Question
QUESTION: I just bought a large split leaf philodendron and some of the leaves are getting little dark brown dots on them and then turning yellow. Do you know what this is and what is causing it?

ANSWER: Could be any number of things.  Let's narrow it down.

Are the little Brown dots RAISED off the leaf, or are they more like a leaf discoloration?  Are the dots more like bumps, or are they the actual color of the leaf?

Do you see any Yellow around the dots, or just the dots?

Are there any other symptoms you see -- Brown edges, larger dots (circles), etc?

Foliage plants frequently suffer from attacks by Bacteria.  An essay by University of Minnesota Extension, 'Bacterial Leaf Diseases of Foliage Plants', points out, 'The most severe and devastating diseases of foliage plants are caused by bacteria belonging to the genera Erwinia, Xanthomonas and Pseudomonas.'  Pseudomonas cichorii is responsible for a disease called Bacterial Leaf Spot on Philodendrons and other plants.  There's no shortage of diseases a plant can catch.  New plants are prime targets.  Yours probably was symptomatic while still at the store, sick with something it caught while in transit, or in storage, or at the greenhouse.

Not because anyone was negligent.  But because when you get a bunch of plants together in less than ideal conditions, they're bound to catch something.

The entire report is on their website:

http://www.extension.umn.edu/distribution/horticulture/DG1170.html

The cure is probably simple.  Like they say at U of Minn, 'Provide plants with light conditions that are optimum for their growth. Sun-loving plants should get full sun, and all others should be placed near an east window or given supplemental lighting.

Avoid placing plants where there are conditions of high humidity, crowding, or poor air circulation. Do not mist plants and avoid wetting the foliage when watering, as bacteria need water to multiply and spread to healthy leaves.'  That may sound simple, but it works.  Plants DO have immune systems, they DO fight disease, and they DO recover.

Remove the leaves that are dotted but don't remove more than one a day, and don't remove it if it is only slightly affected.  'If the disease is systemic and has spread throughout the plant, affecting the stems as well as the leaves, the plant cannot recover.  We recommend destroying the plant to prevent spread of the bacteria to healthy plants.'

If these are bumps, you have a scale problem.  Let me know if you think these are bumpy and we'll discuss a plan of action for that, instead.

Take good care of your Philodendron and it will most certainly improve and eventually prevail.

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

QUESTION: Thanks for the information. Before I read your answer I dug up the plant to look at the roots and they are all mushy and dead. I tried cutting back to healthy roots but they were really slimy all the way back to the plant. The outside of the root would just slide off and leave a white string. I cut them back as much as I could and put it in new soil. Is there any hope or anything else I can do?

Answer
Sounds awful.  Way too much water for that poor plant.  You just purchased this, yes?  Must have been to hell and back to get this bad.  See if they will give you a replacement -- and check the roots before you take it home this time.

Mushy roots are what you get when you water too much and don't let the water drain out.  The slime you observe on the roots is actually a bacteria multiplying all over the degenerating tissue, rotting the roots.  This stuff is largely anaerobic.  Just giving that part of the plant air will wipe out a lot of them, and begin the healing process.

These plants are fairly tough.  Make sure this plant has a light, WELL DRAINING soil and preferably you are growing it in an unglazed, porous, Terracotta pot with a big hole at the bottom to let out all the water.

I would repot in new soil simply because the soil it has must be filled by now with pathogenic bacteria and who knows what kinds of fungi and mold.  Stay away from the pre-fertilized designer soils.  You want a plain and simple soil.  NO fertilizer.  Seems you may have done that already.

Go easy on the light -- you want to give it enough but not too much.  Remember, this plant is sick.

A product called 'Messenger' replicates the immune system response of plants to fight disease.  It would be perfect for this situation.  Let me know where you live (zipcode) and I'll see if they sell it near you.  This product was invented at Cornell University's School of Agriculture and it is a miracle cure for a lot of problems; it would be just what the doctor ordered if you were able to use it now on your Philodendron.

Thanks for writing.  Keep me posted.