Pest Management Planning

You can anticipate certain pest problems by knowing the crop history of a field. If a field has been in sod, for instance, you can expect grubs. When sod is killed, root-feeding grubs remain. These grubs will feed on the roots of liners planted into the field unless control measures are taken. In the case of certain nematode-sensitive crops like American boxwood, testing a field for presence of harmful nematodes is a good idea. Contact your county Cooperative Extension Agent for assistance in taking a proper sample for nematode assay.

Pest management is a primary cultural consideration in designing the layout of a field nursery. Plant locations and potential pesticide programs are easily changed during planning but are expensive to alter once the field has been planted. In addition to proper field nursery design, any practice that will reduce stress on the plant while promoting healthy, vigorous growth will reduce pest problems. Practices such as draining waterlogged soils, irrigating when necessary, ensuring good air drainage (by removing windbreaks or barriers to the down-hill flow of cold air), and providing proper chemical and physical preparation of soil, also help keep plants less stressed, healthier, and relatively insect- and disease-free.

Give careful consideration to crop rotation practices where allelopathic relationships may affect the growth of the next crop planted. Some crops leave residues that suppress or prevent other crops from growing. The most familiar example of allelopathy is suppression of many plants within the root zone areas of black walnut trees. Growers report, however, similar problems when planting deciduous shrubs after boxwoods, yews after yews, oaks after oaks, poplars after poplars, and many rosaceous crops such as cotoneaster, pears, mountain ash, hawthorn, or quince in rotations.

Crops with complementary pest problems should not be grown in the same fields or fields close to each other. An awareness of these instances can help reduce pest problems such as, for example, cedar-apple rust in crabapple and cedars. Other crops may be negatively affected by pesticides used on neighboring crops. For instance, burford holly is extremely sensitive to and can be defoliated by dimethoate (Cygon) phytotoxicity. Therefore, crops that may be sprayed with dimethoate should be placed away from hollies to avoid spray drift.