Yolo County Blogs
When are seasonal heavy rains welcomed but worrisome? When rains fill reservoirs, but also turn fields into seas of standing water! Such has been the case in northern California which has seen torrential rains in recent weeks. After 5 years...
“Ganoderma's been around for a long time,” said Bob Johnson, a UC Davis graduate student who is leading the study for his doctoral thesis under the direction of UC Davis plant pathologist Dave Rizzo. “The tree failure we're seeing may be that we've now reached such a density of almonds here, that the problem just seems more widespread. Or it may be a new Ganoderma species in our state.”
The UC Cooperative Extension nut crops advisor in Fresno County, Mae Culumber, speculated that air quality regulations prohibiting the burning of orchard prunings may have allowed fungi to grow in slash piles in agricultural areas. However, the cause of the problem is currently unknown.
Ganoderma is a genus of fungi with about 80 known species. It is typically considered a forest pest in the U.S. and, in terms of agriculture, poses problems for the palm tree industry in the tropics. The Ganoderma now being found in California agriculture grows in the living heartwood of almond, peach and other stone fruit trees. The presence of the fungus doesn't appear to impact tree production. The only outward sign is development of rather large shelf-like mushrooms on the trunks called conks.
“Once you see conks on the tree, it is essentially dying from the inside out,” Johnson said. “The conks release trillions of spores which wind and water move through the orchard and to neighboring orchards. It's next to impossible to stop the spread.”
A farmer in Hanford recently pulled out and destroyed every tree in his 120-acre orchard because of Ganoderma infection.
“This was a 9- or 10-year-old orchard, just when the grower starts making money after investing in its establishment,” Johnson said. “Instead, his trees were just falling down right and left and he pulled out the orchard.”
Culumber called Johnson out to a Fresno County orchard where the farmer is starting to lose trees.
“In his orchard, every fifth tree has a massively sporulating conk,” Johnson said. “Growers see the conks, but they don't realize they are the infectious part of Ganoderma fungi.”
Culumber said other orchards in the area also have active conks.
“I know of at least two locations within a square mile,” she said. “One is very progressed, and I talked with another grower with early symptoms.”
Johnson is calling on farmers to contact him if their trees have fallen over due to decay in the trunk or if they have seen conks on tree trunks.
“We need to understand the distribution and incidence of Ganoderma infection in order to develop management strategies that will limit the impact of this disease,” Johnson said.
To report trees potentially infected with Ganoderma, contact Johnson at (530) 302-6301 or firstname.lastname@example.org.
Adding biochar to a farm's field is an irreversible decision, so understanding its long-term impacts is essential for farmers to make informed decisions.
Biochar, a charcoal created from organic materials burned at high temperatures and added as a soil amendment, has been shown to increase pH and soil fertility in areas with more weathered, acidic soils, like the tropics. But a new study shows its impact on productive soils like those in California's Central Valley may be quite different.
Findings from a four year study conducted at the Russell Ranch Sustainable Agriculture Facility at UC Davis showed an increase in corn yields in the second year after adding biochar, but through different means than have been observed elsewhere.
The study, published in the journal Agriculture, Ecosystems and Environment, used biochar made from walnut shells, cooked at 900°C from an orchard in Winters, Calif. Biochar was added to a plot rotating tomato and corn crops at the Russell Ranch Sustainable Agriculture Facility at UC Davis, a long-term research facility focused on using farm management practices similar to those used at commercial farms.
Short term boosts in yields
“A lot of biochar lab studies look at intricacies of how biochar changes nitrogen cycling, so I was very focused on looking at that in the field,” says Deirdre Griffin, Ph.D. candidate in soils and biogeochemistry at UC Davis and lead author of the study.
But instead of a change in the nitrogen cycle, the biochar affected potassium, phosphorous, and calcium in the soil, causing an 8 percent increase in corn yields. The increase, however, didn't happen until the second year after application.
That delay may be due to biochar's hydrophobic nature — it repels water when first in the ground, and may only start to interact with soil after significant time. After year two, the yield benefits of biochar dropped off, and by year four showed no difference compared to plots without biochar.
“The benefits that we saw were from direct fertilization from biochar, in which case growers might be able to see the same boost in yield if they applied a little more fertilizer,” says Griffin. “We didn't see much change in the soil properties that could have more lasting effects. But those things could still be impacted in the coming years as the biochar continues to age.”
To see continued yield increases like these, growers may need to apply biochar regularly, which is not its intended purpose and may pose challenges for growers. Biochar can be dusty, dispersing black soot as it is applied. Growers can wet biochar to limit its dust, but without overcoming that challenge, repeatedly adding biochar to the soil may limit its appeal.
Many biochars, many functions
Like compost, different biochars act differently in the soil. Different sources (type of shell or other organic material), treated at different temperatures, and added to varying soil types can all impact what benefits a grower may see from biochar.
Carbon sequestration, not included in this study, is broadly understood as a benefit of biochar, and some research is looking at its potential to pull heavy metals from soils.
“When biochar research started flourishing, people started seeing positive results in tropical systems and got excited about it,” says Griffin. “Because of our soils and agriculture, we don't necessarily see the same benefits in our systems. But every biochar is different, and we need to understand their characteristics, to engineer them for different systems and different purposes. And we're still working to understand that.”
Griffin's study is ongoing and Russell Ranch and will continue to provide insights on biochar's impacts over time.
Having a long-term study that uses realistic farm practices will help build the understanding of the role of biochar in already fertile soils, and have strong data showing how biochar really acts in the long run, so farmers making the irreversible decision to add biochar know exactly what they are investing in.
