Winter barley: An emerging crop

Several winter/facultative two-rowed barley varieties have been released in the United States; however, they generally exhibit limited winter hardiness and are not ideal varieties for Minnesota. Consequently, increasing winter hardiness is the main emphasis in the University of Minnesota’s winter/facultative breeding program.

Target environment

Southern Minnesota is the target environment for this winter/facultative barley, where the average annual extreme minimum temperatures do not drop below -25oF (USDA Plant Hardiness Zone 4B). Winter climate in this area is not as harsh as northern Minnesota and the possibility of double cropping may exist.

If the breeding program can develop varieties with sufficient and reliable winter hardiness, these lines can be tested in the central and northern parts of the state for their adaptation. Despite steady progress in barley breeding, there is still a great need for improved barley varieties that provide the raw material for a wide array of end-use products, especially for malt. The complexity of both malting quality and winter hardiness traits makes simultaneous improvement a challenge for barley breeding.

Autumn-sown winter/facultative barley varieties have many advantages over the traditional spring-sown barley that is currently grown in the Upper Midwest and other regions of the country:

• Higher yields -
  In many regions, winter/facultative barley often produces higher yields than spring barley.
• Disease escape potential -
  Because autumn-sown winter barley matures earlier, it may help the crop escape from common “summer” diseases such as stem rust (Puccinia graminis f. sp. tritici), and FHB (caused primarily by Fusarium graminarum), depending on environmental conditions. FHB is particularly devastating because it can not only lower yields, but also severely reduce grain quality through mycotoxin contamination by the causal fungus.
• Ecological services -
  Autumn-sown winter barley also provides various ecological services. It has a significant advantage in weed suppression and can typically be grown with no herbicide applications. When compared with winter wheat, winter barley utilizes nitrogen more effectively, enabling the crop to produce higher yields with fewer fertilizer inputs.
• Avoid wet spring planting delays -
  Autumn-sown winter barley can eliminate the risk of planting in Minnesota’s increasingly common wet springs and take advantage of the extended cooler spring and fall growing conditions that favor barley growth and development.
• Ease labor demands -
  Sowing winter barley in the autumn and harvesting in early summer allows growers to spread out their labor demands and utilize farm machinery more efficiently.

Challenges

Autumn-sown winter barley is not without its challenges:

• Lack of winter-hardiness -
  A lack of sufficient winter hardiness to reliably survive the harsh Minnesota winters is a major challenge.
• Other diseases -
  Not commonly observed in spring-sown barley could become important in autumn-sown winter barley (see disease section below).

Since 2011, the craft beer industry has experienced greater than a five-fold increase of expansion in Minnesota. A bill passed in the Minnesota State Legislature in 2011 allows craft breweries to make and sell their wares on site.

Minnesota is an ideal location for growing barley because of its productive soils and centralized geography to major malting facilities. The state is home to two large malting companies:

1. Rahr Malting Company in Shakopee is the largest malting plant in the world with a capacity of 460,000 MT.
2. Busch Agricultural Resources Inc. (BARI) is located in Moorhead, Minnesota.

In addition to these large malting companies, the malting volume of smaller craft malt houses is growing in the state. In 2017, Minnesota boasted over 150 craft breweries.

Malting companies would like to source locally produced barley to reduce the high cost of shipping grain from the west. Moreover, many craft brewers are interested in environmental sustainability and are seeking to source all locally-produced ingredients.

Introducing winter barley to the dominant corn-soybean cropping system may contribute both economic and environmental benefits to the grower, farm, and the greater landscape. Cropland accounts for 51% of the total land area in Minnesota as of 2018 and agricultural land management choices can have major effects on water quality.

Economic advantage to malting barley

As mentioned above, barley used for malting is an important value-added commodity for producers. High quality barley grown to malting specifications can receive a substantial premium over feed-grade barley. If barley does not meet the standards for malting, it may be classified as feed grade, resulting in a substantial reduction in price. In addition, establishment costs for growing winter/facultative barley will also vary from farm to farm, affecting the bottom line.

Double cropping winter barley and soybean in the same year may also be a possibility. In southern Minnesota, the growing season may be long enough to facilitate a double-cropping system. This would enable winter barley to share some of the large acreage traditionally planted to soybean.

The extensive summer annual cropping systems actively grow for only a few months in Minnesota, leaving fields fallow for much of the year. Without crops covering the land, fallow ground is vulnerable to wind and water erosion, as well as nutrient runoff. Nutrient runoff can build-up in lakes, streams and rivers and negatively affect water quality. A double cropping system could provide cover for a much longer period of time (Figure 4).

Although double cropping small grains and soybean is commonly practiced in the southeastern part of the country, the growing environment in the Upper Midwest is markedly different. Nonetheless, exploring whether double cropping winter barley in combination with a second, short-season , summer annual like soybeans, dry beans, or peas is possible is worth exploring.

