- Author: Gabriele U Maier
Dr. Gabriele Maier, Professor of Extension, Beef Cattle Herd Health and Production, UC Davis
September 2024
What happened? The California Department of Food and Agriculture (CDFA) announced in a press release on August 30th, 2024 that highly pathogenic avian influenza (HPAI) was detected in three dairies in the Central Valley. The outbreak of this flu virus in dairy cattle was first reported in the Texas panhandle in the spring of this year after several dairy herds had cows become sick with an unidentified illness. The affected cows were lethargic, had a fever, some had clear nasal discharge, diarrhea or dry feces, dropped in feed consumption and milk production, and most remarkably shed thick, colostrum-like milk. Most of the affected cows recovered after a couple of weeks, but their milk production did not reach the same levels as before they became ill. Veterinarians were unable to determine the cause of these outbreaks for some time, but dead birds on the dairies and cats with neurological signs finally raised the suspicion for avian flu. Cats and other mammals often become neurological when infected with HPAI and cats on dairies become infected when drinking raw milk. Samples collected from affected cows indeed came back positive for HPAI and since then, dairy herds in multiple states across the U.S. have tested positive for the virus. For a current and historical overview of affected states go to the United States Department of Agriculture (USDA) dashboard. As of September 3rd, 2024, a total of 14 states have diagnosed cases in 197 herds.
How did this virus get into dairy cattle? It is now believed that the virus spilled over from birds to dairy cattle in a single event, i.e. one cow was infected in Texas through bird droppings or a dead bird, and the virus has since spread from cow to cow only. Flu viruses change often, which is why we need a new flu vaccine in people every year. When a host such as a bird gets infected with two types of flu viruses at the same time, the viruses can reassort their genetic material. By random chance events, the newly assorted virus is now capable of infecting a new host, in this case cattle.
How has the virus spread between cattle so quickly? HPAI is shed in large numbers in the milk, even before cows show clinical signs of disease. It is very likely that the virus spreads between cows on a dairy through milking machines. The virus is also shed in small amounts in urine, nasal secretions, and saliva. In a study where dairy heifers were experimentally exposed to the virus via an inhalation mask, heifers only had a temporary increase in nasal discharge without any other clinical signs. However, the same researchers infected the udder of lactating cows experimentally through the teat canal and were able to reproduce the same disease symptoms seen on the affected dairies: abnormal milk, decreased feed intake, watery diarrhea or dry feces, a significant drop in milk production and clear nasal discharge. A preliminary version of this study is available online. Even though there are quarantines and movement restrictions in place for herds where HPAI is found, the rapid spread of the disease shows how interconnected the cattle industry is and how fast and far pathogens can travel. The virus has also been spread from cows to domestic poultry, which are susceptible to HPAI. When HPAI is found in domestic poultry, the typical outcome is that all birds are euthanized. For all these reasons, biosecurity is of utmost importance to curb the spread of HPAI among cattle and poultry.
Is there a risk to people? So far, only a few cases of avian influenza have been reported in dairy workers, none in California yet, and all have had mild symptoms and have recovered. Humans luckily do not appear to be the main target species of this type of avian flu virus even when directly exposed to infected cows, but personal protective equipment (PPE) is highly recommended for those working on dairies. Human safety is paramount, and the USDA offers financial support for affected premises to purchase PPE, such as gloves, goggles, and masks for farm workers. Early on, it was also determined that pasteurization inactivates HPAI virus, so the milk supply stays safe. The USDA is also confident that the meat supply is safe and will be adding H5N1 monitoring in dairy cows at slaughter to its program later in September. It is, however, not recommended for people to consume raw milk as milk appears to be the main vehicle for transmission and may not be safe to drink.
