I have brown spots, and a few holes on the newly unrolled leaves of my 24" A. Titanum coming out dormancy. Any suggestions?
Ive never grown this species, but I'd say you should be giving it higher humidity. If it is in a dormancy, keep the soil fairly dry. Water it again once it comes out of dormancy. Dont water too heavily, though.
Do a search on the Aroid l forum history of posts. There is a near constant chatter on this species and the world's most knowledgeable botanists on this genus are on there all the time. There are a few folks on the forum from the part of the world where the species is found in nature.
Be sure and tick off all the years after you type in your search term. Also, keep the search term brief. The responses will come back for 15 years. You can also ask the question directly.
The species is from Sumatra and the jungles there have extremely high humidity. My specimen has never shown the problem you are having but it is housed in a high humidity tropical atrium. I was recently at the Missouri Botanical Garden in their research greenhouses and they have at least 10 specimens. Some are mature while others are still smaller. They never allow their soil to dry out but keep it evenly but slightly damp all the time. The soil mix is extremely loose and if you pick up a handful it will easily filter through your fingers. I specifically asked about the soil consistency and dampness and Emily told me not to allow it to dry. Emily Coletti is Dr. Croat's assistant.
If you aren't a member of Aroid l just look up the International Aroid Society website and there is a link to join. You don't have to join IAS to particate on Aroid l. If you're going to be in Miami in late September you can visit with Scott Hyndeman who grows this plant all the time. He and a number of experts in this species will be at the International Aroid Show on September 20 and 21 at Fairchild Tropical Botanic Garden.
Here is a link that might be useful: Aroid l history of posts
I just found this on the Bonn Botanical Garden site. It might help. The botanists that care for their s;ecimens often post on Aroid l.
Compost:80% peat continuously fertilized / 10% sand washed,
10% fine pumice, with a thick drainage layer at the bottom.
Watering:During vegetation period keep evenly moist, not too wet,because of danger of rotting; when the leaf starts withering, stop watering! Fertilization:March - October weekly 1 x 0.3% Wuxal super 8/8/6" (or something equivalent) until water runs out of the flowerpot. November - February the same concentration (0.3%
8/8/6) every three weeks; stop fertilization when the leaf is withering.Temperature:maximum: 34Â°C optimum: 26Â°C minimum: 24Â°C ; Air humidity:80-85% relative humidity
Location in a greenhouse:Keep in a very warm and humid
greenhouse. Light conditions:at very light sun exposed places, in summer(April until September) it is necessary to shade, in winter as much light as possible. Dormancy:Vegetation period between 12 and 20 months. When
the leave is starting to wither, the dormancy period begins (2-4 months). This period ends when a new bud is visable.
If you care for the plant in other ways than suggested that could be the cause of your problem. You can find all of this plus photos on the Bonn Botanical Garden website.