Definition of Pesticides, Fungicides and Insecticides

Reply to comment:

'What is the difference between fungicide, pesticide and insecticide? What negative effects do they have and do you have any tips for avoiding them?
By Anonymous on Rose Blackspot Treatment on 25/08/10'


Thank you for your comment. I should have clearly defined these terms for you earlier, at least as far as their use in this blog is concerned. My apologies.


Generally, a pesticide is the collective term which includes both insecticides and fungicides.

DEFINITION OF PESTICIDE

The Chemicals Regulation Directorate at http://www.pesticides.gov.uk/ defines a pesticide thus:

'The term 'pesticide' covers a wide range of products, all of which are used to control plant 'pests'.
Pesticides for plant protection purposes include:

• weedkillers (herbicides)
• slug pellets (molluscicides)
• fungicide sprays
• animal repellents
• hormone rooting powders
• insecticides
• plant growth regulators
• lawn sand treatments.'

As far as this blog is concerned, I use this definition. I think we get confused because the textbooks split plant problems into the two categories: pests, and diseases. This rather implies that pests only include members of the animal kingdom and diseases of the plant kingdom.

The problem is further complicated when we consider an insecticide as something that kills insects. In itself this is fine, but what about a caterpillar, the larva of the moth or butterfly; or a leatherjacket, the larva of a daddy longlegs (crane fly) - are these insects?

DEFINITION OF INSECTICIDE and FUNGICIDE

I think Wikipedia defines an insecticide thus:

'An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. ...'

and fungicide thus:

'Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores . Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals. ...'

Although there is some dispute about exact definitions, I hope this has helped and not made you more confused.

The combined fungicide/insecticide referred to with regards to roses is used to control principally aphids, and fungal diseases such as blackspot, rust, mildew, etc.


As for negative effects, these arise because pesticides don't just kill the pests and diseases intended, but also beneficial organisms both on and around the plants and/or in the soil.

However, we need to understand that things have moved on since the early days of the organochlorine pesticides such as DDT, which did not break down in the soil, nor in the body and hence had devastating cumulative consequences through the food chain. Far more safety testing is now carried out, and pesticides are being withdrawn from the market all the time (although we need to ask: 'If the testing is so good, why do these products need to be withdrawn? Why were they released in the first place?'). We should also understand that the ordinary gardener has access to only the 'tamer' pesticides; the rest are used commercially.

In my opinion, few - if any (myself included) - persons are qualified enough to really discuss pesticides and the full implications of their use. We are somewhat in the dark as far as certain aspects are concerned; although some of their effects are plain for all to see and opine about.

What I have done with the blog is to point out opinions as they have arisen with regard to descriptions and reasons for various operations performed in the garden. It might be best done this way. It wasn't intentional; just the way it worked out. And, of course, I also try to show how to both minimise their use and use them more safely (at least I hope that's what I do).


As far as tips are concerned, you have touched upon the crux of the blog. Part of my growing philosophy is to produce a garden which will work with minimal, and preferably no, use of pesticides. As stated recently, to a large extent this has been achieved. But to extend the diversity of the blog I have taken on new projects, and I think it is from these that the pest and disease problems have arisen (though to be fair, I did have some pests before).

Very soon I shall be doing an analysis of the year's operations, and from this you will see my proposals. They are too extensive to detail here; although you should know that they are based upon cultural techniques rather than control. I'll explain what I mean by this, shortly. Watch out for the posting. Coming soon.

Best wishes,

Jimini