Should we be using aspirin as a pesticide?

Organic gardeners, like myself, must try to remember that everything is made out of chemicals including ourselves and the vegetables we eat.  Some chemicals are more dangerous than others.  This includes “natural” chemicals like belladonna (atropine) and digitalis.  A great number of medicines started their lives as plant extracts like these.   Salicylic acid has been found in most plants and was first extracted from the bark of a willow.  Aspirin (acetylsalicylic acid) is made from salicylic acid. 

Some scientists asked the question why do plants produce this chemical and it turns out to be part of the plants immune system; the way that it combats disease and pests.  There is a lot more information here:

  http://www.news.cornell.edu/releases/Dec03/take_two_aspirin.hrs.html

This is not the only immune system that has been discovered in plants; however it is the one that amateur gardeners could use to help them in their garden or allotment. 

http://www.sciencedaily.com/releases/2007/10/071004143125.htm

What about trying aspirin? I have tried it on virtually all my allotment vegetables, however it seems to be more effective when sprayed on seedlings.  

Now that Derris and Pyrethrum have been proscribed in the UK, there is little for the amateur gardener to use against pests and diseases.  Picking off pests might be alright for gardens and allotments but whether this is viable for farms I would question.  Maybe aspirin might be a way of preventing pest damage to crops that is a little gentler to the Earth than artificial, petrochemical pesticides. 

There is much that is unknown about the use of aspirin and there may be unforeseen damage to insects other than those attacking vegetables.  Yet, I have been spraying with aspirin since March 2008 and I have seen lots of ladybirds on my vegetables.
The most noticeable affect that I have seen is the reduction of whitefly on my winter brassicas. It almost encourages me to start to grow kale again.

The two unknowns about aspirin application to plants are the dosage and the timing. I have used 2 tablets in 10 litres (2 gallons) of water. I only sprayed seedlings once but the veg. about once a month.   I have used dissolvable aspirin in these experiments.  I know that other people are using willow water made by marinating fresh cut willow branches in water.  As some organic gardeners object to the use of synthetic aspirin, willow, a good source of salicylic acid, water could be used instead.  So we could argue that spraying with aspirin is similar to spraying with nettle or comfrey extract as a pesticide.
A more effective way of extracting salicylic acid from willow bark is to make it into a tea using boiling water. 

Rather than using the organic label, I would rather the: "natural" label. Maybe that is just as difficult to define, but I mean by it that I am using nematodes, fungi and bacteria to combat diseases and pests. And I use a barrier rather than chemicals that are not usually found in nature. Aspirin, as I said at the beginning, is found in most plants.  I would suggest that it may be one of the more benign of the chemicals that plants produce and therefore a chemical that we can use to advantage on the allotment. 

Comfrey tea

I have said in several of the previous posts that I use comfrey, sweet cicerly and  nettle teas to inoculate charcoal.  I also use them as liquid fertilizers. 

I have grown comfrey (Symphytum officinale) for about 30 years now.  It has a beautiful pink purple flower and large dark green leaves.  It can grow up to 1.5m tall and is rather a thug in the vegetable plot if you allow it to be.  I have five 25ft rows of it.

Comfrey bed 

My plants are not the sterile  Bocking 14 and they produce seeds prolifically.  They will spread.  Their roots are very thick and robust and you can use them to propagate new plants.  They are, indeed, very good ground cover plants because little will grow under them particularly if you grow them closely.  

Neat comfrey coming out of the butt.
This butt does not have a tap

Whenever I feel in the mood I cut down the comfrey and put it into a butt (a water barrel) with a tap at the bottom.  The comfrey rots down to a black liquid and that can be drained out of the barrel.  Some people cover the comfrey in water but it is unnecessary.  The liquid is relatively high in potash (Potassium) so it is good for fruit and flowers.  Its percentage NPK is 0.74:0.24:1.19 for the Bocking 14 comfrey

(http://organicgarden.org.uk/gardening/comfrey) 

which compares very favorably with commercial tomato liquid fertilizers. 

However, it costs nothing!

What goes into the barrel stays in the barrel.  It will all rot down regardless of how tall the comfrey grows.  It does get coarser as it gets bigger and takes a little bit longer to break down in the barrel but it still forms the black liquid.  Now, you might think that the decaying comfrey would block up the tap at the bottom of the butt but it decomposes so quickly that it rarely if ever blocks the tap. 

I kept a large bottle of comfrey liquid for about 3 years and it still seemed to be alright. I keep my comfrey for about 6 months to a year in the butt but I keep topping it up as I crop the comfrey. It lasts over the winter as well. 

Nowadays I bury most of the allotment undiseased waste in the comfrey bed and let the comfrey recycle it for me. It gets a dose of manure or lawn mowings along the rows when I have nowhere else to store them.

The stinging nettle (Urtica dioica) and Sweet Cicerly (Myrrhis odorata) also make valuable liquid fertilizers.  Ref: “Ear to the Ground” by Ken Thompson.

Both worm tea and comfrey tea seem to make tomatoes grow.  I don’t know the NPK ratio for worm tea but I don’t think that it would be too different from comfrey tea.  

Comfrey does smell when it is rotting down and that is why I put it in a covered water butt.  I do not put water with it because that makes it smell even worse.  If you are constantly using it, like I am, then the smell does not seem to be so bad.  I use it on all the vegetables although things like beans and peas together with tomatoes and pumpkins seem to thrive on it.  

Hunts (see comment below) said that he found maggots in the dried comfrey liquid.  I reckon that these were rat tailed maggots. They are larvae of one of the hoverflies such as Eristalis tenax.  The larvae are one of the few that will live in very polluted water.  While some hoverfly larvae feed on aphids, Eristalis tenax larvae probably live off bacteria or other microorganisms living in the polluted water.  

So how to make comfrey tea that will not go ‘off’.  I think that Hunts’ went off because all the water in it evaporated away.  So,  run it into old orange squash bottles –the large ones with a handle at the top.  Screw on the top and this will prevent the adult hover flies from reaching the liquid.  I have kept comfrey liquid for some time like this.  You can then dilute it down however you want.  I dilute  it down like Tomorite plant food. 

Nowadays, I put the comfrey liquid into a lidded dustbin full of charcoal so that the marinating charcoal soaks the tea up and I can put it onto the soil in a more sustainable form.  I suggest, and there is very little evidence I can quote on this, that the comfrey liquid nutrients will not be leached out of the soil quite so readily in this form.  This is one of the main principles behind the development of a method of creating Terra preta type soils in England's temperate climate. 

As Mikey says in the comments below, the comfrey leaves can be put into the worm bin as in the photograph below.  

However, I would fill this little bin up several times over with the amount of comfrey leaves that I produce.  So the large bins are also brought into service.  In addition to comfrey leaves, I put most of my pernicious weeds in this worm bin.  Bindweed Convolvulus sepium  and horse tail Equisetum arvense ( arvense meaning of the field) are the two main weeds added to the bin.  Comfrey leaves or not, the bin produces copious amounts of black tea like liquid which get mixed with the comfrey liquid manure.  In the front of the worm bin is an area of nettles Urtica dioica  which is also added to the worm bin and the comfrey bins.  It is all grist to the mill.