USE OF MULTILINE CULTIVARS AND CULTIVAR MIXTURES FOR DISEASE MANAGEMENT

Abstract

The usefulness of mixtures (multiline cultivars and cultivar mixtures) for disease management has been well demonstrated for rusts and powdery mildews of small grain crops. Such mixtures are more useful under some epidemiological conditions than under others, and experimental methodology, especially problems of scale, may be crucial in evaluating the potential efficacy of mixtures on disease. There are now examples of mixtures providing both low and high degrees of disease control for a wide range of pathosystems, including crops with large plants, and pathogens that demonstrate low host specificity, or are splash dispersed, soilborne, or insect vectored. Though most analyses of pathogen evolution in mixtures consider static costs of virulence to be the main mechanism countering selection for pathogen complexity, many other potential mechanisms need to be investigated. Agronomic and marketing considerations must be carefully evaluated when implementing mixture approaches to crop management. Practical difficulties associated with mixtures have often been overestimated, however, and mixtures will likely play an increasingly important role as we develop more sustainable agricultural systems.

Multiple cropping systems as drivers for providing multiple ecosystem services: from concepts to design

“…The cultivar or plant species are totally mixed (mixed intercropping) or arranged in alternate rows or in strips (row intercropping) (Ghaley et al 2005;Pelzer et al 2012). The number of associated plant species or cultivars can vary, but there are usually two species, such as a cereal and a legume, or two to four cultivars of the same species (Zhu et al 2000;Mundt 2002). In group B (relay or sequential cropping), plants are not grown together at the same time but in crop sequences.…”

“…For instance, cereal crops can disrupt insects in their visual search for smaller crops (Ogenga-Latigo et al 1992) or prevent dispersal by wind. Resource dilution and habitat fragmentation were both shown to contribute to the efficient control of disease in crop associations in lowinput farming, with various success stories for cereals (Zhu et al 2000;Mundt 2002).…”

Wheat Variety Selection to Maximize Returns and Minimize Risk: An Application of Portfolio Theory

“…Garrett and Cox (2008) stated, ''Mixtures of at least two crop cultivars increases the genetic diversity and has been shown to be effective at reducing disease and pest severity, increasing yield stability, and strengthening resilience of the crop to physiological stress.'' Wheat mixtures are also commonly grown in the Pacific Northwest (Mundt, 2002). Cox et al (2004) provided evidence that cultivar mixtures can increase yield and reduce yield variability.…”

Biotic interactions, ecological knowledge and agriculture

“…However, selecting for such a mix of characteristics would be difficult and time consuming, so alternative approaches to plant breeding have been proposed based upon building diverse composite cross populations that are then subjected to natural and artificial selections in varied environments (Phillips & Wolfe 2005). Others advocate the use of mixtures of cultivars within a field to improve crop production (Sarandon & Sarandon 1995) and disease management (Mundt 2002).…”