Roos et al. (2010) surveyed the effects of climatic changes on plant diseases and pests of various crops in Sweden. The crops investigated include: Brassica crops, cereals, potatoes, sugar beets, and tomatoes. Traditionally, the climatic conditions in this region have protected crops from several diseases; the cold winter temperatures have usually prevented the survival of various pathogens. With the increase in average temperatures, however, crops have become increasingly susceptible to pathogenic invasion. The prolongation in the vegetation period, caused by these climatic changes, was shown to be a root cause of the observable increase in disease resilience. Changes in precipitation have also demonstrated negative effects on crops. In their study, the authors observe the increasing damage in crop health caused by global warming, projecting an increase in severity in the future. Furthermore, Roos et al. promote further investigation in preventative strategies, citing options such as genetically modified crops to alleviate the ramifications of increasing temperatures.—Daniela Hernández
Roos, J., Hopkins, R., Kvarnheden, A., Dixelius, C., 2010. The impact of global warming on plant diseases and insect vectors in Sweden. European Journal of Plant Pathology 129, 9–19.
Sweden is currently facing climatic changes that have the potential of dramatically altering the integrity of food crops. Studies have shown that the region is expected to experience a higher temperature change than the global mean change. Roos et al., at the Swedish University of Agricultural Sciences, project that these changes will ultimately alter vegetation periods. A temperature increase of 4oC is predicted to cause an increase of one to two months in the longevity of the vegetation period; it is also predicted that in the southern regions the change could be up to three months. The projection for the southern regions is of special interest since the bulk of crops grown in Sweden, is done so in the southern temperate zone. The climatic changes are also expected to lead to an overall increase in rainfall during the winter, which could ultimately affect crop health. Due to the recurring freezing and thawing processes these environmental changes would result in, plant roots are expected to undergo severe damage. The damages to the roots could essentially make the crop susceptible to pathogenic invasion. Furthermore, the authors conclude that although a certain crop might be better adapted to withstand winter conditions, the crop might not be able to survive the added stresses caused by the climatic change.
The increase in longevity of the growing season, coupled with the changes in precipitation suggests that Swedish crops will increasingly become more vulnerable to disease and pests. For example, wheat and barley are expected to face an increase in attack by some rust diseases, such as brown and yellow rust, caused by the prolongation of the vegetation period. Additionally of great concern, is the potato disease, late blight, which is caused by the oomycete, Phtophthora infestans. Trends of higher temperatures and increased humidity are expected to create favorable conditions for late blight to thrive in. The authors also suggest that an increase in mean temperature will result in an increase in the number of insects, which will result in an influx of different kinds of pathogens.
Roos et al. recommend an overall increase in measurements for protecting crops against the ramifications of global warming. To mediate the damaging effects of diseases on crops caused by climatic changes in Sweden, the authors suggest further development in genetically modified crops that can withstand pathogenic aggression. Additional research is warranted to decrease the dependency on pesticides in order to protect crops against disease, and thus also decrease the risk of potential damages to human health.