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March 2006 |
Pesticide
Potpourri
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 The
oomycete
Phytophthora capsici is the
plant pathogen responsible for Phytophthora blight, a
devastating disease of bell pepper, cucumber, pumpkin, and related crops
occurring worldwide. This pathogen
caused major losses in Florida vegetable production during the past decade,
especially on bell pepper and summer squash.
Weeds have been shown to be alternative hosts for diverse groups of
plant pathogens, including the oomycetes. Until recent work by UF scientists, P. capsici had only been recovered from common purslane (Portulaca oleracea) under field conditions. Based on samples collected from nine Palm
Beach County, FL,  vegetable farms during 2001and 2002, Carolina wild geranium (Geranium carolinianum), American black nightshade (Solanum americanum), as well as purslane were found to be alternative hosts for P. capsici. None of
these weed species exhibited plant mortality or disease symptoms. Isolates of P. capsici
recovered from weeds were shown to be pathogenic on bell pepper, resistant to
the fungicide mefenoxam, and most (92 percent) were
of one of the two mating types (A1).
These alternative hosts may play a role in the persistence of this
important pathogen in Florida vegetable fields in the absence of a host crop
and when the pathogen did not produce oospores, which are survival structures
formed when two mating types interact.
(Plant Disease, 3/2/06).
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 A senior development manager for Syngenta Seeds said that the company is at least six years
away from rolling out what would be the world's first genetically modified
wheat seed, and the company is now trying to determine if it should continue
with the controversial project. Syngenta has recorded good results from five years of field
trials for a type of genetically modified wheat that is resistant to Fusarium infection, which has cost U.S. wheat farmers
millions of dollars in losses in the last several years. But if
the company is to proceed, it must gain the support of major food companies and
other players in wheat processing, adding, "It takes a cooperative effort
from the entire industry to launch the first biotech trait in wheat." National Association of Wheat Growers chief
executive officer Daren Coppock was cited as saying
the profitability of wheat farming is in decline and consequently farmers are
increasingly replacing wheat acreage with corn, soybeans and other crops, and
that without advancements to help farmers fight disease and drought and other
problems, wheat farmers will continue to struggle to survive, adding, "We
have a problem. We don't have the luxury
of dancing around this topic anymore."
(Reuters, 2/23/06).
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 North Carolina pesticide
investigators are planning frequent checks to tomato fields in Brunswick and
Pender counties operated by an agribusiness firm charged with
the largest violation of pesticide laws in state history. Ag-Mart, a Plant City, Florida-based firm
owned by a Philadelphia conglomerate, was ordered to pay $184,500 after Agriculture
Department inspectors visited a farm last April and found one pesticide was
applied more than three times as often as the law allows. The department said workers had inadequate
training and protective gear. Field
hands worked in freshly sprayed fields that weren't safe to re-enter for up to
seven days, according to the state's report.
(AP, 2/23/06).
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 The International
Maize and Wheat Improvement Center (CIMMYT), in collaboration with public and
private partners, has developed and tested 26 imidazolinone-resistant
(IR) maize hybrids, across 18 sites in several sub-Saharan African countries. Imidazolinone-resistance
in this instance was selected from mutation-derived populations. The imidazolinone-coated
seeds offer an effective protection against striga, a
flowering parasitic plant with devastating effects on crop production in
sub-Saharan Africa. In trials,
IR-hybrids show a 50 percent increase in yield and provide close to 100 percent
striga control.
(Crop Biotech Update, 2/24/06).
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 Researchers at UC-Riverside in
partnership with Affymetrix, have developed the first
commercial citrus microarray chip. The array will be used to develop new
diagnostic tools for the improvement of citrus and post-harvest handling, as
well as to understand mechanisms underlying citrus diseases. The chip is made up of a glass wafer on to
which nearly one million different pieces of citrus DNA are deposited on a grid
using methods similar to those used to produce computer chips. The glass wafer is encased in a plastic
container somewhat smaller than the size of a credit card. To use the chip, researchers purify RNA from
plant tissue, amplify it with labeled precursors, and then "wash" the
chip with the RNA sample. If a gene is
being expressed in the tissue, its corresponding RNA will be present and bind
to the complementary DNA sequences on the chip.
(UC-Riverside, 3/2/06).
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- In a recent issue of Journal of Environmental Quality,
Dartmouth Researchers outlined processes that occur when historic farmland is
developed. The researchers confirmed
that arsenic and lead from older pesticides does not travel much further than
ten inches from the surface. However,
these metals are now associated with the fine silt and clay particles, which
are more susceptible to erosion.
Consequently, precipitation on newly developed lands may wash these
metals into receiving watersheds.
(Journal of Environmental Quality, 1/3/06).
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 The USDA’s Animal and Plant Health Inspection Service is
amending the regulations governing the importation of fruits and vegetables in
order to allow certain types of peppers grown in approved registered production sites in
Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua to be imported,
under certain conditions, into the United States without treatment. The conditions to which the
importation of peppers will be subject, including trapping, pre-harvest
inspection, and shipping procedures, are designed to prevent the introduction
of quarantine pests into the United States. The measure is effective as of 3/7/06. (Federal Register, 3/7/06).
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 The long horn beetle,
Rhytidodera bowringii, has been
found at the Port of Miami. This beetle
is credited with destroying over 100 mango plantations on Hainan Island in
southern China. It burrows into a mango
tree trunk, causing limb breakage and eventual tree death. (AP, 3/10/06).
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