- Author: Ben Faber
This is a cross-post from the "Topics in Subtropics" blog.
Join us on alternate Tuesdays in May and June, 3:00 pm to 4:00 pm, for this opportunity designed for middle and high school students. Treemendous Tuesdays is a collaboration of U.S. Forest Service, Los Angeles Center for Urban Natural Resources, California Project Learning Tree, California 4-H, and University of California Agriculture and Natural Resources.
Five webinars will be hosted every other week starting May 5 and ending June 30. These events are free and registration is required. Flyer is attached. Dates, topics, and link to registration are below.
Please share this online opportunity with organizations, community members, teachers, parents, and students. We look forward to giving students a glimpse of the wonders and benefits that trees offer!
- May 5: Invasive Species (invasive shot hole borers)
- May 19: Invasive Plants & Trees
- June 2: Benefits of the Urban Forest
- June 16: iTree
- June 30: Living with Fire
Register https://ucanr.edu/survey/survey.cfm?surveynumber=29846
- Author: Annemiek Schilder
In this weekly blog, Dr. Annemiek Schilder, Director, UCCE Ventura County and Hansen Agricultural Research and Extension Center, shares her observations about the natural world across the seasons. As she says:
"Gently observing your surroundings with curiosity will teach you some amazing things. There are so many fascinating things happening under our noses, only wanting for an observant eye."
During a recent stroll through the Master Gardener Demonstration garden at the Hansen Agricultural Research and Extension Center, a narrow-leaf milkweed plant with stems and leaves covered in yellow caught my eye. A closer look revealed teeming masses of yellow aphids along the stems, as if festively dressing up the plant. But aphids are never a festive sign to the gardener as their voracious feeding stunts plant growth. In addition, their sugary excretions may attract ants and promote unsightly fungal growth called sooty mold.
Narrow-leaf milkweed (Asclepias fascicularis) is a perennial plant native to California and an important food source for the caterpillars of monarch butterflies along their migration route. Milkweed plants produce chemicals called cardenolides (cardiac glycosides) that monarchs store in their bodies to protect themselves from predators. Can you guess what part of the body these chemicals act on? Indeed cardenolides speed up the heart rate, making for a rather unpleasant experience for a bird looking for a tasty meal. Narrow-leaf milkweed plants actually have very low levels of cardenolides, but the monarch's striking color pattern is enough to signal toxicity to would-be predators.
Aphids make milkweed plants less hospitable for monarch caterpillars. The striking yellow aphids −Aphis nerii, also called milkweed aphids or oleander aphids−feed on plants in the dogbane family, including oleander, milkweed and periwinkle. They have a yellow pear-shaped body with black legs, antennae and cornicles. Cornicles are the stovepipe-like projections on the aphid's back used to secrete a wax-like substance for self-defense. Aphids are typically wingless until they get too crowded and develop winged individuals that fly away in search of new host plants.
Aphids feed by inserting their mouth parts, which are shaped like a straw, into the plant, sucking up plant sap which contains all the necessary nutrients for the aphid to thrive. The extra sugar and water are excreted as honeydew. Milkweed aphids are able to rapidly colonize plants in the spring and early summer through parthenogenesis, a process whereby female aphids produce female offspring without mating. The aphid daughters, which are exact clones of their mothers, quickly start producing their own babies. In addition, they bypass the egg laying phase by giving birth to live young, which is called vivipary. Looking through a magnifying glass, you may see the little baby aphids being born right in front of your eyes!
As I was taking some close-up photos, I noticed the aphids intermittently twitching, almost in unison. This strange phenomenon, exhibited by this particular aphid, is called CTKR (Collective Twirling and Kicking Response). It is a collective defense mechanism against natural enemies! By simultaneously twirling their bodies and forcefully kicking their hind legs they discourage natural enemies like parasitoid wasps from attacking them. If you look closely, especially later in the season, you may see evidence of this type of parasitism: little puffed-up aphid bodies with a hole in the middle. These aphids have been parasitized by a wasp larvae which molted into adults and escaped through the hole.
