Posts Tagged: organic
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.
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.
For more detail on weed management for organic vegetable crops, Click here.
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.
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.
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.”
“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.
Well before 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
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.
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.