PLANT INDUSTRIES 319 



that a tree or a bush filled with a large amount of perfect 

 fruit or berries is not a usual occurrence in nature. Horti- 

 culture attempts to use the plant as a machine for producing 

 a large amount of perfect fruit ; to secure this result we must 

 make careful use of every known agency that will help the 

 machine to work well and that will protect it from those 

 things that in nature would injure it or reduce the value of 

 its product. The state agricultural experiment stations pub- 

 lish instructions for spraying orchard and garden plants. 



299. Gardening. Gardening has to do in the main with the 

 production of plants whose growing parts men use for food. 

 The list of plants thus used is a long and constantly increas- 

 ing one, and although the gardening industry is extending 

 rapidly, it is not keeping pace with the increasing demands 

 for its products. Both vegetable and flower gardening have 

 problems distinct from those of other plant industries. Both 

 are highly intensive in their nature and present new problems 

 in such matters as soil selection and replenishment, cultivation, 

 harvesting, marketing, and the prevention of disease. 



Wild plants of many kinds are used as medicines, and some 

 of these are grown in large quantities in gardens especially 

 designed for that purpose. 1 



300. Plants and the soil. The plants that constitute the 

 basis of plant industries depend in large measure upon their 

 relation to the soils in which they live. Soils are very differ- 

 ent from one another, some by their nature prohibiting the 

 life of certain kinds of plants and making possible the growth 

 of others. Some of the facts about differences in soils are 

 known, others are matters of vigorous argument between 

 scientists, and still other problems are recognized by all as 

 still wholly unsolved. That the structure of the soil, has 

 much to do with its appropriateness for plant life is generally 

 recognized. Our coarsest gravelly soils consist of much rock 



1 "Wild Medicinal Plants of the United States," Bulletin 89, Bureau of 

 Plant Industry, U.S. Dept. Agr., 1906 ; " American Medicinal Leaves and 

 Herbs," Bulletin 219, Bureau of Plant Industry, U.S. Dept. Agr., 1911. 