What happens now in California? The staff at the Animal Health branch at CDFA had been preparing for the moment when HPAI would be detected in a California dairy herd. Factsheets and regulations are posted on a dedicated website. Lactating dairy cattle moving interstate from California require a Certificate of Veterinary Inspection and a negative HPAI test within seven days of movement. All dairies are urged to increase their biosecurity including cleaning and disinfection of vehicles to transport cattle, restriction of worker movement between dairies and poultry facilities, limiting visitor access to premises, wild bird deterrence, etc. All lactating cattle shown at fairs must have a negative PCR test for the virus from a milk sample within seven days before arriving at the fair. Enhanced biosecurity for dairy cattle at fairs has also been outlined in a factsheet.
Is there a vaccine? There is no vaccine for cattle yet, but several pharmaceutical companies are working on the development of such vaccines. The USDA is also conducting research into a vaccine. If or when a vaccine for cattle will become available is still unknown today, but the flurry of activity is a promising sign.
What do beef ranchers need to consider? No beef cattle have been found to be infected with HPAI to date. Spread within a beef herd would likely be limited because cows aren't being milked. However, beef cows are likely not immune to the virus. Therefore, biosecurity should also be on ranchers' minds, especially for those who have contact with dairy cattle or domestic poultry. You do not want to become a fomite. The biosecurity training provided by the Beef Quality Assurance program is a good starting point to learn how to prevent spread between cattle or between cattle and poultry. Chapter 3 in the BQA manual is full of good information. For example, a trailer that is used to transport cattle from multiple herds should be thoroughly cleaned and disinfected between loads. Changing clothes and washing boots between visiting different herds should also be practiced. Limiting visitors to the ranch and keeping a visitor log is also encouraged.
The avian influenza outbreak in California dairy cattle is a stark reminder of the unpredictable nature of viral diseases and their ability to cross species barriers. It is important to follow the science, listen to guidance from experts, understand that sometimes things change, and we need to adapt with the change. We have successfully overcome Covid19 – we will also get through avian flu in dairy cows. Keep checking the CDFA website to stay informed on the development of this new cattle disease.
- Author: Heather Hamilton
I have always loved zinnias for their vast range of colors and beauty. We once had a farm near me that you could go and pick your own flowers to bring home and enjoy, sadly they are no longer there. Since they moved on I decided I would try and plant some by seed this year. It was so easy and I want to say I got fairly quick results. Several different varieties have been grown over the years, with the first being, Z. peruvians which was introduced in the early 1700's. In the late 1700's, the Zinnia elegans or also known as the Z. violacea which is the most familiar one seen in the garden. This is the one that I am growing. Zinnias are an annual plant with flowers being composites, like daisies. They consist of florets that surround a disc, which may be single, double, or semi-double flowers. They thrive in sunny, hot conditions with lots of water if grown in pots. It is a fabulous addition to my cottage garden and makes a great display in floral arrangements. Needless to say, I will plant these every season moving forward. Next, I want to try the giant varieties. Cheers to growing another all-time favorite cut flower!
- Author: Help Desk Team
It's getting close to the end of our summer gardening season. Now is the time to start thinking about next summer's garden. Do you have annual flower or vegetable varieties that did really well in your garden, and you'd like to grow them again next year?
Saving seeds to plant for a new crop is an ancient but simple and enjoyable process. In fact, it was routinely practiced until the 19th century when seed companies started to multiply. Seed saving is especially useful if the seeds for the item you want are hard to find. Additionally, it enables you to replant varieties that are well-suited to your garden's particular conditions.
Saving seeds from your own garden will start with seeds from the healthiest plants and produce that have the characteristics you want. You might choose the flowers that last the longest, or a vegetable plant that is most productive. You should also choose seeds from plants identified as “open pollinated” or “heirloom”. Seeds from hybrid varieties may not grow into plants even remotely like the variety you are growing.
Some plants such as tomatoes and most beans self-pollinate so their seeds will grow true to the variety. Others are pollinated by insects (e.g., squash and cucumbers) or wind (e.g., corn). If the original seeds are from open pollinated wind- and insect-pollinated plants, saved seeds may give unexpected results if there are other varieties of that vegetable or flower growing nearby. Flowers with easy-to-save seeds include calendulas, columbines, foxgloves, nasturtiums, poppies, sunflowers and zinnias.
