Diversification of Host Plants as a Strategy in the Control of Plant Diseases

Author(s): Henrique Maia Valerio, Carlos Roberto Casela

With the purpose of to avoid or to reduce some of those inherent problems to the agricultural systems based on monoculture, it should be introduced and handled the diversity in the best possible way. In a high level, the monoculture of species is difficult of being modified, at least in short space of time. At the level of the varieties of plants, the diversification is relatively easy of being handled, mainly in the mixture form of cultivars, varieties or hybrid (simple, double or triples) in the farmings. These mixtures can be produced in commercial scale, with excellent results in relation to most of the experimental scales, or for small producers at a low cost, seeking a good level of control of diseases and stability in the productivity. The composition of the mixtures can be modified transiently to delay or to reduce the selection of new races capable to overcome the resistances of more than one of the components of a mixture. The main disadvantage is that the quality of the mixtures cannot be acceptable for the final consumer of the product of these diversified farmings. However, mixtures of varieties, hybrid or of lineages, can significantly improve the control of some of the most common diseases disseminated by the air and for the water. For this reason, cultural practices more diversified are, consequently, recommended to complement the resistance of the hosts, in matter, in the Sorghum bicolor-Colletotrichum sublineolum pathosystem and to reduce the selection pressure in fields.

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