Technical Abstract: Field experiments were conducted near Weslaco, TX, (Lat. 26 degrees 8' N) between 1999 and 2001 in order to evaluate the field performance of pre- and post-mycorrhizal- inoculated tomato and onion (2001, only) transplants. In 1999, >Heatmaster= tomato (Lycopersicon esculentum, Mill.) transplants were inoculated at 17 kg/ha with Glomes intraradices (Reforestation Technologies, Salinas, CA) at transplanting; in 2000, >Heatmaster= and >Florida 47' plants were treated at transplanting and exposed to two irrigation regimes; and in 2001, >Heatmaster= plants were either pre- or post-transplant inoculated and grown in a light (Hebbronville) or heavy (Raymondville) textured soil. In all years, cumulative fruit yield from mycorrhizal-treated plants were significantly greater by the second and/or third harvests, but final season yield, fruit number and average fruit weight were usually similar to controls. Marketable yield and fruit number tended to improve when plants were treated with mycorrhizae. Onion (Allium cepa, L.) cultivars, Granex 1015Y and Terlingua, inoculated with mycorrhizae in a seedling mix or at transplanting and planted in Hebbronville and Raymondville soils tended to have greater yields and accelerated maturation, but bulb soluble solids at harvest were similar when compared to uninoculated plants. Bulbs from mycorrhizal-treated plants were more uniform in diameter. Bulbs stored at 13.2 C for 120 days suffered less soluble solids and weight loss if they were from mycorrhizal-treated plants. Bulb sprouting was not affected by any treatment.