Orchard Floor Management
The orchard floor consists of the tree rows and alleys between these rows. Weeds must be managed in rows to ensure vigorous growth and good yields. Especially in semi-arid climates and irrigated orchards, weeds are major pests competing with trees for water, nutrients, and in extreme cases, light. Weeds can also provide habitat for rodents that can feed on tree bark and roots. Orchard alleys serve several functions, providing access to trees, limiting erosion, and providing habitat for beneficial and not-so-beneficial organisms (e.g. weeds, insects, rodents).
The ability of weeds to compete with fruit trees is well documented. Weeds are especially competitive during establishment and with fruit trees grafted onto dwarfing/semi-dwarfing rootstocks. One experiment showed that grass growing near the trunk of apple trees delayed the onset of fruiting, reduced trunk circumference, and reduced shoot growth when compared to trees grown with bare ground surrounding them. Early and mid-season weed control (May-July) has greater impacts on tree growth and yields than late season, i.e. August (Merwin and Ray 1997). Grasses were more competitive than broadleaf weeds. In another experiment, adding more nitrogen did not overcome the competition imposed by grasses. In the semi-arid climates of the intermountain west, weeds will grow where there’s water and so irrigation systems (e.g. drip, micro-sprinklers, over-head sprinklers) will affect weed pressure and management.
Just as orchardists develop management plans to deal with insect and disease pests, an orchard floor management plan will help keep weeds in check. The orchard floor management plan is best determined before the orchard is planted. Management practices for orchard floor management should be executed in a timely manner during the lifetime of the orchard. This chapter describes some factors to consider while making decisions about how the orchard floor will be managed.