 |
Innovative Tart Cherry Orchard Systems
Michigan State University scientists have evaluated orchard-scale
ground cover experiments in established commercial orchards and
in a new tart cherry orchard at the Northwest Horticultural Research
Station. They studied orchard floors covered with compost, mulch
or cover crops such as crimson clover, berseem clover, white clover,
white Dutch clover, Michigan red clover, crown vetch, indigo vetch,
alfalfa, rye, annual ryegrass, hard fescue and Buffalo grass. So
far, findings include:
 Season-long
populations of beneficial mites were attributed to the use of
a red clover cover crop.
Season-long,
vegetation-free strips using either herbicide or mulch increase
pest mite populations.
Orchards
with ground covers—irrigated but not treated with herbicides
to manage weeds—had fruit yields that were not significantly
lower than conventional practices over a five-year period. Note
the irrigation may be critical in this system to prevent the ground
cover from competing with the fruit trees for water.
Adding
mulch, cover crops and/or compost increases soil organic matter,
populations of beneficial soil microbes and amounts of active
soil carbon and nitrogen available to trees.
Fewer
beneficial nematodes, more plant-parasitic nematodes and more
nitrate leaching were associated with lower-quality conventional-system
soils.
Hay
or straw mulch, applied 6 to 8 inches deep, improved tree growth
and yields despite higher pest mite populations.
Nitrate
leaching—greatest in spring and fall—was substantially
reduced by vegetation growing under trees during these periods.
In-row
soil population densities of beneficial nematodes, mycorrhizae
and earthworms were greater under an organic production system.
Young
trees benefited from adding mulch or compost but can be severely
stunted by competition with groundcover plants for moisture and
nutrients.
Trees
with heavy mulches produced soft fruit in two of seven years.
The scientists also are examining the impact of mixed-species hedgerows
on insect pest movement into and out of orchards. In addition, they
are evaluating insect pheromone mating disruption, mass trapping
of plum curculio, 14-inch groundcover bands around mulched center
lines, and intercropping with such income-generating woody species
as sea buckthorn and Siberian pea.
Orchards offer advantages over annual row crops in biological pest
control, says MSU IPM tree fruit integrator David Epstein. Because
they do not undergo major renovation every year, orchard systems
can be developed to let beneficials get established. “Ground
covers can be used to encourage beneficials to build up their populations
and remain in the orchard throughout the year,” he says.
How much the beneficials actually reduce pests, however, depends
on weather, pest populations and the effectiveness of growers’
monitoring programs. “To say that if you plant red clover
you’ll never have to spray for mites again would be erroneous,”
says Epstein. “But if you know what’s out there—what
levels of pests, predators and parasitoids you have—then you
can make an informed decision as to whether or not you can save
a spray.” (For more information about this project, see http://www.ipm.msu.edu/tartcherry.htm)
Previous Section | Top
| Next Section
|
