Oats

Description

Oats are annual grasses belonging to the genus Avena, in the family Poaceae and are grown primarily for use as livestock feed. Several species of oats are grown commercially in different regions of the world, including Avena sativa (common oat), Avena byzantina (Algerian or red oat), Avena nuda (naked oat) and Avena sterilis (the sterile or animated oat). Like wheat, oats generally have been developed into different varieties that are adapted to planting at different times of the year. Spring oats are planted for a late summer harvest, whereas Winter oats are planted for harvesting in early to mid summer. Overwintering varieties are more commonly grown in regions with mild winters. Oats generally possess an upright stem and fibrous root system. The inflorescence consists of a number of branches, or racemes, and spikelets (20–150 per plant) which usually contain three florets or flowers (naked oats produce 3–7 flowers per spikelet). Generally, two seeds (kernels) are produced per spikelet, but sometimes only one develops. Ancestors of the common oat, Avena sativa and the closely related Avena byzantina originated from the Fertile Crescent of the Near East.


Uses

Oats can be rolled or crushed to produce oatmeal or ground to produce oat flour. Oats may also be used in the production of several baked goods such as oat cakes or oat bread. The vast majority of commercially grown oats are used as livestock feed.


Propagation


Basic requirements
Oats grow best in cool, moist climates, with the optimum temperature for growth being between 20 and 21°C (68–70°F). The plants will thrive in well drained soils but are adapted to grow in many soil types, requiring a pH between 5.5 and 7.0. Oats are less tolerant of drought and heat than other cereals but, like other small grains, tolerate acidic soils well.

Propagation
Oats are propagated from seed which can be sown in Spring or in Fall depending on the variety, prevailing climate and the intended use. Commercially produced oats are drilled into a prepared seedbed. Seedbeds should be firm and free of any weeds or vegetation. If oats are being grown to harvest grain then the recommended seeding rate is 60–90 lb of seed per acre. This should be increased slightly if the seeds is being sown by broadcasting as is commonly the case in small-scale production or home gardens. Seeds should be sown at depths of 3–7 cm (1.2–2.8 in) allowing 15–17 cm (5.9–6.7 in) between rows.

General care and maintenance
Soil should be tested prior to planting oats in order to establish the rate of fertilizer and lime application required. Lime is often applied to raise the pH of the soil. if pH is too low, yields may be reduced. Nitrogen should be applied to oats after seedlings emerge at a rate of 20 lb per acre. Further applications are made throughout the growing season based on the specific soil and rotation schedule. In addition to nitrogen, oats require phosphorus and potassium for optimal growth. The rates of application of these nutrients should be based on the results of a soil test.

Harvesting
Oats are ready to harvest when the kernels are at the “hard dough” stage when the grain moisture content drops below 14%. The plants will have lost their green color and appear yellow-brown. The kernels harden and cannot be dented with a fingernail. Commercially produced oats are harvested by combine. Small-scale productions can be harvested by hand cutting. After harvest, the grain must be dried before being stored.


References

CABI Crop Protection Compendium. (2010). Avena sativa (oats) datasheet. Available at: http://www.cabi.org/cpc/datasheet/8061. [Accessed 26 February 15]. Paid subscription required.

Mask, P. L., van Reissen, H. W. & Ball, D. (1994). Production guide for oats. Alabama Cooperative Extension System. Available at: http://www.aces.edu/pubs/docs/A/ANR-0.... [Accessed 26 February 15]. Free to access.


Common Pests and Diseases

Scab
Fusarium spp.

Symptoms
One or more spikelets on newly emerged head bleached; pink or orange fungal masses may be visible at the base of infected spikelet; infected spikelets do not produce seed or produce shriveled and/or discolored seed; severe infections can cause the kernels to have a chalky appearance and are frequently lost during harvest
Cause
Fungi
Comments
Fungus survives between seasons on host plant debris - other host include corn, wheat and barley; fungus can survive on host debris for several years; warm, moist conditions promote the spread of the disease when present
Management
Control of the disease can be difficult; crop rotation to a non-host is recommended for at least one year; applications of appropriate fungicides if available can help to control the disease in conjunction with the other measures detailed here

Anthracnose
Colletotrichum graminicola

Symptoms
Red to brown oval lesions on the leaves; black fungal structures may visible on lesions; crowns become bleached and then turn brown; plants are more susceptible to lodging
Cause
Fungus
Comments
Fungus survives as spores on seeds and crop debris; spores can be spread by wind or splashing water; nutrient deficient plants are more susceptible to the disease
Management
Provide plants with adequate levels of fertilizer; rotate crops to improve soil quality; control weeds in field; turn crop debris into soil after harvest to limit release of spores; avoid planting oats in soils with a high pH`