More information on biochar can be found on the UC Division of Agriculture and Natural Resources' Biochar Blog, the Solution Center for Nutrient Management, and the Biochar Database managed by associate professor Sanjai Parikh at UC Davis.
OK, it's January and raining outside. So we can forget about water issues, right? Farmers know better. Water planners know better. Snow pack is only a fraction of normal as of today, and most of the south state is still under...
This time of year, you're probably thinking “Ahh, pecans!”
And particularly, “Ahh, pecan pie!”
We do love our pecans. The U.S. produces 80 to 95 percent of the world's pecans, and most are grown in Georgia, according to the UC Davis Fruit and Nut Research and Information Center (FNRIC). In 2014, the U.S. produced 133,165 tons of pecans (in-shell) valued at more than $400 million. Of that, California contributed 2,500 tons, valued at a little more than $10 million, or less than 2 percent.
“Although pecan trees have existed in California for more than a century, the first commercial orchard in California was established in the mid-1970s in the Clovis area," FNRIC relates on its website. “Since then, pecan production has spread throughout the Central Valley, but it is not nearly as widely cultivated as other nut crops (almond, pistachio and walnut) in California." The nuts thrive on long, hot summers for proper maturation.
The pecan (Carya illinoinensis), native to Mexico and the southcentral and southeastern regions of the United States, is a member of the Juglandaceae family, which includes hickory and walnut. "Remains of pecans were found in archaeological excavations in Texas with human artifacts dating back to 6100 B.C.," according to the Nutcracker Museum. "The pecan, which is native only to North America, was found in or near river beds, and was a staple in the diets of both the natives and the early settlers."
“What's great about pecans is that they are delicious!” says Amy Block Joy, emeritus UC Cooperative Extension specialist, who, true to her name, finds "joy" in pecans. “They are one of my favorite nuts.”
“Pecans are an excellent source of vitamin E and other antioxidants, fiber, some B-vitamins and are also good sources of potassium, copper, iron, manganese and zinc,” says Joy, who holds a doctorate in nutritional sciences from UC Berkeley. “They are a rich source of oleic acid, a mono-saturated fatty acid. Pecans do not contain any cholesterol.”
And nuts are good for you, she said, noting that a study published recently in the journal BMC Medicine reported that having a daily amount (at least 20 grams) of nuts "cut people's risk of coronary heart disease by nearly 30 percent, their risk of cancer by 15 percent, and their risk of premature death by 22 percent.”
Meanwhile, all over the country — especially the South — pecan pie is synonymous with the holidays. It's an iconic Southern cuisine, a 19th century invention, that probably originated in the 1800s. Harper's Bazaar published the first known pecan pie recipe in 1886. Today, cooks clamor to make it their own — adding everything from bourbon to rum to chocolate to orange zest.
My late mother, born and reared on a Texas ranch where pecan trees flourished, treasured the pecan pie. She always pronounced it “Peh-CAHN” (never PEE-can) and prefaced it with "rich." Not “rich,” as in wealthy, but rich as in “don't-eat-too-much-of-this-or-you-will-engage-in-a-hate-relationship-with-your-scales.” If you're thin and have to "stand up twice to make a shadow," as the Southern saying goes, then no worries!
Did you know that pecan pie is the state dessert of both Texas and Oklahoma? And that the pecan is the "state nut" of Alabama and Arkansas? In Tennessee, it's known as the "state health nut." That's because it is!
In the Garvey household, our favorite pecan pie recipe is loaded with nuts — two cups. That's 66 pecans per cup or a total of 132 pecans, says nutritionist Amy Block Joy, who knows how to put the "nuts" in nutrition. We know how to put the pie in the pantry, and then to the holiday table.
Garvey's Unforgettable Southern Delight Pecan Pie
Makes 9-inch pie
3 eggs, large
1 tablespoon cornstarch
1 cup dark corn syrup, Karo
3/4 cup loosely packed brown sugar (don't press down)
1 tablespoon of white sugar
1 to 2 tablespoons of good quality dark rum (we used Myer's original dark Jamaican rum)
1/4 cup butter, melted
1 teaspoon pure vanilla extract
2 cups toasted pecans, halves only
One 9-inch unbaked pie crust (recipe below)
Preheat oven to 350 degrees. Spread pecans on baking sheet and toast at 350 degrees for 6 to 10 minutes. Set aside. In medium bowl, beat eggs with a fork or wire whisk. Add cornstarch and mix until blended.
Add corn syrup, sugar, rum, butter and vanilla. Stir in toasted pecans. Pour mixture into pie crust. Cover outer crust with loosely placed, crimped aluminum foil to prevent excess browning.
Bake at 350 degrees for about 50 minutes. At 40 minutes, remove aluminum foil from outer crust and cook for another 10 minutes, or until knife inserted in center comes out clean. The center should be slightly firm to the touch but a bit jiggly.
Place pie on wire rack and let cool at room temperature for two hours before serving.
Crust for 9-inch pie:
1-1/4 cups all-purpose flour
1-1/2 teaspoons granulated sugar
1/2 teaspoon salt
1 stick or ½ cup of cold unsalted butter, cut into chunks
1/4 cup ice water, plus an additional tablespoon if needed
In a medium bowl, combine flour, salt and sugar. Cut butter into flour mixture until it resembles coarse crumbs. Gradually sprinkle the water over the dry mixture, stirring until dough comes together enough to form a ball. Wrap dough in plastic wrap and refrigerate for at least one hour. Roll the dough out into a 12- to 13-inch circle. Place in pie plate and let it overhang 1/2-inch. Crimp the crust.