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September 6, 2011

 

 

·        Scientist probes the sex life of corn

·        Wind power makes greenhouses greener

·        Record drought imperils Texas fall veggies

·        Feds seek new rules for child ag workers

·        Study tackles pesticide-prostate cancer link

 

 

Scientist probes the sex life of corn

 

(mercurynews.com) – In a sun-dappled cornfield on the Stanford University campus, romance is in the air.

 

There's a LeBron James-like swagger to the tall male tassels. Round female ears await, coquettishly.

 

But corn conception, and development, is poorly understood. So biology professor Virginia Walbot devotes her career to tackling one of botany's big puzzles: the sex life of corn.

 

"It is really one of the deep, fundamental mysteries of plants," she said during a recent walk through late summer's towering stalks. "It is exceedingly important to understand every step of the process, so we can produce better seeds for American farmers."

 

Her lab's discoveries in developmental biology could help change how corn is grown and boost yield.

 

An estimated 80 million acres of corn are planted in the United States every year. Innovations in plant reproduction could add to the productivity of that acreage if, for example, farmers could plant more densely and use less gas, fertilizer and water.

 

But that juicy ear on your picnic plate? It almost didn't happen.

 

The parent plant could have just as easily decided to make a big green leaf instead, Walbot said. No one knows why, or how, corn decides to create a female ear or a male tassel. Or simply grow more vegetation.

 

"How does that switch occur, from being vegetative to reproductive? What are the early steps that it commits to, to produce sperm or eggs?" she said. "It's still unclear."

 

Walbot has a lifelong affection for corn, having helped grow and sell it from her family's truck farm in Southern California, on fertile acreage now covered by a runway at Los Angeles International Airport.

 

As a little girl, "I asked for plants, not dolls," she recalled.

 

Studying at Stanford, then Yale University, she became interested in the bigger picture: plant development and evolution. The most pivotal moment in her life came in the 1970s, when she met pioneering geneticist Barbara McClintock, who also worked with corn. They shared long phone conversations, then Walbot visited McClintock's Cold Spring Harbor lab -- and she was hooked.

 

Rich corn history

 

Like McClintock, Walbot is part of a long tradition of scientists who have found corn to be the perfect organism for answering some of the fundamental questions about plant genetics and development.

 

That's because each ear has a few hundred seeds, making it easy to generate huge populations very quickly. This means that even a rare event, like a particular mutation, is easy to find.

 

Her small Stanford field is rich with corn history, evoking memories of "The Farm" that drew founder Leland Stanford to the peninsula. Adjacent is the small summer home -- now boarded up, its paint peeling and doors latched -- where Nobel Prize-winning geneticist George Beadle lived in the early 1940s so he could be close to his plants.

 

"We keep track of every ear, in perpetuity," she said. "It's like the kings and queens of England. We can go back 30 years and tell you the whole history of a plant -- who's who. ... It's very valuable material."

 

There's nothing illicit going on in this field. Rather, Walbot's team practices "safe sex," so each pollination is carefully controlled. Walbot pollinates by hand, carefully selecting mates.

 

Then, to prevent added random pollination, the pollen-laden tassels are covered with paper bags so they won't drift onto nearby ears, which are the corn's eggs. The ears are also bagged. Then each bag is identified with the date of pollination, and its parentage: "8/16 - 88-11," for instance.

 

In these dwindling summer days, pollination is almost over. Then Walbot will wait for seed to mature.

 

She'll harvest from Sept. 20 to Oct. 10. Then the ears will be placed on wax paper and stored for a week in a warm walk-in drying room.

 

Once dried, seeds are stored -- they can last a decade -- in a special room near her campus laboratory, where it's cool and dry. Or they may be sent to a national seed bank in Illinois; Stanford has contributed 40,000 seeds there.

 

Answers in the shoots

 

Using microscopes and high-end tech tools, Walbot studies the kernel's DNA to learn what genes, or sequence of genes, might trigger development. She also studies mutations that alter how genes behave.

 

This is what's different about plants: Unlike animals, they are continuously making new organs, like leaves, from scratch. So scientists such as Walbot can study the development of the same type of organ, over and over.

 

"It's like a human producing new hands every week," she said. "If you need to repair a watch, you'd grow little bitty hands. Or if you want to play the piano, you'd grow really long fingers.

 

"We don't have that flexibility, but a plant does."

 

She thinks this difference relates to how creatures respond to stress. Animals can move when times get tough. But plants are stuck in place -- so they're forced to change. They might drop leaves. Or if times improve, add new leaves, grow tall, or reproduce.

