Green Gardener

[ragamala]

Having bought one of their products (unrelated to the below) I received an interesting brochure.

Thinking ahead to next year maybe, I was wondering whether any of these "under glass" pest control measures from this source had been tried/tested/recommended by anyone here?



https://www.greengardener.co.uk/shop/pe ... glass.html

[ralphrmartin]

Ages ago, I looked into a biological control for mealy bug (or was it red spider - mealy bug I think). I decided not to go for it as
- they were only active over a rather limited temperature range
- they needed windows kept shut to prevent them flying away, which would make things far too hot
- if they did work, they would die out as they would be no prey left, and would need buying all over again when pests reappeared

[MikeDom]

I tried 2 of the controls last year. For various reasons, one of my greenhouses was rammed with plants meaning I couldn't physically get into it around September time, and I suffered a severe whitefly outbreak on my caudiciform pelargoniums and a significant mealy bug outbreak on all other plants. Last time I buy from that seller on Fleabay.

I used the Encarsia wasps for the whitefly - 3 applications at 2 week intervals. Didn't see any difference for about a month afterwards and then the whitefly suddenly and completely vanished, so I hail that a total success, haven't seen a single whitefly since. Sprays are no use at all on whitefly.

For the mealy bugs I used 10 Cryptolaemus adults that look like ladybirds. Since releasing them I never saw them again despite sealing the greenhouse with insect netting to prevent escape. The worst thing was just watching them walk past mealy bugs when they were released. The mealy bug problem persisted into this spring when I emptied the greenhouse and manually got rid of the pests (and lost quite a few plants). Weekly inspection is now sufficient to prevent mealy bugs, the odd one reappears every other month. I wouldn't be misled by the hype, if I remember correctly they have a 65 day life cycle so it would be over 2 months before those 10 would increase in number and the temperatures have to be quite high - by that time I would expect to have had a few more hundred mealy bugs. Wouldn't recommend this at all.

Hope this helps.

[Ali Baba]

I have used 2 species of mites to control thrips this year with some success. I still have thrips but the damage to plants and flowers is minimal so I will definitely top up the mite population from time to time. Cheaper and more effective than spraying which is next to useless for thrips


Sent from my iPhone using Tapatalk

[Terry S.]

Ali Baba - I suspect that the thrips would have disappeared without the help of the predators. When I have seen WFT in the greenhouse it has been during the spring and autumn months when the temperatures have been moderate. Conditions in the greenhouse over the last two months have probably been too high for thrips. For any biological experiment to be meaningful there has to be a control and for most of the things that we try in our greenhouses, we have no controls. Has anyone else noted the low prevalence of WFT during the hotter months?

[juster]

In line with what Mike says above: I tried the 'ladybird' control for mealy but some years ago, completely useless, it made no difference at all. I have never tried Encarsia but have friends who use them with complete success.

[Ali Baba]

Hi Terry you make a valid point, one seasons anecdotal evidence isn’t a controlled experiment! I have found articles that support your idea that WFT is less able to reproduce at higher temperatures, specifically temperatures above 31C stop larval development.
However I started mite control in early spring when it was still cool using a different mite which is supposed to control overwintering thrips and then switched to a less cold tolerant mite once it warmed up. I certainly noticed the difference before the heatwave arrived for what it’s worth. It will be interesting to see what happens in future years


Sent from my iPhone using Tapatalk

[ragamala]

Thanks all for the replies. I'm thinking the general opinion is somewhat sceptical.

At the moment I rely on a set of carnivorous plants to keep "visitors" down, I guess that isn't a perfect match with the other sort of biological control on offer.

[Terry S.]

But they are a lot more interesting than predatory mites!!!

[ragamala]

But they are a lot more interesting than predatory mites!!!

Certainly are! You can feed a pet and have it respond. OK you can't take them for walks, but....