Nematode Population Changes under Crop Rotation Sequences: Consequences for Potato Production
- Howard Ferris ,
- Becky B. Westerdahl and
- Harry L. Carlson
Soils of the Klamath basin of northeast California and southeast Oregon that are used for a potato (Solatium tuberosum L.) cropping system are frequently infested with Meloidogyne chitwoodi (Golden, O'Bannon, Santo & Finley) and Pratylenchus neglectus (Filipjev & Schuurmans-Stekhoven). These studies were conducted over a 7-yr period to determine nematode population changes under crop rotation sequences, and the impact of those changes on potato crop yield and quality. The surface blemish rating of a summer-grown potato crop has a log-linear relationship with the population level of M. chitwoodi measured either the previous fall, or with lower reliability, in the spring before potato planting. Yield of Grade no. 1 potato was negatively related to population levels of M. chitwoodi measured the previous fall, although total yields were not affected. On crops that are hosts to M. chitwoodi or P. neglectus, seasonal multiplication rates of the nematodes were log-linearly related to populations measured the previous fall. The relationship between crop yields, or nematode multiplication rates, and spring nematode population levels were weaker due to the imprecision of spring population assessments. Overwinter survival rates of both nematode species were log-linearly related to population levels measured in the fall. Preliminary analysis of the impact of seasonal climatic variation suggests that the models may underpredict potato tuber blemish and nematode population increase one year in five, when higher soil temperatures prevail. The predictions of crop damage and nematode population change allow crop and nematode management decisions hased on population assessment.
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