Anyway, it would have to be in either in spawn chunks or in chunks currently loaded by active players to exist. Is it in spawn chunks?
Blocks like sugar cane are only randomly ticked within chunks which are 128 blocks of a player so it doesn't matter if they are in spawn chunks; I also really doubt that simple random block updates can ever cause any lag unless the server is already having performance issues (there are about 200 chunks within ticking range; assuming there are an average of 5 sections loaded per chunk this is 1000 sections, each of which has 3 blocks randomly ticked per game tick for a total of 3000 random block ticks per game tick).
I've never had any issues from fields of hundreds of crops, or noticed any increase in tick time (usually 2 ms or less out of a maximum of 50 ms, despite hundreds of tile entities and dozens of entities at my main base in the spawn chunks (note that the first image shows 312 mobs loaded, far beyond the vanilla "E:" value of 113 total entities; it is higher even when at my base since the "E:" number only shows client-side entities while "mob counts" is server-side). Of course, 1.6.4 performs better than newer versions even without my own optimizations).