PLACEMENT OF INFESTED PLANT MATERIAL

In a field that is uniform in soil characteristics, cropping history, and in past and present management practices, garlic clives that come from different seed lots are planted. Some are infested with stem and bulb nematode (D. dipsaci). During the growing season, irregular areas of poor-growing infested plants are visible across the field. These areas correspond directly to those in which the infested cloves are planted and are interspersed between areas of good growth where noninfested clove material is planted. If this rield is subsequently planted to another host crop in a short rotation, then the ensuing infection and plant damage wil correspond to those previous introduction sites. In this example, the primary determinant of nematode distribution is the placement pattern of infested propagative plant material. If environment and management conditions favor nematode infection, such as under rotation with other susceptible crops, then the areas of infestation will spread and coalesce until the entire field is infested.

From: McKenry, M.V. and P. A. Roberts. 1985. Phytonematology Study Guide. University of California, Division of Agriculture and Natural Resources.

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