Fall planting date trials

In winter wheat, planting date can greatly influence winter survival and yield. To evaluate the effect of planting date on winter survival of winter barley in Minnesota, a planting date experiment was conducted:

• Time of study - The study was conducted from 2009 to 2018.
• Locations - Five locations were selected in Minnesota - Two in the northern half of the state and 3 in the southern half (Figure 5). The locations represent two diverse regions for testing the viability and agronomic performance of winter barley. The area between Moorhead and Crookston exemplifies the current spring barley production zone in Minnesota.
• Varieties - Three varieties with varying levels of winter hardiness were selected (Table 1).
• Planting dates - Winter barley was planted at four dates in two-week intervals from early-September to mid-October.

Winter survival results

Overall, the three locations in southern MN (St. Paul, Rosemount, and Lamberton) experienced much greater survival than the two locations in northern MN (Crookston and Moorhead). When more than 50% of the initial stand survived the winter, the varieties in the trial developed a sufficiently adequate canopy to suppress weeds and warranted to be harvested for grain. The variety McGregor met the 50% winter survival threshold to viable grain yield more than half of all of the site-years in southern to central MN (Table 2).

Optimal planting window

The 50% survival threshold is associated with an accumulation of 500-1400 Growing Degree Days (GDDs) between planting and freeze-up in the fall. However, this does not apply to winter barley tested in northern Minnesota, where less snow retention and colder temperatures increase winter injury risk.

Optimal fall planting windows for Minnesota are listed in Table 3. These ranges factor in both the optimum fall GDD accumulations and later planting dates to avoid barley yellow dwarf virus (BYDV) infections.

The currently available winter barley varieties that are adapted to the Midwest are only marginally winter hardy for southern Minnesota and not winter hardy enough for Northern Minnesota.

As new winter barley varieties with better winter hardiness are developed by the University of Minnesota and successful winter survival becomes routine, other best management practices, including fertility management, disease and pest management will become more important.  Management of powdery mildew and barley yellow dwarf virus will likely be key to successfully introduce winter barley as a winter annual in the current corn/soybean cropping system. Some of those management issues and questions are introduced and detailed below.

Nitrogen input requirements are relatively low for barley. Thus, the crop should be grown under moderate nitrogen fertility conditions, because high fertility will impact malting grade in the following ways:

• Reduced kernel plumpness.
• Increased grain protein content.
• Increased risk of lodging.

Target grain protein concentrations between 11.5% and 13% when determining the appropriate nitrogen fertility levels. Fertilizer recommendations for spring barley production in Minnesota could be relevant for winter barley production. However, additional research is needed to validate whether or not these recommendations are appropriate for winter barley.

Further research to examine other agronomic management practices such as planting density, row spacing, and fertility management will be crucial to the successful production of winter barley. While breeders will continue to develop winter/facultative barley varieties that can consistently survive and thrive under winter conditions in Minnesota, producers should do everything they can to plant at the proper time, depth, and in better drained fields to  increase the chances of winter survival. 

The most economically significant disease in Minnesota is Fusarium head blight (FHB), also known as scab. FHB can cause yield losses by reducing kernel development. The fungus causing FHB (primarily Fusarium graminearum) also produces a mycotoxin (DON), which is harmful to humans and animals. For this reason, the threshold for DON content in malting barley is very low (< 1 ppm).

Disease development

Barley spikes become prone to infection by F. graminearum as soon as they emerge from the flag leaf sheath. Infection is favored by prolonged wet weather and high humidity.

The typical early symptoms of FHB on barley include tan to dark brown lesions at the base of the kernels (Figure 6). These symptoms can spread across the entire kernel within a few days under warm, moist conditions. Early infections result in complete sterility of florets, whereas late infections may only reduce yield slightly.

Autumn-sown winter barley typically heads early (early June) and may avoid weather conditions that are most favorable for FHB infection and development.

Growers can use the national Fusarium Risk Assessment Map or state based models for Minnesota and North Dakota to check for the risks of FHB infection throughout the growing season.

Management

Plant resistant varieties

Consider planting moderately resistant varieties, when available. For example, two winter two-rowed malting barley cultivars, Endeavor and Calypso, displayed superior resistance to DON accumulation in North Carolina. However, these particular varieties are not adapted for our climate.

Fungicide applications

Consider applying fungicide if there is risk for FHB development. Researchers in North Carolina found that the fungicides prothioconazole + tebuconazole (Prosaro®) applied six days after full spike emergence significantly reduced FHB severity in winter barley compared to no fungicide or fungicide applied at spike emergence.

