Balcony Herb Garden: Thrips

July 2013. Having come back after several weeks away, I have discovered that the thrips have had a field day with a number of my plants! At first look, I just thought that many of the plants were suffering from neglect and the effects of either too much rain or swelteringly hot temperatures - typical summer weather here in Hong Kong.

However, I had been aware of small, dark, slim creatures lurking on the plants for some time already. I just didn't know what they were and didn't realise that they could cause a fair amount of damage.

The plant that I realise now has had thrips for a while is my beloved Sawtooth Coriander whose aroma I find mesmerising. While it has always seemed healthy and producing new leaves and new plants, I had noticed that the undersides of the plants had large silvery patches and black dots. I suspected something was not quite right but couldn't figure out what was causing it. While unsightly, it didn't seem to bother the plant much.

It was only recently that I noticed the slim, black insects crawling around. And now having done some reading up, I realise that these must be thrips. The telltale signs were: the silvery patches and the shape and size of the insects. (More information here.) I also now realise that probably quite a number of my plants were attacked while I was away. These include the chillies, basils (sweet, italian, thai, lemon - all to varying degrees), curry leaves and parsley. As these were previously healthy and showed little sign of attack, I suspect the weather and lack of attention while I was away must have contributed to them being weakened and therefore made them more vulnerable to attack.

I have had to throw away the sweet and italian basils as they were beyond redemption. The lemon/thai basils, parsley and sawtooth coriander have been pruned and sprayed daily with a dilute soap mixture and also plain water. These don't actually get prevent the thrips but keep them at bay while I try to nurse the plants back to health. I have also had to throw away some of the more badly affected chilli plants but some of them I have kept and they seem to be managing to fight off the attack themselves. The same for the curry leaves, I'm hoping.

As many of the gardeners have shared on various websites, the best way to deal with pests is to keep the plants healthy. So I'm working on that as the best way to go as while I'm not being strictly organic in my methods, I am trying to avoid any strong chemicals if I can. That said, I also suspect that my use of organic fertiliser (oh what a smell it has!) is actually attracting some of these pests!