How to Manage Pests

Pests in Gardens and Landscapes

Site preparation

In nearly all landscapes, soil must be loosened if young trees and shrubs are to grow well. Drainage may also need to be improved. It may be necessary to break up or penetrate hardpan, for example with a backhoe, to provide greater soil depth. Install drain pipe, drain tile, or a sump if needed to ensure adequate drainage and good plant growth. Aeration tubes, however, have not been shown to be effective in increasing soil aeration in the root zone.

Before planting, mark out a planting area that is at least two to three times the diameter of the root ball. Rototill, shovel, bore, or use an auger to mix the soil within this area to the depth of the plant's root ball. Mix the soil well. Adding organic matter to the planting hole of trees and large shrubs has not shown consistent benefits. Amending the entire potential root zone of trees is generally not practical, and amending soils around established plants will damage roots. Amendments can help before planting certain shrubs such as camellias or azaleas, which are adapted to well-drained acidic soils and will do poorly without amendment. If added, organic matter should be well composted and constitute no more that about 25% of the soil volume in the upper 12 inches of the soil. Mix it well into the topsoil. A 2- to 3-inch layer of mulch also can be added to the surface after planting.

Site preparation

Provide adequate drainage before planting. One method is to create a sump by augering one or more holes, each 1 to 4 inches in diameter, through impermeable soil or hardpan. Auger down at least 3 feet or deeper if necessary to penetrate to more permeable soil. Fill the holes with pea gravel or sandy loam soil before planting.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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