Garden and greenhouse enthusiasts who grow tomatoes should look out for plants giving off a distinctive odour.
The Royal Horticultural Society (RHS) reported that recent research carried out in Germany and the Netherlands shows that this could be the first sign that the specimen is a host to the botrytis fungus.
Affected plants have higher than normal levels of the hormone methyl salicylate, which can be detected 32 hours after infection occurs.
This is long before the first visual signs of damage appear and could give gardeners a welcome head start in identifying potential problems.
"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," explained Wageningen Universitys Roel Jansen, who led the research.
He added that identifying a problem early could prevent the need for pesticides and save more healthy plants.
Meanwhile, the RHS recently revealed that a horticulture enthusiast in the Isle of Mann has discovered that a plant in his garden is a Gladiolus x brenchleyensis, which was believed to have become extinct.