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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
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
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
As a little girl, "I asked for plants, not dolls," she recalled.
Studying at Stanford, then
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
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
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."
Wind power makes greenhouses greener
"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
"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
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
One of Chelf's challenges has been getting growers to follow his operating rules.
One would-be customer in
"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
"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."
Record drought imperils Texas
(
“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
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
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
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
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
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
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
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.
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
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
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.
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
The authors used the state cancer registry to recruit 173
white and Latino seniors in
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
"
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.
"
She said the department works with county agricultural commissioners to track pesticide drift, immediately investigate reports and issue civil penalties.
End Transmission