Shooting season is over and all the new shoots are now fully grown and branched out. At first, there was no issues related to direct sun exposure. I suspect the problem started when the sun position got high enough and its strength became harmful for delicate plants. I observed first signs of leaf damage as soon as the shoots started branching out. Then damage became more and more evident and even the newest leaves immediately got damage, some even before unfolding. Spraying the bamboo with insecticide and fungicide didn’t help much. Leaves were a bit healthier, but that could be just because the leaves started getting less variegated at the same time, changing from completely yellow to yellow with green stripes. Sun is also starting to lose some of it’s strength as days are getting shorter.
At first I wasn’t sure about the exact reason, because I also found spider mites on both variegated bamboos. With time, issue became more and more apparent. The shaded leaves that were hidden inside the bamboo clump became hard to miss- they remained healthy and mostly undamaged. Sadly, both bamboos are placed in full sun which makes them suffer leaf damage during most of the summer. Leaves in the fall should be healthy again. Last year, bamboos were much shorter and received a lot of shade from plants growing around them, this year, they became too tall for that and I’ll be able to see when they stop getting sunburns. The first leaves are also the most delicate. Luckily, most of the leaves that are damaged would fall off eventually before the end of the summer when the plants fully leaf-out.
changing their location
In a year or two, I’ll try to find them a more protected location with more shade. I might even divide them for the first time and try them in “different depths of shade”. Currently, finding them free space is a problem, which I hope I can resolve.
… An update a couple of weeks later…
In just a few weeks, the spot of one seedling got shaded and I successfully removed the mites as well. At the same time, laves started getting more green, just like expected. The shitty humid weather held on during most of early summer and in mid July, seedlings looked better. They started growing branches and started to look much, much better.