Aphids are like sitting ducks: they usually remain in place while feeding. They will only move if their food runs out or something is irritating them. That makes them a convenient prey for the lady beetle, a very effective natural enemy. In the picture, you can see an adult lady beetle as well as a lady beetle larva, which looks like a tiny black alligator, feeding on aphids. They can eat hundreds of aphids per day and thousands in a life time! Lady beetles are good friends indeed.
Related Reading:
/h4>/h4>- Author: Rose Marie Hayden-Smith
Nearly two tons of fruit and vegetables grown at UC's Hansen Agricultural Research and Extension Center (HAREC) in Santa Paula have been donated to Food Forward and the Ventura Unified School District (VUSD), destined for children and families.
Some of the vegetables – planted by volunteers and farm staff - became available when UC HAREC's farm field trips were canceled due to COVID-19. Other vegetables were harvested from the student farm located at HAREC, a partnership with VUSD and the city of Ventura. Kale and lettuce at the student farm were planted by youth from DATA and Montalvo schools.
Every fall and spring, volunteers from the UC Master Gardener program propagate seedlings for schools, bundling them into variety packs of vegetables and herbs, which are given to schools with gardens. Because of COVID-19, plants were given to schools for direct distribution to families. Ventura Unified School District staff partnering in this effort include Kara Muniz, Director of Food and Nutrition Services; Ashely Parrish Decker, Nutrition Educator, who runs the Student Farm; and Alise Echles, RDN.
Additional fruit and vegetables were harvested from HAREC's citrus demonstration area, the site's educational gardens and the farm grounds.
UCCE's education program manager Susana Bruzzone-Miller said, “We are saddened that spring field trip season is cancelled and miss the sound of children delighting in harvesting, sometimes for the very first time. But, it warms my heart that our field trip garden can help feed so many families in need.”
John Antongiovanni, farm manager, worked with the farm staff to organize the harvest. He said, “Working together during this difficult time is very rewarding.”
Food Forward is a gleaning organization that helps residents turn the surplus produce grown on their property into a nutritious food source for local communities. Rick Nahmias, founder and executive director, indicated that the Food Forward Backyard Harvest team remains active, and may be reached via phone at 805.630.2728 or email.
- Author: Rose Marie Hayden-Smith
Online Educational Resources
Since we're all learning and working from home, our education team has created a virtual learning page packed with wonderful resources about agriculture. You can enjoy these lessons and stories from your computer, tablet or phone. Check back often, as we're adding content.
The Buzz About Hedgerows
Hedgerows are an approved practice under California Department of Agriculture's Healthy Soils Grant Program. That means, growers are eligible to receive grant funding for planting hedgerows. But what exactly are the benefits of hedgerows and why are they worth planting? As a perennial planting it can have immediate impacts on the soil, but what else? The answer lies largely in the pollinators and beneficial insects they attract.
Read the latest from our #climatesmart #ag community education specialist Alli Fish.
Resources You Can Use
University of California researchers and program staff are working to answer questions and provide information and resources relating to the food system and COVID-19. Check out this post, which contains resources about food and farm safety, gardening and more.
UC ANR Expands the Role & Reach of its Sustainable Ag Program
University of California vice president for agriculture and natural resources Glenda Humiston has announced changes to UC ANR's Sustainable Agriculture Research and Education Program (SAREP).
"Since 1986, SAREP has supported scientific research and education to advance agricultural and food systems that are economically viable, sustain beneficial ecosystem services, and enhance the quality of life in local communities. Moving forward, California farms and food systems face an ever-larger set of challenges: shifting consumer demands,invasive pests, climate change, additional regulations, lack of access to labor, and more. The need for new technologies, better systems and effective problem-solving is greater than ever.
