Yuzu plant infestation with ? thrips
Around 4 years ago I bought a Japanese yuzu fruit. When I arrived back home I put it in to the fridge and then completely forgot about it for around six months, by which point it was covered in mould! I decided to plant the pipe and to my surprise, they all germinated and I now have 15 plants ranging from 60cm to a metre tall.
Last year, I noticed lots of sciarid flies buzzing around the compost and I used nematodes and biological control (with a bacterium called bacillus thuringiensis) as well as yellow sticky traps - all these seemed to help but not clear the flies completely. Throughout this period the plants themselves looked fairly healthy, so I was content to let them be. However, this year I’ve had an outbreak of what I think are thrips on the plants - the leaves are yellowing and dropping off, and new growth is distorted and covered in dark spots. I’ve attached some photographs. I’ve also noticed eggs and little white crawling insects on the underside of leaves; as well as the larval stage on the pot base. I’ve tried everything I can think of - several types of predatory mite both in the compost and on the leaves, sticky traps, and getting rid of larvae by regularly washing and cleaning the pot bases - but nothing seems to be helping.
The yuzus are planted in special citrus compost and fed with citrus compost as I was worried the yellowing was a sign of mineral deficiency. I’ve also tried using an organic Neem Oil based spray on the leaves but this has made no difference.
I’d be devastated to lose my little orchard of yuzu plants after investing so much time and care on them, does anyone have any suggestions for ways of eradicating thrips and sciarid flies? I’d rather avoid using pesticides but if this is the only way to save the plants I’d give them a go.