Effect of Residue Management on Barley Production in the Presence of Net Blotch Disease

Abstract

Three residue management schemes were evaluated to determine the effect of barley ( Hordeum vulgare L.) straw residue on disease incidence and agronomic qualities of two barley cultivars over a 3‐yr period. Half of the no‐till, one cultivation, or burned plots that were planted with either a leaf spot susceptible or a leaf spot resistant cultivar, were sprayed with several applications of Tilt fungicide (propiconizole —1‐[[2‐(2,4‐dichlorophenyl)‐4‐propyl‐1, 3‐dioxolaa‐2‐yl]methyl]‐1H‐1,2,4‐triazole) at 4 fl oz/acre. The disease resistant cultivar Baronesse had a higher yield than the susceptible cultivar Harrington in all 3 yr by an average of 14 bu/acre. Application of Tilt fungicide had a similar effect on both cultivars and increased the yield of Harrington by an average of 9.6 bu/acre and Baronesse by an average of 9.0 bu/acre. Test weight and percentage plump seed were higher with Baronesse than with Harrington. Percentage seed protein and percentage thin kernels increased with disease susceptibility. Although the experimental design did not allow for direct comparisons among residue management treatments, the impact of residue management tended to vary over the 3 yr. Highest yields were harvested from the burned treatment in 1994 and 1995, while this same treatment produced the lowest yields in 1993. Research Question Concern about soil erosion caused by both water and wind has prompted the small grain producer to adopt management practices that maintain crop residues on the soil surface. The purpose of this research was to determine the impact of net blotch on barley production under three residue management schemes. Literature Summary Under semi‐arid conditions, no‐till annual spring wheat production has been shown to be the most efficient practice from the standpoint of yield and water‐use efficiency when compared with sweep tillage in a crop‐fallow system. Some of the major obstacles to adoption of practices that maintain residue on the soil surface are weeds, insects, and diseases. Producers have to develop strategies to minimize the losses from these pests if they are to maintain an economically viable small grain operation. Although the use of resistant cultivars or pesticides can be effective in minimizing the impact of residue‐related pests, growers often do not know how much these choices will affect yield and grain quality. One of the important foliar diseases whose severity is related to residue management in barley is net blotch. Study Description This research was conducted on the Western Triangle Agricultural Research Center at Conrad, MT, from 1993 to 1995. Test plots in all 3 yr were placed on land planted the previous year with ‘Harrington’ barley. The standing residue varied between 3500 and 4500 lb/acre. Three separate residue treatment areas were as follows: (i) all residue burned with essentially no residue remaining on the soil surface, (ii) residue tilled one time just prior to seeding using a sweep cultivator, and (iii) standing residue left untilled. Each strip was divided into four blocks (replicates) and four treatment combinations (two cultivars with and without fungicide application) randomized within each block. Just prior to seeding, the entire plot area was sprayed with 0.9 qt/acre of glyphosate and top‐dressed with 60 lb N/acre as urea. Two barley cultivars were used for seeding. Harrington, a net blotch susceptible cultivar, and ‘Baronesse’, a cultivar that has some resistance to net blotch. Twelve‐row plots 20 ft long with rows 12 in. apart were seeded concurrently with 100 lb/acre of 11‐51‐0 fertilizer. The fungicide propiconizole (Tilt) was applied to half the plots at a rate of 4 fl odacre of formulated product. The first application was at the four‐leaf stage in all 3 yr, with a second application at flagleaf emergence. In 1994, a third application was made at the head emergence stage. Leaf spots that developed were identified as being caused by Pyrenophora teres f. maculata based on isolations made onto sterile media. Applied Questions Does residue management affect the development of barley net blotch? Initial disease readings were always lowest in the burned area, but later readings taken post‐flowering were similar throughout the plot area. The lack of response to residue management may have been due in part to the relatively small size of our plots and to the fact that they were adjacent to each other, which would allow secondary inoculum to spread throughout the test area. Does residue management affect the agronomic qualities associated with spring barley? Test weight was greatest for the cultivar Baronesse and increased with fungicide treatment. Kernel plumpness was less affected than was yield by the various treatments with the largest differences developing in 1995 when the yield potential was greatest (Table ). Harrington had higher grain protein than Baronesse, especially in 1993 and 1995. The foliar fungicide treatment affected grain protein only in 1995, where application of fungicide reduced grain protein (but not statistically significantly) over the no‐fungicide treatment. These data show the impact on total production as affected by management practices (i.e., cultivar selection, residue management, and application of a foliar fungicide). While the fungicide application certainly has a significant input cost factor associated with it, the two other practices probably are less associated with significant costs, though certainly not without some cost (i.e., difference in seed cost, since Baronesse is a proprietary cultivar, and the cost of herbicides for weed contiol in a no‐till system). Recommendation Barley producers can reduce the impact of foliar disease when using either minimum or no‐till production schemes by cultivar selection, and by use of a foliar fungicide if their yield potential will justify the latter. The data we collected also suggest that additional research efforts by barley breeders to increase the resistance of their new cultivars will be worthwhile. Effect of residue management practices on barley yields from 1993–1995 at Conrad, MT. Yield (bu/acre) 1993 1994 1995 Residue/cultivar Tilt No fungicide Tilt No hngicide Tilt No fungicide Not Tilled Harrington 78.1 69.2 46.0 42.9 106.7 82.5 Baronesse 84.2 73.3 51.3 46.8 135.5 113.7 One Cultivation Harrington 61.2 61.3 49.2 44.7 104.9 86.8 Baronesse 72.0 71.3 48.8 47.5 133.3 117.7 Burned Harrington 59.2 55.3 51.3 50.9 111.3 87.8 Baronesse 70.4 67.1 61.2 55.9 139.8 122.2 LSD ( P = 0.05) 7.2 5.8 8.4 LSD values are to be used to compare either between cultivars or spray treatment for each residue treatment.

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