, and extensive underground root system, control or eradication is difficult. It is distributed across Colorado in elevations ranging from 4,000 - 9,500'.
Pigweeds, Amaranthus spp.
Pigweeds, members of the Amaranth family, are weed pests in several cropping systems. A. hybridus, smooth pigweed, was the first triazine resistant plant documented. A. retroflexus, redroot pigweed is probably Colorado's most common species. A. lividus, is a prostrate species with a notch in the tip of the leaf. A. spinosus, spiny amaranth, has sharp, stron spines on the stem. A. graecizans, breaks off at the ground line and being round shaped is blown around by the wind. Redroot pigweed is ALS herbicide resistant.
Quackgrass, Elytrigia repens
Quackgrass, a member of the Grass family, is an aggressive perennial reproducing by seed or spreading by a shallow mass of long, slender, branching rhizomes. Quackgrass is on the Colorado noxious weed list. Rhizomes are usually yellowish-white, sharp-pointed, somewhat fleshy. These rhizomes are effectively spread by tillage, increasing the distribution of the population in a field. They are able to penetrate hard soil or even tubers and roots of other plants. Stems are erect and usually 1 - 3' tall. Leaf blades are 0.25 - 0.5" wide, flat pointed and have small auricles at the junction of blade and sheath. Leaf sheaths and upper leaf blade surfaces are thinly covered with soft hairs. Spikelets are arranged in two long rows, flatwise to the stem. Florets are either awnless or have short, straight awns. Tillage is an effective control by depleting food reserves and bringing rhizomes to the surface.
Tansy Mustard, Descurania pinnata
Tansy Mustard, a member of the Mustard family, is a native winter annual, 4 - 32" tall. The plant is covered with fine hairs. The stem is erect, branched and 4 - 30" high. The flowers are small, pale yellow, and occur in small clusters at the tips of elongating racemes. Leaves are alternate and pinnately dissected, 2 - 4" long. Tansy mustard has stellate pubescence and racemic inflorescences. Petals are yellow, yellowish-green to cream. Pods are linear with two rows of seed in each seed pod. Tansy mustard spreads by seed from early to late summer. It is dispersed throughout Colorado up to 8,000' in elevation.
Wild Oats, Avena fatua
Wild Oats, a member of the Grass family, is an annual weed, 1- 4' tall with erect, hollow stems. Although oats are grown in Colorado as a crop, the wild species is very different and is on the Colorado noxious weed list. Leaf blades are 0.125 - 0.625" wide with open sheaths and membranous ligules. Seedling leaves twist counterclockwise. The inflorescence is an open panicle, 4 - 18" long, drooping, spikelets contain 2 - 3 florets which disarticulate above the glumes. Seed are yellow to black, narrowly oval, 0.25 - 0.5" long. This species is distinguished from domestic oats by the twisted awn which bends at right angles and a horseshoe shaped scar at it seed base.
Key Weed Management Strategies
Herbicides-
Pesticide: 2,4-D (Weedar 64)
Pesticide: bromoxynil (Buctril)
Pesticide: bromoxynil + MCPA (Bronate)
Pesticide: dicamba (Clarity)
Pesticide: glyphosate + 2,4-D (RT Master)
Pesticide: MCPA (Rhomene; Amine; Rhonox LVE)
Pesticide: picloram (Tordon 22K)
Pesticide: thifensulfuron + tribenuron (Harmony Extra)
Critical Pest Management Issues
Weed control is an important consideration when planting oats. Winter annuals can be a problem, but can be eliminated by planting at the proper time, and with proper management and pre-plant weed control. Weed problems are also dependent upon the field's weed history. Using oats as a cover crop for alfalfa limits herbicide use.
Oats are sensitive to injury from herbicides. Applications must be made early when weeds are small and oats are in the 5-leaf stage to reduce negative effects on the oats. Late summer or early fall herbicide application on stubble is an effective control of annual or perennial weeds after harvest.
Insect and disease problems are not as prevalent as weed problems. Insecticides such as carbofuran and methyl parathion control aphids which transmit many disease problems. Seed treatment fungicides such as captan, carboxin, and mancozeb are primarily used to control diseases problems.
ALS herbicide resistance can be selected for very quickly, even after two applications. More commonly, population pressure due to consecutive applications or continuous production of the same crop year after year using only ALS herbicides selects for resistance. In many situations, resistance is selected for along right-of-ways and then resistant biotypes move into agricultural fields. It is important to rotate herbicide modes of action to prevent future cases of herbicide resistance.
Weeds, diseases, and insects can all develop resistance over time to pesticides. When the same pesticide is used consecutively over a period of time, the target pest can become resistant to that pesticide and render the pesticide obsolete.
