Luck et al. (2011) conducted a review of the impact of climate change on diseases that affect wheat, rice, soybeans, and potatoes. Because these crops are a key source of food and oil, understanding the factors that affect their availability is crucial. The authors found that the relationships between climate change, pathogens, and host crops vary among crop type and the location in which they are cultivated. Additionally, the data show varying crop responses to differing climate change factors such as precipitation, temperature, storm frequency, and atmospheric CO2 levels. The authors conclude that further research is warranted to gain a deeper understanding of the complex relationship between climate change and plant disease incidence. —Daniela Hernández
Luck, J., Spackman, M., Freeman, A., Trebicki, P., Griffiths, W., Finlay, K., Chakraborty, S., 2011. Climate change and diseases of food crops. Plant Pathology 60, 113–121.
The authors suggest that an increase in temperature will negatively affect the wheat stripe rust-causing pathogen, Puccinia striiformis (Pst). Data gathered from China between the years 1950 and 1995 showed that an increase in temperature caused a decrease in Pst infection. Moreover, this correlation shows that an increase in temperature is projected to cause a general decrease in wheat yield. The slowest warming projections predict a 25–44% decrease in wheat yield, whereas the fastest warming projections predict a 60–79% decrease in wheat yield. Additionally, changes in precipitation are expected to affect wheat diseases. Wet cool summers, for instance, are expected to create more favorable conditions for aphids that will ultimately intensify the spread of yellow dwarf viruses.
The data gathered on rice diseases show how different climate factors affect epidemics in different ways. In general, rice blast, a disease caused by the pathogen Magnaporthe grisea, is expected to increase under most scenarios, with temperature change being the most influential factor. In cool subtropics, increasing temperature was shown to cause an increase in the rice blast severity; however, an increase in temperature also showed a decrease in rice blast epidemics in warm/cool humid subtropics. The effect of CO2 changes on rice crop diseases was also observed. The data show that rice grown under higher levels of CO2 has more severe leaf blast epidemics; conversely, panicle blast incidence remains unchanged under the same conditions.
The literature on the subject also points out that an increase in the frequency of storms, caused by climate change, will result in an increase in the dispersal of plant pathogens. Luck et al. researched this correlation through data focused on soybean crop diseases. Hurricane Ivan, for example, introduced Phakopsora pachyrhizi to Louisiana and succeeded in spreading it throughout eight different states. This pathogen affected the soybean crops by causing Asian soybean rust on the plant. Another severe storm, hurricane Wilma, was linked to the dispersal of the pathogen, Xanthomonas citri. This pathogen attacked citrus orchards and spread throughout the state of Florida. Thus the researchers found that climate change factors will not only affect pathogens biologically, but will also affect their dispersal.
Luck et al. indicates that climate change is expected to cause a general decrease in potato yield by 18–32%. Moreover, the actual effect on the potato diseases will vary among the climate factors. An increase in CO2 levels, for example, is predicted not to cause a significant change in early blight incidence caused by the pathogen, Alternaria solani. Furthermore, data also show that an increase in temperature coupled with changes in precipitation will increase the potato crops’ susceptibility to bacteria such as Pectobacterium carotovorum and Pectobacterium chrysanthemi.
The present research conducted by Luck et al. briefly reviewed changes in some of the most pressing diseases that affect wheat, rice, soybeans, and potatoes; the effects of climate change on these diseases were also reviewed. Since there are several climate parameters that can affect pathogens, the authors suggest more experiments be conducted measuring the severity and dispersal of crop diseases under a combination of these factors. Moreover, they also recommend data be collected to take into account the effect of disease management practices on pathogens.