THK PI.ANT WORI.D 299 



PLANT DISEASES. 



This exhibit is designed to show some of the more important diseases 

 of the principal orchard and truck crops and the methods of their treat- 

 ment. Plats of young fruit trees, vegetables, and other crops, one-half 

 of which have been treated by spraying for the prevention of diseases, 

 demonstrate the beneficial effects of such treatment. 



NITROGEN-FIXING BACTERIA. 



Certain plats are devoted to the growth of leguminous crops, with 

 a view to showing the effect of inoculating such crops with bacteria, in 

 order to enable them to secure atmospheric nitrogen. In a small struc- 

 ture erected on one of the plats are grown various legumes and other 

 plants in pots containing known quantities of nutrient salts to demon- 

 strate the importance in crop production of an adequate nitrogen supply, 

 and also to show the relation between bacteria securing nitrogen from 

 the air and the use of nitrogenous fertilizers. 



PLANT-BREEDING INVESTIGATIONS. 



The exhibit of the Plant-Breeding Laboratory consists of a demon- 

 stration by means of cotton and corn plants of some of the results obtained 

 by the practice of plant-breeding methods. 



CEREAL INVESTIGATIONS. 



The cereal exhibit is a living representation of the different groups of 

 cultivated grains arranged in logical order, showing the actual charac- 

 teristics and manner of growth of a number of the principal varieties of 

 each group. Within each group there is also, so far as possible, a 

 secondary arrangement of varieties according to the country in which 

 they are most commonly grown. Under cereals are included all agricul- 

 tural plants of which chiefly the seeds are used as food either for man or 

 for animals. The different grains actually shown are corn, wheat, oats, 

 rye, barley, buckwheat, rice, kafir corn, milo maize, and proso or broom- 

 corn millet. 



In four of the plats there is a special experiment showing the effects 

 of the treatment of oats and wheat for the prevention of smut. 



SEED INVESTIGATIONS. 



The large plats in this exhibit are sown with different grades of com- 

 mercial grass and clover seeds to show the difference in crop return when 

 high-grade seeds and when low-grade seeds are used. The small plats 

 contain weed plants whose seeds are most frequently found among com- 

 mercial seeds. 



FIBER-PLANT INVESTIGATIONS 



In the space assigned to fiber-plant investigations are growing all of 

 the plants used in the production of fibers now found in commercial 

 quantities on the market in this country. There are specimens of abaca 

 from the Philippines, henequen from Yucatan, palma istle and lechu- 

 guilla from Mexico, fiber plants from New Zealand and Mauritius ; also 

 flax, hemp, jute, and ramie, and the typical kinds of cotton grown in 

 this country, in Egypt, and in India. 



