RNA spray halves grey mould damage in lab tests, including fungicide-resistant strains
Researchers at the University of Malaga and the La Mayora institute (UMA-CSIC), led by Dolores Fernández Ortuño, used a spray of double-stranded RNA to switch off a gene that helps the fungus Botrytis cinerea resist fungicides. On tomato leaves and apples, a single application cut lesions by 40-50% at its peak and protected the fruit for up to 14 days, including against multi-resistant strains. The caveat: these are lab tests; field trials and regulatory approval for this kind of product are still to come.
A grey fuzz on strawberries, grapes or tomatoes: that is Botrytis cinerea, grey mould, one of the fungi that spoils the most crops. And more and more strains can shrug off the fungicides used against it.
A team from the University of Malaga and the La Mayora Institute for Subtropical and Mediterranean Horticulture (UMA-CSIC), led by Dolores Fernández Ortuño, has tried a different route. Instead of a chemical fungicide, they spray the plant with double-stranded RNA designed to switch off a gene that helps the fungus defend itself against those products. The study is published in Plant Disease.
One spray, two weeks of protection
On tomato leaves and apples, a single application shrank lesions by 40-50% at its peak, and the effect lasted up to 14 days. It also worked on strains resistant to several fungicides at once. Combined with low doses of the fungicide fludioxonil, it did better than either on its own, which points to a way of using fewer chemicals on farms.
The plant itself is not modified: the RNA is applied from the outside, like any other treatment, and acts on the fungus.
Still in the lab
The tests were run under controlled conditions. The next steps are to check whether the spray works as well in greenhouses and open fields, and to get this kind of product approved before it can reach farmers.
