- (Public Value) UCANR: Building climate-resilient communities and ecosystems
Produce Exposed to Smoke
When assessing the safety of exposed produce, the difficulty is knowing what has been burning. If it is just vegetation smoke then it's probably safe to eat produce after rinsing off the ash (just the same as having a bonfire in your garden), although it might still taste/smell smoky.
If the air pollution has particulate matter from treated timber, tires, non-food grade oils, or anything plastic or chlorinated that burned it may include a mixture of Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, and metals. Exposure to fire retardant may have also occurred.
An unpublished literature review on the health impacts of PAHs from traffic-related air pollution on lettuce grown in urban agriculture found that:
- Some PAHs can be absorbed into plant tissue, and so cannot be simply washed off.
- The health risk from eating these PAHs is a small proportion of the health impact from breathing them, and it is far below the EPA's level of concern for lifetime cancer risk.
- It is possible that the health benefit of eating the vitamins and nutrients in green leafy vegetables might outweigh that negligible negative impact.
- There is not enough research available on the cumulative impacts of air pollution on produce to make any solid conclusions about the health impacts.
Produce Safety after Urban Wildfire study conducted following Oct 2017 fires in Sonoma County.
Fires & Food Safety flyer by USDA FSIS, 2/2013.
Food Safety after Fire by USDA FSIS, 8/2013.
Some technical guidance tip sheets and power points that may be helpful can be found here:
- Soil Sampling, Risk Mapping & Exposure Prevention - Rob Bennaton
- Contaminants in Soils, Data Collection-Interpreting Test results and Minimizing Exposure by Cornell University
- Testing Laboratories in California
- UCCE Soils in Urban Agriculture
- Best Practices for Produce Safety After A Fire
- Produce Safety After a Fire Tool Kit
California Bay or CA Laurel or Headache Tree or, heaven forbid, Oregon Myrtle is a tree native to the west coast where there is water. In the rainy forests of northern CA and Oregon and the wet creek areas in ravines and canyons of southern CA.
Walking around a barannca the other day along a still wet section of the Ventura River, there was a fruiting bay tree. Fruit that look just like little avocado fruit to which bay is related.
Umbellularia californica is in the Lauraceae along with Persea americana, but sometimes still listed as P. gratissima.
Bay gets its name from the strong bay laurel odor similar to the culinary laurel – Laurus nobilis –, which is not related to avocado. The odor can be so pungent, that taking strong whiffs of it could bring on a headache, hence the alternative name. The tree can attain a 30 feet height as a single trunked tree or be multi-trunked. The wood is gorgeous hard and is notable in the construction of musical instruments. The seeds were roasted and eaten like acorns. There's been a recent craze to eat dried, ground, powdered avocado seeds which has been discouraged by the CA Avocado Commission.
On the north coast, this tree is subject to Sudden Oak Death – Phytophthora ramorum. It is also subject to avocado root rot, just like avocado. It is also the only California native that is subject to Laurel Wilt Disease which is ravaging the laurel forests of the southeast.
CA Laurel in Flower looks a lot like an avocado flower, hence the reason for being in the same family
2020 Climate Action and Agriculture Symposium
Information and documents related to the 2020 Climate Action and Agriculture Symposium Webinar featuring information on current climate trends and agricultural impacts, soil health and updates about related projects in San Diego and neighboring counties.
