Vine Weevil Concentration for soil drench - puzzled.

[gerald]

10ml per 8 litres of water

It's not vague, you just have to be able to understand the German instructions

I assume in Portugal you're allowed to use this stuff, as you can in much of Europe?

[jfabiao]

10ml per 8 litres of water

It's not vague, you just have to be able to understand the German instructions

I assume in Portugal you're allowed to use this stuff, as you can in much of Europe?

We don't have BI 58 in Portugal, as far as I know. But we do have other dimethoate-based insecticides (the brand I use is called "Perfekthion", from BASF), and it's this product that is a little vague about its use as a drench. Looking it up online, it says BI 58 is a 38% dimethoate concentration, whereas Perfekthion is rated as 400 g/l, both emulsion concentrates, so it's pretty much the same. Thanks.

Incidentally, this and most other agrotoxic products are off-limits to individuals in Portugal. You have to be certified - which I am - to buy and use them. Certification involves taking a course and a final exam on numerous things not necessarily related to plant health, rather on legislation, equipment operation, disposal of empty containers and leftover spray, etc.

[gerald]

That's the kind of course I've been considering going on myself.

Perhaps the BCSS can organise one on behalf of its members.

Then finally perhaps we'll be able to rid ourselves of these tiresome pests once and for all!

[Geosec]

That's the kind of course I've been considering going on myself.

Perhaps the BCSS can organise one on behalf of its members.

I think you mean a BASIS course, but I don't think that will help you much. I am a retired agronomist and BASIS qualified, so I can advise on agrochemicals (but not apply them!) For that you need a different qualification module, and there are numerous ones, knapsack, tractor mounted etc. It is unnecessarily complicated, but then someone is making money on the training.

The main problem is that nearly all the useful chemicals have been banned in the UK, even for professional users. Unless there is a mass market for a product it is not worth the manufacturer to keep updating the safety data, which they are obliged to do every couple of years, and which costs them millions. So the product registration lapses and the product gets withdrawn. I suspect this will happen to the neonicotinoids as they now only have clearance for 'protected crops' ie in greenhouses where the bees can't get at them.

The other issue with dimethoate etc is that it was too persistent, which we would think is what we want, but the regulators like products that break down quickly, preferably within 24 hours, and cannot be detected in edible products.

Finally if you store professional products it has to be in an 'approved' location, and this has to inspected. You really don't want to know all the necessary rules that this entails.

Checking the professional acetamiprid product (now withdrawn for open crops) this was a 20% active ingredient water soluble granular product applied at 1 gram per L water and sprayed onto crops. ie 200mg a.i. per Litre diluted. Our Bug Clear Ultra is 5% a.i. per L CONCENTRATE, diluted 0.06L per L water = 0.3mg a.i. per Litre. Unless my maths is up the spout that is not much a.i.! The harvest interval for the professional product is 14 days, which will give you some idea of the persistence.

[Geosec]

It's been a long day, 3ml/L not 0.3 ml/L

[iann]

Dimethoate wasn't so much banned in the EU, as rendered unusable due to the strict residue requirements for crops. It was simply too persistent to be able to use it in any meaningful way. Still available for sale in some EU countries last time I checked, but completely outlawed for retail sale in the UK long ago.

I think Acetamiprid just isn't taken up well through roots, probably it binds to soil too quickly. The recommended soil drench concentrations in the home-use products are several times stronger than the sprays, but that doesn't entirely capture how much you need to use. The real quantities depend on the size of the plant and can be supplied by less liquid of a higher concentration or more of a lower, within sensible limits. The instructions give you some idea, but mostly based on pot size so a bit hard to judge. Does a Gymnocalycium need more or less than a Fuschia? In any case, not great for treatment of root mealies or vine weevils but one of the few options left in this country.

As mentioned, spraying an effective systemic may give good control of pests that feed on the roots, but it is very hard to know if it will work and if it actually did work.