Hi all,

My young black magic Colocasia is having a problem. The periphery of the leaves have very recently started browning (pictures below). Using a 10x loupe magnifier, I cannot see any obvious pests, although small white dots are present on the upper surface of some leaves. Otherwise, it seems to be growing well adding a new leaf every 1-1.5 weeks. A Colocasia giganticia is under the same conditions described below and is not having problems.

Soil:: MG with 50% sand/pebbles. pH is a bit high at 7.5, so I recently added lime (before the browning started).

Watering:: About weekly (when surface is dry). I check the soil moisture periodically and it's never dry, always moderate to wet.

Humdity: It is dryish here (60% humidity, or so). I mist at least once per day (never before going under the lamps) and have ordered a humidifier.

Fert: 24/8/16 about every other week.

Light: Was under two 96w CFs, now under 432w T5 HO at night (started browning before the switch). It gets minimal indirect light during the day.

Pests: Adjacent plants had aphids, although they seemed to dislike the Colocasias. I treated with Bonide anyway along with mechanical destruction.

Thanks for the help!

Robin

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