Several foliar fungal diseases have been found in winter barley trials in Minnesota. As winter barley production increases in the state, it is possible that these diseases will become more prevalent. These include powdery mildew, leaf rust, and leaf scald. Barley yellow dwarf is caused by a virus and is discussed in a separate section below.

Powdery mildew (Blumeria graminis f. sp. hordei (previous epithet Erysiphe graminis f. sp. hordei)

Powdery mildew is caused by a fungus that overwinters on stubble and straw or volunteer barley and certain wild grasses. Heavy, succulent plant growth favors mildew development.

The most common signs on barley include powdery, gray-white, or buff-color spore masses on the leaves, leaf sheaths, and spikes (Figure 7). Yellowing, browning, and ultimately leaf death follows heavy powdery mildew infection.

The best management strategy for mildew control is to plant resistant varieties. Although some effective fungicides are available for barley, they are an added input cost for growers. Another important management strategy is to reduce inoculum survival from one season to the next by

• Rotating crops.
• Eliminating crop residue.
• Controlling volunteer barley and weed hosts.

Foliar fungal diseases

Once a foliar fungal disease has been diagnosed, the next decision is to determine whether a fungicide can provide adequate economic control. The decision to apply a fungicide depends on several factors:

• Growth stage
• Crop production practices
• Disease incidence in a field
• Location of the disease in the canopy 
• Yield potential
• Host resistance
• Weather forecast

Once winter barley has reached the flowering stage, there are fewer options for managing these diseases. The Field Crop Plant Disease Management Guide for small grains includes guidelines for fungicide applications in North Dakota. While most are also labeled for Minnesota, it is important to check the label.

Fusarium head blight

Prothioconazole + tebuconazole (Prosaro®) and metconazole (Caramba®) are currently the most effective fungicides for FHB suppression. Application of these fungicides should be made as soon as the crop is fully headed.

Prosaro and Caramba are both labeled for control of all the other economically important fungal diseases. However, note that both fungicides are labeled for only one application per season when applied at the recommended FHB rates. Each can be used in separate applications, because Prosaro and Caramba have different active ingredients.

Another potentially important disease is barley yellow dwarf. This disease is caused by the barley yellow dwarf viruses (BYDV), which are transmitted by aphids.

Winter/facultative barleys sown in the autumn can be infected early by this disease, decreasing both the vigor and winter hardiness of the crop. Barley can also be infected with this disease in the spring.

Symptoms caused by BYDV are highly variable due to various host plant factors, such as genotype, age and physiological condition. They may begin as uneven blotches of bright yellow discoloration on the tips and margins of older leaves (Figure 10). The discoloration then progresses down to the base, covering the entire leaf within a week or two. When barley plants are severely infected at an early age, they may fail to head and remain in a “rosette” with leaves that are shortened and thickened with serrated margins.

Strategies to reduce barley yellow dwarf infection include eliminating grass hosts that may serve as a reservoir for the viruses and reducing populations of the aphid vectors. Planting date can also have a significant effect on disease levels. Autumn-sown barley should not be planted too early. Otherwise, it will be exposed to virus-carrying aphids for a longer time and will sustain greater damage from the disease before the onset of winter. Based on preliminary observations of autumn-sown barley in Minnesota, a late September to early October planting date is recommended to reduce exposure to BYDVs.

Loose smut (Ustilago nuda) is a seed-borne disease caused by a fungus. It can be introduced into new production areas by sowing infected seed. Therefore, clean seed or seed treated with a fungicide should be used whenever possible. The incidence of loose smut in barley may vary from year to year.

The loose smut fungus infects barley during the flowering stage. When seeds harvested from these plants are sown the following season, the disease manifests itself at the heading stage. Infected seeds on the spikes are completely replaced by dark smutty spores of the fungus (Figure 11).

Fungicide seed treatments can control this pathogen, since the interval between planting and infection is short enough that fungicides are still effective. Seed treatments primarily control seed-borne diseases.

Development of sensitive and rapid seed health tests would allow more effective targeting of seed treatments to those seed stocks that require them.

Diseases, such as scald and net blotch, survive on crop residue. Therefore, rotation with a non-host crop will minimize initial in-field inoculum levels for the current season's crop.

In contrast, barley leaf rust, powdery mildew, and BYDV can only persist on living hosts. Barley leaf rust spores travel by wind from the southern US or survive on volunteer barley plants. Powdery mildew may be found on barley volunteers and stubble, while BYDV hosts include cereal regrowth and perennial grasses.

Consequently, when volunteer plants from the previous spring-sown cereal crop overlap with the autumn-sown winter barley, the disease cycle continues and the so-called ‘green bridge’ is created. This increases the risk of an early onset of aphid-vectored BYDV, powdery mildew, and/or leaf rust. Killing the wheat and barley regrowth as early as practical will minimize fall infections from these diseases and destroy the green bridge.