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Basic Substances; what are they and how can they used for pest and disease control on farms?

Basic substances comprise twenty different compounds which are authorised for plant protection uses within the EU (and UK since Brexit). While not primarily described as ‘pesticides’ they can be used to control pest and pathogens. The specifics of their approval and their prescribed application procedure are laid out in EU Regulation 1107/2009.

Most of the basic substances listed have been approved for use for the last ten years in the EU and UK. However, before now, nobody has put all the information together from all the regulations and reports in an easy to understand document for farmers to use. As such, the take up of basic substances in the UK over the last decade has been very poor. So at Eutrema we thought that we would take up the challenge of analysing the countless EU documents, and pull out all the useful information that applies to UK farmers.

The EU established the category of basic substance, to accommodate European organic growers who were using a range of compounds in pest and disease control for which there was no economic case to register them as a pesticide.

The compounds that were considered for inclusion as basic substances were not novel, so couldn’t be protected by costly patents, and thus agrochemical companies would never bother to go through the costly registration process for them. Plus the compounds were deemed safe as they were already widely used for centuries, or were safe enough to (literally) eat as food ingredients in the majority of cases. As a result, the EU came up with ‘basic substance’ and instigated a light touch authorisation process (by their standards at least). The resulting authorisations can be used by anybody, regardless of whether they instigated the authorisation or not, and even if they are not an organic farmer!

Below we have given a brief description of each of the substances and the way they can be used on a farm. Simply tap on the name of the basic substance in the title to be taken to a link containing the full EU prescribed application protocols for each crop.

Chitosan hydrochloride

Functions: fungicide, and bactericide

Crops: sugar beet, potatoes, fruit berries & small fruits, vegetables, cereals, spices, and ornamental bulbs

Chitosan is our favourite of all the basic substances because it is effective, fully soluble, approved for use on lots of different crops, and for the control of any fungal or bacterial disease. This is contrasted with the other compounds on this list, which have questionable efficacy, are not soluble in water, can only be used on a few crops, and to target only specific pathogens. As a result, chitosan is a silver bullet waiting to be discovered by farmers.

Chitosan is the soluble form of chitin; the structural polysaccharide found in insect exoskeletons and fungal cell walls. Plants use the presence of chitosan as a ‘non self’ signal, and turn on their plant defence mechanisms in its presence.

Chitosan forms a micro-polymer on the surfaces of plants as it dries, and due to its cationic nature (positive charge) it can flocculate any microbes present on the plant surface. These features combined make it a potent ‘elicitor’ biofungicide.

We have covered the use of chitosan in more detail on our previous blog posts.

To purchase chitosan solution, please visit our shop.


Function: fungicide

Crops: fruit trees, gooseberry, market vegetables like cucumbers, lettuce, tomato, endive, ornamentals, and grapes

These natural compounds are fatty substances that contain both hydrophobic and hydrophilic sections. As such, they are termed ‘amphiphilic’. Lecithins are the same phospholipids that cell membranes are composed of and they are extracted commercially from either legumes or sunflower crops. The main commercial use for lecithins are as emulsifying agents in food, but they also have use as components in surfactants and lubricants.

As a basic substance, lecithins can be used as a fungicide in most horticultural crops. It is thought that lecithins have fungicidal activity due to its action on inhibiting the fungal hypha strands as they attempt to gain access to the plant cells.

Unlike chitosan (above), lecithins are not fully soluble in water, so you will need to be able to keep your tank agitated when spraying a lecithin emulsion, and be on the look out for nozzle/filter blockages. Plus, the authorisation for lecithins only covers horticultural, not agricultural crops. As such, chitosan would be our first choice in most situations when looking for a fungicide amongst the basic substances. Perhaps the only exception would be when trying to control water mould (oomycete) pathogens that cause late blight (Phytophthora infestans) in potatoes and tomatoes, and red core (Phytophthora fragariae) in strawberries. These are very pernicious pathogens that will not respond well to the mode of action of chitosan (elicitation) and you would be better to control directly. As lecithins are approved for use against these Phytophthora diseases lecithin could be a useful option to incorporate into a trial.

If you wish to source pre-prepared lecithin concentrate for use as a basic substance please get in contact with Eutrema.

