Need Help ASAP

I am new to growing. I have about a 3week old plant in an aerogarden. One of my plants is beginning to have this white crusty substance building up on the its stem. What may be causing this? I have a pic but not a good one of the stem...will post more when i get the chance, does plant look healthy?

do u have any pics? could just be the stem growing and sheding its old stem

noobin it . stem shed man . relax dont panic it will fall off. i thought my aerogarden wa soooo badass at first and now i want to get rid of it. trust me its a hassle when growing weed considering the roots will grow out of control . stick to soil