See:
http://www.pakbs.org/pjbot/abstracts/39(5)/2.html
Link: www.pakbs.org/pjbot/abstracts/39(5)/2.html
This may also be of interest:
http://hortsci.ashspublications.org/cgi/content/abstract/43/1/264
Link: hortsci.ashspublications.org/cgi/content/abstract/43/1/264