“UC ANR envisions positioning SAREP to serve as a much broader umbrella of sustainability, addressing all aspects of the triple-bottom-line: people, planet and prosperity,” Humiston said. “To accomplish this, SAREP will provide leadership and support to several promising initiatives and will facilitate our ability to capture synergies among them. Those include agritourism, ecosystem services, regional food systems, community and economic development and more.”
The full announcement is available here.
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/h4>/h4>/h4>
- Author: Alli Fish
Hedgerows are an approved practice under California Department of Agriculture's Healthy Soils Grant Program. That means, growers are eligible to receive grant funding for planting hedgerows. But what exactly are the benefits of hedgerows and why are they worth planting? As a perennial planting it can have immediate impacts on the soil, but what else? The answer lies large in the pollinators and beneficial insects they attract.
The most basic definition of a hedgerow is dense vegetation planted in a linear design. Perennial grasses, shrubs, and even short trees are all candidates for hedgerow plantings, provided they meet the conditions of the local climate and soil. Growers plant hedgerows to achieve one or more of the following desired outcomes:
- To increase habitat for pollinator and beneficial insect populations
- To create a living barrier or fence
- To reduce chemical drift or odor movement
- To intercept airborne particulate matter
- To act as a low windbreak or reduce dust
- To increase carbon storage in biomass and soils
- To provide food, shelter, and shade for aquatic organisms in nearby aquatic habitats
All of these benefits make the case for planting hedgerows on any agricultural operation. In Ventura County, avocado growers stand to see a compelling case for hedgerow plantings with particular attention to pollination services.
There are many different pollinators who visit avocado flowers, from native bees to flies to honey bees. Some come in the daytime, others visit at night. In the likelihood that honey bees and other pollinators will continue to decline, it is imperative to study the importance of native pollinators on key crops and identify ways to increase habitat for resident populations (NRC 2007; Nordhaus 2011; PHTF 2015; Koh et al. 2016; Sánchez-Bayo and Wyckhuys 2019; DiBartolomeis et al. 2019; Garibaldi et al. 2013). This information not only helps the pollinator populations thrive, but helps avocado growers acquire free increased pollination services for fruitful trees. Several researchers have published accounts of increased pollinator diversity and numbers in hedgerow and field edge planting studies across various agricultural systems (Heller et al. 2019; Long and Anderson 2010; Long et al. 2017; Williams et al. 2015).
In Ventura County, we are seeing some fascinating and relevant research around the impact of hedgerows on pollinators in avocado orchards. A collaborative research project involving Dr. Ben Faber, Avocado Advisor for UC Cooperative Extension Ventura County, and Dr. Gordon Frankie, professor and research entomologist at UC Berkeley and lead investigator of the UC Berkeley Urban Bee Lab, seeks to understand long-term impacts of hedgerows on pollinators of avocado trees. The project, which began in 2014 with three participating avocado ranches, has indicated increased pollinator activity, increased native bee populations, and increased diversity of species with the presence of hedgerow plantings (Frankie, Faber et al. 2020). The results indicate the importance of diversity of pollinator species, not just the honeybee, to avocados. In continuing this research, the team seeks to address the unanswered questions of which pollinators are the most effective at pollinating avocados and which are the most effective at influencing fruit set. A particularly exciting and novel aspect of this project is looking at whether or not there are nocturnal pollinators visiting California avocados. Nocturnal pollinators have been well documented in New Zealand (Pattemore et al, 2018), but none have been yet recorded in California avocados.
Maintaining hedgerows is critical to providing additional habitat for an abundance of pollinators. Creating and maintaining that hedgerow and for which pollinators can be a daunting task to embark on. Luckily for avocado growers, Dr. Frankie and Dr. Faber's team are working with Southern California growers to develop a pollinator garden manual. The manual will provide clear pictures of key pollinators and key plant species that pollinators are drawn to. Detailed imagery, descriptions, and maintenance tips will help make the decision making around planting a hedgerow much easier.
Speaking of selections, there are key plants that are drought-tolerant, easy to maintain, and well-suited for Ventura County's climate. See the table below for some ideas.
