Organic Growing In Holticulture

By studying the principles of horticulture, one is able to learn how and why plants grow and develop. In. this way, horticulturists are better able to understand the responses of the plant to various conditions, and therefore to perform their function more efficiently. They are able to manipulate the plant so that they achieve their own particular requirements of maximum yield and/or quality at the correct time.

The text therefore introduces the plant in its own right, and explains how a correct naming method is vital for distinguishing one plant from another. The itnernal structure of the plant is studied in relation to the functions performed in order that we canunderstand why the plant takes its particular form.The environment of a plant contains many variable factors, all of which have their effects, mod some of which can dramatically modify growth sod development. It is therefore important to estinguish the effects of these factors in order to have precise control of growth. The environment which surrounds the parts of the plant above the round includes factors such as light, day-length, temperature, carbon dioxide, oxygen, and all of *me must ideally be provided in the correct puportions to achieve the type of growth and development required. The growing medium is the means of providing nutrients, water, air, and usually anchorage for the plants.

In the wild, a plant will interact with other plants, often of different species, and other organisms to aeate a balanced community. Ecology is the study of this balance. In growing plants for our own ends we have created a new type of communitywhich creates problems — problems of competition for the environmental factors between one plant and another of the same species, between the crop plant and a weed, or between the plant and a pest or disease organism. These latter two competitive aspects create the need for crop protection.It is only by identification of these competitive organisms (weeds, pests and diseases) that the horticulturist may select the correct method of control. With the larger pests there is little problem of recognition, but the smaller insects, mites, nematodes, fungi and bacteria are invisible to the naked eye and, in this situation, the grower must rely on the symptoms produced (type of damage). For this reason, the pests are covered under major headings of the organism, whereas the diseases are described under symptoms. Symptoms (other than those caused by an organism) such as frost damage, herbicide damage and mineral deficiencies may be confused with pest or disease damage, and reference is made in the text to this problem. Weeds are broadly identified as perennial or annual problems. References at the end of each chapter encourage students to expand their knowledge of symptoms.

In an understanding of crop protection, the structure and life cycle of the organism must be emphasized in order that specific measures, e.g. chemical control, may be used at the correct time and place to avoid complications such as phytotoxicity, resistant pest production or death of beneficial organisms. For this reason, each weed, pest and disease is described in such a way that control measures follow logically from an understanding of its biology.