2019 ASHS Annual Conference

Pine bark is the most common substrate used in container production of nursery crops. Previous studies have demonstrated an improvement in plant health from cultivation in pine bark media, which could be a function of beneficial microorganisms colonizing the bark and inferring resistance to bacterial, fungal, and viral diseases. Yet, little attention has been paid to the chemical composition of leachate associated with pine bark media. Phenolics are known to have positive or negative effects on plants growth and health depending on their chemical composition. Thus, the aim of this research was to identify water-soluble phenolic compounds in pine bark extract as a precursor to testing the effects of specific compounds on plant health in container culture. Pine bark was mixed with water in 1:1 (v:v), stirred for 24 hours, then filtered to remove solids. The aqueous extracts were then subjected to a liquid-liquid extraction with ethyl acetate (1:1, v:v). The organic fraction was concentrated under vacuum, reconstituted in 10% methanol (aq), and analyzed using ultra-performance liquid chromatography-mass spectrometry with multiple reaction monitoring. A variety of phenolic acids were identified in water-soluble extracts from pine bark, including benzoic acid, caffeic acid, p-coumaric acid, ferulic acid, gallic acid, gentistic acid, 3- and 4-hydroxybenzoic acids, p-hydroxyphenylacetic acid, salicylic acid, and vanillic acid. Some of these compounds, including salicylic acid, are known to benefit plant health, which will be addressed in subsequent studies.