Question
QUESTION: Hi I was wondering if you can help me out as I cant find any info as regards to my problem.. I have a Polyscias Fabian Aralia which I purchased last November.  It has been doing very well and seemed very healthy. Since two weeks ago it has started to turn the upper large leaves yellow and is shedding them.  All the upper ones (which are quite large) will soon drop off. Im very careful as how i water it as I have lots of humidity. Light is not a problem as it is situated next to a balcony.  What am I doing wrong?

ANSWER: Sandra,

From what your are saying I suspect that you have a Polyscias fruticosa - Ming rather than a Polyscias scutellaria - Fabian. The following website has more info on aralias and you can google for more info.

I believe that your problem could be aphids, those are the insects that most bother aralias. They are tiny, black or brown and cluster in groups on the trunk or growing tips. They suck on the plant and can cause leaf dropping as you describe. Look for them with a large magnifying glas and if you find clusters spray them immediately with isopropyl alcohol then head to your garden center or plant nursery to find a systemic insecticide that they reddommend that will keep the insects away for good. Another insect that could be a problem is whitefly. If you bump the plant and tiny insects fly out of the leaves it is white fly.

If insects fly out of the soil that is a different problem. That would be fungus gnats and would indicate you are keeping the plant too wet. You say that you are very careful as to how you water it as you have lots of humidity but you did not say how you water it. The yellow leaves can be caused by too much or too little water or by insects. The surface of the soil should dry out but the soil should not get totally dry. However you should also not allow the plant to have any excess water in the drain tray. An hour after you water it you should empty the drain tray.

If you have more questions feel free to write again. Good luck.

Darlene



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

QUESTION: Dear Darlene

First of all thanks for your prompt reply. I appreciate it very much. I have confirmed that I own a Polyscias scutellaria - Fabian (it has round leaves-dark green colour). Can you please give me the website where I can find further info on Aralia's as you did not list it above. Thanks!

I have checked out the plant and in fact I have found tiny fine cobwebs(sort of) having tiny brown dots on the stems. (it is true one has to use a magnifying glass!)Is Isopropyl alcohol the same as surgical spirit?
I water the aralia (and all my other plants) once every two weeks as my house is very humid. As regarding light, all my plants are in an open plan area, therefore I do not think light is a problem.

I also have a smaller aralia (also fabian polyscias) and I have also noted that it has like 'white cotton' - what can I use for this?

Last thing I would like to ask is can the sunlight from the balcony (although having a fine curtain filter) yellow the leaves(the upper big ones) of the aralia or do you believe that it the aphids.

I have only started this hobby about 3 years ago, and have not had much luck to tell you the truth, I am glad that I have found someone who can help me out.

I thank you once again and look forward to receving your advice.

Regards
Sandra Mizzi - Malta

ANSWER: Sandara,

Yes, I believe that surgical spirits are isopropyl alcohol.  It should say on the bottle how strong the concentration is. If it is stronger than 70% you need to dilute it with water, 2 parts spirits and 1 part water.

You have been hit hard with insects. The one with the webbing is spider mites. The one with the white cotton is mealy bugs. You need to spray the entire plants as soon as possible with the spirits then get to a plant nursery or garden center and see if they have a systemic insecticide that you can use on these plants. That will get rid of the insects with a lot less labor. If not you need to thoroughly pray the plants with the spirits twice a week for a month.

Actually with the curtain filter they may not be getting enough sun. These plants like a half day of full sun actually shining on them. That may be part of your problem that they are weakened because they are not getting enough sun and insects attack weakened plants.

The top 2-3 inches of soil should dry out between waterings but the plant should not totally dry out. Do not allow it to sit with excess water in the drain tray. It must be in a pot with a drain hole and drain tray. The pot with the drain hole can be set in a more decorative larger pot but you must be able to remove the plant and empty excess water so it is not sitting in water. If the pot doesn't have a drain hole the plant is always sitting in water no matter how long you let it dry out between waterings. They do not work.

The web site is: http://www.denverplants.com/foliage/html/arafab.htm
Another is: http://www.tropicopia.com/tropicopia/house-plant/detail.np/detail-280.html

Good luck.

Darlene


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

QUESTION: Hi Darlene

Thanks for your reply.  

There was me thinking that the Aralia was yellowing the upper large leaves cause I left it behind the curtain (sheer curtain) having sun direct on it for a couple of hours.  Yesterday I sprayed them with the spirits and I will try to get a good insecticide which wont harm the aralia's them being such a sensitive plant. But in the meantime, I will continue using the spirits twice a week. I hope I will manage to save this plant as it was my pride and glory!

Thank you very much for your prompt advice.

Regards
Sandra Mizzi

Answer
Sandra,

You might try opening the sheers and moving at least the smaller one closer to the window and see if that helps. If it does try moving the larger one to a sunnier location. The yellow leave will not turn green again but with mor sun the plant will replace them sooner with new leaves. Good luck.

Darlene