Plastic UV reflective mulch (metalized mulch) and wheat straw mulch delayed colonization by Bemisia argentifolii Bellows & Perring and the incidence of aphid-borne viruses in zucchini squash. No insecticides were used in either mulch treatment. The mulches were compared with a preplant treatment of imidacloprid and an untreated, unmulched control. In 2000, yield of marketable fruit in the plastic and straw mulched plots was approximately twice that from the imidacloprid plot. In 2001, yield from the straw mulch plots was twice that of the imidacloprid and plastic mulch plots. Yields from both mulched plots and from the imidacloprid plots ranged from 3 to 12 times higher than those from the control plots. The mulches were more effective than a preplant application of imidacloprid in reducing the incidence of both B. argentifolii and aphid-borne viruses. Plants growing over the plastic mulch and the straw mulch grew more rapidly and reached a larger size, as determined by plant dry weight, than did those growing over bare soil, with or without imidacloprid. The spectral quantum flux from the plastic averaged between 80 and 90% of ambient spectral quantum flux values in the UV (300–400-nm) range. Spectral quantum flux values of wheat straw were similar to those of the reflective mulch and ambient near 300 nm but were virtually identical to bare soil beyond 320 nm. The metalized mulch reflected 94% of the incoming photosynthetically active radiation (PAR) in the 400–700-nm range compared with ambient, whereas the straw mulch reflected 85%. Bare soil reflected only 41% of incoming PAR compared with ambient.