Well it’s spring and the soon the plants will be growing in your garden – and the pests won’t be far behind. However Gardeners are more aware about the damage that chemicals have done to the environment and there is more and more demand for information about biological control.
Here at the Nursery we’ve been busy getting ready to support you. We’ve overhauled the site, created a brand new catalogue and found some new products to help you keep our garden in good heart. You see we’re not just garden suppliers – we run a plant nursery that grows organic veg (as Fletching Glasshouses) and provides Plants to deliver delight via Plants4Presents
We are firmly committed to grow healthy plants without the use of pesticides. This has been quite a steep learning curve for us and every growing season we have had to deal with spider mite, aphids, slugs, whitefly and caterpillars. We’re keen to pass our growing experience on to our customers.
Last year, for example, the drought in the early summer meant that spider mite were rampant in greenhouses and polytunnels and in some areas even outside. In fact for the first time they were more of a problem than slugs. We noticed that many gardeners left it a bit late to treat spider mite and they were not as successful as usual because in the hot dry conditions of late summer the standard predator, phytoseiulus did not establish well.
So this year we have a couple of other predators for this pest, one for the early season and one for the late seaon.
The Number Two SpiderMite Killer – Amblysieus californicus
This predator is often used in addition to Phytosieulus to provide additonal control.
It has advantages and disadvantages. The main plus point is that these predators will not die (or eat each other) if they cannot find enough spider mite to eat – because they can also live on pollen, or on other prey. This means that they can be used as a preventative measure in March or April when you can’t yet see any spider mite – or in later in the year for small outbreaks.
The other advantage is that Amblysieus is not so temperature sensitive – it will be active to some extent from 8 degrees to 35 degrees – again this is why it is used early season and late season. And whereas Phytoseiulus requires a damp atmostphere (relative humidity over 60 percent), Amblysieus will thrive under the hot dry environment typical in a summer glasshouse.
The only disadvantage of Amblyseius (apart from the price!) is that they don’t eat quite as fast as the Phytoseilius so it if you have got a big infestation we would recommend Phyto.
Amblyseius californicus are supplied in plastic tubes with vermiculite granules. On receipt of your order, please read the instructions before opening the tube! For more information about Amblysieus click here – a standard pack costs £40.
The Flying Killer – Feltiella acarisuga
These are native midges which target red spider mite, laying their eggs among their colonies. When the eggs hatch then the worm-like larvae will eat the eggs, young and adults. Their common name is sometimes given as “Predatory Gall Midge”.
These killers have some advantages over phytoseiulus, especially when used early or late season. Because the adults hunt out their prey, they will reach the hot spots that the gardener may miss. (With a large crop it is very tedious and difficult to spread phytoseiulus accurately by shaking out of the tube. Phytosieulus has to crawl to its prey, while the midges can fly quite a distance)
They will devour large quantities of red spider mite, and are active in spring and autumn when light levels are lower. They will be active from 15 degrees, although they will act quicker when warmer. They prefer more humid conditions than the predatory mites.
For that reason the midge is recommended for early season control when you know from previous experience that there are overwintering red spider mite sheltering under leaves. Like Phytoseiulus, this predator won’t thrive unless they have spider mites to feed on.
This control is not recommended for the hot dry conditions of mid summer. You should also take account of the fact that the cocoons and the midge larvae are visible to the naked eye, so this is not a solution for ornamental plants (flowers).
The Predatory Gall Midge is supplied it a tub of cocoons. Adult female midges emerge from the cocoons, mate inside the tub then fly off to lay their eggs amongst spider mite infestations. The treatment is more expensive than the phytoseiulus but if you have a known problem on a sizeable crop then one tub is excellent value because if you introduce the midges in the right conditions they will establish and breed just from one tub. click here
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