Submitted to: Plant Growth Regulator Society of America Meeting
Publication Type: Proceedings
Publication Acceptance Date: November 22, 1999
Publication Date: N/A
Technical Abstract: Peach tree size has been restricted when trees were grown continuously with grass after tree planting. However, control of excess vegetative growth of fruit trees was inconsistent when grass was planted beneath mature trees. This research determined the effect of seven grasses on growth, leaf nitro- gen concentration, and yield of 8-year-old peach trees and on weed abundance. Trees of 2 cultivars ('Loring' and 'Redhaven') of peach (Prunus persica (L. Batasch) were planted in separate orchards in 1987 in a split- plot design with grass as a main effect and time as the subplot. Nine treatments were installed as ground covers beneath peach trees in 1995; Festuca arundinacea; Lolium perenne, var Manhattan II; Lolium perenne, var. Linn; Agrostis gigantea; Dactylis glomerata; Phleum pratense; Bromus Bromus carintus; weedy control; and herbicide control (simazine, glypho- sate). In general, grasses reduced vegetative growth & yield in Loring and Redhaven cultivars. For example, compared to herbicide treatments, orchard grass reduced shoot length by 27% in Loring and by 15% in Redhaven. Fruit- bearing branch length was reduced with orchardgrass by 30% in Loring and 19% in Redhaven. Orchardgrass affected fruit yield more than vegetative growth reducing yield by 37% and 24% in Loring & Redhaven, respectively. All grasses were not equally competitive, Linn perennial ryegrass never significantly affected growth or yield. Weedy treatments also didn't differ from herbicide treatments in peach tree growth and yield. The results indicate that peach cultivars respond differently to grass competition but the relative competitiveness of grass species was similar for both cultivars. Grass competition can reduce growth of mature peach trees but this reduction did not translate to reduced pruning time per tree.