Another Gillet rival was John Rock (born Johann Fels), whose large, Fremont-based California Nursery Company (established in 1865) introduced French prune scion wood in 1886 and claimed to sell the best varieties for dessert prunes. Gillet had made the same claim since 1883. For several years, Gillet's advertisements denounced unnamed rivals, whom he said fraudulently claimed his nursery stock as their own. Of the German-born nurseryman, Luther Burbank said, "John Rock is the most learned man in his profession to be found in California."
