check this thread out bro, will answer all questions you have. i found this very helpful:
http://www.icmag.com/ic/showthread.php?t=159960
ps. if you do have root aphids, i found merit 75 works like a charm.
http://www.icmag.com/ic/showthread.php?t=159960
ps. if you do have root aphids, i found merit 75 works like a charm.