UCCE Master Gardeners of San Joaquin County
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UCCE Master Gardeners of San Joaquin County

Posts Tagged: organic

Are weeds taking over your garden?

My calendar says November but the weeds in my garden think it’s spring. That nice rain last month followed by warm, sunny days has prompted them to grow like, well, weeds and that’s not good news for my winter crops.

What’s a gardener to do?

Like so many other gardeners, I turned to the folks at the UC Davis Weed Science Program. Housed in the UC Davis Department of Plant Sciences, the “weeders” are experts at helping growers and gardeners improve plant production by controlling weeds.

Tom Lanini shares weed advice at UC Davis Picnic Day 2011.
What are the most effective organic tools for controlling weeds? That’s what I, and thousands of others, want to know. You don’t have to be an organic grower to seek organic tools for fighting weeds. Synthetic herbicides come with a cost to growers and the environment, so more and more farmers are seeing the value in employing organic tools with or without other means.

Which tools work the best in which situations? Here’s a quick overview, courtesy of Cooperative Extension Specialist Tom Lanini, who specializes in weed control in vegetable crops.

Mulches – Researchers test them all – plastic, bark, wood chips, other porous material, even what they call live mulches like clovers and fava beans. Mulches block light, which weeds need to grow. “I think mulches can be the best organic option for fighting weeds, especially for vines and trees,” Lanini says. Mulches are also a key weed-fighting component in organic strawberry and many other crops.

Organic sprays – Coverage is the key. “No matter what type you use – oils, soaps, acids, etc. – if you don’t spray-to-wet, 100 percent coverage, the weeds will grow back,” Lanini says. Temperature and the age of the weed matters too. Apply in temperatures above 75 degrees when weeds are very young – about a week old – for best results.  Broadleaf weeds are easier than grasses to control with sprays.

The most effective organic spray Lanini has found so far is good old-fashioned vinegar, the kind you use to make pickles. The trouble with that is, the FDA has yet to approve it for controlling weeds. “You can eat it, but can’t spray it on your weeds,” as Lanini says. There are herbicides with vinegar as their active ingredient, but they are much more costly than household vinegar.

Flamers – These propane-fueled devices quickly raise the temperature of the weed to more than 130 degrees, rupturing its cell membranes. Grasses are hard to kill by flaming because the growing point is protected underground. Flamers require quite a bit of fuel, which can be costly.

Solarization has become an important method of weed and disease control in organic desert vegetable crops. In this system, four to six weeks of solar heat under clear plastic film will kill weed seeds and pathogen propagules.

Cultural practices are extremely important in all vegetable crops especially in organic crops. Crop rotations result in shifting environments that do not favor any one weed. Use of preplant irrigation followed by shallow tillage, or flaming is a very effective method of reducing the potential weed infestation during the crop cycle.

Weeding and thinning by tool or machine is a time-honored solution. Never underestimate the value of a hoe.

You can read more about the UC Weed Science Program here and access the Weed Research and Information Center web site here.

For more detail on weed management for organic vegetable crops, Click here.

Posted on Tuesday, November 1, 2011 at 8:42 AM
Tags: organic (10), Tom Lanini (1), UC Weed Science Program (1), weeds (64)

Alternatives to fumigation and improving fumigant efficacy

Synthetic soil fumigants such as chloropicrin and 1,3-D are used by some commercial growers to control soilborne pathogens, weeds and nematodes prior to planting strawberries, onions, tomatoes, eggplant, peppers and spinach.

These fumigants and all other biocidal products with the potential to harm the environment and human health are highly regulated by the federal Environmental Protection Agency, the state Department of Pesticide Regulation, and county agricultural commissioner's offices.

UC Cooperative Extension farm advisor Oleg Daugovish and his collaborators work hard to find effective, environmentally safe and economically viable ways to improve efficacy of fumigants and to investigate alternatives to soil fumigation. The Ventura County Cooperative Extension website has archived audio and visual presentations, which include the following topics:

  • Assessment of permeability of commercial tarps under a variety of cultural practices and in various soil and environmental conditions is expected to lead to better understanding of maximizing fumigant effectiveness while reducing emissions.
  • Growing in substrate (soil-less culture) allows growers to produce crops with minimal plant disease and weeds without using fumigants.
  • Heating soil using steam is a successful way to disinfest it. However, the process to generate steam in a field can be slow and very expensive. Researchers are working to find ways to improve speed while reducing cost.
  • Most organisms, including plant pathogens, cannot survive without oxygen. Researchers are investigating an organic method to create anaerobic (oxygen-free) conditions to treat soil before planting.
  • Planting mustard as a cover crop can provide many positive benefits, one of which is allelochemical compounds. These compounds found in mustard are similar to those found in fumigants. Current research shows it is possible to use this green biomass to prepare fields for production.

