Hi Dutchhobby,
You can spray neem oil on the leaves. I'll send you a link that I always use, which already contains an emulsifier. And I'll send you a link from Zamnesia on how to use neem oil.
This neem oil is what I always use:
https://www.berivita.com/neemolie_met_emulgator_mix_water?gclid=CjwKCAjwgaeYBhBAEiwAvMgp2hLcelUcwNcn2V6bQA6kDQr2pfGKx615VUJyconZuTvPwU6d_NLkABoC_7YQAvD_BwE
And here's how to use neem oil:
https://www.zamnesia.nl/wiet-kweken/351-neem-olie
Good luck!
If you have any questions, feel free to send me a private message! π