Thrips are driving me mad....
I am getting flower buds, sometimes even whole spikes destroyed by thrips. Personally I cannot even see them, ( my eyesight is deteriorating with "age related macular degeneration" and some retinal damage caused by operations to repair detached retina etc) and they are extremely small. But younger visitors say they have seen them - tiny black dots.
I think I have had them in my greenhouse for years, when I grew a different set of orchids, and I complained that I could not get clean foliage on my soft leaved oncidiums - the ones which used to be called odontoglossums. It was only when I started growing cymbidiums, with much thicker and harder leaves that the characteristic bulls eye markings, so obvious when the leaves are seen against a strong light, such as the evening sun shining almost horizontally into the greenhouse, that the thrips identification was made. Then I realised that the "dirty" leaves were actually the same thing but much smaller, and so many that they made the leaf look dirty. I had no problem with flowers though, nor did I with most cymbidium flowers, at least not the usual run of modern novelty hybrids. I did buy a few of some new Japanese bred hybrids like Eastern Bunny, and suddenly I was losing whole spikes.
Most people seem to think that thrips means Western Thrips, which I understand are creamy in colour and a lot bigger than my kind.
I read up about them, seems there are thousands of species, all different, and what kills one ( e.g. The biological cucumerin thingy,) doesnt work with others.
So, when I had that cymbidium problem, and found out the life history - probably goes egg, grub which does the feeding, then a spell in the soil/compost doing the metamorphosis into the flying insect, I realised that spraying is only going to work by contact, and not on the larva in the soil. And another complication is that in warm weather, the flying stage lasts just hours, and the sap sucking and hence plant damaging stage may only last a few days - so the chance of catching them is not high.
Enter systemics, and soil drenches to tray and catch them at all stages. That bad cymidium year, maybe 2015, I tried many different chemicals doing all of these things. With a large greenhouse it sometimes cost $25 to do the whole lot with one chemical, so I must have spent hundreds...and then I got problems with oncidiums not flowering or producing tiny distorted flowers due to chemical damage.
My cattleya phase is very recent. I have now got upto maybe two or three hundred plants mostly at or approaching flowering size, and now have a dozen or more in flower most of the time- this is all very recent, as I say. But now I am getting spike damage on the cattleyas, and at a count today I found almost one in three of the newly opening spikes have damage.
I sprayed all plants in the house with Provado systemic (Bayer) in Seprember, so it looks as though it was ineffective. There is one other systemic easily available in UK (Bug Clear) and I'll try that tomorrow.
Obviously my sulphur vapour weekly treatment is not helping this problem. I wonder if any other fumigant might ? Or anything else ? Help !
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Originally Posted by ksriramkumar
