Amarillo, Texas
July 16, 2008
 |
|
Chips on the left
are from potatoes infected with the zebra chip
disease, which alters the sugar levels and
causes the sugar to carmelize and give a burned
appearance, according to Dr. Don Henne, Texas
AgriLife Research assistant research scientist.
Credit: (Texas AgriLife Research photo by Kay
Ledbetter) |
|
Dr. Don Henne isn't wasting his
degree when he's standing by the deep fryer waiting for potato
slices to turn brown. He's conducting research that will help
the potato industry and consumers.
Henne, an assistant research
scientist in the Texas
AgriLife Research plant pathology program in Amarillo, is
one of many who are trying to find answers about zebra chip.
Zebra chip is the latest disease to plague the potato industry,
especially those in the chipping business.
Dr. Charlie Rush, AgriLife Research plant pathologist and leader
of the program, began working on the project at the request of
local producers in early 2007. His work later became a part of
the Zebra Chip State Initiative through the Texas Department of
Agriculture.
The initiative brought together researchers from throughout the
state and country to try to find answers for zebra chip, Rush
said.
"When we first began working on it, the pathogen and vector were
unknown," he said. "Only recently have researchers began pinning
those down."
Rush said Henne was brought into the program in May because of
his experience and background. His primary responsibility is to
help understand the factors that impact disease onset and
spread. Zebra chip is a disease that alters the sugar levels in
the potato, Henne said. The sugar caramelizes and turns the chip
brown when it is fried, giving it an off taste and burnt
appearance. While it is not harmful, it is a cosmetic and taste
concern for consumers.
Potato growers have had to abandon entire infected fields,
costing as much as $2 million a year in damage, he said.
Henne, who has a degree in entomology, is trying to chase the
potato psyllid, the insect that likely carries the pathogens
which cause the disease. He is trying to find out what makes it
move through a field, as well as when it moves and how fast.
He has visited grower fields from Weslaco to Pearsall and Olton
to Dalhart already this year, as well as made contact with other
zebra chip researchers around the nation to familiarize himself
with this new chipping potato disease.
Zebra chip first appeared in Mexico and Guatemala in the early
2000s. It has been found in potato fields through South Texas
and the Rio Grande Valley and now up into the South Plains and
Panhandle regions.
The disease presents itself as curled leaves and stunted growth
in the plant itself, and then the tubers exhibit a brown striped
or mottled pattern when sliced, Henne said.
AgriLife Research and other scientists around the country have
studied the vector or insect that transmits the pathogen, he
said. Others are trying to identify the pathogen or bacteria
that actually causes disease in the plant when the psyllid feeds
on it.
Henne and other Amarillo-based researchers are working with
commercial growers to monitor the movement of the insect and
disease appearance. At the same time, they have established
potato plots at the Texas AgriLife Research Station at Bushland
and are doing some greenhouse work.
"We're focusing on the epidemiological aspects of the disease,"
Henne said. "We are trying to understand how the disease
progresses in a potato field over time. We are looking at canopy
structure, edge effect and how the insects are landing in fields
and distributing the disease."
Henne and Dr. Fekede Workneh, an AgriLife Research quantitative
plant disease epidemiologist, have planted six acres of potatoes
at the Bushland station where they are looking at planting
dates, canopy structure and insect dispersal.
Potatoes are planted in late March to early June in the
Panhandle, so they are experimenting with planting dates – May
2, May 28 and June 16 – at Bushland to see if there is a
relation between insect movement and disease severity.
"We are also working in the lab to graft diseased portions onto
healthy plants to understand the movement of the disease through
the plant," Henne said.
"We want to understand how the disease progresses so we can
focus management practices on specific areas," he said. "Do the
insects move up the plant, down or out from the stem? Some
varieties have more canopy than others and is that acting as a
natural bridge for insect movement?"
There is no adequate control for the insect or the disease at
this time, he said.
Because there are other diseases that have similar symptoms as
zebra chip, Henne said, one of the challenges they face is being
able to correctly identify diseased plants in the field.
"When we find plants that appear to be infected, we bring the
tubers back to the lab where they are sliced and fried to make
the final determination," he said.
Henne said they hoped to have some management suggestions on how
to help alleviate the problem for growers by the end of this
year. |
|
