Barley Ecology and Management

Background and Objectives

Short-term experiments can lead to low input management recommendations that are profitable in the short-term, however, it is doubtful if such practices would continue to be profitable due to carryover effects of uncontrolled weeds and diseases. Many cow/calf producers in central Alberta plant continuous barley for silage and seed, limiting agro-ecosystem diversity and favouring pest outbreaks. The objective of this experiment was to determine the cumulative effects of seeding rate, barley type, rotations and herbicide rate on wild oat management and disease. Barley variety/seeding rate/herbicide rate combinations were seeded in 2003 on previous barley (2001) and canola (2002) stubble to evaluate the rotational and seeding rate impact on reducing input costs and minimizing the risk associated with disease pressure under continuous barley situations.

Methods

Field experiments were conducted at Beaverlodge, Fort Vermilion and Lacombe, Alberta and Brandon, Manitoba in 2001, 2002 and 2003. Two barley varieties, Peregrine (short) and AC Bacon (tall), were seeded at 200 and 400 seeds per m² in the continuous barley each year. Barley seeded at 100 seeds per m² is equivalent to approximately ¾ bushel, however, this can change every year depending on barley type, variety and seed weight. In addition, hulled barley emerges at approximately 75% of seeds planted, whereas, hull-less barley emerges at approximately 60% of seeds planted. Planting by number of seeds per ft² or m² ensures the targeted plant establishment. Rotational barley included a canola crop that replaced the short and tall barley in 2002. Herbicide treatments were applied at full, half (H) and quarter (Q) recommended rate. Results from trials at Beaverlodge and Fort Vermilion were similar in nature to those in Lacombe. Only Lacombe and Brandon results are shown.

Results

Lacombe
Weed biomass and grain yield: Continuous barley had wild oat biomass that was 2.5 times that of rotational barley. Tall barley with a high seeding rate and a quarter of the recommended herbicide rate significantly reduced wild oat biomass compared to short barley with a low seeding rate and a quarter of the recommended herbicide rate in continuous and rotational barley (Fig. 1a). Wild oat biomass was increased 11 times and 23 times when short barley was grown compared to tall barley at half and a quarter of the recommended herbicide rate, respectively. Grain yield was 8% higher from rotational barley than continuous barley (Fig. 1b). Grain yield increased with the high seeding rate compared to the low seeding rate for both the short and tall barley.




Fig.1. Relationship between barley rotation (barley/barley), barley type (short vs tall), herbicide rate (H=50% recommended and Q = 25% recommended) and seeding rate (200 and 400 seeds planted per m²) on (a) wild oat biomass (kg/ha – 1000 kg = ½ ton/acre) and (b) grain yield (kg/ha - 1000 kg = ~20 bushels) in 2003 at Lacombe, Alberta.

Brandon
Weed biomass and grain yield: Tall barley with a high seeding rate and half the recommended herbicide rate significantly reduced wild oat biomass compared to short barley with a low seeding rate and half the recommended herbicide rate. Only tall barley and high seeding rate reduced wild oat biomass at the quarter herbicide rate compared to the other treatments (Barley*seed rate* herbicide rate, P<0.02) (Fig. 2a). Wild oat biomass was increased 5.2 times and 1.7 times when short barley was grown compared to tall barley at the half and a quarter of the recommended herbicide rate, respectively. Grain yield was 13% higher from rotational barley than continuous barley, 65% higher from a tall barley than a short barley, and 24% higher when seeding at 400 seeds per m² than 200 seeds per m² (Fig. 2b). Reducing the herbicide rate reduced grain yield but yield loss was recoverable using half the recommended herbicide rate when combined with the higher seeding rate for both short and tall barley (data not shown).




Figure 2. Relationship between barley rotation (barley/barley), barley type (short vs tall), herbicide rate (H=50% recommended rate and Q = 25% recommended rate) and seeding rate (200 and 400 seeds planted per m²) on (a) wild oat biomass (kg/ha – 1000 kg = ½ ton/acre) and (b) grain yield (kg/ha - 1000 kg = ~20 bushels) in 2003 at Brandon, Manitoba.

Disease: Overall, the levels of scald, net blotch and other leaf spots observed at Lacombe and Brandon in 2003 had limited influence on barley productivity. Nevertheless differences among treatments, especially for net blotch, indicate that disease risk can be reduced through crop rotation and cultivar choice. Potential disease increases due to increasing seeding rate can also be countered through the use of crop rotation and/or cultivar choice.

Summary

• Cultivar selection, seeding rate and rotational management provide ecological approaches to managing weeds and disease.
• Integrating a competitive barley type and a high seeding rate is an ecological tool for weed management in monoculture or rotation.
• Pest management strategies are not always compatible. The positive weed management strategies of higher seeding rate had a minor negative effect on disease management.
• Grain yield was positively affected by ecological crop management.
• Continuation of this study will help to explain the relationship between disease pressure (i.e. crop health) and weed management in an integrated crop management (ICM) system.

Clayton, G.W. (1), J.T. O’Donovan (2), R.B. Irvine (3), K.N. Harker (1), T.K. Turkington (1), N.Z. Lupwayi (2), and R.H. McKenzie (4)
Agriculture and Agri-Food Canada, (1) Lacombe, (2) Beaverlodge, Alberta, (3) Brandon, Manitoba, Canada;
(4) Alberta Agriculture, Food and Rural Development, Lethbridge, AB

Presented at the 18th North American Barley Researchers Workshop, July 17-20, 2005