Malformation of Californian Red Onions

Onion    gisborne, victoria, australia

Dear Plant Village
When taking up my mature Californian Onions I noticed that about 10% have protrusions emanation from their base. These protrusions appear similar to the bulblets that grow on my lilliums with which I use to propagate further lilliums.
Are you aware of what these growths are?
As an experiment I have replanted some with the growths intact and have seperated some growths and planted them individually
Thank you very much for your assistance
Yours sincerely
Lindsay Armstrong

Posted by: lindsay armstrong (3 points) lindsay armstrong
Posted: December 26, 2014


This sounds like Basal Plate Splitting or Basal Plate blow-out. See the attached image from Washington State University and this page http://mtvernon.wsu.edu/path_team/oni...

Does that look like your problem? Please upload some images

If it is then it is not an infectious disease but due to uneven irrigation. "If the soil is repeatedly over-irrigated, dried, and over-irrigated again, onion bulbs are likely to develop split basal plates" according to the Washington University Page above.

The same diagnosis is given on p53 of this document on Onion diseases by Seminis (a seed company) http://www.seminis.com/sitecollection...

It is possible that the wounding allows soil microorganisms and bulb mites to colonize the bulbs.

Cut the onions and check the basal plate (very bottom) for discoloration or softness. Post photos too please

Posted by: David Hughes (52 points) David Hughes
Posted: January 2, 2015

You need to log in if you'd like to add an answer or comment.