FOR IMMEDIATE RELEASE                           Contact: Michael Sund, Director
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May 2, 1995                                     Corporate Communications
                                                (619) 453-8030


                         MYCOGEN TO CHANGE FISCAL YEAR

      SAN DIEGO, Calif. -- Mycogen Corporation (Nasdaq: MYCO) announced today 
that its board of directors has approved a change from its current calendar year
end to a fiscal year ending August 31, effective August 31, 1995.

      Jerry Caulder, Mycogen's chairman, president and chief executive officer, 
said the change is being made to better match financial reporting with the 
company's business cycle. Since its December 1992 acquisition of the Mycogen 
Plant Sciences seed business, more than 70 percent of Mycogen's 1993 and 1994 
operating revenues have come from the sale of planting seeds, and Caulder said 
the company expects the seed business to be the primary source of its future 
revenue growth.

      "Seed inventories reach their lowest point of the year in August, and 
production, marketing and promotional expenses are concentrated in the fall," 
Caulder explained. "This will put Mycogen on the same reporting cycle as other 
publicly traded seed companies and give a much more timely and accurate picture
of the company's finances."

      Carl Eibl, Mycogen's executive vice president - finance and legal affairs,
said Mycogen will remain on its present reporting cycle for the quarter ending 
June 30, and then report an audited eight-month year ending August 31, 1995.

      Mycogen is a diversified agricultural biotechnology company that develops 
and markets environmentally compatible biopesticides and planting seeds for 
improved crop varieties to control pests and increase food and fiber production.