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Garden Issues

The role of the gardener can have a profound impact, not only to the patch of land under their control but also, and perhaps more significantly, to it’s surrounding area. In this section I cover the topics I find important enough to influence the way I go about my work in and around the garden.

I guess we all know what the main influence is - the use of chemicals! There has always been debate surrounding this issue. Over the years the gardener has regarded chemical use as a fundamental part of horticulture; fertilizers used to improve crop health and yield, and herbicides and pesticides widely used as an ally in the fight for order in the garden! Before I continue there should first be some background information.

The use of Weedkillers or Herbicides, fall into four categories:
        • Contact - kills only the parts touched by the chemical.
        • Systemic or Translocated - applied to the plant and absorbed into the circulation, killing the entire plant, including roots and suckers.
        • Residual - applied to the soil, absorbed via the roots into the circulation killing the entire plant. Remains active in the soil killing any seedlings that germinate later on.
        • Hormone - selective to broad-leaved weeds and used mainly to control lawn weeds. Absorbed into the plant destroying the cells.

        The terms, Selective, Non-selective and Total refer to the mode of action of the herbicide:
        • Selective - kills only certain plants, leaving others unharmed. As mentioned previously, herbicides for use on lawns contain a systemic herbicide which runs off the narrow, channeled grass leaves, but wets the broader weed leaves. There is also a chemical for killing grass weeds among broad leaved ornamentals.
        • Non-selective - kills most 'green' plants they touch. This can be either in the form of a contact or systemic herbicide.
        • Total - for use on scrub-land, or overgrown neglected areas, killing both woody and green plants. Total herbicides remain active in the soil for many months to several years depending on the chemical used.

Based on the pest or disease being controlled, there are five groups under the heading 'Pesticide':

Insecticide - used to control insect pests, (aphids and white fly).
Acaricide - used to control mites, (red spider mite).
Molluscicide - used to control mollusc pests, (snails and slugs).
Vermicides - used to control vermin pests, (moles and rabbits).
Fungicide - used to control fungal diseases, (mildew and blackspot).

Pests may be killed in three ways:
Contact - kills by direct contact with the chemical usually through the skin of the insect, does not need to be eaten.
Stomach ingestion - Chemical on the foliage is eaten.
Fumigant - Kills insects via the breathing mechanism. Only used in enclosed spaces such as a glasshouse as the chemical is combined with an inflammable substance to give off toxic smoke or vapour when lit.

Fungicides are available in either Contact or Systemic forms.

There are Organic and Inorganic Fertilizers:

• Organic - derived from once-living sources, i.e. plant and animal remains, (Hoof and Horn, Bonemeal and Fishmeal). Slow Release - provides nutrients over a long period.

• Inorganic - derived from non-living sources, produced synthetically by chemical methods, (Sulphate of Ammonia, and Sulphate of Potash). Fast Release - instantly available nutrients ready for the plant to absorb.

Inorganic fertilizers containing only one major plant nutrient are referred to as a Straight Fertilizer. For example:
Sulphate of Ammonia - N 21%
Sulphate of Potash - K 48%
They provide a specific nutrient to suit a crop needs, usually as a Tonic.

A Compound Fertilizer contains two or more major nutrients, examples of which would be:
• Inorganic - Growmore - N 7% / P 7% / K 7%
• Inorganic - Monoammonium Phosphate - N 11.8% / P 61%
• Organic – Fishmeal - N 6-10% / P 5-12% / K 1-2%
• Organic – Bonemeal - N 3.5% / P 18%

Compound fertilizers supplement the major nutrients in one operation. Available with varying proportions of N.P.K. to suit particular crop needs and varying requirements throughout the season.

Fertilizers are applied as a:
• Base Dressing - to the soil before planting.
• Top Dressing - to the plant during the season, normally Spring or if deficient.
• Liquid Feed - by watering-can or hosepipe attachment, or in irrigation systems in the glasshouse. Liquid feeds can be useful during dry weather.
• Foliar Feed - rapid feeding supplement and tonics. Foliar feeding is short lasting.
• Controlled Release – chemical nutrient slow release, temperature based.