Featured Organizations and Programs:
- San Diego County Farm Bureau
- Spadra Farm, California State Polytechnic University, Pomona
- CDFA-Healthy Soils Program
- Composting Resources, County of San Diego
- Resilient Roots: Climate Smart Agriculture & Food Systems,
Climate Science Alliance
- Carbon Farming, Resource Conservation District of Greater San Diego County
- Solidarity Farm
- San Diego County Food Vision 2030, San Diego Food Systems Alliance
Technical Reports and Resources:
Compost and Mulch Market Study, County of San Diego (PDF Download,2.1 MB)
by the County of San Diego and Hidden Resources
Mulch Resources from Ben Faber, Ph.D., UCCE Farm Advisor (PDF Download,994 KB)
Questions and comments always come up about the use of mulch in orchards. Mulch has its benefits and drawbacks and they need to recognized in order to manage it. It serves to combat erosion and root rot, but it can also burn. Mulch and wood piled up against tree trunks and near trunks can cause damage to those trunks. A Fillmore grower actually goes through the orchard with a blower to move mulch away from trunks when alerted to fire. On the other hand, irrigated orchards have been shown to be effective at suppressing fire encroaching on homes. And mulches can suppress weeds and reduce water use, but it's possible that importing material for mulch can introduce weeds.
So where to read more about fire? Check out some of the blogs from the past.
Mulch and green waste applied to orchards
- Green Waste, Yard Waste, Whatever You Call It- It has Simple Rules for Use
- A Safer Source of Inexpensive Orchard Mulch
- Avocado planting holes
- Cellulase Production by Various Sources of Mulch
- A Caution on Free "Compost/Mulch"
- A Safer Source of Inexpensive Orchard Mulch
- Mulch, Avocados and the Home Garden
- Mature Compost Does NOT Kill Phytophthora
- Use of Mulch in Organic Orchards Called into Question
Mulch and Landscapes
Why are avocado roots coarse, but dense, while grass roots are a fine mat?
It has long been one of the best kept secrets in the underground world: what determines the variation in form and function of plant roots? An international team of researchers, led by scientists from Wageningen University & Research and the German Centre for Integrative Biodiversity Research in Halle-Jena-Leipzig, has revealed the strategies that roots use to invest in their tissues: do-it-yourself or outsourcing. In Science Advances they present a new framework that allows us to understand the variation in form and function in roots. “It felt like discovering a hidden treasure”.
Plants, like many other organisms, follow rules of economics when investing in their tissue. The currency is not money, but carbon and nutrients. This economics gradient flows from ‘live fast, die young' such as the Lathyrus or ginkgo, to ‘slow and steady' as the oak does. This economic theory works well for leaves. It was long assumed that the same principle applied to the roots, but researchers' efforts to deliver proof, failed repeatedly.
Each of us had a piece of the puzzle, but no-one had the whole picture. There it is: You can do it alone, or work together. Plants are just like humans. Liesje Mommer
A new collaboration gradient: an onion outsources
This problem has now been solved using a database of root characteristics of 1781 plant species from around the globe. In addition to the classical ‘fast-slow' gradient, there is a second, independent axis that is essential in understanding the form and function of plant roots. This axis is the ‘operational' gradient for nutrient uptake. It goes from a do-it-yourself strategy with many thin roots, such as followed by the cuckoo flower, to a policy of outsourcing, such as the onion. The onion collaborates intensively with soil fungi, forming a partnership of roots and fungi (mycorrhiza). “Roots that work together with fungi must make room for an 'exchange counter' - sugars go from the plant to the fungi and nutrients go the other way around. That "counter" takes up space in the outer cells of the root, which are therefore thicker than in "do-it-yourselfers", says Prof. Liesje Mommer of Wageningen University & Research. “This new operational axis shows how roots have different ways of functioning.”
Figure: Plant root strategies. Plant roots worldwide vary in their strategy for obtaining nutrients. Do-it-yourselfers have all their equipment on baord. Outsourcers form alliances with soil fungi in exchange for sugars.
This new framework for understanding variations in root characteristics offers recommendations to better understand the way roots work. This insight is useful in future research to predict the subterranean plant response to changing environmental conditions, or to launch new breeding programmes.
Professor Liesje Mommer on how the project was started: “It was a collaboration between renowned researchrs from Europe and the United States, during an inspiring workshop in Leipzig. We knew a treasure was buried underground near the plant roots, and that finding it required collaboration. Each of us had a piece of the puzzle, but no-one had the whole picture. There it is: You can do it alone, or work together. Plants are just like humans.”