Pesticides: how green should we be?

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Pesticides: how green should we be?
« on: November 23, 2011, 05:42:27 PM »
In her thread in this section on treating a lemon tree pest, Carole raised the much wider question of using pesticides in general:

Quote from: Umbrian on November 23, 2011, 07:29:26 AM
As I said in my last posting ezeiza, the Lemon tree in question is small and so to treat the pest with a paintbrush is not too arduous! I was aware of David's concern about "spraying Methylated spirits around" but have to add that I am sure serious gardeners ,such as us who use the forum, would always proceed with care and caution especially when treating a subject with edible fruits. I, and my friend who owns the Lemon tree in question, try to be as "green" as possible but sometimes have to resort to more drastic measures. David added that the success of treatment with Methylated spirits has not been proven but the fact that three replies recommended it seems to be good proof to me that in fact it does work.  
How do other members feel about this and the whole question of what we can use to eradicate unwanted pests in our gardens?

I agree with Carole about us being "serious gardeners" and expect that all of us on the forum are very careful indeed when using any pesticide, whether it's one that even the most extreme organic folk would reckon is harmless, or one that certainly is not environment-friendly but is the only treatment that works, and that therefore some of us do use, taking great care to ensure that the way we use it is not damaging.
This forum is a wide-open forum, and whichever end of the organic/environmental spectrum people come from, all are equally welcome to put their point of view (that's me talking with my Moderator hat on   ;) ).
It will be really interesting to hear what everyone thinks, about just how green we should all be.
« Last Edit: November 26, 2011, 05:09:56 PM by Alisdair »
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society


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Re: Pesticides: how green should we be?
« Reply #1 on: November 26, 2011, 06:49:56 PM »
I am quite a lazy gardener when it comes to treating pests. I gnash my teeth but seldom take any drastic measures. My most serious "pests" are the procupines :( that live in the woods around us and since we did not think it either practical or enhancing to our property to fence the whole of our land I have learnt to live with them. (This means that all of by bulbs have to be in pots and iris are out but since there are so many things I am keen to grow this is no big deal)
Greenfly, on roses, for example I eradicate as far as possible with my fingers but do not really have many roses. The only thing I really try to curb by spraying is the dreaded Peach Leaf Curl. With true beginner's luck the first year my tree fruited I had a wonderful crop but in subsequent years I have been fighting a loosing battle despite using a proprietary fungicide at the appropriate times, a task I find most boring!
I can quite understand however that gardeners who are really serious about certain species want to protect them as far as possible from pests and diseases and I have no problem with this since, as I said in the post that resulted in this thread, I am sure that the kind of people who belong to this forum are responsible people who use any kind of treatment/deterrent with due caution.
MGS member living and gardening in Umbria, Italy for past 19 years. Recently moved from my original house and now planning and planting a new small garden.



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Re: Pesticides: how green should we be?
« Reply #2 on: November 26, 2011, 08:02:10 PM »
I try to avoid pesticides as much as possible, but every now and then I use them as well, and I try to find something that’s not too harmful. But as a parasitologist I know what a big the problem resistance to antiparasitics is. I believe it is very important to know exactly what you are fighting to be able to choose the best remedy, and to use the right dosage. If you under-dose, you may kill most of the parasites, but there is a risk of letting the more resistant ones survive,  and after a few times with such practice, you may end up with a resistant strain, it doesn’t take very long.
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

David Bracey

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Re: Pesticides: how green should we be?
« Reply #3 on: November 30, 2011, 11:42:47 AM »
A few comments about resistance. It can occur in insects, diseases and weeds.  As far as insects are concerned resistance may depend on the pest species.  For example red spiders tend to select for resistance quite quickly even if they are exposed to new chemical groups.  Another insect which seems to develop resistance quickly is the housefly in Denmark.

Many diseases for example Mildews also select for resistance quite quickly. Strategies to slow down resistance have been developed and largely include alternate spraying with products from different chemical groups or mixtures of two chemicals preferentially with different modes of action.

Resistance also depends on which pesticide is being used. Products with a single mode of action and products which are systemic tend to select for resistance quicker than muliti-site or non-systemic products.

Resistance thus depends on many factors including the pest species, the pesticide being used and other selection pressures including frequency of application, pest life-cycles, dosage, climate etc.

Can we influence resistance in the backgarden?  Frankly I doubt it.  It`s a bit like helping the environment.  We all do our bit and feel good about it.  Whether we make any difference at our level is doubtful.
MGS member.

 I have gardened in sub-tropical Florida, maritime UK, continental Europe and the Mediterranean basin, France. Of the 4 I have found that the most difficult climate for gardening is the latter.