To read more about Daugovish's research, visit http://ceventura.ucdavis.edu/Com_Ag/comveg.

Posted on Thursday, September 22, 2011 at 5:18 PM
  • Author: Chris M. Webb

U-pick organic strawberry season opens on coast

Swanton Berry Farm near Davenport

The U-pick strawberry fields at Swanton Berry Farm near Davenport on the coast are formally opening on May 28, but if you drive out there now, you’ll get a chance to pick without a crowd. Talking to Barrett Boaen, the U-pick manager, I got to the bottom of just why their berries, also sold at local Whole Foods stores, look and taste so good.

Partly it’s the ‘Chandler’ variety, chosen for its old-fashioned sweetness and flavor although it yields only about two-thirds as well as some varieties. It’s also about not pumping up production with too much nitrogen or irrigation (more details here). Mostly, though, it’s about the picking process. A strawberry grower visiting from the East Coast recently bought two flats from the farmstand, saying he couldn’t help himself, he had never laid eyes on such beautiful organic berries, and he knew who to congratulate—the pickers.

The workers at Swanton Berry Farm


You and I are unlikely to come close to picking as well as Swanton’s unionized employees, some of whom have more than 20 years of experience at the farm. They recognize when a strawberry is as ripe as it can be, when it’s red and sweet all the way through (strawberries don’t continue ripening once they are picked). Although a less ripe berry is firmer, with a longer shelf-life and easier to transport, it has less flavor, so the pickers wait a day or two for any berry with a green tip or white shoulders to ripen perfectly. They discard berries that are soft on one side (from raindrops settling on the fruit) or have a cat-face look, which is lygus bug damage.

Moving along the rows, which are banked up to 18 inches high to reduce back strain, they harvest each perfectly ripe berry, with its green calyx attached, in a “twist and flick” motion: “you put tension on the stem above the calyx, and rotate it, so you can see 360 degrees and whether there’s any damage to the berry; then with just the right tension, the berry will pop off naturally,” explains Boaen.

In the U-pick fields, which have ocean views, visitors pick for pleasure, hopping from row to row, enjoying the fresh air, and the fragrance of the berries and the earth. Compared to the serious work in the other 20 acres of strawberries, “the 3 acres of U-pick are a playground,” says Boaen, “We provide people everything they need to be happy.”


U-pick tent at Swanton Berry Farm
Last week the fields were dusted with a zillion white flowers, which means a burst of fruit coming soon, but the cool wet weather this spring sealed the fate of the season. Growers need lots of fruit early, to sell before cherries and other fruits arrive on the market. Instead the late winter rains knocked off or damaged the flowers, and hail beat up the berries.

“It can be demoralizing,” Boaen admits. “All that energy put into the fruit after the excellent warm January was wrecked.”

Fortunately, the farm has several other crops, and the strawberry fields are filling with new berries. You can pick them this summer for $2.50 per pound (10 percent discount for bicyclists). Bring your own containers if you remember, a windproof jacket and boots in case of fog or mud, and most of all, Boaen recommends allowing plenty of time to enjoy yourself.

By mid-June, Swanton ollalieberries will be ripe, and by mid- or late July, the blackberries will be ready. Farm tours are available by reservation. Organic strawberry and ollalieberry jams, and five other kinds, are available at the farmstand or online.

Swanton's farmstand
Swanton's farmstand

Posted on Thursday, May 12, 2011 at 11:56 AM

Growing organic farmers

Well bef

ore Safeway launched a line of organic products or Craigslist posted openings for school garden coordinators, UC Santa Cruz was training students for careers in organic farming.

The UC Santa Cruz Apprenticeship in Ecological Horticulture started in 1967 when the concept of organic was in its infancy. Forty-three years later, organic has gone mainstream and the apprenticeship program is more popular than ever.

A recently published study looking at the apprenticeship’s last 20 years found that a large percentage of its alumni are still involved in growing and marketing organic food and teaching others how to do so.