Equisetum arvense (horsetail extract)

Function: fungicide

Crops: fruit trees, ornamental trees, strawberries, potatoes, cucumber, tomato, and grapes

This compound is an extract of horsetail. Yes, the same weed you have been struggling to get rid of in that waterlogged field 😆! So this is really great news, you can go harvest the weed, make up a potion, and spray as a fungicide. The issues it can be used to control include:

  • Various fungal diseases of fruit trees, including scab (Venturia inaequalis), mildew, and peach leaf curl (Taphrina deformans).
  • Both downy and powdery mildew on grapevines.
  • Damping off (Pythium) and powdery mildew on cucumbers.
  • Early blight (Alternaria solani) and Septoria blight (Septoria lycopersici) on tomatoes.
  • Grey mould, powdery mildew, red core, and anthracnose fruit rot (Colletotrichum acutatum) in strawberries.
  • Early blight, late blight, and powdery mildew on potatoes.

Of these diseases, the ability for farmers to use horsetail extract to control downy mildew, damping off, and potato blight is of particular note as there are not many products that are effective against these pernicious oomycete pathogens.

If you wish to purchase horsetail extract concentrate for use against potato blight please get in contact with Eutrema.

Horsetails are very ancient plants, that have survived since the time of the dinosaurs. As such, it contains some potent biochemicals that the plants have used to ward off pathogens for hundreds of millions of years. Some of the biochemicals that horsetail is notably high in include; silicates, alkaloids, tannins, and saponins. Any one of these could account for the extract’s fungicidal activity, but unfortunately, there isn’t much information on the mode of action for this compound as a fungicide.

Urtica (nettle extract)

Functions: insecticide, fungicide, and acaricide

Crops: fruit trees, bean, potato, leaf vegetables, elder tree, rose, spiraea, cabbage, rape seed, radish, grapevine, and cucumber

This compound is simply an extract of nettles. Yes, another use for a very common farm weed! Basic Substances certainly prove the old adage that a weed is ‘just a plant you haven’t found a use for yet’…

Nettle extract has a wide range of uses under basic substance regulations, including; insecticide, fungicide and acaricide (mite killer).

As an insecticide, nettle extract can be used to control aphid infestations in a wide variety of agricultural and horticultural crops. However, its authorisation for the control of flea beetle (Phyllotreta cruciferae) in brassicas is most of note. As I am sure many reading this post know, the number of compounds that can be used against flea beetles has dramatically reduced in recent years; not least the loss of neonicotinoids seed dressings. So why not consider a potential new weapon in the fight against flea beetles that can completely wipe out any brassica of sugar beet crop?

Nettle extract can also be used to control the following pests:

  • Diamondback moth (Plutella xylostella) on brassicas
  • Codling moth (Cydia pomonella) on apples
  • Spider mites (Tetranychus urticae) on beans and grapes

As a fungicide it is notable for its authorisation for the control of both early and late blight in tomatoes and potatoes respectively and the control of damping off (Pythium) in cucumbers.

The full list of diseases it is authorised for the control of includes:

  • Alternaria leaf spot /damping off disease on brassicas and apples
  • Powdery mildew on cucumbers* and grapes.
  • Septoria blight (Septoria lycopsersici) on tomatoes*.
  • Various rots and blights on apples caused by the fungi Botrytis cinerea, Rhizopus stolonifer, and Monilinia laxa.
  • Early blight (Alternaria solani) in tomatoes*
  • Late blight (Phytophthora infestans) on potatoes
  • Pythium root rot in cucumbers*.
  • Various diseases in roses*, including; rose black spot (Marsonia spp.), rose rust (Phragmidium mucronatum), leaf curl (Monilinia) and powdery mildew.

*For this use it must be added to a mulch before being applied to the crop

As with horsetail extract, the actual product applied is a mixture of various biochemicals from within the plant that could potentially be leading to its action against pests and pathogens. The leading candidates in nettle extract are thought to be acetic acid, chlorogenic acid, or formic acid.

Once you have managed to harvest the nettle stems without stinging yourself, you will have to steep them in water for 3-4 days and then apply to the crop. Unlike horsetail extract, you do not heat the concoction. After the 4 days are up you filter off the liquid, dilute down and apply to the crop.

If you wish to source pre-prepared Urtica extract concentrate for use as a basic substance please get in contact with Eutrema.

