植物病害の薬剤防除

Abstract

As the world population increases, we also need to increase food production. Chemical control has been critical in preventing losses due to plant diseases, especially with the development of numerous specific-action fungicides since the 1960s. In Japan, a host-defense inducer has been used to control rice blast since the 1970s without any problems with resistance development in the pathogen. Leaf blast has been controlled using a labor-saving method such as the one-shot application of a granular mixture of fungicide and insecticide to nursery boxes, which became mainstream in the 2000s. However, the need for many choices of fungicides that have several modes of action was demonstrated by the development of resistance to cytalone dehydratase inhibitors. In Europe, many pathogens have threatened cereals since the great increase in cereal production in 1970s, creating a large market for broad-spectrum fungicides. In Brazil, Phakopsora pachyrhizi was distributed to large soybean acreages during 2000s, and the outbreak of soybean rust resulted in a large increase in fungicide use. While the importance of chemical control is recognized, fungicide resistance is an avoidable problem; published guidelines on countermeasure and manuals on testing sensitivity to fungicides are available. Since chemical regulations have become stricter, new fungicides are less likely to be developed. Our task is to maintain the effectiveness and diversity of the present modes of action for fungicides and implement countermeasures against the development of fungicide resistance.