Protecting vegetables against a host of disease and insect pests is the goal of Dr Ismael E BadilloVargas a Texas AampM AgriLife Research insect vector entomologist in Weslaco

Protecting vegetables against a host of disease and insect pests is the goal of Dr. Ismael E. Badillo-Vargas, a Texas A&M AgriLife Research insect vector entomologist in Weslaco.

Fighting the war on insects and pathogens of vegetable farming

Staring into a microscope, researching insect genomics, and incubating pathogens under controlled environments may not be considered high profile work. There are no race cars to drive, no bombs to diffuse, and no cheering crowd to speed a player down the field to make a winning touchdown.

But for Dr. Ismael E. Badillo-Vargas, a Texas A&M AgriLife Research insect vector entomologist in Weslaco, the work he is doing could one day mean the difference between having enough food to feed a hungry world or a global agricultural disaster than could leave millions starving.

Badillo-Vargas is one of many researchers prosecuting a war against insects and the diseases they carry, trying to create a better world where vegetables, fruits and food crops of every variety can grow strong and healthy enough to feed a growing world population.

Located in Weslaco and near the banks of the Rio Grande, the Texas A&M AgriLife Research Center is dedicated to providing solutions to some of farming's biggest problems. Because of its location, it may be the best-suited place to conduct research on many of the challenges of agriculture.

Four climatic zones converge in Deep South Texas, the temperate zone, the arid climate of the Chihuahuan Desert, the unique environment of the sultry Gulf Coast, and the sub-tropical zone, an area full of diverse wildlife, plant life and biology of all sorts, including insects and plant diseases not readily found in other growing regions.

In a recent article by Texas AgriLife writers, Badillo-Vargas explained how the diversity of the region fuels research to develop better tools to help farmers grow more food.

CHANGING INSECT POPULATIONS

"Insects presently in the Rio Grande Valley are constantly changing, and they are carried here [from other regions] not only by changing weather patterns that can disseminate them long distances but also by human and commercial traffic to and from the area that didn’t exist [in years past]," he noted.

Badillo-Vargas says where there are new insects, there is a high risk of new pathogens not common to the area as well, meaning an ever-changing environment poses a number of challenges for food producers.

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The Lower Rio Grande Valley is noted for its vegetable and fruit production, but not to the degree of times past. Once a region of roaring productivity of fresh vegetables, the number of farms and producers has declined over the last 40 years as prices dropped, water issues developed and vegetable production across the border in Mexico greatly expanded. Adding to those problems was the large number of new insects and the diseases they carry that came across the Mexican border, many of them traveling from as far away as Brazil.

While the Valley once provided the lion's share of fresh produce to Texas, and contributed greatly to the supply of fresh produce to the nation, the decline of fresh vegetable farming in the Valley has forced the state to become a net-importer of fresh foods. Where once rows of green produce and vegetables stretched outward from Valley towns and cities, large refrigerated warehouses have been built to accommodate imported fruits and vegetables streaming across the border from Mexico.

Badillo-Vargas and fellow researchers at the Weslaco center believe that trend can be reversed. While they believe fresh Mexican imports will continue to be a viable resource for fresh foods, they also believe they can help Texas producers develop profitable vegetable farms once again in the Rio Grande Valley, a return to what they say was once the roots of agriculture in South Texas.

The implication of their work, however, goes far behind that vision.

A CASE IN POINT

In the mid to late 1990s, potatoes produced in Mexico displayed distinct internal brown discoloration when sliced and unacceptable dark stripes and streaks when the affected tubers were processed to produce potato chips. The name "zebra chip" was used to describe the disease. By about 2001, similar symptoms were observed in Texas-grown potatoes in the Rio Grande Valley and many growers suffered serious economic losses because these potatoes were being rejected by processors, which resulted in a number of fields being abandoned.

By 2008, tomato plants in California displayed unknown disease symptoms, and a novel bacterium was shown to be associated with the symptomatic plants. California researchers subsequently detected this new bacterium in diseased potatoes. The bacterium was also found to be associated with the potato-tomato psyllid (Bactericera cockerelli).

A similar set of circumstances was reported in New Zealand greenhouse tomato and pepper crops in 2008 and in 2007 in psyllid-infested greenhouse-grown tomatoes in Arizona.

These well-known pathogens and the insects that served to move them from one area to another are just one example of how bacteria, viruses and fungi can and do spread from one region to the next, and often rapidly. While this spread of plant diseases is nothing new, researchers in Weslaco say the risks are greater today than ever before with the globalization of agricultural trade and transport. Such diseases have decimated vast growing regions in years past, and the promise of more such threats is not only real, but also inevitable unless science can find solutions.

MAKING PROGRESS

Problems of this nature are at the heart of what Badillo-Vargas and his fellow researchers are striving to address in South Texas, and progress is being made.

While insecticide use can go a long way in controlling insects and the diseases they carry, researchers warn that pests can adapt to specific chemicals over time, and once resistance sets in, that chemical (insecticide) ceases to prevent the spread of invading pests.

Researchers say that is why it is important to develop insecticide rotation programs.

Such a strategy would represent a first step in addressing the problem. Cultural practices, such as farming methods—like altering planting dates or changing mulches—represent a second approach to help control insects and diseases. A third and perhaps one of the better tools to help control insects and diseases is biological control, which could involve introducing natural predators to areas where specific types of problem insects populate.

The goal is to develop new strategies and methods that could be combined into an integrated pest management program. For example, in addition to crop rotation, planting schedules and the use of insecticides to combat infestations, researchers are looking at RNA interference, which targets a specific gene in the insect’s genetic makeup that can help control reproduction or otherwise interfere with the insect’s ability to transmit a pathogen. Ultimately, this could provide the best barrier to the movement or vectoring of plant diseases by an insect population.

Many of these tools can be implemented now or could be available in the near future, while other tools could require years of research to develop. But the goal remains the same—to help farmers in the Texas Valley to become productive and profitable by re-establishing fresh produce and vegetable farming in the region by lowering the risks of pest and disease pressure, and ultimately to make these positive changes and procedures available to farmers across the nation and the globe, benefiting every region of the world and providing the opportunity to grow more abundant and healthier fresh foods to meet the growing demand expected in the years ahead.

Badillo-Vargas is joined by Weslaco center researchers Dr. Carlos Avila, an AgriLife Research vegetable breeder, and Dr. Juan Anciso, the Texas A&M AgriLife Extension Service fruit and vegetable specialist, and others. Badillo-Vargas administers the statewide program that tracks migration and population patterns of the potato psyllid and Zebra Chip disease.

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