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Project description

Cape Ivy distribution, ecology, and reproductive biology. (01XN012)
Program Exotic Pests and Diseases Research Program
Principal
investigator
J.M. DiTomaso, Vegetable Crops, UC Davis
Host/habitat Wildland; Riparian
Pest Cape Ivy Delairea odorata
Discipline Weed Science
Review
panel
Natural Systems
Start year (duration)  2001 (Three Years)
Objectives Document the distribution and natural community associations of Cape Ivy in California and Oregon. Distribution maps will give baseline information on the current range of the species, and this information, overlaid with GIS data, will provide the necessary background to develop a model of potential distribution.

Test Cape Ivy for self-incompatibility and determine if the potential exists for viable seed production through out-crossing of segregated populations. Until recently, Cape Ivy has not been considered to produce viable seed in California.

Investigate the biological and ecological limitations to Cape Ivy establishment in new locations within the state.

Final report In 2002, 2003, and 2004, the focus of the cape ivy research was on objective two, reproductive biology. Experiments were performed in the field and greenhouses to address the question,"Is cape ivy self-incompatible in California?" We bagged flower clusters to prohibit cross-pollination, and the seed viability of the manipulated flowers was compared to open-pollinated flowers from the same populations. Additionally, we performed a greenhouse experiment at Bodega Marine Laboratory where we artificially crossed plants from geographically distant locations to see whether seed viability was increased as a result of cross-pollination. For objective one, the distribution and natural community associations, we visited 99 locations in the field and collected seed from 63 of them. This collection represented a larger geographic range of populations than those sampled in 2001, and the seed collected was used for seed biology studies. Seed research included size classes of seed produced at different locations, range of germination temperatures of geographically distant populations, response of germination to light, and germination from different planting depths.

Second-year
progress
In 2002 and early 2003 the focus of the Cape ivy research was on Objective 2, Reproductive biology. Experiments were performed in the field and greenhouses to address the question, "Is Cape ivy self-incompatible in California?" We conducted a field experiment where flowers were bagged to prohibit cross pollination and the seed viability of the manipulated flowers were compared to open-pollinated flowers from the same populations. Additionally, we performed a greenhouse experiment at Bodega Marine Lab where we artificially crossed plants from geographically distant locations to see whether seed viability was increased as a result of cross-pollination. For Objective 1, the distribution and natural community associations, we visited 99 locations in the field and collected seed from 63 of them. This collection represented a larger geographic range of populations than those sampled in 2001 and the seed collected will be used for seed biology studies. Seed research will include size classes of seed produced at different locations, range of germination temperatures of geographically distant populations, response to light, and germination from different planting depths.

First-year
progress
Cape ivy was found to infest 17 community types in 2001 and 2002. In addition, new inland populations were noted in Sonoma, Ventura, and Los Angeles counties. Currently over 1300 locations are included in the GIS database, ranging from Curry County, Oregon, south to San Diego County. The information will be used to develop a predictive model of Cape ivy's potential spread. Cape ivy seeds were collected in February and March, 2001, from 22 locations throughout California and Oregon. Under greenhouse conditions, large filled seeds germinated between 6 and 31 days after planting, and seeds from all locations tested eventually germinated. Contrary to previous reports, this study conclusively proves that Cape ivy is producing germinable seed throughout its range in California. In a temperature germination study of four different populations, results indicate that Cape ivy seed germinated at temperatures ranging from 8 to 29 °C (46 to 84 °F), with seed at the lowest temperatures germinating the slowest. These temperatures match the field conditions where Cape ivy commonly infests.

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