Looks pretty funky... I had that same white mold on my hydro. Same location too. I solved it by spraying it with hydrogen peroxide localized on the mold. I dont know if this is the correct way to do it but it worked wonders for me.
GetThisOrDie Reviewed by GetThisOrDie on . Problem: White mold on roots What is your experience level? (first timer, novice, experienced...) Your Equipment: .1) Type and wattage of lights. (MH, HPS, CFL's, tube fluorescents, LED's) 1000w Lumatek w/ 1000w Hortilux Blue .2) Distance from tops? ~12" .3) Reflector type? (cool tube set-up, bat wing, enclosed reflector, bare bulb...) Magnum XXXL .4) Is there a consistent fresh air supply? Yes .5) Do you have an exhaust fan and a circulation fan? Yes .6) What are the bulb wattages, kelvin ratings, and schedule? Rating: 5