 

But how? In the tips of their shoots is a complicated sequence of genetic on-off switches. That's what she seeks to better understand.

 

"If we understood this early step, we could inhibit it," she said, so farmers could hit a pause button on reproduction. "Or we could help engineer a tassel that's not so huge ... so the plant's energy goes into making more and larger kernels."

 

So she waits for her new kernels to mature in late summer's warm sun, hoping that nature will reveal, begrudgingly, a new clue to the genetic puzzle of plant development.

 

"Every question that is answered raises three more questions," she said, brightly. "You always have more things you can explore, rather than fewer, over time."

 

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Wind power makes greenhouses greener

 

OCEANSIDE, Calif. (CNNMoney) -- From the outside, it looks like a crash-landed blimp. On the inside, it feels like a wind tunnel. For inventor David Chelf, this strange structure -- a high-tech greenhouse with no skeleton, whose lightweight skin is held aloft on breezes from giant fans -- looks like the future of agriculture.

 

"I knew nothing could grow without airflow," Chelf explains. "And I thought if I could work with natural forces, like the wind, maybe I could create a structure that held itself up with very little energy."

 

Chelf, the founder of Airstream Innovations, derived his unusual greenhouse from a single principle: plants grow healthier and more productively in moving air. He prefers a gentle, three-miles-per-hour wind, which he says is perfect for helping moisture evaporate from plant leaves without dehydrating them.

 

When leaves are too wet, diseases and fungus can take hold. When they are too dry, photosynthesis slows or stops altogether. The right amount of moving air makes crops grow more efficiently, he says, adding that his organic strawberry plants use one-third the water and produce five times the berries compared to those grown in fields. A peek inside one of Chelf's greenhouses during a recent visit revealed rows of strawberry plants heavy with red, ripe fruit. On closer inspection, the strawberries tasted as sweet and delicious as they looked.

 

Chelf's greenhouses use high-volume fans that require little outside power because they harness the wind: "I realized I could direct that inside, rather than wasting a lot of energy resisting it," he says.

 

Made of heavily reinforced plastic, his greenhouse is about 33 feet wide and 330 feet long, with a tower for air intake at one end. The upper half of the tower has flaps that open inward, funneling wind to a pair of fans below, which reduces the power needed to keep them spinning. A gauzy netting around the fans catches insects sucked in from the outside.

 

In cold weather, the incoming wind can be slowed to a trickle, allowing the air to be heated before it blows into the greenhouse. In times of extreme heat, air gets cooled the same way it's done in traditional greenhouses: by introducing mist and letting it evaporate, or by using evaporative cooling pads.

 

Armstrong Growers, which sells flowering plants to hotels, amusement parks and other commercial customers in southern California and Nevada, uses one of Chelf's greenhouses for organic growing in its San Juan Capistrano, Calif., location.

 

"We call it our bubble house," says James Russell, Armstrong's vice president. "We find there are no insects, which is super-important when you're growing organically, and we've seen reduced disease. There's just nothing else like it on the market."

 

Richard J. Gladon, an associate professor of horticulture at Iowa State University who specializes in greenhouse design and management, also says Airstream's creation is unique. Although Gladon doesn't think any system can completely eliminate disease or insects, he says the fan-inflated greenhouse "looks like a good, inexpensive way to start growing."

 

An Airstream Innovations greenhouse covers about an acre of land and costs $120,000 installed, which includes fans, the air intake tower and an automatic ventilation control system. Over the last two years, Airstream Innovation's sales have totaled about $1 million. The company has two full-time and three part-time employees.

 

Chelf's ties to the greenhouse business go back decades: He had almost finished a Ph.D. in physics in 1990 when he quit to build a greenhouse with a friend on 10 acres in the Mohave Desert. After the two parted ways in 1996, Chelf worked for a salad grower in Silanas, Calif., and developed a system to shade the plants with low, wire-hoop arches covered in cloth. In 2005, he began growing organic strawberries in a greenhouse he built in Ranchita, Calif., under the brand name Wicked Wilds, and sold them to high-end restaurants in Southern California. He continued experimenting with greenhouse design, ultimately developing one that became the basis for Airstream Innovations.

 

One of Chelf's challenges has been getting growers to follow his operating rules.

 

One would-be customer in Sonora, Mexico, who tested the greenhouse mistakenly believed the door needed to be closed to keep the structure standing. With the door sealed, airflow slowed to almost nothing, nearly killing the crops inside. Another customer pried the exhaust open when a hurricane was on its way, decreasing the pressure inside. The under-pressurized greenhouse collapsed in the subsequent storm.

