The impact of fungicide and herbicide timing on foliar disease severity, and barley productivity and quality

Abstract

. 2015. The impact of fungicide and herbicide timing on foliar disease severity, and barley productivity and quality. Can. J. Plant Sci. 95: 525Á537. There is interest in mixing herbicides with a half-rate of fungicide at herbicide timings for barley in western Canada. At six sites across the Canadian prairies from 2010 to 2012 combinations of herbicide and the fungicide Tilt † (propiconazole) were applied to barley at the two-to three-leaf stage (herbicide and half-rate fungicide), five-to six-leaf stage (herbicide and half-rate fungicide), and/or the flag leaf stage (full or half-rate fungicide only). Each plot area was cross-seeded with tame oat as a model weed prior to seeding. Upper canopy leaf samples were collected for leaf disease assessment at the early dough growth stage. Weed biomass, and grain yield and quality were determined. Total leaf area diseased (a combination of scald, both forms of net blotch and spot blotch) was greater for the two-to three-or five-to six-leaf stage herbicide-only treatments and the combination herbicide and half-rate fungicide treatments compared with fungicide at the flag leaf stage. Yield, 1000-kernel weight, kernel plumpness and test weight were greatest and kernel thins lowest for treatments with a flag leaf stage fungicide application. Split applications of fungicide at the time of herbicide application and at flag leaf emergence did not improve disease management and crop productivity compared with a single full rate fungicide application at the flag leaf stage. Weed biomass was generally not influenced by the treatments because weed control was excellent at all sites. However, yield was lower when herbicide was applied at the five-to six-leaf versus the two-to three-leaf stage. For improved leaf disease management and yield in barley, fungicide applications should include a flag leaf stage timing for adequate protection of upper canopy leaves, which are key contributors to yield and grain filling. Delaying herbicide application to the five-to six-leaf stage in an attempt to accommodate a fungicide application reduces barley yield due to early-season weed interference.Key words: Fungicide, herbicide, timing, leaf disease, barley Turkington, T. K., O'Donovan, J. T., Harker, K. N., Xi, K., Blackshaw, R. E., Johnson, E. N., Peng, G., Kutcher, H. R., May, W. E., Lafond, G. P., Mohr, R. M., Irvine, R. B. et Stevenson, C. 2015. Impact du moment d'application des fongicides et des herbicides sur la gravite´des maladies foliaires ainsi que sur la productivite´et la qualite´de l'orge. Can. J. Plant Sci. 95: 525Á537. Les producteurs d'orge de l'Ouest canadien souhaiteraient ajouter un fongicide, a`la moitie´du taux recommande´, au moment de l'application des herbicides. De 2010 a`2012, a`six sites des Prairies canadiennes, les auteurs ont applique´des me´langes d'herbicide et du fongicide Tilt † (propiconazole) a`de l'orge parvenu au stade de la deuxie`me ou de la troisie`me feuille (fongicide a`la moitie´du taux recommande´et herbicide), a`celui de la cinquie`me ou de la sixi...

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“…Kernel plumpness was not affected by an extra fungicide application in Z32. These results agree with those observed by Turkington et al (2015), whom conducted split applications of fungicide at the time of herbicide application (tillering; earlier than in our study) and at flag leaf emergence and concluded that the split applications did not improve disease management and crop productivity compared with a single full rate fungicide application at the flag leaf stage.…”

Winter Wheat Yields Are Increased by Seed Treatment and Fall‐Applied Fungicide

“…From a disease management perspective, these results are consistent with Fernandez et al (2014), Turkington et al (2004;, and Poole and Arnaudin (2014), who reported that direct protection of the key upper canopy leaves from cereal leaf disease is critical for maintaining seed yield. Fungicide applications at early crop growth stages, like that used in the current study, will not provide direct protection of upper canopy leaf tissue (Poole and Arnaudin, 2014;Turkington et al, 2004Turkington et al, , 2015. The yield gains could therefore be related to plant responses to prothioconazole that improved plant defense systems against abiotic stress.…”

Does the Application of a Fungicide after a Herbicide Reduce Soybean Injury and Increase Yield?

“…Other studies have suggested that strobilurin fungicides increase water use efficiency of plants under water deficit conditions [19] [21]. Effect of non-disease physiological effects in host plants have been reported to increase soybean yield [22] [23] [24]. Fungicide manufacturers and some researchers have documented crop yield increases following the foliar application of strobilurin fungicide (and some other fungicides) even when there is no disease is visibly present at the time of ap- [24].…”