The oils of Mentha pulegium and Mentha rotundifolia (Mints) were distilled and then tested for their antimicrobial abilities. (If you’re interested in the specific oils/properties etc check the link to the abstract at the end of the note)
Bottom line though is that both mint species had a strong microbial activity (they killed bacteria) and they also exhibited a very strong “repellant” effect. Bottom line of the research says “these are potential additives to food and pharmaceuticals”
They also repelled Rhyzopertha dominica (Grain Beetle) at significant levels.
The real bottom line for gardeners is that essential oils – when mixed at roughly 3-8% (3-8 parts to 100 parts of water. 3-8 tablespoons of oil to 100 tablespoons of water) will both fight bacterial problems and “may” act as a repellent for other insects. (Note this was tested on grains so there may not be crossover to other crops but it would be an interesting experiment in our gardens.
Using these concentrations of oil is too expensive for use in the garden but it may have application on your seed starting areas. I note you’ll reduce problems with adequate ventilation (I use a small fan blowing across my seedling areas) but this may be an alternative if you do get into trouble. Personally, I’d start with the lowest possible option (1 part of oil to 100 parts of water) and I’d test a few seedlings first before spraying the entire crop. You can never tell whether this will work on all plants.
Another folk remedy this speaks to is using a strong mint tea as a disinfectant and repellent. Again, test carefully.
Here’s the link to the abstract at Science Direct.