some do some don't it is matter of choice and hard find out since good giant growers do not tell all there secrets and sometimes none of them.

As far as Fertilizers go we are all organic. For insecticides and Fungicides we go with a prevention program. We use a systemic insecticide called merit. Then end the season with rotating fungicides every 10 days. You can do it organic. Although I do not understand why you would want to. The giant is for display only. We are organic on all our veggies.

You can use rock dust for giant vegetables and go 100% organic. Pests and diseases are usually the result of overfertilization (which can occur with compost too), lack of ground cover, or general lack of plant diversity in growing conditions. Pesticides can make things worse since they kill off the predatory insects that keep pests in check, and pests tend to come back faster than predators.

I agree with rainydays that giants are mainly just for show (although it's possible to grow tasty giants, they just aren't practical unless you want to feed a crowd) but I would never spread poisons in the environment I'm living and working in, especially not if any plants nearby are meant to be eaten.