To quote the RHS; "garden chemicals or pesticides, such as insecticides, fungicides and weedkillers, are perfectly safe, providing they are used in exactly the way described on the container or packaging". Safe to whom? Obviously their referring to the plant and operator!
Click here to read the entire article.

Are the use of chemicals in the garden safe to the wildlife and the environment? One thing for certain is that if you get the dosage wrong there can be significant consequences to your plants, wildlife and the soil. Many people; “love that plant so much I will give it some extra food!” Too much fertilizer can in fact kill the plant or plants their feeding. The run-off from overdosing your plants with pesticides and herbicides may not only kill every insect that visits, but seep into the soil and destroy the organisms there as well!

As gardeners, it is our choice not to use chemicals in the garden, and this choice does not need to be informed. However, if we do decide to use chemicals, that choice must be informed - at the very least we should read the label! Garden chemicals must also be stored and disposed of correctly. If you run a gardening business and use chemicals as part of that business, you are required by law to have a licence to do so.

From 1995 to 2004, European Community Legislation has gradually withdrawn many products, drastically limiting the choice of available concoctions! To my understanding, this withdrawal program has not necessarily been for health and safety reasons.The Health and Safety Executive website has plenty of advice.

Many gardeners feel they must apply a fertilizer or a plant will suffer. I garden over clay and as such, once the soil structure is improved, and providing you garden organically, the need for supplementary nutrition is not normally necessary. But due to nutrient leaching, sandy soils may require fertilizing from time to time.

So, if you do decide to use a fertilizer, were back to choice again -this time between an organic or inorganic type.

The amount of nutrient availability in inorganic fertilizer is more guaranteed, but there is little variation in nutritional value between the two types. The big difference is that organic fertilizers feed the soil and then the plant. The nutrients in organic fertilizers are not released until broken down by the soil micro-organisms and therefore last longer. The consequences of this are a slow release of nutrients, provided over a longer period of time, resulting in steady growth and avoiding a lush, succulent surge. Lush growth makes a plant susceptible to extremes of heat, cold, or drought and at risk of disease and insect attack.
Inorganic fertilizers feed just the plant over a short period and will require frequent use, which could be considered a disadvantage; but there are another three that are perhaps more significant:

• The nutrients are soluble in the soil and as such are readily washed away by rain or irrigation.
• Due to the chemical salts used to make them, over application can "burn" seedlings and young plants causing Reverse Osmosis. This will dry a plant out, causing at best a severe check to growth or at worst, the demise of the plant or plants.
• Regular use can build up concentrations of salts that can reach toxic levels in the soil. The salts can also crystallize and form a ‘pan’ that prevents water moving down through the soil.

I decided several years ago to limit my use of chemicals in the garden - about the same time I stopped using Peat. I never used chemicals on or around fruit or vegetables anyway - the thought of eating produce in this way is not one that appeals too much! I avoid pesticides completely, but would as a last resort, use Glyphosate to help control the dreaded Bindweed and top-dress with Growmore. Over recent years however, I now rarely use it at all.

Following ecological and organic principles helps to develop a garden with a vastly reduced reliance on chemicals, and without wishing to sound flippant; as will a tolerance of a few holes in a vegetable leaf, and dare I say one or two grubs in your fruit! For me, it is all about balance. I can tolerate - providing the damage by a pest or land taken over by wildflowers (weeds), is limited - and this is where those organic/ecological principles come in.

Having said all this, growing Food Produce successfully will demand special attention. It’s fair enough to tolerate a bit of pest damage, but it can be hard to swallow (no pun intended), if the fruits (again, no pun intended), of your labour serve only to feed the local wildlife!

Let’s take one scenario - growing your greens! I think we are all aware of the relationship between the cabbage and the cabbage white butterfly. There are two species; the large cabbage white butterfly (Pieris brassicae) and the small cabbage white butterfly (Pieris rapae). They can be seen from July to September looking for hosts for their eggs. Their small green caterpillars have a huge appetite for brassicas, and in little time make them not worth you eating! The butterflies may have up to three generations in a single year. In autumn the final generation pupates and overwinters as a chrysalis, to become butterflies the following July and start the cycle again.

