Weed Control in Orchards

Introduction

zonein young nonbearing orchards. Maintain the full
width of the vegetation free zone in newly planted
orchards to achieve maximum tree growth.
Sod between the tree rows prevents soil erosion,
provides traction for equipment, increases soil organic
matter, improves soil structure and water permeability,
and furnishes shelter for beneficial insects. The sod
should not include plants that are an alternate host for
insect pests, or diseases and nematodes that attack the
fruit tree. In addition, the sod should be easily
maintained, tolerant to drought, require little or no
fertilization, and compete minimally with the fruit tree.
Tall fescue or hard fescue perennial grass sods are
recommended for orchard row middles. Both types of
fescue are tolerant to disease, drought, low pH and low
fertility. They compete effectively with weeds, do not
spread or creep into the tree row by rhizome or stolen
growth, and are semi-dormant during the hot dry summer
months. Tall fescue is more vigorous and is more easily
established, but requires more frequent mowing. Newly
developed "turf type" tall fescue varieties are vigorous,
and have a lower mowing requirement than the traditional
'Kentucky 31' tall fescue, but have not been evaluated in
orchards. Hard fescues grows more slowly and close to
the ground and has a minimal mowing requirement, but
is moderately slow and difficult to establish.
The addition of clover or other legumes is not
recommended for orchard sods. Although legumes do fix
nitrogen, release for plant use unpredictable, and often at
the wrong time of year, which can reduce winter
hardiness. Legumes are also alternate hosts for pests such
as cat-facing insects, nematodes, and tomato ringspot
virus which causes stem pitting in stone fruits and union
necrosis is pome fruits. Legume bloom frequently
coincides with apple bloom, and is preferred by bees and
other pollinators.
Preparation for sod establishment should begin before
the orchard is planted. Control perennial weeds and
nematodes, correct soil pH and nutrient deficiencies first.
Complete primary tillage operations the summer before
the orchard will be planted. Build gently sloping raised
ridges to improve drainage in the future tree rows before
sowing grass or planting trees. Orchards planted flat have
developed depressions in the row between the strips of
sod due to the improving soil structure in the sod
compared with the vegetation free strip.
The success of a sod planting will depend on accurate
seeding and timing. Sow tall or hard fescue in late

The control of unwanted vegetation in orchards
provides several advantages. Weeds harm the crop in the
following ways:

1. Competing for light, water, nutrients, and space.
2. As alternate hosts for harmful insects, diseases,
   and nematodes, and by providing cover for
   undesirable animals.
3. Adversely affecting crop quality and/or reducing
   yield.
4. Impeding or preventing harvest.

Control Measures

Weed identificationis the first step in a successful
weed control program. A knowledge of the weed species
in an orchard is needed for control measures to be
successful and economical. Plan control measures when
the weed is most susceptible.
Good cultural practicescan reduce manyweed
problems. Control difficult perennial weeds before
planting a new orchard. Sow areas in the orchard where
bare ground is not desired to a cool season grass that will
not compete vigorously with the trees but will suppress
weeds. Prevent weed seed production.Many weeds can
produce 10,000 to over 100,000 seeds per plant. Most
will be "hard" seed that will not germinate for several
years. One good year of weed seed production can result
in a supply that will last many years. Preventing seed
production of new "hard-to-control weeds" is particularly
important.

Orchard Floor Management. Recommended
management of the orchard floor includes maintaining a
vegetation free zone in the tree row, and establishment of a
perennial grass sod between the rows. Integration of
vegetation management with insect and disease control
programs is essential. Maintain the vegetation free zone
in the tree row to prevent competition with the fruit tree.
The width of the vegetation free zone should be about
forty percent of the distance between the tree rows in most
orchards. The width may vary, however, depending on
soil fertility, water holding capacity and exposure to
erosion. Do NOT reduce the width of the vegetation free

1998 New Jersey Commercial Tree Fruit Production Guide

37