Let seeds mature on the plant before collecting. This usually means leaving them longer than you would for good eating quality and letting some seed heads dry on the plant rather than deadheading. Determining when to harvest for seed saving is generally based on whether the seed is classified as wet or dry. Tomatoes, peppers, eggplants, and squash are examples of wet seeds. Wet seeds should be collected when the vegetable is slightly overripe. Beans and peas are dry seed plants. They should be harvested after the pods are fully mature and dry, and the beans or peas inside are hard.
After harvesting, there are three steps: cleaning, drying, and storing.
To clean wet seeds, separate them from the fleshy vegetable, rinse until they are clean, and spread them out to dry thoroughly. Dry them on a screen or a pan as the dried seed can be difficult to separate from paper towel or newspaper.
Some wet seeds, such as tomatoes, need another step before rinsing and drying. This mimics a natural process that lets beneficial microorganisms develop to remove a gelatinous coating on the seeds and destroy seed-borne diseases. Soak the seeds in their own juice (add about half as much water) for several days until a white mold appears. Swirl them daily. The viable seeds will sink to the bottom. Drain off the mold and anything floating, rinse the seeds well, and proceed with drying.
Cleaning dry seeds is easier. Dry seeds and pods are produced by beans, peas, lettuce, chives, most crucifers, and most flowers. After the pods or seed heads are fully dry, remove the seeds from their surrounding pods and membranes, also known as ‘chaff'. One method to remove the chaff is to rub the seeds against something mildly abrasive, such as a screen. Then, put the seeds in a jar; pour the seeds into another jar outside in the wind, or in front of a fan, and let the air carry the chaff away.
Make sure seeds are completely dry before storing. Store dried seeds in an airtight container in a cool place to avoid exposure to moisture and heat. Mark the container with the name of the plant, the date, and any notes on color, location, or size.
For more information on saving seeds, see these links:
• Beginners guide to seed saving: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=11597
• Seed saving basics: https://mgsantaclara.ucanr.edu/garden-help/how-to/seed-saving/
• Saving seeds of popular plants: https://mgsantaclara.ucanr.edu/garden-help/how-to/seed-saving/saving-seeds-of-popular-plants/
• Video: https://www.youtube.com/watch?v=edUwq0wMztM&t
• Book: What We Sow by Jennifer Jewell
Help Desk of the UC Master Gardeners of Contra Costa County (SEH)
- Author: Bodil Cass
F\ig Wax Scale has recently been detected in the environment in the San Diego County. This insect is commonly intercepted at ports of entry, especially on shipments of palms, but has not previously established a reproductive population in California to our knowledge.
Fig wax scale is an A-rated, actionable invasive pest by CDFA, due to its high potential to damage fresh fruit production through lowering yield, increased production costs, disruption of export markets, and vectoring of plant viruses including grape vine leaf-roll virus. It is a polyphagous phloem feeder and a potentially devastating pest of many high-value crops including almond, grape, citrus, pistachio, avocado, cotton,fig,palms,pear,and ornamentals.In the USA it is currently only found in Florida, although it is distributed throughout much of the rest of the world and frequently affects citrus and fig production in Europe. The environmental conditions throughout much of California are considered favorable for this scale to establish if it is not eradicated and prevented from re-entering.
For more on this scale and other recent topics, check out the Topics in Subtropics Newsletter:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=60446
- Author: David Layland, UC Master Gardener of Napa County
It's getting close to what I call California native plant season. Fall and winter are the best times to plant natives, and that's also when the Napa Valley chapter of the California Native Plant Society (CNPS) holds its annual plant sale. The sale this year is on Saturday, October 5, and Sunday, October 6. For more information about the sale, visit the chapter's website.
My experience with California native plants began several years ago when my wife and I decided to spruce up the landscaping in front of our home. The existing landscaping was okay but had suffered from a bit of neglect. For years we had concentrated on the grounds behind our home where we had planted fruit and olive trees, vegetable and ornamental flower gardens and a small vineyard.
