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Ozone and Sulfur Dioxide Effects on Reproduction and Host-Parasite Relationships of Selected Plant-Parasitic Nematodes. D. E. Weber, Plant pathologist, Terrestrial Ecology Division, Corvallis Environmental Research Laboratory, U.S. Environmental Protection Agency, Corvallis, OR 97330; R. A. Reinert(2), and K. R. Barker(3). (2)Plant pathologist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, North Carolina State University; (3)Plant pathologist, Department of Plant Pathology, North Carolina State University, Raleigh, 27650. Phytopathology 69:624-628. Accepted for publication 15 December 1978. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1979. DOI: 10.1094/Phyto-69-624.

The effects of air pollution on the reproduction of five species of plant-parasitic nematodes with different feeding habits and host effects were studied by exposing soybean or begonia hosts to ozone (O₃) and sulfur dioxide (SO₂), singly or in combination, and to charcoal filtered (control) air. Exposure of infected soybean plants to O₃ and an O₃-SO₂ mixture inhibited reproduction and development of Heterodera glycines and Paratrichodorus (Nanidorus) minor, but the increase of Belonolaimus longicaudatus usually was unaffected. Exposure of soybean host plants to SO₂ enhanced the reproduction of Pratylenchus penetrans compared with that in plants exposed to the charcoal filtered air control or to O₃. Foliar injury of begonia by O₃ or an O₃-SO₂ mixture inhibited the increase of Aphelenchoides fragariae. The suppresive effects of A. fragariae were greater in leaves pre-exposed to O₃ or an O₃-SO₂ mixture before rather than after leaves were inoculated with nematodes. The growth of nematode infested soybean plants and leaves of begonia was inhibited by O₃ and the O₃-SO₂ mixture compared with that of similar control plants grown in the presence of nematodes and charcoal filtered air. Nodulation of soybean plants inoculated with B. longicaudatus and P. minor was suppressed by O₃ and the O₃-SO₂ mixture. The inhibition of nodulation of soybean by H. glycines was extensive; the pollutants had no further detectable effect.