Tons of pests on Gai lan (Chinese brocolli)
I saw some holes in my gailan(or kailan). I think it's categorized as a type of kale and also called chinese brocolli. I tried to take some pictures, but the quality isn't that good. It really had a whole bunch of different kinds of pests that I've never seen before. There were small green worms. Lots of dusty white specks that were ovalish; it almost seemed like mold. There was some holes in the leaf, but it was covered with some web looking like material. A last pest that I saw was this small black bug with yellow markings on its back. Sometimes I saw a pair of those black bugs walking with their butts stuck together (one walking backwards, one walking forwards. I think they were mating). There's so many pests on those veggies that I just cut them all down and threw them out. I really want to plant these and I was wondering how do I kill these pests so I can enjoy my gailan. Thanks in advance!
Green worm is in the middle bottom portion of the pic