CalClim: California Climate Data Archive

CALIFORNIA CLIMATE WATCH
CURRENT ISSUE: February 2006

Read the full newsletter here: PDF format

Agricultural Pests to be Just as Nagging in the Future

By Laura Edwards
Western Regional Climate Center

Before the recent snows and cold snap left snow in my yard, spring-like weather was upon us in February, bringing with it thoughts of spring gardens and blooming bulbs. What does my backyard vegetable garden have anything to do with climate change, you may ask? Well, it isn't so much the garden in my backyard, but climate changes do have impacts on gardens and farms of all sizes through weeds, insects and disease.

Different pest management practices may need to be used to control new pests or increased biomass of weeds with a changing climate. Warmer, wetter, cooler or drier conditions have varying results depending on the plant, pest or weed type. For plants, there are 2 primary categories that have been studied for their response to elevated carbon dioxide (CO2) levels in the atmosphere, C3 and C4. C3 plants produce a 3-carbon chain organic acid during photosynthesis, and C4 plants produce a 4-carbon chain organic acid (1). C3 plants comprise about 95% of known plant species, and contribute to 90% of the per capita food supplies worldwide (2). 14 of the 18 "world's worst weeds" are C4 plants. Controlled environment chamber studies have shown that C3 plants respond to increased CO2 by growing faster and larger, by 10-143%, increasing their carbon intake. This is also called the CO2 fertilization effect. C4 plants do not respond with the same stimulated growth response. In some studies where C3 and C4 plants are in competition, "C3 species generally benefit from CO2 enrichment at the expense of C4 species". (2) This is good news for those who want to decrease carbon in the atmosphere, as the fertilization effect seen in C3 plants is beneficial for carbon storage, and may reduce the effects of C4 weeds.

This stimulated growth in crops can be good or bad news for weeds and insects. This is where pest management gets more complicated--when changes in crop growth, irrigation, and natural climate intermingle. If the climate warms or cools, the geographic range of various pests can migrate or adapt to new climate conditions. If warming occurs, tropical species may move to higher latitudes with their increasing temperature-favorable range and lack of cold stress. Some weeds and insects prefer moist conditions, and some climate models have forecast wetter conditions in some areas with an increase in global mean temperature. This particular effect has been experienced in desert regions that have been converted to irrigation farming, making an environment favorable for these non-native types of pests.

The application of herbicides and pesticides can have mixed results when trying to control the invasion, spread, or the harm of pests in agriculture. Temperature, precipitation, soil moisture, wind and humidity each play a role in the effectiveness of pest treatments. Current methods may not be as influential in a future climate. In addition to the long-term changes in these parameters, changes in extreme events (their frequency and intensity) and large-scale phenomena like the Inter-Tropical Convergence Zone (ITCZ), a weather feature of the tropical regions, can move pests like locusts to new regions.

Agriculture is a huge business in California, grossing $31.8 billion in 2004 (3). California is also a unique location in that it is the sole provider (99% or more) of at least 12 specialty crops, including almonds, figs, raisins, artichokes, olives and walnuts. The largest fraction, $9.66 billion, or 30%, of the state's gross agricultural income comes from fruits and nuts. Milk and cream are the state's single top commodity, accounting for $5.37 billion in 2004. Agriculture is a large source of revenue for the state, and it couldn't be done without pest management. Worldwide, crop production losses due to weeds amount to about 12%, but is as high as 25% in primitive agricultural systems.

At home in our yards there are pests that can invade our structures, landscapes, turf and gardens. The University of California, Davis' Integrated Pest Management Program has online resources on how to best manage weeds, insects and pests of all types in your home and garden. They present a combined approach of non-chemical and chemical methods of controlling pests, whether it is in your backyard vegetable or flower garden, or your large-scale agricultural business. There are pests of all shapes and sizes, adapted to all climate regimes. One type or another will always be present, but there are tools to control them, even under future changing climate conditions.

References:
1. Mackenzie, Fred T., 2003. Our Changing Planet, 3rd ed. Prentice Hall, New Jersey, 580 pp.
2. Patterson, D. T., J. K. Westbrook, R. J. V. Joyce, P. D. Lingren, and J. Rogasik, 1999. Weeds, insects and diseases. Climatic Change, 43, pp. 711-727.
3. California Department of Food and Agriculture, 2005. California Agriculture Highlights 2005. http://www.cdfa.ca.gov/
4. University of California-Davis Integrated Pest Management website: http://www.ipm.ucdavis.edu/index.html

Last updated 7/25/06.

