The A-Z Plant Health Handbook for New Zealand,
   by Jon Muller.

SOLUTIONS FOR PLANT PROBLEMS

The Organic Approach

(Excerpts)

There has been a growing interest in alternative means of solving both plant and human health problems. Organic gardening is becoming a popular way of growing plants as the side effects of using pesticides become more evident.
There are a number of principles underlying organic gardening. The criteria for organic gardening are:

1. chemically treated artificial fertilisers and pesticides are not used;
2. all surplus organic matter must be recycled; and
3. conditions are created in the garden that favour beneficial species, such as predators and parasites.

Soil and soil improvement

(Excerpts)

Soil is derived from thousands of different 'parent' materials-the original material on which soil is formed. For example, parent material can include volcanic ash or alluvium derived from rivers. This explains the diversity of soils found throughout New Zealand. The two main components of soil are mineral matter and the remains of once-living organisms. The mineral component can include gravels, sand, silt and clay. Material from living organisms, 'organic matter', can include leaves, branches and animal remains.

Cultural practices

(Excerpts)

Providing the right environmental conditions for your plants is essential for optimum growth. Practices such as mulching, weeding, adding fertilisers, watering and pruning, if correctly done, will favour the growth of your plants.

Alternative methods of preventing and controlling pests and diseases

(Excerpts)

Predators and parasites
A good example of a predator is ladybirds feeding on aphids. You can encourage predators by providing shelter, food, water, and breeding sites for them. Plant a mixture of flowering plants, especially members of the daisy, mint, cabbage and yarrow families. Buckwheat and blue tansy (Phacelia tanacetifolia) have both been found to provide food for predators and parasites of insects. These plants need to be sown successively to provide a continuous source of food.

Physical methods of control
You can use traps such as the codling-moth pheromone trap, which emits a scent (pheromone) attractive to the male moths, which in turn get stuck on the sticky material at the base of the trap. This trap can be used when the moths are flying in spring. You can also trap the caterpillars as they descend the tree in summer, by wrapping a cardboard band around the base of the tree and regularly checking and destroying the insects inside. Insect pests can also be attracted to certain colours.

Companion planting
Each plant has a unique role to play in its natural environment. Plants can benefit other plants in various ways. Plants with strong scents can camouflage desirable plants from pests, such as pennyroyal among cabbage. Nasturtium attracts aphids, protecting desirable plants such as tomato. Rosemary stimulates the growth of sage. As well as attracting predators, yarrow helps with the uptake of nutrients to neighbouring plants-another good reason to leave it in your garden.

'High Health' and resistant plants
Some plants that commonly get virus infection are produced free of this virus.

Botanical pesticides and alternative materials
There are a number of pesticides that are derived from plants that can be very effective in controlling pests and diseases. For example, garlic, derris dust and neem oil are effective against insect pests. The neem tree, Azadirachta indica, has a compound called azadirachtin which prevents the insect from moulting, causing death. Other compounds in this tree reduce mobility and inhibit feeding.

Biological control
Pathogens or disease-causing organisms often target specific hosts, which may make them useful to control certain problem pests or diseases.

Chemical control

(Excerpts)

It is really important to use chemicals sparingly. You should never use them week in week out regardless of whether the pest or disease is present. Apart from wasting money, you would be exposing yourself and the environment to chemicals, and running the risk of building up resistance by the pest. Also, chemicals can kill beneficial insects such as ladybirds. If you use chemicals, you need to use them at a time in the pest and disease life cycle when they are most effective.

Selecting pesticides

Pesticides are marketed under a trade name. Each product has what are called active ingredients that kill that pest or disease-causing organism. For example, Orthene is the trade name of an insecticide (insect killer) containing the active ingredient acephate, which kills insects. Some pesticides contain more than one active ingredient. For example, Shield contains an insecticide and a fungicide (fungus killer).

Using pesticides safely

The three most important things to do before using pesticides are read the label, read the label, and read the label again, then follow the instructions! The label will give instructions about the active ingredient, the pests controlled, how to use the product safely and what to do if poisoning occurs. It will also give directions for use, and which plants it can be safely used on.

Excerpts

Looking after Roses & Camellias

List of plants included

Key to problems

Causes & Solutions

Guide to Chemicals
&
Alternatives to Chemicals

Introduction

Table of Contents

Links

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Acknowledgement