During a drought, salts that would normally be leached out by rainfall stay on the surface. Growers are forced to irrigate with groundwater to wash salt out of the plants' rootzone.
Mark Bolda, UC Cooperative Extension farm advisor in Santa Cruz County, told AgAlert, a publication of the California Farm Bureau Federation, that in Northern California many strawberry and cane berry fields are being affected. The result will be loss in yield.
In a blog post Bolda wrote in December titled A tsunami of salt is on the way, he said strawberry growers across the state need to keep running that water until we get some rain.
"There is so much salt building up in these soils right now," Bolda said more than two months ago.
The most serious damage, the Californian reported, is occurring in the Oxnard area and Choachella Valley.
Scotch broom (Cytisus scoparius) and Portuguese broom (Cytisus striatus). Brooms were introduced as ornamentals, but also were used extensively for erosion control along roadsides and in mined areas.
Now growing profusely in California forests, on roadsides, and wildlands, brooms:
- Crowd out out desirable vegetation
- Form impenetrable thickets that limit access to some areas
- Shade out tree seedlings, and make reforestation difficult
- Burn readily, increasing the intensity of fire, and carry fire to the tree canopy
- Are toxic to cattle and horses and unpalatable to most wildlife
- Produce abundant, long-lived seed
- Are able to fix atmospheric nitrogen, giving broom a competitive advantage over native plants
Management of these and other weeds are presented in the recently published second edition of Forest and Right-of-Way Pest Control. Invasive species that create a dangerous wildfire hazard and crowd out desirable vegetation and wildlife are examples of why this book emphasizes vegetation management and pesticide handling, including correct equipment calibration and effective herbicide application. The second edition also provides broader coverage of insects, plant pathogens, vertebrate pests, and the various practices to manage them, recognizing that lands commonly have multiple uses and when and how pests are managed depends on many considerations with sometimes conflicting goals.
Experts with Cal-Fire, Caltrans, PG&E, USDA Forest Service, private industry, the University of California (UC) Berkeley and Davis campuses, UC County Cooperative Extension offices, and the California Department of Pesticide Regulation (DPR) contributed to Forest and Right-of-Way Pest Control, prepared by UC ANR's Statewide Integrated Pest Management Program.
Forest and Right-of-Way Pest Control is available for $35 online in the UC ANR Catalog. The table of contents and more information about the book are available on the UC IPM website. You can also preview and electronically search the contents on Google Books.
It looks harmless enough – a light dusting like baby powder sprinkled on the leaves. But powdery mildew can attack new buds and shoots, stunt growth and distort plant development. If not controlled, the fast spreading fungus can cause billions of dollars of crop damage in California. For example, powdery mildew is the most significant disease affecting grapes in California, with all productive acreage treated to help minimize loss. Borne by the wind, its spores race through fields and can easily damage a season's crop, resulting in losses of 30 percent or more.
Growers combat powdery mildew with sulfur, fungicides, and other deterrents, but treatment is costly, and timing is difficult. But a much more precise strategy may be on the way.
With the funding from UC Berkeley's Bakar Fellows Program, which supports early-career faculty conducting commercially promising research, Wildermuth is applying her discoveries to protect commercially valuable crops. She uses a plant in the mustard family popular with researchers for it small, sequenced gene and a short life cycle.
“We've already identified the parallel genes in a number of important crops,” she said. “By targeted breeding to limit these genes' powdery mildew-promoting effects, we should be able to protect plants without extensive chemical treatments.”
When powdery mildew spores land on a leaf, the spore germinates and bores through the leaf surface to make a lobe-shaped feeding structure. The fungus also influences nearby plant cells, manipulating the leaf cell physiology to gain nutrients. A high nutrient supply is needed to support the large fungal network on the leaf surface and the formation of new spores, which propagate the infection.
Wildermuth's lab used a highly refined technique under an optical microscope to scrutinize the fungus-plant interaction and focus in on the plant cell housing the fungal feeding structure and the neighboring leaf cells.
"We can see these cells under the microscope and use the laser to cut them out. The dissected cells literally drop into a tube below," she said. "It's quite fun to do."
The research team isolated the cells and extracted the RNA. They then determined which genes are turned on and which are turned off in specific cells at the infection site versus uninfected cells. They zeroed in on genes likely to be critical to the infection process, and used plants in which these genes were knocked out in order to see if the plants respond differently to powdery mildew.
The lab identified a set of genes that actually help the mildew fungus steal more food from the plant. The process, called endo-reduplication, allows cells in the leaf to increase production of DNA without dividing – one of the few ways cells can increase their metabolism and size, Wildermuth says.
“The fungus induces endo-reduplication in the plant cells underneath the feeding structure, and gains access to more nutrients in the leaf.” This, in turn, spurs fungal growth and reproduction. “We showed that if the DNA-enhancing process is blocked, the fungus gets put on a diet, and its proliferation is limited,” she says.
The Bakar Fellowship supports her current effort to determine whether similar genes in grapes, tomatoes and other crops threatened by powdery mildew can be targeted to limit the fungus's growth. Crop strains in which these genes are less active or even absent could be selectively bred to thwart fungal growth.
National Public Radio.
This presents a financial dilemma for almost every rancher in Nevada, California and Oregon as one of the worst droughts in a century maintains its grip on the West.
For the story, reporter Kirk Siegler spoke to Ken Tate, UC Cooperative Extension specialist in the Department of Plant Sciences at UC Davis.
He said much of Nevada is going into its third year of severe drought, a situation that's unprecedented even for an arid region accustomed to dry spells.
Tate and his colleagues are helping ranchers squeeze out as much irrigation efficiency as possible, and manage rangelands so the vegetation is more drought-tolerant. But there's only so much that can be done.
"There are not scientific answers to some of these problems. Sometimes there's no solution for not enough rain," Tate said.
The use of plastic emitters in drip irrigation began in 1956 on a Kibbutz in Israel, where, like California, water demand is perennially greater than supply. Drip was introduced into the United States in the early 1960s.
Sun-Star reporter Marina Gaytan spoke to Scott Stoddard, UC Cooperative Extension advisor in Merced County, to get his thoughts about the trend toward drip.
“You can get water savings by using drip, but often times what you're really getting is improved water use efficiency,” Stoddard said. “You've improved your yield for the same amount of water.”
According to a farmer quoted in the story, installing a one-year surface drip system costs about $400 per acre. Some farmers are installing buried drip irrigation, which runs about $1,500 per acre but will last for many years.
Farmers welcome recent rainfall
Ventura County Star
Even though springtime rainfall can cause molds to grow in strawberries, and splashing raindrops can spread fungal and bacterial pathogens, farmers are delighted with the wet weather.
"We're going to lose some fruit, but that's a small price to pay," said Oleg Daugovish, UCCE advisor in Ventura County.
Before the rain began to fall, Daugovish advised growers to apply protective fungicides and open up plant canopies to expose the inside of the plants.