Crown rust
Puccinia coronata

Symptoms
Chlorotic flecks or brown necrotic spots on leaves or stems; yellow streaks or patches on foliage; brown necrotic streaks on foliage; raised orange pustules may be present on lesions
Cause
Fungus
Comments
One of the most destructive oat diseases
Management
The most effective method of controlling rusts is to plant resistant varieties of oats; planting oats early allows them to mature before spores reach plants and escape most damage

Loose smut
Ustilago avenae

Symptoms
Early emergence of heads; dark green or black masses in place of kernels
Cause
Fungus
Comments
Spores rupture out from protective membrane on heads; fungus can survive in infected seed
Management
Use only certified smut-free seed; treat seeds with hot water prior to planting to kill fungi; treat seeds with systemic fungicide (fungi inside seed) fungicide; grow resistant varieties

Powdery mildew
Erysiphe graminis

Symptoms
Patches of cottony, white-gray growth on upper surface of leaves which turn gray-brown; chlorotic patches develop on leaves opposite fungal growth; fungal fruiting bodies usually become visible as black dots on the mildew
Cause
Fungus
Comments
Disease emergence favors heavy nitrogen fertilization; high humidity and cool temperatures
Management
Planting resistant varieties is one of the best ways to protect plants from powdery mildew; other control strategies include: application of appropriate foliar fungicides, if available; removal of crop debris from field after harvest to reduce the level of overwintering fungus; removal of volunteer oat plants which can act as a reservoir for the disease

Armyworms
Mythimna unipunctata
Spodoptera praefica

Symptoms
Entire leaves consumed; notches eaten in leaves; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside
Cause
Insect
Comments
Insect can go through 3–5 generations a year
Management
Organic methods of controlling armyworms include biological control by natural enemies which parasitize the larvae and the application of Bacillus thuringiensis; there are chemicals available for commercial control but many that are available for the home garden do not provide adequate control of the larvae

Stinkbugs
Euschistus spp.

Symptoms
Damage to head during milk or soft dough stage; stink bugs often carry pathogens in their mouthparts which can cause secondary infections; adult insect is shield-shaped and brown or green in color; may have pink, red or yellow markings; eggs are drum shaped and laid in clusters on the leaves; larvae resemble the adults but are smaller
Cause
Insect
Comments
Adult insects overwinter under leaves, on legumes, blackberries or on certain weeds such as mustard or Russian thistle
Management
Remove weeds around crop which may act as overwintering sites for stink bugs and practice good weed management throughout the year; organically accepted control methods include the use of insecticidal soaps, kaolin clay and preservation of natural enemies

Wireworms
Aeolus spp.
Anchastus spp.
Melanotus spp.
Limonius spp

Symptoms
Death of seedlings; reduced stand; girdled stems and white heads; wireworm larvae can be found in soil when dug round the stem; larvae are yellow-brown, thin worms with shiny skin
Cause
Insect
Comments
Larval stage can last between 1 and 5 years depending on species
Management
Chemical control impossible in a standing crop, must be applied at preplanting or as a seed treatment; if wireworms are known to be present in soil fallow field during summer and till frequently to reduce numbers; rotate to non-host crop where possible; avoid planting susceptible crops after a wireworm infestation on cereals without either fallowing of applying appropriate pesticide

Aphids (Bird cherry-oat aphid, Russian wheat aphid, Corn leaf aphid, etc.)
Rhopalosuphum padi
Diuraphis noxia
Sitobion avenae

Symptoms
Yellow or white streaked leaves; flag leaves may be curled up; plants may be stunted and tillers may lie parallel to the ground; plants may turn a purple color in cold weather; insects are small and soft-bodied and may be yellow, green, black or pink in color depending on species; insects secrete a sugary substance called "honeydew" which promotes the growth of sooty mold on the plants
Cause
Insect
Comments
Fields should be checked for aphid populations periodically after emergence
Management
Sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use; in commercial plantations aphid numbers are usually kept in check by predators and natural enemies; beneficial insect populations should be assessed before chemical control is considered; if no beneficial insect populations are present and aphids are damaging then apply appropriate insecticides

Barley yellow dwarf
Barley yellow dwarf virus (BYDV)

Symptoms
Stunted growth of plants; yellow green blotches at leaf tip, leaf margin or leaf blade; leaves turning bright yellow, red or purple
Cause
Virus
Comments
Transmitted by aphids; symptoms more apparent in colder temperatures
Management
Grow resistant or tolerant varieties; avoid planting crop very early or very late when aphid populations are high