THE DUSTERS are working in * large numbers from Orange } County Airport, according to \ W. li, (Bill) Nichols, airport *manager. Three outfits . . . in-! eluding Troy Colboch and his * Airborne Agricultural Service *! Corp. bunch from Cypress Air- 1 park . . , are at the Santa Ana field.Nichols said the dusters , . . quite a few using helicopters . . . are spraying grain crops to kill wild mustard and wild radish, i Crop dusting really is big busi-; ness in Orange County.Nichols added that plans and specifications for the new runway will be in the hands of theCAA early this week. He said l e hopes bids will be received in time for work to start about March 1. The federal government has supplied $10,000 for the froject.ON THE SERTECT «f rrm.