Furfural as a Fungicide

As early as 1923, it was discovered [47] that furfural is a very effective fungicide. It was found that while even high concentrations of formaldehyde (10 to 15 %) do not prevent the growth of the mold penicillium, one of the most common fungi, as little as 0.5 % furfural is sufficient to entirely prevent the growth of mold even under conditions otherwise most favorable. 

It was observed that furfural is particularly effective in inhibiting the growth of wheat smut (Tilletis foetens). This fungus is killed when the wheat is soaked for 3 hours in an 0.05 % aqueous solutuion of furfural, whereas with a formaldehyde solution of the same strength a period of 12 hours of soaking is necessary to destroy the smut. 

Most noteworthily, as far as seeds are concerned, it was observed that their treatment with furfural does not diminish their germination power to any significant extent, whereas treatment with the same concentration of formaldehyde proved massively toxic. Wheat can be soaked for 6 hours in an 0.5 % aqueous solution of furfural with a reduction of only 4 % of the germination power of the seeds, whereas the same time of soaking in 0.5 % aqueous formaldehyde destroys the germination power completely. 

From the treatment of seeds, the application of furfural as a fungicide was extended to growing plants and to wood. 

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