'Smelly' plants early warning
30 October 2009
New research has shown tomatoes under attack from the botrytis fungus give off a substance with a distinctive odour that can be measured under greenhouse conditions, allowing early detection and treatment before disease takes hold.
A team of scientists in the Netherlands and Germany discovered significantly higher levels of the plant hormone methyl salicylate emitted by tomatoes infested with botrytis. The raised hormone levels were detectable at about 32 hours after infection – well before visible symptoms of the fungus appeared.
Botrytis causes grey mould, a devastating fungal disease in commercial greenhouses where it can spread rapidly in the high humidity and close growing conditions to ruin entire crops. Under pressure to reduce chemical pesticides, Dutch growers have until now relied on time-consuming crop inspections to detect the disease early.
Roel Jansen of Wageningen University in Holland, who led the research, believes bio-indicators such as hormone levels can act as early warning systems, allowing more precise targeting of anti-fungal sprays.
“The trend in greenhouse horticulture is for fewer but larger greenhouses, so an outbreak of a disease therefore forms an even greater threat as it can easily spread throughout the entire greenhouse,” he said. “If you can identify a plague in a greenhouse on time there will be even less need for pesticides.”