Future weed, pest and disease problems for plants

Authors: Ziska, Lewis; Runion, George

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/1/2005
Publication Date: 3/1/2007
Citation: Ziska, L.H., Runion, G.B. 2007. Future weed, pest and disease problems for plants. Book Chapter. In: Newton, P.C.D., Carran, R.A., Edwards, G.R., Niklaus, P.A., editors. Agroecosystems in a Changing Climate. Boca Raton, FL: CRC Press. p. 261-287.

Interpretive Summary: Recently the human population surpassed six billion. As populations increase, fossil fuel burning and deforestation will continue to be human-derived sources of atmospheric carbon dioxide[CO2]. Overall the documented increases in atmospheric [CO2] are likely to change the biology of agricultural pests in two fundamental ways. The first is climate instability, the second is the direct stimulation of plant growth by rising [CO2]. In this review we examine what is currently known regarding the impact of rising temperature and [CO2] on weeds, insects, and pathogens. We conclude that much of our current knowledge is based on single factor experiments. Although useful, these experiments are limited in their ability to predict consequences for agro-ecosystems. We suggest that our current knowledge base could be improved by an integrated ecosystem approach that considers multi-factor responses particularly at the ecosystem level. These approaches would include quantifying CO2 and temperature changes in host-plant performance, anticipating the range and establishment of insect and pathogen migration, and weed-crop interactions, as they relate to changes in climate. Overall, any accurate assessment of future threats will be dependent on modeling efforts that recognize that interactions at the community level are governed by a complex set of feedbacks between soil, plant, atmosphere, and pest populations.

Technical Abstract: As climate and atmospheric carbon dioxide [CO2] shift in response to anthropogenic change, the outbreak and damage induced by agricultural pests, principally weeds, insects, and diseases may increase. Although the interaction of climate/[CO2] and the impact of agricultural pests has been recognized, few integrated studies quantifying their potential response exist. In this review, we examine what is currently known regarding agricultural pests and how they could potentially respond to climatic change. The impacts of climate are multi-faceted and include the direct effects of CO2 and concomitant changes in climate on weed growth and weed/crop competition; secondary CO2-induced effects on crop hosts (digestibility, chemical defenses, canopy micro-climate) that may affect insect fecundity and pathogen success; and, temperature/precipitation changes that directly alter where and when pathogen or insect outbreaks occur. While providing a tentative mechanistic basis for both the direct and indirect consequences of [CO2]/climate, we also determine, in part, how current pest management efforts might fare in a future climate. While the current review is problematic in many areas, our overall goal is to begin a synthesis of what is known and to derive a preliminary set of key climatic questions to address in the context of pest biology and agro-ecosystems.