In case your 4th column contains spaces you can split with a limit. Here I am opening the file contained in a HEREDOC as opposed to using the automatically opened DATA file handle.

johngg@shiraz:~/perl/Monks$ perl -Mstrict -Mwarnings -E '
open my $inFH, q{<}, \ <<__EOF__ or die $!;
1 2 3 delta
1 2 3 apricot
1 2 3 blue cup
1 2 3 charlie
1 2 3 yellow banana
1 2 3 bravo
1 2 3 echo
1 2 3 fox
__EOF__

print for
   map { substr $_, 50 }
   sort
   map { pack q{A50A*}, ( split m{\s+}, $_, 4 )[ -1 ], $_ }
   <$inFH>;

close $inFH or die $!;'
1 2 3 apricot
1 2 3 blue cup
1 2 3 bravo
1 2 3 charlie
1 2 3 delta
1 2 3 echo
1 2 3 fox
1 2 3 yellow banana
[download]

Just another way out of many.