Why are the leaves of my Jackfruit plant turning brownish?

Question

Goodday, about 5 months ago, I planted two jackfruit seeds I brought with me from Malaysia in pots and so far, they have been growing well. I live in The Netherlands and as it is winter, I keep them inside on my windowsill.
The last weeks the 3 bottom leaves of one of the plants have turned brownish. I water the plants thoroughly when the top layer has dried and I applied a diluted liquid fertilizer once or twice these past months. What could be the problem causing the discolouration on the photos? There is a bit of draft near the window, but I try to protect them from it by keeping them in a small greenhouse. I hope you can help me. Thank you!

Answer 1

It appears to be a minor leaf fungus affecting the lower leaves. But since the newer growth looks good I wouldn’t worry about it. Just snip off the infected leaves to limit dispersal of fungal spores.
It’s not water deficit, or the upper leaves would suffer first. Be careful not to over water, jackfruit trees are subject to root rot.

https://www.gardeningknowhow.com/edible/fruits/jackfruit-trees/growing-jackfruit-trees.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm

I’m looking out my window at our jackfruit tree in the garden here in Thailand. It’s about 3 years old and 3 meters tall and just growing its first fruit.