Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2001
Publication Date: N/A
Interpretive Summary: Growers can benefit from technology that reduces size and increases fruit production of peach trees. Less annual vegetative growth can reduce the amount of pruning and improved efficiency of protective sprays. Peach tree size can be reduced when young trees are grown continuously with grass after tree planting. However, trees grown continuously with grass are slow wto fully utilize orchard space. This experiment was designed to determine if grass competition could be used to reduce undesirable vegetative growth and increase fruit production efficiency of peach trees that were fully grown and occupying orchard space. Seven grasses with different competitive capacities were planted beneath 8-year-old peach trees in 1995 and growth and yield was measured for 4 years. Most grasses reduced both vegetative growth and yield. However, all grasses were not equally inhibitory; 'Linn' perennial ryegrass and brome grass did not affect growth or yield. All grasses reduced broadleaved weeds. The results indicate that grass competition with mature peach trees will reduce vegetative growth but will also reduce yield without improving yield efficiency. This information is useful to peach growers, extension specialists, and researchers conducting ground cover studies.
Technical Abstract: Competitive effects of different grass species were evaluated on growth, yield, leaf nitrogen, and leaf water potential of 8-year-old peach (Prunus persica (L.) Batch.) trees and on weed abundance. In general, grasses reduced vegetative growth and yield. Orchardgrass was one of the most competitive species and it reduced vertical water sprout length by 27% in 'Loring' and by 15% in 'Redhaven', compared to herbicide treatments. Orchardgrass affected fruit yield more than tree vegetative growth, reducing yield by 37 and 24% in 'Loring' (predominantly in the 508 to 635 mm size class) and 'Redhaven' (predominantly in the > 635 mm size class), respectively. All grasses were not equally competitive, 'Linn' perennial ryegrass did not significantly reduce growth or yield in 'Redhaven'. Control treatments with weeds also did not differ from herbicide treatments in peach tree growth and yield. Grass and weed ground covers consistently reduced peach tree leaf nitrogen by at least 10%, compared to herbicide treatment, possibly due to reduced root growth in peach trees. 'Redhaven' peach root density in the top 10 cm of soil was nearly 12 and 1 cm.cm-3 in herbicide strips and in weedy or ground-covered strips, respectively. However, peach leaf water potential was not affected by grass and weeds, indicating that peach trees were absorbing water from soil beneath grass roots. Weed weights were significantly reduced by all grasses compared to untreated control. Grass competition reduced growth, yield, and pruning weights of mature peach trees, but the reduction in vegetative growth did not significantly reduce pruning time per tree. Grasses that are less inhibitory to peach yield may be useful for weed management in orchards.