 

"It's been a great learning experience, seeing the things that can go wrong," Chelf says. He spent the last year making the greenhouse "idiot-proof."

 

Stan Cox, a senior scientist with The Land Institute in Salina, Kan., a non-profit organization that conducts breeding and ecological research for sustainable growing, says he's seen ideas similar to Chelf's in other forms and places, but never assembled in this way.

 

"His ideas are new to greenhouse use, and he's found a way to organize it, package it and market it," Cox says.

 

Chelf acknowledges that he didn't invent inflatable structures or ventilation, but he's implemented them in a novel way to make his greenhouse a unique and affordable option for growers. For evidence of how well it works, he points to those strawberries: "The proof," he concludes, "is in the eating."

 

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Record drought imperils Texas fall veggies

 

(Texas A&M AgriLife) – If you like leafy green vegetables, such as spinach and cabbage, you may find them to be in short supply this fall due to the drought, according to a Texas AgriLife Extension Service expert.

 

“The problem we’re having right now is that we’re starting to plant some of these crops like cabbage, and we’re having heck keeping it wet enough to get it up and get it growing,” said Dr. Larry Stein, AgriLife Extension horticulturist for southwestern Texas. “The other challenge we are having right now is that we don’t know how much water we’re going to have for the fall if it doesn’t rain soon.”  The Winter Garden area and surrounding region grows a wide range of vegetable crops, including onions and broccoli, Stein said. It grows most of the state’s spinach crop. Most are cool-season crops and are planted in the fall and grown under irrigation.

 

This year, despite the drought, many area vegetable growers had a pretty good year because no rain meant less disease pressure. That all could change with this fall’s plantings, he said. Stein said the region did get some rain last year, but not enough to cause the rivers to run. “We had an inch here, two inches there, but we never had any running water,” he said. “So we have rivers that have not run in three to five years. The Nueces is about dry. If they don’t run, we won’t have any gravel water we can access.” With recharge from the rivers and faced with heavy demands through irrigation this summer, the Edwards, Carizzo-Wilcox, and other local aquifers are all low, according to Stein. “Basically, we’re starting to suck air from some of these wells,” he said. “We’ve got all these plans to plant, but if we don’t get some rain soon, we’re not going to have a whole lot of water to work with.” Stein noted that the large vegetable production areas in South Texas were better off water-wise because the watersheds had been recharged there from summer storms.

 

AgriLife Extension district reporters compiled the following summaries:

 

Central: Hot and dry conditions continued, and pastures were in horrible condition. Trees were going dormant or dying. Livestock producers continued selling off large numbers of cows, but remaining cattle were reported in fair condition. Hay prices were high.

 

Coastal Bend: The region had another hot, dry week with temperatures in the 100s in most counties. Some rainfall was reported throughout the district, but not enough to alleviate drought conditions. Cattle continued to be sold off due to lack of water, grazing and hay. Cattlemen were culling deeply into herds.

 

East: As much as 4 inches of rain fell in some areas, but most received only scattered showers. Even where there was heavy rain, it was not enough to rollback drought conditions. Water levels in ponds continued to drop. Some producers continued to buy hay for livestock while others further culled herds. Daily temperatures were well into the triple digits, breaking historical records in many areas. Burn bans remained in effect in all counties. More than 450 acres burned in Harrison County. Feral hog damage increased. There were reports of armyworms and chinch bugs in pastures. Livestock remained in fair condition.

 

Far West: Conditions remained hot and dry for most of the region. There were scattered, light showers, but rangeland pasture conditions continued to decline. Many trees began to shut down and shed leaves early. Burn bans remained in effect. Pecans entered the gel stage in some orchards, and nuts were reported to be average sized. In Ward County, pecans were dropping early due to lack of water. In El Paso County, alfalfa growers were taking a fifth cutting. In Winkler County, cotton growers reported an unexpected outbreak of boll-rot disease. In Upton County, cotton bolls began to open, and plants were short because of the dry weather.

 

North: The drought continued. Temperatures remained very high, and soil moisture levels very short. Some areas had spotty showers, but not enough to have much effect. Livestock producers continued to feed hay and supplements, while others were reducing their herds at a rapid pace. Many livestock producers were buying corn and grain sorghum stalks that were recently baled. There were concerns about high nitrate levels in these forges. Stock ponds were either very low or completely dry. The continued drought was still negatively impacting pastures and cotton. Pasture conditions were poor to very poor. Nearly all row crops except cotton were harvested.