If you are going to harvest nettles for use as a basic substance, make sure the ones you harvest are true stinging nettles (Urtica), and not the very similar looking ‘dead’ nettles (Lamium). Dead nettles look almost identical to stinging nettles (especially when not flowering), but are actually members of the completely untreated mint family.

Salix spp. Cortex (willow bark extract)

Function: fungicide

Crops: apple, peach and grape

Another botanical extract, this time it is an extract of willow stems. Again, another plant that can be a weed on boggy farmlands (it’s almost like a trend is developing here)!

Willow has a long history of use in medicine (as a pain reliever) and in horticulture where extracts have been used as natural rooting hormone. However, as a basic substance it is used as a fungicide.

Unfortunately, its use as a fungicide is limited to only apple, peach, and grape crops. On these crops it can potentially control peach leaf curl, scab, and powdery mildew. However, most of note is its authorisation for the control of very troublesome downy mildew in grapes.

The exact mode of action, or biochemicals involved in in willow extract’s fungicidal action remains unclear. However, for one of the few plants that positively thrives in waterlogged soils, it is not surprising that it contains potent anti-fungal biochemicals.

Like horsetail extract, the stems need to be steeped in hot water (80°C) for two hours, filter, then diluted and sprayed onto the crop. Again, unless adequately preserved we definitely do not recommend storing the concentrate for long as it will ferment.

If you wish to source pre-prepared Salix extract concentrate for use as a basic substance please get in contact with Eutrema.

Onion oil

Function: Insecticide (deterrent)

Crops: umbelliferous crops (carrots etc.)

Onion oil can be used to control carrot fly infestations in umbelliferous crops (carrots, celeriac, parsnip, parsley root). Sounds good right?!

Unlike all the basic substances described above, this product is not sprayed on the crop. Instead it is placed in small containers positioned throughout the crop to act as either a repellent or to mask the natural smell of the crop.

While this method of application is pretty labour intensive, it is fairly simple and we think worth looking at for major carrot growers.

If you need to source some onion oil, then please get in touch with Eutrema.

Mustard seed powder

Function: fungicide for seeds treatment

Crop: wheat (seed coating)

It’s not hard to see why mustard might be useful as a pesticide! This one though is only allowed in one specific scenario; as a coating for wheat seeds to prevent fungi. The main active biochemicals found in mustard are the glucosinolates. These are the same chemicals released when mustard is grown as a green manure and then ploughed into the soil to control soil-borne pathogens. While glucosinolates are also toxic to many insect pests, mustard seed powder is not currently authorised for use as an insecticide.

Sunflower oil

Function: fungicide

Crop: tomato

I can already visualise you reaching to open the kitchen cupboard from just reading ‘sunflower oil’! Unfortunately, this one is just for the tomato growers, where they can use it as a fungicide to control powdery mildew (Oidium neolycopersici). While this may seem strange, there are published reports of academic studies showing that sunflower oil was far more effective at controlling mildew than grape, rape, corn, peanut, or soya oil. While this might be impressive, you’d feel a bit conned if you bought a fungicide and found out that behind the trade name and fancy label, it was just sunflower oil.

As with lecithins, you will need to ensure that the tank is agitated constantly, otherwise you could have issues with nozzle blockages or the oil interfering with future agrochemical sprayed. For this reason, we prefer using chitosan for mildew control in most crops.


Functions: Insecticide, and fungicide

Crops: apple, maize, sweetcorn, and grapes

A kitchen staple with sucrose being better known simply as ‘sugar’. Sucrose can be used as an elicitor of plant defence mechanisms in apples, grapes, maize, and sweetcorn. Unlike chitosan, which is an elicitor against fungal pathogens, sucrose is used as an elicitor against insect pests and oomycetes (water mould). This includes:

  • Codling moth (Cydia pomonella)
  • Corn borer (Ostrinia nubilalis)
  • Vine leafhopper (Scaphoideus titanus)
  • Downy mildew (Plasmopara viticola)

These are some of the most devastating pests and diseases in commercial horticulture. We would be very impressed if simply spraying sugar water on vines could control downy mildew, which is an extremely nasty pathogen. We will reserve judgement until we see compelling evidence. We would actually probably avoid spraying sugar on our vines and look for other alternatives anyway, as sugar water could encourage other pathogens, such as sooty mould.


