This study compared the effect of weed control and orchard floor management (OFMA) options including organic mulch on summer annual weed interference in a newly established peach orchard. Weed interference where no preemergence (PRE) herbicides were applied, including vole damage, caused 29% peach tree mortality, reduced tree trunk cross-sectional area (TCSA) 62% by the fourth year of orchard establishment, and reduced fruit yield and fruit number in 1999 by 73 and 75%, respectively, but had no effect on fruit size. Compared with a no-till or conventionally tilled orchard floor, the population of grassy weeds within the tree row was greater in killed perennial ryegrass sod (PRS) plus hard fescue residue mulch treatments but was less in killed PRS plus tall fescue residue mulch treatments. Among the no-PRE treatments, the tree row broadleaf weed populations were suppressed in killed PRS with or without the addition of fescue residue mulch to the tree row when compared with the no-till or conventionally tilled orchard floor treatments. PRE herbicide treatments strongly affected peach fruit yield and TCSA but not average fruit size. There was no effect among the killed PRS, with or without hard or tall fescue residue mulch treatments, on peach fruit yield, TCSA, or average fruit size when compared with the no-till or conventionally tilled orchard floor treatment options. All treatments with herbicide had higher yields in 1999 than those without herbicides.

Nomenclature: Hard fescue, Festuca longifolia var. Reliant; perennial ryegrass, Lolium perenne L.; tall fescue, Festuca arundinaceae Schreb. var. Kentucky-31; vole, Microtus sp.; peach, Prunus persica (L.) Batsch var. Candor.

Additional index words: Drive row, orchard floor management, summer annual weeds, tree row.

Abbreviations: OFMA, orchard floor management; PRE, preemergence; PRS, perennial ryegrass sod; SAW, summer annual weed; TCSA, trunk cross-sectional area.