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California Climate Watch Archive All data in the Climate Watch is provisional and subject to change. Please contact us for updated and quality-checked data. *Previous California Climate Watch* Issues 2006 2005 2004 Monthly Weather Summaries** 2006 2005 2004	CALIFORNIA CLIMATE WATCH CURRENT ISSUE: February 2006 Read the full newsletter here: PDF format Agricultural Pests to be Just as Nagging in the Future By Laura Edwards Western Regional Climate Center Before the recent snows and cold snap left snow in my yard, spring-like weather was upon us in February, bringing with it thoughts of spring gardens and blooming bulbs. What does my backyard vegetable garden have anything to do with climate change, you may ask? Well, it isn't so much the garden in my backyard, but climate changes do have impacts on gardens and farms of all sizes through weeds, insects and disease. Different pest management practices may need to be used to control new pests or increased biomass of weeds with a changing climate. Warmer, wetter, cooler or drier conditions have varying results depending on the plant, pest or weed type. For plants, there are 2 primary categories that have been studied for their response to elevated carbon dioxide (CO2) levels in the atmosphere, C3 and C4. C3 plants produce a 3-carbon chain organic acid during photosynthesis, and C4 plants produce a 4-carbon chain organic acid (1). C3 plants comprise about 95% of known plant species, and contribute to 90% of the per capita food supplies worldwide (2). 14 of the 18 "world's worst weeds" are C4 plants. Controlled environment chamber studies have shown that C3 plants respond to increased CO2 by growing faster and larger, by 10-143%, increasing their carbon intake. This is also called the CO2 fertilization effect. C4 plants do not respond with the same stimulated growth response. In some studies where C3 and C4 plants are in competition, "C3 species generally benefit from CO2 enrichment at the expense of C4 species". (2) This is good news for those who want to decrease carbon in the atmosphere, as the fertilization effect seen in C3 plants is beneficial for carbon storage, and may reduce the effects of C4 weeds. This stimulated growth in crops can be good or bad news for weeds and insects. This is where pest management gets more complicated--when changes in crop growth, irrigation, and natural climate intermingle. If the climate warms or cools, the geographic range of various pests can migrate or adapt to new climate conditions. If warming occurs, tropical species may move to higher latitudes with their increasing temperature-favorable range and lack of cold stress. Some weeds and insects prefer moist conditions, and some climate models have forecast wetter conditions in some areas with an increase in global mean temperature. This particular effect has been experienced in desert regions that have been converted to irrigation farming, making an environment favorable for these non-native types of pests. The application of herbicides and pesticides can have mixed results when trying to control the invasion, spread, or the harm of pests in agriculture. Temperature, precipitation, soil moisture, wind and humidity each play a role in the effectiveness of pest treatments. Current methods may not be as influential in a future climate. In addition to the long-term changes in these parameters, changes in extreme events (their frequency and intensity) and large-scale phenomena like the Inter-Tropical Convergence Zone (ITCZ), a weather feature of the tropical regions, can move pests like locusts to new regions. Agriculture is a huge business in California, grossing $31.8 billion in 2004 (3). California is also a unique location in that it is the sole provider (99% or more) of at least 12 specialty crops, including almonds, figs, raisins, artichokes, olives and walnuts. The largest fraction, $9.66 billion, or 30%, of the state's gross agricultural income comes from fruits and nuts. Milk and cream are the state's single top commodity, accounting for $5.37 billion in 2004. Agriculture is a large source of revenue for the state, and it couldn't be done without pest management. Worldwide, crop production losses due to weeds amount to about 12%, but is as high as 25% in primitive agricultural systems. At home in our yards there are pests that can invade our structures, landscapes, turf and gardens. The University of California, Davis' Integrated Pest Management Program has online resources on how to best manage weeds, insects and pests of all types in your home and garden. They present a combined approach of non-chemical and chemical methods of controlling pests, whether it is in your backyard vegetable or flower garden, or your large-scale agricultural business. There are pests of all shapes and sizes, adapted to all climate regimes. One type or another will always be present, but there are tools to control them, even under future changing climate conditions. References: 1. Mackenzie, Fred T., 2003. Our Changing Planet, 3rd ed. Prentice Hall, New Jersey, 580 pp. 2. Patterson, D. T., J. K. Westbrook, R. J. V. Joyce, P. D. Lingren, and J. Rogasik, 1999. Weeds, insects and diseases. Climatic Change, 43, pp. 711-727. 3. California Department of Food and Agriculture, 2005. California Agriculture Highlights 2005. http://www.cdfa.ca.gov/ 4. University of California-Davis Integrated Pest Management website: http://www.ipm.ucdavis.edu/index.html Last updated 7/25/06.