Fungal spores record Iroquoian and Canadian agriculture in 2nd millennium a.d. sediment of Crawford Lake, Ontario, Canada

Pollen analysis identified domestic Zea mays (corn, maize), Phaseolus vulgaris (kidney bean), Helianthus annuus (sunflower) and Cucurbita pepo (squash) accompanied by spores of fungi, many of which cause crop diseases, such as Ustilago maydis (=U. zeae, corn smut), Puccinia sorghi (corn rust), Uromyces appendiculatus (bean rust) and Puccinia graminis (wheat rust). Spores were most abundant in two intervals, ca. a.d. 1300 to ca. 1500 when prehistoric Iroquoian agriculture flourished near the lake and since 1830, when historic Triticum aestivum (wheat) agriculture began. In addition to dispersal by wind, Branta canadensis (Canada goose) also transported fungal spores to the lake via their dung. Spores of fungi that parasitize crop plants may be more abundant than pollen of their host plants and therefore spores may more readily indicate ancient agriculture.