The Science & Economics of Blister Rust on Pine in North America Due to Climate Change

Introduction

Climate change is warming the Earth, causing changes in the landscape and creating conditions optimal for diseases to thrive. The disease triangle shows that three elements are needed for a disease to grow and establish itself successfully (Sturrock et al., 2011). They are a susceptible host, a virulent pathogen, and a favourable climate. The changing climate can increase the prevalence of a favourable environment, creating an optimal environment for a pathogen to attack a host (Dudney et al., 2021). A particularly problematic disease is blister rust in pine stands in British Columbia.

Blister Rust & Climate Change

Blister rust affects hard pines, creating a fungus on the tree’s inner bark. It causes deformity, growth reductions, mortality, and decreased seed production (Johnson, 1986). The pine tree acts as the host in the disease triangle for the fungus to grow during favourable conditions. Blister rust is causing major mortality and health issues in pine, creating concerns for the future use of pine for lumber.

Climate change is causing an environment that enables this disease to thrive in North America. Blister rust needs a cool environment with sufficient moisture to thrive (Dudney et al., 2021). Climate change is shifting species abundance from more arid regions to colder regions in the north that were previously considered inhospitable. Aridity plays a critical role in changing host-pathogen interactions, and the increasing drought in arid environments may reduce infection rates by inducing stomata closure and making it more difficult for pathogens to access the host. Whereas cooler, more northern areas provide the moisture needed for pathogen reproduction (Dudney et al., 2021).

Blister rust ranks as one of the worst tree pandemics in history. The impact it has had in recent years, and is continuing to have, on pine stands has the potential to cause major damage to the timber industry. White pine blister rust has been particularly problematic in Canada, and Figure 2 shows the growing distribution of infection across the country. The economic setbacks can be devastating if the disease spreads to areas not used to fighting this disease, which are more susceptible to damage, with no alternate species planted.

Economic Loss

A similar problem arose with the mountain pine beetle outbreak. More than 53% of merchantable pine had been attacked, and Corbett et al. (2015) estimated a cumulative present value loss of $57.37 billion in GDP and a $90 billion decline from 2009 to 2050. The pine beetle outbreak showed that economic loss from such an outbreak can be large, so it would be in our best interests to prevent a similar outbreak from happening again. The loss of profitable lumber from blister rust may be substantial, and the cost of applying control measures to these stands may be as well.

Control Measures

A control measure may be alternate host species removal, as each tree requires an alternate host plant to be infected first before it transfers to the tree. The cost of alternate species removal, or the thinning of infected trees, would be high in cost. As of now, the question is whether to invest in control measures to limit the number of pine trees infected or plant alternate conifer species that do not get infected by blister rust, although it may not be as desirable in the lumber industry.

Deployment of pines from the south into other areas has shown to be successful in combating fusiform rust. Seedlings with a resistant gene from control mating have been deployed over forest plantations struggling with rust issues. Sneizko et al. (2021) state the estimated return investment for every dollar spent on fusiform rust resistance is $5–20. If the same can be done to other strains of rust with similar economic gain, there is a good incentive to put in the time and initial investment into more genetic research and experimentation. Hagle and Grasham (1988) performed an experiment to determine the net value of stands with either no treatment, pruning, or pruning with excising. Their study shows the greatest net value was with the treatment of both pruning and excising, while the least net value resulted from the no-treatment control.

The results of these two studies show that there may be the most economic benefit from exerting control measures on infected stands to decrease the negative effects the disease has on the trees and hope that the trees can still grow to be good lumber that can be economically benefited from.

Media Attributions

Figure 1: “Cronartium ribicola J.C. Fisch” by André Carpentier, Natural Resources Canada, Canadian Forest Service, and Laurentian Forestry Centre (2015), via Government of Canada, is used under the Government of Canada Terms and Conditions.

Figure 2: “Locations where Cronartium ribicola has been found” by Natural Resources Canada (2007), via Government of Canada, is used under the Government of Canada Terms and Conditions.

References

Carpenter, A., Natural Resources Canada, Canadian Forest Service, & Laurentian Forestry Centre (2015). Cronartium ribicola J.C. Fisch. [Image]. Government of Canada. https://www.exoticpests.gc.ca/photo/disease/001837/WyJDcm9uYXJ0aXVtIHJpYmljb2xhIiwiSi5DLiBGaXNjaC4iXQ

Corbett, L. J., Withey, P., Lantz, V. A., & Ochuodho, T. O. (2015). The economic impact of the mountain pine beetle infestation in British Columbia: provincial estimates from a CGE analysis. Forestry: An International Journal of Forest Research, 89(1), 100–105. https://doi.org/10.1093/forestry/cpv042.

Dudney, J., Willing, C. E., Das, A. J., Latimer, A. M., Nesmith, J. C. B., &Battles, J. J. (2021). Nonlinear shifts in infectious rust disease due to climate change. Nature Communications, 12, Article 5102. https://doi.org/10.1038/s41467-021-25182-6.

Hagle, S. K., & Grasham, J. L., (1988). Biological and economic feasibility of pruning and excising white pines for blister rust control (Report No. 88-6). USDA Forest Service, Northern Region, Pest Management.

Johnson, D. W. (1986). Forest Insect and Disease Leaflet 62: Comandra blister rust. U.S. Department of Agriculture, Forest Service. https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev2_026341.pdf.

Marty, R. J. (1966). Economic guides for blister-rust control in the east (Res. Pap. NE-45). U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. https://www.fs.usda.gov/research/treesearch/3862.

Natural Resources Canada. (2007). Locations where Cronartium ribicola has been found [Map]. Government of Canada. https://www.exoticpests.gc.ca/es-details/disease/24.

Sniezko, R. A., Smith, J., Liu, J-J., & Hamelin, R. C. (2014). Genetic resistance to fusiform rust in southern pines and white pine blister rust in white pines—A contrasting tale of two rust pathosystems—Current status and future prospects. Forests, 5(9), 2050–2083. https://doi.org/10.3390/f5092050.

Sturrock, R. N., Frankel, S. J., Brown, A. V., Hennon, P. E., Kliejunas, J. T., Lewos, K. J., Worral, J. J., Woods, A. J. (2011). Climate change and forest diseases. Plant Pathology, 60(1), 133–149. https://doi.org/10.1111/j.1365-3059.2010.02406.x.