How to Manage Pests

UC Pest Management Guidelines

Field-grown trees and shrubs are generally grown in rows to facilitate planting, weeding by hand or mechanical cultivation, and cultural operations such as pruning or grafting. Most weed control in established plantings is accomplished by cultivation or with preemergent herbicides, but perennial weeds need to be controlled before the ornamental crop is planted.

Crop Rotation. In some cropping systems a field is fumigated before planting. During the growing season, cultivation, herbicides, or other weed growth suppression methods are used. After the crop is harvested (either bareroot in winter or potted in spring), the field is planted to a cereal crop in fall (wheat, oats, or barley) and harvested the following spring. Herbicides can be used in the cereal crop that will reduce weed problems in the next tree cycle.

Solarization. Soil solarization is a valuable tool to clean up a site before a fall planting (see "Solarization" under "General Methods of Weed Management").

Cover Crops. Cover crops, especially winter annuals such as barley, oat, wheat, or combinations of these with rose clover, may be planted between tree rows in early fall. Cover crops reduce erosion and help maintain soil organic matter when the cover is worked into the soil in spring. Mow the cover crop and work it into the soil before it seeds to reduce competition with the crop.

Mulches. To reduce weeds in the row, field-planted cuttings can be planted into a paper mulch. After planting, mulches (organic or geotextile) can be placed along the sides of newly planted stock. Organic mulch must be deep enough to shade out all weed seedlings as they germinate. The geotextile materials must be placed so no light gets to the soil around the plant or weeds will grow around the base of the plant.

PUBLICATION

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Weeds
C. A. Wilen, UC IPM Program, UC Cooperative Extension, San Diego County
Acknowledgment for contributions to Weeds:
C. L. Elmore, Vegetable Crops/Weed Science, UC Davis

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