 

Rolling Plains: Dry, hot weather continued, with more than 70 days of 100-degrees or higher temperatures this year. As reported last week, there will be little to no dryland cotton harvested this year, but recent reports indicate only a portion of the irrigated will be harvested either. Irrigated cotton producers continued to apply water, but with poor results. Some cotton stands were flowering but had no bolls. Pastures were in very poor shape. Other ranchers were hanging on to cattle, feeding on a daily basis, hoping for some moisture in the near future. Pastures were in very poor shape with livestock being sold or heavily supplemented. With hay prices as high as they’ve ever been, producers were looking for feeding options. Summer calves that were born in midday were lost because of overheating. In Hardeman County, the cities of Quanah and Chillicothe entered stage 4 water rationing, and all yard and landscape watering was prohibited. Residents were asked to police their neighborhoods and report excessive water use or leaks.

 

South: The region received rain, mostly light scattered showers, but heavier rains fell in some areas. Parts of Jim Wells County got as much as 1 inch; the Kleberg/Kenedy County area, about a half inch; Webb County, about 1.5 inches; and western Zapata County from 1 inch to 1.5 inches. Mostly, the rains cooled things down somewhat but did little to raise moisture levels, which remained short to very short in the southern part of the region and very short throughout the rest. Some rangeland and pastures greened up, but overall remained in poor to very poor condition. Cattle ranchers were taking advantage of the high market prices and selling down herds due to the difficulty of obtaining hay, supplemental feed and water. In Atascosa and Frio counties, dryland crops dried up, while irrigated crops, such as peanuts, were doing well but demanded a lot of water. Cotton harvesting was ongoing there. In Zavala County, land preparation for fall cabbage, onion and spinach crops continued, and the cotton harvest was ongoing. In Hidalgo County, the cotton harvest was nearly finished, and irrigators were actively watering citrus and sugarcane.

 

South Plains: There were some very scattered showers, but no significant accumulations. Burn bans were extended. Cotton fields entered the final cut-out stage of growth, and producers cut back on irrigation and were preparing for an early and quick harvest. Many fields were already showing open bolls, but the bolls were smaller than normal. Cattlemen continued to struggle with lack of grazing, hay and water.

 

Southeast: In Burleson County, irrigated corn yields were about 70 bushels per acre, while dryland corn was baled for livestock forage. Many soybean fields were being baled for forage too. The cotton harvest began, with dryland cotton fields averaging from 0.25 to 0.3 bales per acre. Brazoria County had scattered showers, with some areas receiving as much as 3 inches. However, the scattered showers were followed by very dry, hot days with temperatures as high as 106 degrees, which limited grass response to the moisture. Rice farmers continued to bale rice chaff and stubble for hay. The average asking price was $45 per roll, with yields of about four bales per acre. Forage nutrient content tests showed rice chaff hay and stubble hay to be averaging 8.4 percent crude protein and 43 percent total digestible nutrients. Many calls continued to come in requesting information on nutrient content and feeding suggestions for rice hay.

 

Southwest: The drought continued with no rain forecast. Records show it has been about 70 days since the last economically significant rain in mid-June. In addition, record high temperatures of 110 degrees and high, dry winds created dust storms and aggravated the drought. The entire region remained in wildfire-alert status. Many water tanks were dry. Forage availability remained well below average for this time of the year. The cotton harvest was ongoing with excellent yields realized from fully irrigated fields. However, overall production was expected to be down significantly as most dryland and partially irrigated cotton failed. Sweet corn, recently planted for an early fall harvest, made good progress under heavy irrigation. Peanuts, pecans and landscape nursery crops continued to make good progress wherever irrigation water was available. To save carefully developed herd genetics, ranchers reduced pasture stocking rates to the minimum and continued to provide heavy supplemental feeding.

 

West Central: Extremely hot, dry conditions continued. Burn bans remained in effect. No dryland crops survived the drought. Irrigated crops continued to suffer from high temperatures, and producers had a hard time keeping up with water demands. There was no field activity due to lack of soil moisture. Without rain soon it was predicted there would be no fall crops planted. Rangeland and pasture conditions continued to decline, and producers further decreased the size of their herds while increasing the amount of supplemental feed and water hauled. Hay was in very short supply. Most small livestock operators have already completely liquidated their herds. Some larger ranches were holding on to core herds, hoping for conditions to improve.

 

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Feds seek new rules for child ag workers

 

WASHINGTON (Reuters) - The Department of Labor is proposing revisions to child labor laws that would strengthen safety standards for young agricultural workers, the government said last week.

 

The revisions would extend restrictions on child labor, including barring children under 16 from cultivating tobacco or operating most power-driven equipment, in the first update to the Fair Labor Standards Act concerning child farm workers since 1970.

