Question
I have a "tropic" dieffenbachia houseplant that I have grown over 6 ft.  I noticed however, that on the leaves and stem of the plant are a bunch of small brown thing looks like a seed.  But I also noticed that my plant hasnt been lookin the same.  It appears the leaves large but are dying around the the bottom of the leave as well as the tip of the leaves themselves.  Are these brown seed looking things common or is there something eating at my plant?

I await your speedy reply.  And thank-you so much for having this website.

Jeanene

Answer
Hi Jeanene,

If the 'small brown things' are slightly raised and scrape off easily with your fingernail and there is some stickiness on the tops of leaves or under the plant, then those are scale insects. They are best treated by using a spray made of 5 parts water, 1 part rubbing alcohol and a squirt of liquid dish soap. Thoroughly drench all leaf and stem surfaces until they are dripping wet. This is messy, but complete coverage of all surfaces is critical if you want to also eradicate the scale juveniles that are translucent and nearly invisible. After spraying, wipe off the visible scale insects with a soft cloth or sponge. If you are thorough, one treatment is enough.

If your Dieffenbachia is 6 feet tall, it has probably lost a lot of lower leaves and may need support to prop it up. This is quite common with Dieffenbachias. The only remedy is to prune back the stems to a height of 1 - 3 feet. This means removing all the leaves, but as long as the plant and stems are healthy, you will see new growth emerge from just below the point where you make the pruning cut. That new growth will grow upward from there. The pruned off top portion can be rooted as a separate plant or in the base of the existing plant.

Browning of leaf tips may be due to using tap water that is hard. If so, use filtered or distilled instead. Over or under watering may also cause this tipping. If your Dieffenbachia is in the right sized pot, then you should water only when the top quarter of the soil feels dry and then water thoroughly.

All of this information is explained in greater detail in my articles on indoor plant pests and on Dieffenbachia care that I will email for free to you (or anyone else) who sends a request to me at [email protected].

Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

Visit my website at  www.HorticulturalHelp.com