Research Update

 

Jeff Gillman

 

 

The past few months have seen quite a few research papers published in scientific journals that are relevant to the nursery industry of Minnesota.  Papers include information on new Elm cultivars, new and interesting intercropping systems, and propagation time for ornamental grasses as well as others.  Keep in mind that this research may have been conducted in a climate very different from Minnesota and, as always, we do not endorse the use of products that are inconsistent with their labels.

·         With the rising popularity of ornamental grasses it is important to know when these grasses can best be propagated through divisions.  Cunliffe and Meyer conducted a study examining the best time to propagate 5 different grasses.  They found that plugs of little bluestem, divisions of feather reed grass 'Karl Foerster', and redflame miscanthus could be handled in the fall and reach a salable 1 gallon size within one year.  Prairie dropseed and varegated Japanese silvergrass were much more effectively produced from spring divisions1. 

·         Two new elms have been developed in Italy that are resistant to Dutch Elm Disease as well as being attractive.  'San Zanobi' and 'Plinio' are hybrid elms whose parentage includes Ulmus glabra, Ulmus pumila, and Ulmus minor among others2.

·         Using groundcovers to control weeds is not a new concept.  Martin Quigley from Ohio State has, however, come up with a new twist.  Planting multiple groundcovers in a particular area, instead of just one, will reduce weeds.  Some combinations include sweet woodruff and lily-turf, violet and St. Johnswort as well as sweet woodruff and bearberry among many others3.

·          Many biological and biorational compounds have been recommended for the control of Pythium.  In a test to find whether any of these products worked successfully, Gracia-Garza et. al. found that Mycostop and Actino-Iron were both about as effective as metalaxyl at controlling the obvious symptoms of Pythium on Poinsettia.  Ratings of root systems, however, gave a different story with metalaxyl treated plants having root systems far superior to the other treatments4.

 

Literature Cited

1 Cunliffe, B. A. and M. H. Meyer.  2002.  Propagation tima affects winter survival and finishing date for ornamental grasses.  Journal of Environmental Horticulture 20(4):201-203.

2Santini, A., A. Fagnani, F. Ferrini, and L. Mittempergher.  2002.  'San Zanobi' and 'Plinio' Elm trees.  HortScience 37(7):1139-1141.

3 Quigley, M. F.  2003.  Reducing weeds in ornamental groundcovers under shade trees through mixed species competition.  HortTechnology 13(1): 85-89.

4  Gracia-Garza, J. A., M. Little, W. Brown. T. J. Blom, K. Schneider, W. Allen, and J. Potter.  2002.  Efficacy of various biological agents and biorationals against Pythium root rot in poinsettia.  HortTechnology 13(1):149-153.