Diseases
Damping off and Seedling Blight, Fusarium spp., Pythium spp., Rhizoctonia solani, Bipolaris sorokiniana, and Drechslera avenae
Pre- and post-emergence damping-off and seedling blights in oats can be caused by many different pathogens. Soil-inhabiting fungi such as Fusarium spp., Pythium spp., and Rhizoctonia solani commonly cause these diseases. In oats, Bipolaris sorokiniana and Drechslera avenae are also fungi which produce seedling blight symptoms. When pre-emergence damping-off occurs, seedlings fail to break the soil surface. The germinating seed rots while still in the ground. With post-emergence damping-off, seedlings still in the cotyledon stage will rot at the soil line. The stem appears pinched and plants fall over. Seedling blights occur after true leaves emerge. The developing root system rots and plants collapse. Seedling diseases are problems when soils are cold and wet at or immediately following planting. These conditions can delay germination or stress developing seedlings, which allows pathogens to attack. Crusting caused by poor soil preparation or hard rain, or excessive trash on the surface also contributes to disease. Fungicide seed treatment such as captan or mancozeb combined with avoiding cold wet soils and good soil preparation will best manage these diseases.
Covered Smut, Ustilago segetum or U. kolleri
Covered smut is a fungus carried on seed. The symptoms include blackish masses of smut spores replacing kernels. The smut mass tends to remain enclosed by a whitish membrane until broken by harvesting. Chaff is not completely destroyed as it is with loose smut of oats. Resistant varieties are the best management of this disease in a field, but seed treaments with disinfectants is not uncommon.
Crown Rust and Stem Rust, Puccinia coronata and P. graminis
Rusts are caused by Puccinia in small grains. They are characterized by light orange-brown pustules that occur on leaves and stems. Many but not all rust pathogens require alternate hosts. One or both of these may be of economic importance. Rusts overwinter in debris, volunteers and alternate hosts or are blown up from the south each year. Resistant varieties are best for controlling this disease, but even more important in late plantings.
Helminthosporium Leaf Spot, Drechslera avenae (Helminthosporium avenae)
Helminthosporium leaf spot or drechslera leaf blotch is a spot causing fungal disease mainly occuring in the leaves. Lesions on leaves are small initially, enlarging to long stripes of dead tissue. Sometimes distinct spots do not form but leaves wither as if by drought. It is usually associated with cool weather. Crop rotation should help reduce the amount of inoculum in a field and lessen losses due to the disease. Foliar fungicide treatments with mancozeb can be effective, but do not provide complete control.
Bacterial Leaf Blight, Pseudomonas syringae pv. striafaciens
Bacterial leaf blight occurs in poorly drained wet areas. The bacteria is easily spread in the field by tillage equipment, surface water and animal life in the soil. Bacterial leaf blight usually only occurs on the upper leaves. Small water-soaked lesions form and eventually coalesce into larger lesions that may cover the entire leaf. These spots can advance rapidly and cause blight and are generally associated with sprinkler irrigation in cool, wet weather. The bacteria overwinter on and in seed, as well as in debris. Bacteria can survive for up to two years on crop debris. Management practices for bacterial diseases include use of pathogen-free or treated seed, crop rotation, plowing in plant debris, and use of copper-based bacteriacides.
Barley Yellow Dwarf Virus
Barley yellow dwarf virus (BYDV) is a luteovirus that infects many crops including barley, corn, oats, and wheat. The vectors are a group of aphids, including greenbugs, oat bird cherry aphids, corn leaf aphids and English grain aphids The symptoms in oats are a red to purple color and the leaves twist inward. Plants are stunted and have a stiff, crumpled appearance. Tillering is reduced and heads do not fill. Individual leaves turn yellow from the tips in a zig-zag pattern that leaves the midvein green. The virus survives in aphids, grassy weeds, volunteer plants and fall-planted cereals. Infected plants are located at random in a field where winged adults have landed. These plants develop into foci of disease. The disease is favored by cool, wet weather in the spring and early summer. Management of BYDV depends on late planting of oats to avoid fall infection or early planting of oats to avoid infection at early growth stages. Use of insecticides is seldom economical. There are some sources of resistance in oats. Delaying fall planting will help reduce the disease by avoiding high aphid activity.
Loose Smut, Ustilago avenae
Oat heads infected with this fungus are brownish black in color as compared to the normal green color of healthy heads. Infected spikelets become black spore masses which replace heads and ears. The fungus is transported mainly by the wind to healthy heads. When infected seed germinates, the fungus is activated and starts growing within the plant, keeping pace with the growing plant, and by heading time it has replaced the oat spikelets with the characteristic black spores. Certified disease- free seed, resistant varieties and seed treatments with fungicides such as carboxin keep this disease in check.
Key Disease Management Strategies
Cultural Controls
Accurate timing and application of irrigation water, in addition to accurately timed planting will reduce pest pressures on the oat crop.
Fungicides-
Pesticide: captan (Captan 30DD)
Pesticide: captan (Captan 400)
Pesticide: carboxin + thiram (Vitavax 200)
Pesticide: mancozeb (Penncozeb 75DF)
Pesticide: mancozeb (Dithane M-45 )
Frank Peairs, Small Grain Insect Entomologist, Colorado State University, Department of Bioagriultural Sciences and Pest Management, Fort Collins, CO 80523, (970) 491-5945, fbpeairs@lamar.colostate.edu
Authors
Sandra K. McDonald, EditorLindsay Hofsteen
Colorado Environmental and Pesticide Education Program Assistant
lyerkes@lamar.colostate.edu
Bioagricultural Sciences and Pest Management
Lisa Downey
Colorado Environmental and Pesticide Education Program Assistant