Complex sentence: In 1878, Burpee dropped his partner and founded W. Atlee Burpee & Company, mainly for garden seeds, but poultry wasn't dropped from the Burpee catalog until the 1940s.
Split into simpler sentences: In 1878, Burpee dropped his partner and founded W. Atlee Burpee & Company. THe company soon switched to primarily garden seed, but live poultry wasn't dropped from the Burpee catalog until the 1940s.