Submitted to: Invasive Plant Science and Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/11/2012
Publication Date: 8/1/2012
Citation: Johanning, N.R., Preece, J.E., Young, B.G. 2012. Chilling and chipping influence plant growth and reproduction of star-of-Bethlehem (Ornithogalum umbellatum). Journal of Invasive Plant Science and Management. doi.org/10.1614/IPSM-D-12-00004.1. Interpretive Summary: Star-of-Bethlehem is a persistent and aggressive invader of pastures and cropland. Although its movement to new fields is slow, once established in a field, star-of-Bethlehem populations can rapidly increase in area and density. Leaf emergence at multiple times in the spring makes foliar herbicide applications very difficult to plan ensuring no plants escape treatment. Additionally, very few herbicide options have proven effective on this pest. The results from this research show that star-of-Bethlehem does not require chilling to emerge; however, chilling may delay plant growth and leaf emergence. Therefore, the winter climate and exposure of a field may greatly determine star-of-Bethlehem leaf emergence and subsequently the timing of herbicide applications. Tillage has also been used as a control measure; however, due to its perennial growth habit and propagation through bulb formation, it is probable that tillage may actually increase plant densities rather than decrease them. Greenhouse experiments simulating tillage through chipping of star-of-Bethlehem confirm that chipping of bulbs does not lead to a fewer number of bulblets produced but rather equal to greater populations present. From these findings, grower practices and future research should be focused on evaluating effective herbicide options and applications timings for management of star-of-Bethlehem.
Technical Abstract: Greenhouse studies were conducted on two southern Illinois star-of-Bethlehem biotypes to determine the influence of chilling and bulb chipping on plant growth and reproduction. Chilling was not required for leaf emergence of dormant bulbs, but an increase to 10 weeks of chilling proportionally delayed leaf emergence by 41 and 42 days for the Murphysboro and the Marion biotypes, respectively. Bulb chipping did reduce plant height when compared to plants from nonchipped bulbs. Also, chipped bulbs produced a greater number of small daughter bulbs compared to nonchipped bulbs; however, total bulblet production was variable and dependent on biotype, mother bulb size, and chipping treatment.Overall, bulb chipping did not have any negative influence on star-of-Bethlehem and may promote increased daughter bulblet production.