What do you do? Regular spraying with the insecticide Pyrethrum is one answer. The powdered flower heads of three species of Chrysanthemums are the main sources of Pyrethrum and being a natural substance, its use is considered acceptable as part of an organic method of gardening. But again - would you want to eat your greens afterwards!

If you do not wish to use a chemical in their control, what do you do then? In all honesty, it is pretty laborious. Inspect your plants regularly, particularly once the first butterfly is seen! Lift the leaves and crush the cylindrical shaped yellow egg clusters stuck to the leaf underside (right). Pick off any caterpillars that you find. Or grow another veg instead!
Small Cabbage Whiite eggs

Poisonous Plants.

Many plants are toxic, some are highly toxic. A few are renowned for their medicinal qualities - but may be dangerous and even fatal if eaten. The following are thought to be amongst the most toxic of the plants readily available to buy for our gardens:

Autumn crocus - Colchicum spp. Harmful if eaten.
Lily of the Valley - Convallaria spp. Harmful if eaten.
Broom - Cytisus spp. Harmful if eaten.
Daphne Mezereon. Harmful if eaten. Skin irritant.
Larkspur - Delphinium spp. Harmful if eaten.
Foxglove - Digitalis spp. Harmful if eaten.
Golden Rain – Laburnum spp. Harmful if eaten.
Castor Oil Plant - Ricinus communis. Harmful if eaten.
Yew - Taxus baccata. Harmful if eaten.
Spindle Tree - Euonymus spp. Harmful if eaten.
Spurge – Euphorbia spp. Harmful if eaten. Severe skin and eye irritant.
Prickly Heath – Gaultheria spp. Harmful if eaten.
Common Ivy - Hedera helix. Harmful if eaten. Skin allergy.
Christmas Rose - Helleborus spp. Harmful if eaten. Skin irritant.
St. John's Wort - Hypericum perforatum. Harmful if eaten.
Calico Bush – Kalmia spp. Harmful if eaten.
Privet - Ligustrum spp. Harmful if eaten.
Lobelia spp. Harmful if eaten.
Lupin - Lupinus spp. Harmful if eaten.
Daffodil – Narcissus spp. Harmful if eaten. Skin irritant.
Scilla spp. Harmful if eaten.
Snowberry – Symphoricarpos spp. Harmful if eaten.
Solomon's Seal – Polygonatum spp. Harmful if eaten.
Tulip – Tulipa spp. Harmful if eaten. Skin allergy.
Wisteria spp. Harmful if eaten.
Corn Cockle - Agrostemma githago. Harmful if eaten.
Aloe vera. Harmful if eaten.
Bluebell - Hyacinthoides spp. Harmful if eaten.
Hyacinth - Hyacinthus spp. Harmful if eaten. Skin irritant.
Morning Glory – Ipomoea spp. Harmful if eaten.
Yellow Iris - Iris pseudacorus. Harmful if eaten.
False Acacia - Robinia psuedoacacia. Harmful if eaten.
Spanish Broom - Spartium junceum. Harmful if eaten.
Peace Lily – Spathiphyllum spp. Harmful if eaten. Skin and eye irritant.
Arum Lily – Zantedeschia spp. Harmful if eaten. Skin and eye irritant.
Comfrey – Symphytum spp. Harmful if eaten.

The following are skin irritants only – but may in some cases be severe:

Rue - Ruta spp. Skin irritant with sunlight.
Chrysanthemum (Dendranthema) spp. Skin irritant.
Leyland Cyprus - Cupressocyparis leylandii. Skin irritant.
Common Fig - Ficus carica. Skin irritant with sunlight.
German Primula - Primula obconica. Skin irritant.

The Royal Horticultural Society has a useful PDF document about toxic plants – it was the main source for the information given above. The document has much more information, with many other plants - as such I recommend taking a look! Click Here.


Associated Links:

Garden Principles
The Wildlife

The Soil
The Plant



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