We wanted to plant something different in the front but nothing that required a lot of maintenance or water. We knew we would continue to spend most of our time in the back. The front would remain the poor red-headed stepchild.
After talking with fellow Master Gardeners and doing some research, we started to consider California native plants for our front landscape. When I saw the information below on the CNPS website, I knew we were moving in the right direction:
“While no landscape is maintenance free, California native plants require significantly less time and resources than common non-native garden plants. California native plants do best with some attention and care in a garden setting, but you can look forward to using less water, little to no fertilizer, little to no pesticides, less pruning, and less of your time.”
So, the decision to relandscape with California natives was easy. Then the real work of selecting and sourcing the plants began.
Fortunately, the CNPS website has a search feature that allows you to enter your zip code and find the plants available at nurseries in your area. Today the website shows a total of 8,539 plants, which is a little overwhelming. But once you enter your zip code, the search eliminates plants unsuitable for your area. For my zip code, that number went down to a more manageable 139 plants. When I selected nurseries within 50 miles of my address, options dropped to 74 plants at two different nurseries.
Developing a layout was the next step. For this we turned to an experienced friend who guided us through the daunting conceptual task that produced our new front landscape. When you have limited drawing ability, it sure helps to have someone on your team who can create a design that captures what you had in mind.
With the plan in hand, it was time to head to the nurseries and start plugging actual plants into the layout. We knew we needed plants in a range of heights, from ground covers to a plant five or six feet in height that would be a focal point. We did this task in October, an ideal time to plant natives. They appreciate the cool and rainy weather to ease their transition from the nursery to the ground.
Plant selection turned out to be easy. We arrived at the nursery with a clipboard containing the plant layout and a list of desired plants. The nursery suggested substitutes for plants we wanted that weren't available. After about an hour, we headed home with a truckful of California natives, including white sage, coyote mint, seaside daisy, deer grass, bush monkeyflower, California buckwheat, coffee berry and emerald carpet manzanita.
All our purchases were in 1-gallon containers as this size is easiest to plant. Following advice from Henni Cohen of Napa Valley's CNPS chapter, we made sure we planted wet plants in wet holes.
It has been several years since we relandscaped and I'm happy to report that the plants are thriving. Maintenance has involved just a bit of pruning and none of the plants requires more than a monthly watering. In fact, we were so happy with the front that we replaced one of our vegetable gardens in the back with native plants. I see a trend developing. Eventually, we may give the boot to our ornamental flower gardens in favor of California natives.
Library Talk: Join UC Master Gardeners of Napa County and Napa Public Library for a talk on “Caring for California Native Oaks” on Thursday, September 5, from 7 pm to 8 pm, via Zoom
Learn about oak tree characteristics and specific requirements along with University of California resources to help you provide the care your oaks need to thrive.
Register to receive the Zoom link.
Composting Workshop: Join UC Master Gardeners of Napa County for a free workshop on “Worm or Backyard Composting: Choose Your Own Adventure” on Saturday, September 7, from 11 am to 1 pm, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn the basics of hot and cool composting, worm composting and grass cycling. At the conclusion of the workshop, you may purchase a backyard compost bin for $20 (one per household) or get everything you need to build your own worm composting bin, including the worms. Registration required.
Fall Faire: Join the UC Master Gardeners of Napa County for an entertaining and educational event on Saturday, September 28, from 1 pm to 4 pm, outdoors at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Enjoy exhibits on composting, monarch butterflies, succulents, water conservation, bees and more. The program includes activities for kids, a scarecrow contest, giveaways, and music. Admission is free.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 am until 1 pm at the University of California Cooperative Extension Office, 1710 Soscol Avenue, Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description.
Become a Master Gardener Volunteer: UC Master Gardeners of Napa County is now accepting applications for the Class of 2025. Visit napamg.ucanr.edu to read the informational brochure, then register to attend a mandatory information session for applicants. Application deadline is 5 pm on September 25.