Article on systemics and mealy bugs

[iann]

Interesting that Bayer have stopped using Thiacloprid (and previously the banned Imidacloprid) in their Provado branded inseciticdes, supposedly in advance of possible restrictions in the near future and because of poor publicity. Yet it now pops up in their Baby Bio range. I have to assume that as one of the most successful agri-businesses in the world they aren't idiots, and the only alternative explanation is that they think their customers are idiots.

The neonicotinoids in general have not been banned. Some of them (eg. Thiacloprid and Acetamiprid) weren't affected at all by the 2013 review. Others were heavily restricted, with the intention being that they were not to be used on crops which might expose bees to risk. Supposedly it was for 2 years to be followed by a further review. Four years on and we are still waiting. Of course the UK just banned them entirely amid much publicity, largely ignoring the fact that Thiacloprid and Acetamiprid remained on sale. Portugal may have taken a more nuanced approach or they might just be taking the michael.

[iann]

Am I wrong, Chris, in thinking systemics would be absorbed through the skin, in which case spraying the entire plant would work, even if the stuff migrated upwards later? Or are you thinking of a root drench?

I've re-read my post and it is a bit vaguely worded. By watering I mean from below.

My understanding of the term "systemic" (i.e. if someone uses the word in a post or talk at a meeting) is that they mean the chemical is taken up by the roots and the term "contact" is used for sprays towards the body of the plant which directly hit the insect.

That is how I would use them.

Can spray be absorbed by the skin of the plant? I suppose it could.

These are not the correct definitions. Systemic insecticides are transported throughout the plant, but can be applied through the roots, by spraying onto the leaves or stems, or "from birth" applied to seed. Contact insecticides do not move through the plant and are only affective when they make direct contact with a pest. This limits their use against mealybugs and makes them virtually useless again root mealies.

There is some crossover between the two cases, with some insecticides having "translaminar" action. These are absorbed by the leaves but are not transported throughout the plant. The miticide Abamectin may be the best-known example. These provide longlasting effect by continuing to kill feeding insects in sprayed areas of the plant even if they were never in direct contact with the spray, but they do not have any effect in other parts of the plant that were not sprayed.

Most systemic insecticides are also effective by direct contact. I'm not aware off the top of my head of any that are not also contact insecticides but I suppose such a thing is possible.

[DaveW]

Evidently for once Britain did lift an EU ban on these insecticides in 2015.

"A Defra spokeswoman said: “We make decisions on pesticides based on the science only once the regulators are satisfied they are safe to people and the environment. Based on the evidence, we have followed the advice of the ECP and our chief scientist that a limited emergency authorisation of two pesticides should be granted in areas where oil rape crops are at greatest risk of pest damage.”

Cameron, visiting the Royal Welsh Show on Thursday, said: “The EU put in place the ban on neonics, but if scientists start telling us that these things are safer than they thought then perhaps we can licence them.”

https://www.theguardian.com/environment ... -harm-bees

As to Brexit ragamala it could mean that Britain makes up it's own mind on these matters. As to "gold plating" the unelected British bureaucracy has often been accused of this by British politicians who are supposed to be their bosses and in control of them:-

https://fullfact.org/europe/bees-neonicotinoids-and-eu/

http://www.freshbusinessthinking.com/wh ... of-eu-law/

Lets hope after Brexit Britain starts with a clean sheet regarding these products and bases regulation on pure science and actual risks in use. Certainly many of the products available since we joined the EU hardly seem to be effective for the purpose intended. I have yet to find anything that worked as well as the old "Murphy's Systemic with Rogor." I believe it was called.

[JST]

Does anyone still use methylated spirits? Has anyone found that it harms their plants? I'm going back nearly 30 years, but dabbing mealies with a tiny paintbrush soaked in meths seemed to work then, so I am applying it now. Firstly removing the plant from its pot, knocking excess compost off the roots, then dunking the whole plant in meths. Leave for a few seconds to make sure the roots get a good soaking, then rinse off thoroughly. Leave to dry out in the warm shade of the utility room, then re-pot into scoured-out pots. Leave for a couple of weeks for any damaged roots to heal, then you can start watering again. Only trouble is that you cannot seem to get meths in bottles bigger than half a litre, and I am sure the staff in my local hardware store think I have a drink problem!

[ragamala]

Dave, following your drift is sometimes a little difficult for me. One minute you accuse the UK of exceeding or "gold plating" EU regulation, then the next minute quote examples (of which there are many) of undermining it. One minute (in another thread) you accuse scientists of doing inferior work, now you are asking for policy based on a "pure science".

