Question

Underside of Aralia   QUESTION: I have an Aralia that has recently developed "bumps" on the underside of the leaves.  I have attached a photo.  They appear to be part of the plant as I have not noticed any outburst of bugs.  Coincidentally, they appeared recently after I purchased a smaller Ming as well as changing to a different brand of soil.  Any thoughts?  I haven't been able to find any descriptors anywhere about this.  I've already pruned away 2 mature branches.  New sprouts do not appear to be affected.  Some leaves have turned yellow and fallen off.

ANSWER: Hi Janne:
These bumps look like a condition (not a disease) called edema/odema that is caused by fluctuations in the water pressure inside the plant. Careful watering, especially on cloudy days. More of a cosmetic issue than anything else. Not fatal.

Steve

---------- FOLLOW-UP ----------

QUESTION: Thank you for your response.  I keep this plant indoors, do cloudy days still have an effect on it?  I guess I can stop spritzing it with soapy water in the hopes to discourage bugs.  Can this go away?

Answer
Janne:

The soapy water that you mentioned. Best to use the already prepared stuff rather than "homemade".  The homemade stuff may cause some injury.  One good brand available from garden centers and nurseries is SAFER INSECTICIDAL SOAP.  Be sure to spray your plants outside, then bring it inside after the spray dries.  The spray can leave a residue on your floors/furniture if you spray inside.  Be sure to read the label on the container to be sure it is safe to use on your plants before you purchase.  If you are not sure, spray it on one leaf and watch it for 3-4 days afterwards.

Be careful on watering houseplants.  They don't use as much water as they would outdoors.  Overwatering is the biggest problem w/houseplants.  The bumps will probably not go away on the leaves that have bumps now, but will on the newly forming leaves.  Thes odema spots resemble little "warts".

When I water houseplants, I carry them outside, then water them until the water flows freely out the bottom (thru the drain hole) for a few minutes. Let drain, bring inside and don't water until they start to show signs of being thirsty- like a bit of wilt, then repeat.  Avoid watering a little every day or two.  This can lead to root rot, and death. Plants don't like wet feet for extended periods!

Regards
Steve