|Harrison Jr, Howard|
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/1998
Publication Date: N/A
Interpretive Summary: Corn spurry (Spergula arvensis), which has a world-wide distribution, is counted among the worst weeds. During the fall and spring seasons, almost pure stands may appear in vegetable production fields. These noxious annual weeds mature quickly and produce large numbers of seeds. In the southern USA, where vegetables are grown during the cool seasons, corn spurry severely reduces vegetable yields when not fully controlled. In a field study where naturally growing corn spurry was left unchecked, the yields of English pea and broccoli were reduced by 70% and 90%, respectively. In general, this rather small weed plant can out-compete much larger and normally fast growing crop plants. In order to obtain a better understanding of this weed's biology, a specific study was conducted. It was found that crop growth interference was, to a large extent, caused by chemicals produced by corn spurry. Using chemical analytical methods and biological assays, the compounds responsible or these effects were identified as complex mixtures of sucrose esters. This class of chemicals is also known to inhibit the growth of micro- organisms and has insecticidal properties. This information is important to the development of improved management techniques for corn spurry. The inhibitory compounds it produces also provide a potential source of naturally occurring compounds to control other plant pests such as diseases and insects.
Technical Abstract: Methylene chloride extracts of Spergula arvensis L. (corn spurry) were shown to cause inhibition of seed germination. Solvent partitioning and separation by a combination of silicic acid and Sephadex LH-20 column chromatographic procedures resulted in the isolation of a group of sucrose esters (SE) that exhibited strong inhibition of seed germination. Characterization of the esters by hydrolysis and mass spectrometry of their trimethylsilyl derivatives showed the presence of four different SE groups with from 2 to 7 acyl groups attached to sucrose The SE isomers in greatest abundance contained either octanoic or dodecanoic acid along with two smaller branched chain acids (butanoic and pentanoic acids). This is the first report of SE outside the family Solanaceae.