 

"Children employed in agriculture are some of the most vulnerable workers in America," Secretary of Labor Hilda Solis said in a statement. "Ensuring their welfare is a priority."

 

The Department of Labor said the proposals aimed to "bring parity between the rules for young workers employed in agricultural jobs and the more stringent rules that apply to those employed in nonagricultural workplaces."

 

The proposal comes in response to health and safety concerns for young workers. Earlier this month, a Colorado company pleaded guilty in federal court for violating workplace laws in the death of a 17-year-old boy who suffocated after being sucked under flowing grain while cleaning a bin.

 

The proposed revisions would extend regulations to prohibit child agricultural work with animals, pesticides, timber, manure pits and storage bins.

 

Farm workers under age 16 would be barred from cultivating, harvesting or curing tobacco, and a new nonagricultural hazardous occupations order would prevent those under 18 from being employed in work with farm product raw materials.

 

Grain elevators and bins, silos, feed lots, stockyards and livestock exchanges and auctions would be off-limits to nonagricultural workers under 18.

 

The proposal would also limit farm workers under age 16 from operating most power-driven equipment. All youth in both agricultural and nonagricultural work would be prohibited from using electronic devices while operating such equipment.

 

The FLSA establishes a minimum age of 18 for hazardous work in nonagricultural employment, and 16 in agricultural employment. FLSA's child labor provisions no longer apply once agricultural workers reach age 16, Department of Labor spokeswoman Sonia Melendez said.

 

According to the department, the updates are based on the experience and recommendations of its Wage and Hour Division and the National Institute for Occupational Safety and Health.

 

A complete list of the proposed revisions, which would not apply to children working on farms owned by their parents, will be available in the Federal Register on Friday.

 

The public can provide comments on proposals until November 1, after which a public hearing will be held.

 

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Study tackles pesticide-prostate cancer link

 

(Los Angeles Times) – Researchers at the University of Southern California (USC) have found an increased prevalence of prostate cancer among older men exposed to certain pesticides in Central Valley neighborhoods.

 

The authors used the state cancer registry to recruit 173 white and Latino seniors in Tulare, Fresno and Kern counties who had been diagnosed with prostate cancer between August 2005 and July 2006. They compared them with 162 men without prostate cancer, found through Medicare and tax records.

 

Researchers then traced where the men lived and worked from 1974 to 1999 and compared those locations with state records of pesticide application. Those who lived within 500 meters of places where methyl bromide, captan and eight other organochlorine pesticides had been applied, they found, were more likely to have developed prostate cancer.

 

"This is some evidence that we're doing a very bad job of controlling how you apply pesticides," said Myles Cockburn, an associate professor of preventive medicine at USC's Keck School of Medicine who was among the authors of the study published this spring in the American Journal of Epidemiology.

 

The researchers chose to examine prostate cancer in part because, unlike other forms of cancer, the risk factors are relatively few, Cockburn said.

 

They chose to focus on residential rather than occupational pesticide exposure because of the Central Valley's demographics and because they suspected that previous studies were skewed toward those who handle pesticides, a population also more likely to have worn protective gear, he said.

 

"California's Central Valley has by far the largest use of pesticides and the largest population potentially exposed to them in the United States," he said.

 

The study was funded by the National Cancer Institute, National Institute of Environmental Health Sciences and Department of Defense Prostate Cancer Research Program.

 

Critics questioned the study's findings and definition of pesticide exposure.

 

"Pesticide use doesn't equal pesticide exposure of bystanders," said Robert Krieger, a toxicologist at UC Riverside, who said "contact with potential for absorption" would be more accurate.

 

"Just because you lived in the vicinity of an application doesn't guarantee you were exposed," Krieger said. He questioned whether the men involved in the study could accurately report details that might skew the results, such as whether they used household pesticides.

 

"The attempts to reconstruct exposure in retrospect is extremely uncertain," he said, adding that he and other researchers have focused on workplace pesticide exposures that they can more easily quantify and trace.

 

Krieger said state air monitoring has confirmed that so-called pesticide drift occurs from fields into neighborhoods but that people working with pesticides face much greater exposure than bystanders.

 

Officials at the California Department of Pesticide Regulation had not reviewed the USC study Tuesday, but a spokeswoman defended efforts to guard against pesticide drift.

 

"California's drift regulations are the toughest in the nation," said Lea Brooks, a department spokeswoman. "They include buffer zones to address urban encroachment of agricultural lands and labor-intensive crops."

 

She said the department works with county agricultural commissioners to track pesticide drift, immediately investigate reports and issue civil penalties.

 

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End Transmission