When grain travels, sometimes unwelcome guests hitch a ride

New research can help grain handlers and grain inspectors find key locations for pathogens and pests along rail routes in Australia and the United States, helping to make the food supply safer and address stored grain problems that cost hundreds of millions of dollars annually.

In analysis presented in the journal BioScience, researchers from the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) evaluated how wheat moved along rail networks in the United States and Australia. Through their analysis, they identified US states that are particularly important for sampling and managing insect and fungal problems as they move through the networks.

“The movement of pests and pathogens can be especially important when there are quarantines against the movement of particular species or when pesticide-resistant insects invade new areas and make management more difficult,” said Karen Garrett, a UF plant pathology professor with the Emerging Pathogens Institute and senior author of the study.

Researchers examined important locations including hubs that are linked to many other locations and bridges that link separate parts of the network together, Garrett said.

The analysis revealed that Australia may have a geographical advantage in pest management. The central US is a major wheat-producing area, and wheat can move in multiple directions towards processing centres or American ports for export. In Australia, wheat production tends to move more directly towards the coast for export and, as a result, the internal system is simpler and in some ways easier to manage for pests, Garrett said.

Jim Anderson, professor of food and resource economics in UF/IFAS and director of the UF Institute for Sustainable Food Systems (ISFS), said that understanding the functioning of the world’s food networks and how they can be improved is one of his team’s core missions.

“Pests and fungi can damage grain and leave it unusable,” said Garrett. “In addition to this waste, some fungi associated with wheat produce toxins that are significant health risks if grain contaminated with them is not removed efficiently. These toxins, known as ‘mycotoxins’, pose an important health risk if they are not detected effectively and removed. The movement of quarantined pathogens or pests, or the movement of pesticide-resistant pests, poses a risk to stored grain systems in the locations to which the grain is being shipped — and to the crops growing nearby for some species, Garrett said.

Mycotoxin contamination in US grain has been estimated to cost more than US$900 million a year, she said.

UF researchers are also applying this type of network analysis to other post-harvest networks and crop epidemics so they can identify key locations for detecting and managing the spread of pests and pathogens.

“We are evaluating crop seed systems in several developing countries to identify system strengths and weaknesses for managing diseases of potato, sweet potato, cassava, banana and yam,” Garrett said. “We are also studying epidemic networks for diseases such as soybean rust in the US, to guide strategies for sampling and mitigation.”