Functions: Fungicide, insecticide, and myriapodicide*

Crops: apple, grapes, maize, and sweetcorn

Another sugar, another elicitor. However, fructose has a very niche application; the control of the pest Scutigerella immaculata. This pest is a distant relative of the centipedes that can eat roots of maize in certain situations. To be honest, it’s not a pest I had ever heard of before I started writing this blog post, but hey, if you are suffering from it, you could do worse than applying some fructose!

Fructose can also be used as an elicitor to control codling moth in apples, and leafhopper and downy mildew in grapevines, but with sucrose a lot cheaper and also authorised for this use, we would probably go for the more basic of the two basic substances first.

* = a word I have had to invent just for this blog post!


Functions: fungicide, and bactericide

Crops: protected fruit and vegetables, carrots, bell peppers, cabbage, tomato, ornamentals, ornamental trees, and wheat

Yes, your kitchen cupboards are emptying at a shocking rate! Vinegar contains roughly 5% acetic acid and often seems like a fairly benign substance. However, this is a hidden gem in plant protection. This organic acid (contains carbon) can be used as a fungicide, bactericide, and even a herbicide. Organic herbicides are rarer than rocking horse faeces; so any organic grower should definitely look at this basic substance. The downside though is that it can only be used on ‘medicinal, aromatic, and perfume crops’, and only as a pre-emergence herbicide as it will be phytotoxic to most crop plants too. For this use it is applied in an undiluted form. When used as a fungicide, it can be used to control a lot of different pathogens affecting many different crops:

  • Common bunt (Tilletia caries/Tilletia foetida) in wheat
  • Leaf stripe (Pyrenophora graminea) in barley
  • Alternaria in vegetables, tomatoes, and peppers
  • Various bacterial pathogens in vegetables, including; Clavibacter michiganensis, Pseudomonas syringe, Xanthamonas campestris
  • Grey mould (Botrytis aclada) in vegetables
  • Various bacteria diseases on trees and shrubs, including; Bacterial blight/canker (Pseudomonas syringe pv 5esculin and syringae), and fire blight (Erwinia amylovora).
  • Various rot fungi on trees and shrubs, including; Phellins (Phellinus), tinder polypore (Fomes formentarius), Ophiostoma, Cryptostroma corticale and Verticillium wilt.

While this all sounds great, bear in mind that acetic acid can burn a crop, and so should be used with caution. It is also acidic, so could interfere with nutrient availability and could strip calcium from the leaf.

Always use vinegar of natural origin when using a basic substance. Plus I would strongly urge you never to purchase glacial acetic acid with the view of diluting it down to save money. Glacial acetic acid is not just ‘strong vinegar’, it is an extremely hazardous chemical, which produces noxious flammable fumes, and causes horrific burns if you get it on your skin!


Functions: fungicide, and virucide

Crops: cucumber, zucchini and squash

Yes, as in curds and whey. Whey is the protein removed from milk during cheese production. It can be used as a fungicide to control powdery mildew in squashes, cucumbers and courgettes. However, as with lecithins and the oils listed above, the solution requires constant agitation to prevent sedimentation and blocked filters and spray nozzles. As such, we would always recommend you try chitosan for the control of powdery mildew first.

Whey can also be used as a virucide to control virus diseases. In tomatoes it can be sprayed onto the crop to control tomato (Sinaloa) yellow leaf curl virus (begomovirus). In addition to being sprayed onto the crop, all the tools and workers gloved hands can be dipped in the whey concentrate before handling plants to prevent the transfer of viruses. When used like this it can help control tobacco mosaic virus (TMV), Tomato mosaic virus (ToMV), pepper mild mottle virus (PMMV), cucumber green mottle virus (CGMMV), and tomato brown rugs fruit virus (ToBRFV).

This sounds very promising, so it could be time to head to the health food shop for some bodybuilder unflavoured whey protein, or alternatively just contact your local animal feed supplier!


Function: molluscicde

Crops: every crop

Now this is one we might think twice about before parting with from the kitchen! But with slugs and snails being enemy number one for many growers, this is one we should at least consider. The use of beer in slug traps is well known, and its authorisation as a basic substance closes a legal gap to ensure everybody using it for this purpose isn’t breaking the law.

