Invasive shot hole borer (ISHB) infestations have been identified in Ventura County since 2015 but have not significantly spread. Discovery of the pest/disease complex was found in late 2018 in the urban forest of Meiners Oaks. Citizens Journal recently published an article about the removal of a tree that was at risk for amplifying the local infestation and causing potential other community harm.

The Ventura Agricultural Commissioner supervised the removal of the tree, using grant funds for this purpose from CAL FIRE. The box elder was located on private property and considered to be a hazard to extend the infestation. 

UCCE Ventura has been collaborating to address ISHB with UC insect, disease, education specialists, Ventura County Agricultural Commissioner, CAL FIRE, US Forest Service, several other agencies and non-government organizations. We are locally active in monitoring and outreach. Ventura County Master Gardeners Invasive Pests Outreach Group augments our work through their efforts to educate the public, firewood users and vendors.

Below is a video produced by California Releaf, a nonprofit organization that works to empower grassroots efforts and build strategic partnerships that preserve, protect, and enhance California's urban and community forests. It's been edited for length.

For more information about ISHB, you can also visit the UCANR website.

Learn About California Agriculture

Join us on Thursday, May 21st, 9:30 am PST, for Part 2 of a webinar series on California agriculture, where we'll learn about major crops and production areas. This webinar will feature UCCE Ventura County advisors Andre Biscaro and Ben Faber. Watch it live or view after on YouTube. Part 1 is up. This is an ideal webinar series for the home classroom.

Photo by Adele Payman on Unsplash

Fumigants and Non-Fumigant Alternatives: Regulatory & Research Updates

Growers, PCAs, applicators and supervisors of fumigant and non-fumigant technologies and decision makers should plan to attend this free, virtual educational outreach event, scheduled for Monday May 29th from 8:00 a.m. to 12:00 p.m. This workshop is open to the public. Although targeted to strawberries, most of the learning will generally apply to other crops. The program is being hosted by Dr. Oleg Daugovish, who serves as the Strawberry and Vegetable Crop Advisor for UCCE Ventura County. 

Topics include:

• Most pertinent regulatory requirements for fumigant use and application
• Industry updates on fumigant and non-fumigant tools use
• Fumigant application based on need within fields
• Soil-borne pathogen management

Continuing Education Units are available: 1.5 hours of "Other" and 1.0 hours of laws and regulations have been applied for from California Department of Pesticide Regulation (DPR).

Registration is required and participants will receive a link and instructions prior to the workshop. Register here.

Dr. Oleg Daugovish

Announcing Treemendous Learning Webinars for Middle and High School Students

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 UC Agriculture & 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.

This is a cross-post from the "Topics in Subtropics" blog. 

Credit: Al Soot, Unsplash

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.

Milkweed aphids on narrowleaf milkweed. Credit: Annemiek Schilder

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!

A lady beetle adult and larva hunting aphids on narrowleaf milkweed. Credit: Annemiek Schilder

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.

A lady beetle larva eating an aphid. Credit: Annemiek Schilder

Related Reading:

What's wrong with my peach tree?

'Tis the time for mushrooms

UC HAREC donates fruits and vegetables