Click on photos to see details.

This spring as our fruit trees began to leaf out and grow most of us noticed that they were not flowering and growing properly.  That is because they did not receive enough hours of chilling.  Cool weather and short days in autumn cause most fruit trees, berries, and vines to lose their leaves and go into a state of dormancy, which protects them from winter freezes.  Subtropical plants like citrus and olives do not lose their leaves, but they still have a short dormant or resting period.  While dormant, trees will not begin to grow normally until they have received enough hours of cold temperature, below 45^oF.  This is called chilling.   Chilling breaks down internal inhibitors and helps fruit and flower buds develop properly.  A lack of adequate chilling can result in weakened trees, poor bud break, bud drop, spread-out bloom, poorly developed flowers, and even a complete lack of flowers depending on the type of fruit tree. 

The number of chilling hours (below 45^oF) required by fruit trees varies from about 100 for figs to over 1,000 for apples. It also varies by variety within each species.  It is even more complicated than that.  Using the old system of measurement, which just adds up the number of hours of temperatures below 45^oF (November 2013 through February 2014) we had 1,339 hours in Santa Rosa.  This is slightly above normal, as the historical average is about 1,200 per year with a range of 950 to 2,012 hours.  Consequently, we would not expect to have seen any abnormal growth this spring, but we did.  This occurred because not all chilling hours are equally effective and because chilling hours accumulated at night can be cancelled by warm daytime temperatures. 

Bartlett pear flowering early on the cooler north side of the tree and later on the warmer south side (Photo Alberto Ramos)

To make the chilling system more accurate and useful, several University of California and other fruit tree researchers around the world have been testing another chilling measurement model that places more emphasis on temperature portions between about 35^oF and 55^oF, which are more effective in breaking dormancy than colder temperatures.  It also takes into effect the negation of chilling hours when temperatures exceed about 60^oF.  This is because warm sunny days above 60^oF, of which we had many this last fall and winter, reverses the portion of chilling obtained when it was cold at night.  This system is much more accurate as can be seen in the following chart of chilling portions over the last five years.  It shows that 2013-2014 was the lowest in chilling hours.

Paul Vossen, Specialty Crops Advisor pmvossen@ucanr.edu 

Available as PDF Low Chilling in 2014 Causes Fruit Tree Problems

On Saturday morning, June 28, 35 people attended a sudden oak death (SOD) educational talk and local disease update at our UCCE office. More than half of the people who attended were unfamiliar with the disease, letting us know that we continue to find new people with our outreach. In this 2-hour session, Master Gardener specialists described disease history, biology, and treatment.

Attendees left informed about what can be done for diseased trees on their property, or if they have no disease, how to avoid infection. These talks are given by the Master Gardeners at different locations around the county, periodically throughout the year and on request.

Often the first question asked is “What kind of oak is this and is it susceptible to SOD?” See photos below for common oaks of Sonoma County (click on the picture for a larger version).  

Visit Sudden Oak Death for more information.

If you have a backyard garden, you know that there are times that everything seems to ripen at once.  Or perhaps you enjoy produce gardening, but grow far more than you plan on consuming. What can you do with that excess FOOD? Don't let it go to WASTE!

Until recently, because of health regulations requiring the tracking of food, that produce could not have been sold or donated to restaurants, schools or institutions. Why? Because that food must all come from an approved source - that is, a grower that follows certain guidelines to reduce the likelihood of contamination or food borne illness. 

Last year, the Sonoma County departments of Agricultural Commissioner, Department of Health Services, Information Systems Department and UCCE Sonoma County worked together to create and roll out the Approved Produce Gardener Certificate (APGC). This FREE certification program allows backyard produce growers who follow the required best practices to donate or sell their produce as an approved source grower.  

Visit Approved Produce Gardener Certificate, review the FAQ's then complete the annual registration form.  

1. Enter the responsible party name(s)
2. Enter the garden location(s)
3. Agree to follow each of the best management practices
4. List all of the produce expected to grow in the next year
5. The certificate is good for one year from the date of completion
6. The certificate lists all the produce entered in step 3
7. A copy of the certificate is emailed to the user
8. Provide a copy of the certificate to entities that require produce from an approved source.

School Gardens

In order for schools to use the produce grown in their gardens, the garden must have an Approved Produce Gardener Certificate.

When is APGC not required?

If the garden is certified organic or is registered with the Agricultural Commissioner with a Certified Producer Certificate (for sales at Certified Farmers Markets) or Operator Identification Number (for pesticide use), they do not need to complete the APGC. They will need to provide proof of certification to the entity that requires produce from an approved source.

Questions?

Send an email to klgiov@ucan.edu 

Fair time is also a great time to see 4-Hers in action!  Visit the Livestock area and watch the kids show chickens, rabbits, goats, sheep, swine, dairy and beef cattle.  Showing livestock at the fair requires months of preparation for the market animals (sold at the auction) and years of work for the breeding projects (ongoing dairy and livestock projects).

Check the Livestock schedule and stop by to see the kids show while you are at the fair (look for Junior, Jr or Market on the schedule). The Large Animal Round Robin class on Sunday, August 3 starting at 1pm is where you can see the best showmen/women take their turn at showing all of the different large species: goats, sheep, swine, beef cattle, dairy cattle and horses.  The winner is crowned top showman/woman of the fair.

One way to support 4-Hers is to contribute to the purchase price of or to purchase a market animal.  4-Hers use the auction proceeds to pay back loans taken out to fund the project (bank of mom and dad or actual loan from Sonoma County Grange Credit Union). Any remaining funds are used to purchase next year's market animals, to support their breeding project and/or saved for college.

The Junior Livestock Auctions:

• Lambs – 7/26, 9am
• Goats – 7/26, 1pm
• Rabbits – 7/26, 1:30pm
• Hogs – 8/1, 9am
• Poultry – 8/1, 1pm
• Beef – 8/2, 6pm