Agriculture Reference
In-Depth Information
Managing Alley Crops
For both annual and perennial alley crops, a good practice is to mow ad-
jacent rows alternately, several weeks apart, if possible. Alternate mowing
leaves the predators and other beneficial organisms in every other row un-
disturbed for a time, allowing them to repopulate the mowed rows.
Alfalfa, clover, peas, and other legumes on the orchard floor will fix nitro-
gen, provided they are inoculated with the proper
Rhizobium
before planting.
During establishment of the legumes, they compete with the fruit crop and
other cover crops for nitrogen. When they mature or die, the legumes begin
adding nitrogen to the soil. When alfalfa and clover are cut and the clippings
blown into the fruit crop rows, the clippings add nitrogen to the soil there,
even though the legumes in the alley remain alive.
Be cautious when using legumes in your cover crops. While nitrogen is ne-
cessary for plant growth, too much creates excessively lush, disease-suscept-
ible foliage, reduced flowering, and poor fruit quality. This problem was ob-
served in Washington State University orchard trials with alfalfa alley crops.
Carefully monitor foliage nutrient concentrations and fruit quality. Be pre-
pared to change the types of plants in your alley crop to adjust the nitrogen
availability, if necessary.
Insectary Crops
Sometimes called nectary crops, the primary purpose of these plantings is to
provide habitat for beneficial organisms, such as green lacewings, that are
predators of orchard pests. Many of these beneficial insects depend on nec-
tar, pollen, and other plant materials during certain stages of their life cycles.
Insectary crops provide the habitat needed to complete their life cycles, and
they also provide habitat for sufficient prey to support the predator popula-
tions. The goal in organic pest management is seldom to eradicate the pests.
Doing so eliminates the food for beneficial predators that then leave or die,
leaving our orchards open to rapid reinvasion by new pests. Our goal is to
maintain enough pests to support the predators but not enough to do serious
damage to our fruit crops.