What you seem to ignore is commercial reality. Governments are often driven by industry pressures, and, particularly in the case of areas where there are small profits, like products for amateur gardeners, it is simply not worth chemical companies going through the financial hoop to achieve licensing of a particular product. It has little to do with science. It has everything to do with money.

[Chris L]

Does anyone still use methylated spirits?

I think the Lavender Diffuser Oil (mentioned above) is doing a similar thing. I am only dabbing a bit on where there is a mealy bug - not dunking the whole plant.

Having said that I did get a rescued Astrophytum last year that was riddled with the things and (since it was free) I painted it all over with the stuff. I suppose I'd better check if it has any mealy bugs on.

Really, at the end of the day the only way to be sure of getting all the bugs off a plant is to un-pot it and douse it in the chemical of your choice. No half-hearted measures.

[Cactus Kid]

Does anyone still use methylated spirits?

Yep. I always have bottle in each greenhouse which I dilute with water by approx 50% and dab on with a small paintbrush for minor outbreaks or plunge the whole plant in for bigger infestations. Also have some made up in a small spray bottle.

About this time of year I go through the whole collection and `paint` the pots with it, making sure to get into all of the corners where they like to hide. A good preventative treatment.

Seems to work for me but only kills the adults, not the eggs.

[fruit]

I have also used meths, sometimes undiluted on the tip of a cocktail stick, other times diluted 50:50 with water, painted, sprayed, bathed as required.

If the lavender oil mentioned is the typically available oil that may be used as a few drops on water heated in some contraption with a tea-light then I am sure I have come across mentions that just the diffused vapour may be particularly toxic to some household pets (liver damage).
There are certainly cautions against human skin contact with the concentrated product, probably no wonder that mealies don't like it much

[DaveW]

You have to distinguish between politicians, who are supposedly in charge of the country ragamala and public sector bureaucrats who are supposedly simply their employees. Margaret Thatcher admitted that the TV programme "Yes Minister" was very near the truth regarding the relationships between our elected representatives and the unelected bureaucracy who often have their own agenda's.

Scientists and public servants are merely there to advise, it is then up to politicians to decide regulations and if the electorate do not like it they will vote them out at the election. When it comes to science there is seldom unanimity and the old "Half Life of Facts" rule still applies, saying 50% of all you were taught in school or university will prove to be wrong in your lifetime. Unfortunately we tend to cling to what we were taught rather than accept the new revelations.

For example we have long been told by the Government to cut down salt in our diet to prevent strokes. Now that has been proved wrong:-

http://www.dailymail.co.uk/health/artic ... earch.html

The doctors are still telling patients to fast before cholesterol tests and the NHS is still discarding hundreds of them at taxpayers expense because the patient did not fast before hand, simply because the scientific advisers it uses still trot out the old "facts" they learnt at school. Also our institutional bureaucracy moves very slow to revise out of date information, though it has now been proved fasting makes no difference.

https://www.statnews.com/2016/04/29/fas ... l-testing/

It is easy to find examples of British bureaucratic and scientific opinion to politicians being behind the times and totally unreliable, but I will simply give this this other one. The NHS is still giving out literature on what is a universal healthy diet, even though it has been now proved there is no such thing. Foods that may be healthy for one person may be just the opposite for another. People slavishly following the NHS healthy diet may put on weight rather than loose it.

https://www.israel21c.org/diet-study-ov ... hy-eating/

The point I am making is there are differences of opinion in science as to whether the chemicals we sensibly used in the past are as dangerous to the environment as some of the more hysterical pretend. Also unfortunately when something is wrongly embodied in law in the UK it is often difficult to get it revoked.

Obviously for the UK government to even temporarily revoke that pesticide ban it could not have considered the substance was that dangerous. To slavishly accept any statements from public sector scientists as always being gospel and automatically correct is being very naïve, particularly if other scientists dispute their findings.

To get back to the subject. I was told Meth's was liable to burn the plants and to use rubbing alcohol instead? Gordon Foster told me once that the old "Fowlers Mealy Bug Destroyer", which he eventually took over the manufacture of for a time, was simply rubbing alcohol with some insecticide in it (I can't remember which now) but he said the insecticide had to be changed for another approved one when the original insecticide was banned.

[DaveW]

Just been to the local garden centre to get some insecticide. Bought some Westland Resolva Bug Killer concentrate, since ready mixed chemicals are a bit of a rip off I find as they seem to charge for the diluting water at the same price as the chemical. It says on the packet "Dangerous for the Environment", "Dangerous to Bees" contains 0.75 g/l lambda-cyhalothrin. Resolva Bug Killer Concentrate also gives reduction in the numbers of mealybugs.

Evidently it is approved for use in the EU yet kills bees, so a bit pointless the EU banning other pesticides for the same reason?