In-row plant spacing and date of harvest of 'Beauregard' sweetpotato affect yield and return on investment

The effects of plant spacing (15, 23, 31, and 38 cm) and date of harvest on yield and economic return of 'Beauregard' sweetpotato [Ipomoea batatas (T. ) Lam.] were studied. For comparison, 'Jewel' was included at one spacing. As in-row plant spacing decreased, yield of U.S. No. 1, canners, and total marketable root production increased when plants were harvested 103 days or later after transplanting. The yield of jumbo roots generally increased wi th in-row spacing because of less plant-to-plant competition. Total marketa ble and No. 1 grade yields of 'Beauregard' at the closest spacing (15 cm) w ere greater than those of 'Jewel'. 'Beauregard' roots sized more quickly th an 'Jewel' roots regardless of spacing. The optimal time for harvesting 'Be auregard' was 100 to 110 days after transplanting, while acceptable yields could be obtained as early as 90 days after transplanting depending on mark et prices. Economic analysis of 'Beauregard' spacing data indicated that 23 cm would be the preferred spacing if a late harvest was anticipated, while the 15-cm spacing would be best if harvested at approximate to 110 days af ter transplanting. Thus, sweetpotato growers should place 'Beauregard' at a n in-row spacing of 15 or 23 cm, depending on projected date of harvest, on or before 10 June, to obtain the best yields with the highest return on in vestment.