2023.08.09 | Loss of Tree Crop for the Ranch

pine seedlings during flooding

The devastating March 2023 flood have produced another casualty: Friends of the Fiscalini Ranch Preserve’s crop of Monterey pine (Pinus radiata). An unusually large number of the seedlings had been failing so FFRP volunteer and trained chemist Henry Showell conducted a test for disease. The sampled plants were found to be infected with a fungus-like pathogen, Phytophthora (fy-TOF-tho-ra).  Phytophthora is a special threat to native plant horticulture since it thrives in wet soils often found in nursery conditions. The seedlings will be destroyed rather than risk introducing this pest onto the Ranch.

Phytophthora species are naturally occurring water molds that cause root and crown rot. One species of Phytophthora causes sudden oak death. There is no cure for Phytophthora infestation. Restoration programs must be especially vigilant about not introducing this pest to natural areas since it can devastate landscapes.

The prime goal of establishing the Ranch restoration nursery was to grow plants under hygienic conditions. Unfortunately, the spring flood made that impossible. To secure the trees from rising water, we had to store them for weeks on the ground. Plants should be kept at least 18 inches above ground level to avoid the risk of Phytophthora spores splashing into the soil. The nursery tables on which the plants were grown were undamaged but were awash in contaminated flood water. Although the tables were sanitized before the trees were replaced on them, it is not possible to know if the pest was already present. Finally, after all this the trees were failing to thrive so we may have made the mistake of watering too much. Phytophthora thrives under moist conditions.

Around 400 seedlings will be destroyed, although some may make a final appearance in the Pinedorado Days parade. Soon we will start a new crop using clean soil, pots, and trays on newly cleaned tables. In the meantime, Greenspace-Cambria Land Trust has generously offered to find us seedlings for the Thanksgiving Weekend Tree Planting. Despite setbacks, restoration of the Ranch will continue thanks to dedicated volunteers and supporters.

Article first published in https://cambriaca.org/