Can anyone explain what in the world is going on with my 2 Alocasia Mayan Mask? Both are planted where they receive morning sun until about 11 and then receive an hour of sun from 5pm to 6pm. New leaves are dark green and shiny as it should be. (Pic 1) However, after a few weeks, they become dull and lose their shine. On top of that, yellow dots begin to appear on the tops of the leaves. (Pic 2 shows the beginning of the dots and Pic 3 shows what a leaf looks like a few weeks later. Pic 4 is the underside of the leaf in Pic 3.) At first, I thought maybe it was caused by water droplets remaining on the leaves when they are in full morning sun. But I realized today that not every single leaf have the yellow dots...they may be dull, but don't have the dots. However, the majority of the leaves are both dull and spotted.
Now I have had experience with Spider mites on Colocasia and easily recognize the "speckles" on the leaves. Could this be the cause of the spots on my Alocasia? I don't see any webbing or anything...
Yes, it could be spider mites but it could also be other sap sucking insects that are active at night when it's dark, what I would do IF I were you, remove the worst of the leaves as these leaves are never going to recover and turn a nice green again. use gloves and have a peice of clear bright paper to place the leaf on.
Take the leaf indoors into maybe the kitchen as bright a place as possible, turn the leaf over and use a magnifying glass, look all over the leaf, see IF you find any creatures running about and keep i9n mind, some sap sucking mite can be as small as a pin head so dont rush the search, look in crevices, veins, edges of the leaf and the stem, you may have to tilt, bend or even hang the leaf to do the proper search, both sides of the leaf, also check the bright paper the leaf is laying on.
Next use a clean sheet of kitchen ot toilet tissue and gently rub this along the length of the leaf, look through the magnifying glass to see IF you have loosened any bugs, IF all is clean, then there are no bugs present, but do keep in mind the tissue you swabbed with, leave it aside and keep checking that no tiny specks are moving about.on the tissue.
IF there are sure no signs of sap suckers, then you need to try the search elsewhere, burn the leaf when done searching and the tissue.
Have you used any spray close to the plants, has there been any feeds or other sprays used close by, do you have any earwigs in the garden, they feed at night, IS there enough water reaching the roots of the plants,
Sometimes we think we have watered more than enough then when you stick your finger into the soil about 2 inch down the soil is bone dry.
All these things are a clue to what MAY be wrong, but then you might have to carry on the search but it's a start.
Good luck. WeeNel.