A few weeks ago I purchased a very young Alocasia esculenta Elena on Ebay. The little plant arrived in perfect condition, and I gave it a bigger pot. After about 10 days I noticed the oldest leaf showing yellowing spots on the rims, later on with darker centers, until the whole leaf dried. I didn't think anything serious about it then, until the next and subsequent oldest leaf did the same. The new born leaves do look healthy but I'm sure now that they will be going the same way..
I'm keeping the plant in a warm room in good light, without direct sun, an average of 80% humidity.
Could it be a viral or fungal disease, could it have come with the potting soil I used and most important is a (non-chemical) cure possible? I know if it is viral I'll have to throw the plant

Thanks for any advise!



Backside of the leaf

Hello Myriam,
That looks like black mold on the leaves. I forget what it is called when it attacks plants, but it should be easy to get rid of.If it is reoccuring, you have a contamination point you need to find. I used a cloth with diluted chlorine bleach to dab the surface of the soil of my plant (chlorine evaporates, so it will not kill the plant if you do not drench it) Cut the blackened damaged portions of the leaves away.

Might Neem Oil help?

Thanks Noel and Evan.

I'm not sure Noel if it is Black Mold which is called Stachytbotrys and harbours many types of specie molds.
http://en.wikipedia.org/wiki/S...
I have had experience with a type of black mold on walls when still a student and living in an unhealthy mold-infected house, but I remember they gave off a black powder (spores) when touched. The spots on the leaves of the Alocasia don't seem to have that.

I wish I could get Neem oil over here Evan, I have never seen it for sale, or maybe it has another name..

Done some research myself and came upon this quite interesting site which helps identifying diseases in Taro.

I'm not sure if that is what my plant has but it is the closest I could find on this site;
http://www.ediblearoids.org/Ta...
home page of the site..
http://www.ediblearoids.org/Ho...

Some of the photographs on the Click here to go to the Field Photographs page look similar. http://www.ediblearoids.org/po...

Yes, some do look similar but it is very hard to be sure. But as it is likely fungal I went ahead yesterday, took the plant out of its pot, removed the soil and gave the small bulb which had an offset bulb a soak in lukewarm organic dish soap water for a while. I have been able to cure fungal infected Oxalis bulbs once with this method.
Then I replanted it in another well-cleaned pot in new potting soil I have mixed with Cinnamon and Garlic powder, natural anti-fungicides.
I also cut the two infected leaves leaving only two small healthy ones.
I'm not sure if it will work, we'll see..

Good luck and thanks for the recipes.

I'll let you know if it works!

Myriam, can't you buy Neem Oil online or is shipping, duties,... prohibitively expensive?

Yes, Evan I could buy it online, I found a Dutch site which sells it under the name 'Neem Olie'. Not expensive at all, even no sending costs at an order above 10€!
http://www.berivita.com/

Neem oil has a very impressive list of qualities I was not aware of !
http://en.wikipedia.org/wiki/N...

I'll first have a look in the Indian-Aziatic food stores in Gent, they might have it!

This is a colocasia, if that helps with the diagnosis.

Hello again Andrew,
Even if my diagnosis does not fit, the bleach treatment will kill whatever is attacking the leaves. I had something very similar attacking one of my EE's, & used this method to rid it & the soil of the infection. I sterilized a pair of scissors & removed the affected tissue deep enough into the unaffected growth to be sure it was not infected. I made sure not to cut the veins feeding the rest of the leaf. I then used a mix of 1 part chlorine bleach to 9 parts water with a sponge to systematically sterilize the full surface of the soil. I left the plant unwatered for 1 day afterwards to allow the chlorine to evaporate, & saw no more problems. I said black mold because I found the problem listed as a common problem for EE's when using misting or high humidity in closed rooms. I have since moved my EE's outdoors since they like the higher intensity light & the cooler breezes (relative since I am in South America, EE's do not like "cool" at all). I do not know the affects of neem oil, but if you are careful not to dench the plant with chlorine bleach this will work. I have used this method when mold attacks the soil of my plants several times, & you can see my collection on ATP.
Noel

Hey Noel, this is a tip I've made note of. It should be especially helpful when growing indoors o/w in colder climes. This would make a great "Daily Gardening Idea".

Hi Andrew, thanks for the correction of the name, I tend to confuse the two!

Thank you Noel, I wish I could try your method but alas the two remaining leaves of my Colocasia are very small, there would be hardly anything left if I would cut the affected areas! I'll keep it in mind though for the future.

Yes, the disease has not been beaten, so my method was a failure though i had once cured Oxalis bulbs with it.
I had ordered the neem oil some time ago on the web and it had arrived yesterday. I immediately took action.
Looked up on the web how and in what proportion to dilute it and how to apply it.
So what i have done is giving the soil a drench in the mixture plus also treating the two small leaves.
I'm not sure what's going to happen now, the little plant doesn't look happy at all, maybe I'll just have to accept it will pass away!

Myriam,
You could also force it to go dormant, & treat the risome. That way you could get rid of the old soil, treat the risome while it is dormant, & in a few weeks start a new plant.

I am thankful of my location. It makes this kind of problem rather easy to deal with. In this environment we have to take measures to control the growth of these plants. Some of the plants here are incredibly monstrous. I have an EE now with 2 foot long leaves in my little space, & it is only getting bigger. This is only 1 season of growth also. This plant started out with 6 inch long leaves when I arrived in Colombia back in September. I also collected another this week to replace 1 I sold that has a risome a foot long, & weighs probably 7 or 8 pounds. The leaves on this thing are huge too.

NoelCalvert said:has a risome a foot long, & weighs probably 7 or 8 pounds. The leaves on this thing are huge too.

Next time you can, pictures please Love to see rhizomes and tubers and...

Hello Evan,
Actually the plant looks kind of ridiculous at the moment. The risome was on its side when I collected it, so the plant is sideways now as I am trying to get it to right itself. Here are some photos.For a size reference I put my foot up against the bucket. I wear a size 11 which is just about 11 inches long. The risome is 1 inch from the bottom as there are pieces of porcelain brick in the bottom for drainage. The risome sticks out of the soil about 3 inches also.

Great pics Noel! Looks like you raided the EEar spot you spoke of. I'd wager the one laying on it's side gets enormous once you plant it out at your new place. Looks like you'll be running out of room soon.

What are the first and third photos of the EEar with the speckled petiole from? Looks a bit like an Alocasia. The last 4 photos look like X. violaceum, sound right?

Evan and Noel,
The plant in the first photo (same one in the pot with the bigger green one in the third photo) is an Alocasia - Alocasia plumbea. The last four are X. violaceum.

LariAnn

Thanks LariAnn!