Beer can be used on any crop as a molluscicide when placed in dedicated traps. Don’t spray beer on the foliage, it is not allowed, alcohol is toxic to plants, and it is a terrible waste.

There is no guidance on which brand works best, so I am afraid you will have to hit up the off licence and try a number of different brands, all in the name of agricultural science of course!

Clayed charcoal

Function: Protectant against soil-borne fungi

Crop: grapevines

The last of the basic substances that are of natural origin. This is my second favourite basic substance (after chitosan), simply because it is used to control the hilariously named disease of ‘grape measles’ on grapevines.

Grape measles (aka black measles) is caused by the fungus Phaeoacremonium aleophilium which also has a second scientific name of Togninia minima, and another pathogen called Phaeomoniella chlamydospora. When you look at how complicated these scientific names are, you can see why grape growers decided just to call it ‘grape measles’!

Clayed charcoal is a mixture of charcoal and bentonite and to control grape measles it is buried in the soil. The mode of action is described as ‘protectant’, so that is about as vague as you can get.

At Eutrema we have good stocks of charcoal for use in other industries, so get in touch if you would like some.

Calcium hydroxide

Function: fungicide

Crops: top fruit (pome and stone fruit)

Calcium hydroxide is a chemical made in a factory but is allowed in organic farming as a fungicide on fruit trees.

You will find it on sale under various names including slaked lime, hydrated lime, caustic lime, builders’ lime, or pickling lime. When it is applied in water it is known as ‘lime water’. Calcium hydroxide will burn if you get it on your skin, or in your eyes, and it will certainly burn any foliage. But the good news is that you only apply it in the winter when the plants are dormant and the leaves have long since dropped to the floor. The calcium hydroxide quickly kills the fungal pathogen Neonectria galligena which causes cankers if left unchecked.

As with many other of the basic substances above, this is applied as a suspension, so the solution must be agitated when being applied. As such, we would probably recommend growers look at using Lime Sulphur (calcium polysulphide) as this is easier to apply and fully soluble. See our shop page for more details.

Diammonium phosphate

Functions: attractant for flies

Crops: fruit trees, olive, and citrus trees

This is an interesting basic substance as it is used as an attractant for flying pests. As such it can be incorporated into physical traps. The flies are attracted to the ammoniacal sent and the yeast growth that the compound encourages. In this regard it is used to control the following pests in orchards, olive groves and citrus plantations:

  • Mediterranean fruit fly (Ceratitis capitata)
  • Cherry fly (Rhagoletis cerasi)
  • Olive fly (Bactrocera oleae)

Make sure you don’t get any of this product on the soil though if you are an organic farmer, as any ammonia based fertiliser is banned in organic farming!

Hydrogen peroxide

Functions: fungicide, and bactericide

Crops: tomato, bell pepper, capsicum, lettuce, and horticulture flowers

When first authorised, hydrogen peroxide (H2O2) was simply for use as a sterilising agent for tools and equipment to prevent pathogen transmission. Since then, it has also now been authorised as a seed treatment to control bacterial and fungal diseases on lettuce and flower crops.

Hydrogen peroxide is routinely used in glasshouses as a tool sterilising agent as it is a potent biocide but will break down to water and oxygen in a relatively short time period. As such, you should wait 30 seconds before using the treated equipment on the crop.

The solution used should be 1.5-3.0%, which is roughly the percentage found in grades sold to the general public. However, make sure you purchase fresh material each year as hydrogen peroxide breaks down over months of storage, especially in hot conditions.

Hydrogen peroxide is listed for the control of the pathogens Ralstonia, Solanacerum, and Botrytis cinerea. However, it will kill many more.

When used as a seed treatment on lettuces and flower crops (particularly Zinnia elegans) a 5% (for lower) solution is used to treat the seeds before sowing. Never treat an actively growing plant with hydrogen peroxide as it will burn the foliage (and your skin if you get it on you, so wear PPE).

Sodium Chloride

Function: fungicide

Crops: mushrooms, and grapes


I am sure you are fully aware from school chemistry classes that sodium chloride is simply table salt. Any compound containing sodium is highly toxic to plants, and this is why this product is used as a fungicide and insecticide on mushrooms. Mushrooms are fungi, a group of organisms more related to you and me, than your barley crop. As such, sodium based products can be used on them with far less of an issue. Interestingly, sodium chloride is authorised for use on mushroom crops to control fungal diseases. So presumably the edible mushroom must be more tolerant to salinity than its pathogenic cousins.

