A team at UCD may have discovered how to beat a dangerous wheat mould, writes Dick Ahlstrom.
Infection of wheat by a fungus called fusarium is a big problem for farmers but a potential killer for humans. The mould, which can destroy up to 70 per cent of a crop, produces a toxin so powerful that it has been tested for possible use as a biological weapon.
Fusarium ear blight affects all wheat-growing areas, including Ireland. Now a researcher at University College Dublin may have come up with a valuable new treatment that does not involve fungicides or other chemicals.
"The disease is particularly difficult to control in this climate, with warm and wet conditions, particularly when the wheat is in flower," says Mike Cooke, an associate professor of plant pathology in UCD's department of environmental resource management.
"It has traditionally been controlled by the use of fungicides, but there is concern about the overuse of these chemicals."
Low crop yields are only one issue with fusarium, says Prof Cooke. The mould produces mycotoxins that can persist on harvested wheat. If they get into food supplies the toxins can cause severe illness and even death in animals and humans.With Dr Helen Diamond, a research student, he attempted to induce resistance to the disease by challenging the plant with non-pathogenic forms of fusarium, in effect prompting the plant's immune system to block the disease.
The five main pathogenic, or disease-causing, forms of fusarium are similar to the non-pathogenic forms. "We tested pathogenic and non-pathogenic isolates and also totally non-related fungal forms," says Prof Cooke.
The non-pathogenic organisms were used as "inducers", to sensitise greenhouse-grown wheat to fusarium. They were tested in pairs, to see which combinations gave the best results. The wheat was then confronted with pathogenic "challengers", to see what effect the induced resistance had.
"We got very encouraging results," says Prof Cooke. "We got a 60 per cent reduction in symptoms."
Induced resistance allowed the wheat to hold the disease at bay, with reduced symptoms over 25 days. "It would allow the plant to produce its grain before the disease could knock it out completely."
That means the crop could also be harvested before the fusarium could produce mycotoxins.
Cooke also found that his inoculation of wheat ears "often resulted in a significant increase in number of grains per ear". It more than doubled the incubation period normally needed for fusarium to grow.
The treatment must now be tried on wheat in fields, to confirm its value.