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April 12, 2005; 102 (15)
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Cover image: Rothamsted staff, in the 1930s, sampling the archive of grain, straw, and soil samples from the Broadbalk winter wheat experiment started in 1843 in Harpenden, United Kingdom. Use of this unique, 160-year archive has linked long-term population dynamics of pathogens to air pollution. Modern "molecular archaeology" techniques have enabled the extraction of DNA from fungal pathogens present on wheat harvested in the 19th century. The relative amounts of two pathogens (Mycosphaerella graminicola and Phaeosphaeria nodorum) reveal long-term trends in the dynamics of their populations. See the article by Bearchell et al. on pages 5438–5442. Image used with permission from the Lawes Agricultural Trust.

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April 12, 2005; 102 (15)
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