Measuring interactions in the field between Tylenchulus semipenetrans and citrus hosts
Three surveys were conducted in mature citrus groves to describe the spatial distribution of citrus (Citrus spp.) feeder roots and of Tylenchulus semipenetrans. Feeder root and nematode population density declined with distance from the trunk on both 20-yr-old sour orange (Citrus aurantium L.) and 30-year-old rough lemon (Citrus jambhiri Lush.) rootstocks. Qualitative tree differences were reflected by fewer feeder roots recovered from trees with decline symptoms than from healthy trees. Covariation of roots and nematodes with distance from the trunk was pronounced so that the number of T. semipenetrans g root did not vary with location even under canopies and in bare row middles. In linear regression analyses, roots and nematodes collected from the first 30 cm soil depth explained 75 and 73 percent, respectively, of the variability in densities from 0 to 60 cm soil depth. When nematode population levels in shallow (0 to 30 cm) samples were used to predict levels from 0 to 60 cm in a simulation model, forecasting error declined exponentially with increased numbers of soil cores/sample. A sample strategy for nematode related crop loss assessment in mature groves was developed, based on these survey results. An essential aspect of the strategy in random procurement of samples within a standard unit-area around each tree, rather than utilizing tree architecture to define the sample space
| Main Author: | |
|---|---|
| Format: | biblioteca |
| Published: |
1986
|
| Subjects: | FRUTALES, TYLECHULUS SEMIPENETRANS, FRUTAS CITRICAS, CITRUS AURANTIUM, CITRUS JAMBHIRI, HUESPEDES, NEMATODOS DE LAS PLANTAS, DENSIDAD DE LA POBLACION, PERDIDAS, |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Three surveys were conducted in mature citrus groves to describe the spatial distribution of citrus (Citrus spp.) feeder roots and of Tylenchulus semipenetrans. Feeder root and nematode population density declined with distance from the trunk on both 20-yr-old sour orange (Citrus aurantium L.) and 30-year-old rough lemon (Citrus jambhiri Lush.) rootstocks. Qualitative tree differences were reflected by fewer feeder roots recovered from trees with decline symptoms than from healthy trees. Covariation of roots and nematodes with distance from the trunk was pronounced so that the number of T. semipenetrans g root did not vary with location even under canopies and in bare row middles. In linear regression analyses, roots and nematodes collected from the first 30 cm soil depth explained 75 and 73 percent, respectively, of the variability in densities from 0 to 60 cm soil depth. When nematode population levels in shallow (0 to 30 cm) samples were used to predict levels from 0 to 60 cm in a simulation model, forecasting error declined exponentially with increased numbers of soil cores/sample. A sample strategy for nematode related crop loss assessment in mature groves was developed, based on these survey results. An essential aspect of the strategy in random procurement of samples within a standard unit-area around each tree, rather than utilizing tree architecture to define the sample space |
|---|