Kostas

Unless these patches have been a result of rubbing with something on their way out,this is mineral deficiency,Ca if I remember correctly. A well balanced fertilizer should fix it. It also tends to fix by itself in well rooted plants. Do you maybe overwater? I find it difficult to believe your clay soil is missing basic nutrients. I mostly get this defficiency when establishing pups,on their first few leafs and then it fixes itself. I have mostly connected it with small root systems,overwatering anda bit of rot so watch your watering.
'Ice Cream' and the Pisang Awak cultivars many Ice Cream plants end up being,are ABB and thus cannot get BSV.

When you can,post good pictures of all patterned areas found on your Mysore's leafs to see what's going on with it.

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