“It’s like an incubator,” said lead study author Jan Perez, research specialist with the UC Santa Cruz Center for Agroecology and Sustainable Food Systems. “It’s a place for people to really experiment and live their values and be in a supportive community.”

The six-month residential apprenticeship program, which the center runs in conjunction with UC Santa Cruz Extension, features hands-on training in gardens, greenhouses, orchards and fields. The program combines theoretical and practical instruction, with students not only studying in the classroom but also taking fields trips and marketing organic produce on campus.

Of 299 alumni surveyed, more than 80 percent have done some type of farming or gardening work since graduating, with 65 percent still doing this work. Forty-two percent said they created jobs that did not previously exist and 35 percent are working in an educational area, according to the study in the Journal of Agriculture, Food Systems, and Community Development.

For example, two apprentice alumni started Pie Ranch, a working Peninsula farm that educates high school students from San Francisco to Santa Cruz about sustainable agriculture. The farm, which grows ingredients for pies on its pie-shaped ranch, even has its own apprenticeship program.  

“They’re really spreading what they’ve learned,” Perez said.

Meanwhile, interest continues to spread in the Apprenticeship in Ecological Horticulture. Last year, applications rose to 187 for more than 30 slots. This year’s application period closed Thursday (Sept. 30).

The apprenticeship program takes place at UC Santa Cruz's farm and Chadwick Garden
The apprenticeship program takes place at UC Santa Cruz's farm and Chadwick Garden

Posted on Wednesday, September 29, 2010 at 3:06 PM
  • Author: Alec Rosenberg
Tags: Jan Perez (1), organic (10), UC Santa Cruz (3)

Organic strawberries may be more nutritious and longer lasting

While numerous studies have shown that organically grown foods contain fewer pesticide residues, there has been little convincing scientific evidence that organic crops taste better or are more nutritious.

Now a two-year evaluation of California strawberries has found that organic strawberries, while lower in phosphorus and potassium, had significantly higher “antioxidant activity and concentrations of ascorbic acid [vitamin C] and phenolic compounds, longer shelf life, greater dry matter, and for ‘Diamante’, better taste and appearance” than conventionally grown berries.

The study has been getting a lot of media attention, including coverage in the L.A. Times, Seattle Times and National Public Radio.

Published in the September 2010 issue of PLoS ONE, an open-access, peer-reviewed journal, the study looked at 13 pairs of commercial organic and conventional strawberry agroecosystems. The fields were all in the Watsonville area, where 40 percent of California strawberries are produced. All of the paired farms had been in production at least five years and had comparable soil types. The researchers collected multiple samples in 2004 and 2005, and evaluated the strawberries for minerals, shelf life and phytochemicals. A sensory panel compared the organoleptic properties of three different varieties of fruit.

Regarding post-harvest durability, the organic berries — despite no fungicide applications — had significantly less gray mold and significantly less loss of fresh weight two days after harvest than conventional berries.

“These results indicated that the organic strawberries have a longer shelf life than conventional strawberries because of slower rotting and dehydration, perhaps due to augmentation of cuticle and epidermal cell walls,” the authors wrote.

Mark Bolda, UC Cooperative Extension farm advisor for strawberries in Santa Cruz County, said there are a number of variables that could account for a reduction in gray mold infestation.

“For example, organic plants are smaller in size, have a smaller canopy and consequently are drier because of more air circulation,” Bolda said. “Flowers and fruit subsequently present a drier and less appealing host for this fungus.”

Not surprisingly, the study found that “soils on the organic farms had significantly more carbon and nitrogen, greater microbial biomass and function, and great functional gene abundance and diversity.” The authors attributed this to the fact that the conventional sites were fumigated with methyl bromide and treated with synthetic pesticides, while the organic sites were not and received double the amounts of compost.

The researchers were affiliated with Washington State University, Pullman; Utah State University, Logan; Oak Ridge National Laboratory, Oak Ridge, Tennessee; and University of Oklahoma, Norman.

U.S. consumers continue to clamor for organic foods, sales of which have increased nearly six-fold since 1997 to $21.8 billion in 2008 (3 percent of total U.S. food sales). California produces 87 percent of the nation’s strawberries, of which nearly 5 percent are organically grown.

Posted on Friday, September 10, 2010 at 6:27 AM
  • Author: Janet Byron
Tags: Mark Bolda (2), nutrition (123), organic (10), Strawberries (18), Watsonville (1)

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