Table 1. Main Native Bee Plants Installed in Avocado Orchards 2014-2019
We seek to increase biodiversity, build soil health, and reduce energy use in our agricultural systems to improve our resiliency to climate change impacts, pests, and disease. To keep farming in our families and in our futures. Planting hedgerows is good for the pollinators, which is good for the bottom line and long-term success of the operation.
If you are an avocado grower interested in learning more about the pollinator research project, please contact Dr. Gordon Frankie at the UC Berkeley Urban Bee Lab gwfrankie@berkeley.edu.
Interested in planting hedgerows on your property? You may be able to qualify for a grant through CDFA's Healthy Soils Grant Program to plant hedgerows. Please contact Jamie Whiteford with the Ventura County Resource Conservation District at jamiewhiteford.vcrcd@gmail.comfor more information on how to apply. For those in other areas, Technical Assistance providers are able to discuss the values of hedgerows and funding opportunities for installing them in other agricultural situations: http://ciwr.ucanr.edu/Programs/ClimateSmartAg/TechnicalAssistanceProviders/
References Cited
DiBartolomeis, M., S. Kegley, P. Mineau, R. Radford, and K. Klein. 2019. An assessment of acute insecticide toxicity loading (AITL) of chemical pesticides used on agricultural land in the United States. PLoS ONE 14(8): e0220029. https://doi.org/10.1371/journal.pone.0220029.
Frankie, G., B. Faber, J. Pawelek, R. Thorp, R. Coville, C. Jadallah, E. Takele, S. I. Rios, T. Bean. 2020. Native Pollinators of California Avocado as Affected by Introduced Pollinator Gardens. International Society of Horticultural Sciences Congress. Acta Horticulturae.
Garibaldi, L.A., I. Steffan-Dewenter, R. Winfree, and 47 other authors. 2013. Wild pollinators enhance fruit set of crops regardless of honey bee abundance. Science 339:1608-1611.
Heller, S., N. K. Joshi, T. Leslie, E. G. Rajotte and D. J. Biddinger. 2019. Diversified Floral Resource Plantings Support Bee Communities after Apple Bloom in Commercial Orchards. Scientific Reports 9 Article number: 17232.
Koh, I., Lonsdorf, E. V., Williams, N. M., Brittain, C., Isaacs, R., Gibbs, J., Ricketts, T. H. 2016. Modeling the status, trends, and impacts of wild bee abundance in the United States. Proceedings of the National Academy of Sciences 113:140–145.
Long, R. F. and J. Anderson. 2010. Establishing Hedgerows on Farms in California. UC ANR Pub 8390, Oakland, CA. http://anrcatalog.ucanr.edu/Details.aspx?itemNo=8390
Long, R., K. Garbach and L. Morandin. 2017. Hedgerow benefits align with food production and sustainability goals. California Agriculture 71:117-119. 10.3733/ca.2017a0020.
NRC. 2007. Status of Pollinators in North America. National Research Council of the National Academies. National Academies Press, Washington, D.C.. 307 p.
Nordhaus, H. 2011. The Beekeeper's Lament. Harper Perennial, NY. 269p.
Pattemore, D., M. N. Buxton, B. T. Cutting, H. McBrydie, M. Goodwin, A. Dag. 2018. Low overnight temperatures associated with a delay in ‘Hass' avocado (Persea americana) female flower opening leading to nocturnal flowering. Journal of Pollination Ecology 23(14): 127-135.
PHTF: Pollinator Health Task Force. 2015. Pollinator Research Action Plan. The White House.
Sánchez-Bayo, F. and K. A. G. Wyckhuys. 2019. Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation 232:8-27.
Williams, N. M., K. L. Ward, N. Pope, R. Isaacs, J. Wilson, E. A. May, J. Ellis, J. Daniels, A. Pence, K. Ullmann, and J. Peters. 2015. Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States. Ecological Applications 25: 2119–2131