What I find quite strange is that sodium chloride is also approved as a basic substance for use as a foliar spray on grapevines. Plus the concentration recommended is not insignificant. I would avoid this unless I was really suffering from the Grapevine moth (Lobesia botrana) and would look for any other possible treatment before resorting to salt sprays as they could quickly kill the crop. The quickest way to kill a plant is to pour salt water over it, you can literally see them shrivel up and die in front of your eyes!

I also find it remarkable that the EU have allowed sexist language to slip through the net on the official authorisation, and I quote ‘the user is advised to take into account the salinity of the soil in his decision to apply sodium chloride”!

Sodium hydrogen carbonate

Functions: fungicide, and herbicide

Crops: vegetables, soft fruit, ornamentals, fruit trees, and potted plants


Sodium hydrogen carbonate, also known as baking soda, can be used to control mildew on vegetables, soft fruit, and grapevines, and scab on apples (Venturia inaequalis). But why would you want to? Like sodium chloride, sodium hydrogen carbonate is toxic to plants because it contains sodium. Avoid, leave it in the kitchen cupboard, and use chitosan as a fungicide instead.

It does have a couple of other uses that are more appealing. One of these are in the storage of harvested fruit for the control of blue mould (penicillium italicum) and green mould (Penicillium digitatum). The other is in potted plants to control liverworts (Lunularia cruciata), which is a major weed on ornamental nurseries with overhead irrigation systems.

Talc E553B

Functions: insectifuge, and fungifuge

Crops: fruit trees, olives, and grapevines

Oooh, we have left the kitchen and gone up to Grandma’s bathroom! Talc, or as the chemist like to call it, Magnesium hydrogen metasilicate, can be used as an ‘insectifuge’ or a ‘fungifuge’. I hear you say ‘a what now’? These are compounds that deter insects and fungi respectively, but do not kill them. Basically the talc covers the plant and makes it an unpleasant place for insects and fungi to colonise.

For fruit trees it can be used as a physical barrier to prevent a wide variety of insect and mite pests attacking, including;

  • Psyllids (Psylla spp.), important vectors for viral diseases and a pest in their own right
  • Fruit flies (Drosophila Suzukii)
  • Red mite (Panonychus ulmi)
  • Olive fruit fly (Bactrocera oleae)

Talc can also be used to control powdery mildew, and apple scab (Venturia inaequalis). However, as talc is insoluble, my advice is the same as for the other insoluble fertilizers above that need to be applied as a suspension; unless you can guarantee good tank agitation and do not want major residues on your crop, always consider applying chitosan as a basic substance biofungicide first!

Plus, the use of talc will probably be restricted in the near future It has been proven that talc causes a form of silicosis (a long-term lung disease) and, in its natural from, contains asbestos particles. So not the kind of product you want to be spraying into the air all day long!

Some substances have been rejected for inclusion as a basic substance. This includes mugwort (Artemisia vulgaris) extract, which wasn’t viewed as of not low enough risk to be included as a basic substance, but this does not mean it could not be included as a bio-pesticide under one of the EU’s other schemes (such as their ‘low risk plant protection products’). It just depends on the economics to determine if companies will go to the expense of registering it. This has happened in the past for other natural extracts, and examples of botanic extracts approved for use in pesticides include:

  • Garlic extract: a powerful botanical, but registered under conventional pesticide regulations for the control of nematodes and molluscs in both conventional and organic farming.
  • Various plant oils: including mint, cloves, citronella as insecticides.
  • Spinosad: an insecticide extracted from microbes.
  • Pyrethroids: extracted from chrysanthemums and registered as conventional pesticides.
  • Gelatine: insecticide.
  • Beeswax: pruning sealant.
  • Azadirachtin: insecticide /anti-feedant.

So the basic substances open up a multitude of options for pest and disease control that can be used by any grower in the UK and EU. You will find very few of these on sale by major agrochemical companies. So, if you do need assistance in sourcing them then please do get in contact with Eutrema.

Dr Russell Sharp

Eutrema Ltd

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