Abstract
Twelve field trials were completed in North Carolina from 2005 to 2007 to determine the impact of planting pattern on peanut yield, market grade characteristics, and pest reaction for the Virginia market type cultivars Perry and VA 98R. The first set of experiments was designed to evaluate incidence of Cylindrocladium black rot (caused by Cylindrocladium parasiticum) using a factorial treatment arrangement of two cultivars, two levels of fumigation (none or metam sodium at 112 L/ha), and two levels of planting pattern (single rows spaced 91-cm apart or twin rows spaced 18 cm apart on 91-cm centers). Damage from tobacco thrips (Frankiella fusca) was higher in the cultivar VA 98R planted in twin rows than in single rows or for the cultivar Perry. Visible symptoms associated with Cylindrocladium black rot were not affected by planting pattern. However, in 1 of 3 trials pod scarring as a result of feeding by southern corn rootworm (Diabrotica undecimpunctata Howardi) was greater in twin rows compared with single rows. In the second set of experiments designed to evaluate incidence of Sclerotinia blight (caused by Sclerotinia minor), a factorial treatment arrangement consisting of two cultivars, two levels of boscalid (none or boscalid at 0.44 kg ai/ha), and two levels of planting pattern was implemented. Boscalid decreased Sclerotinia blight incidence at one location, and increased pod yield. Yield of Perry was lower when grown in twin rows versus single rows, but yield of VA 98R was higher in twin rows. Peanut planted in twin rows yielded more than peanut planted in single rows regardless of cultivar or fumigation treatment in some but not all trials, although yield of Perry was lower in some trials in twin rows when Sclerotinia blight was present but not when Cylindrocladium black rot or tomato spotted wilt (caused by a tospovirus) was present. Results from these experiments suggest that planting pattern can have a minor impact on response to pests and that yield and market grades are often improved when peanut is planted in twin-row planting patterns compared with single rows.