BUREAU OF PLANT INDUSTRY. 413 



reduced by the susceptibility of the product to early decay. Somewhat 

 similar conditions exist in relation to other important fruit and 

 vegetable products. The results thus far obtained show that the 

 problems involved are often very complex, but they are of funda- 

 mental importance to horticulture. 



The work on vegetable storage during the coming year should be 

 carried on with special reference to sweet potatoes, onions, and 

 fruits, dealing in a technical Avay with the physiological phenomena 

 to be observed before and during storage. 



Phtsioi^ogical studies of crop diseases. — Cooperative work on 

 physiological disturbances in sugar beets, cabbage, and spinach has 

 been continued. A technical investigation of the oxidase content of 

 diseased plants in relation to other physiological factors has been 

 carefully carried out by Dr. H. H. Bunzel, who has perfected a 

 method for accurately measuring the oxidase reaction. The appli- 

 cation of the method has not only shed light on the diseased condi- 

 tions mentioned, but has contributed fundamental information on 

 normal plant activity. 



The investigations on physiological disturbances of crop plants 

 for the near future will concern chiefly the Irish potato, with inci- 

 dental reference to other field and garden crops, especially cotton, 

 melons, and cowpeas. 



Physiological studies or molds. — The deterioration of grains and 

 other products, accompanied at times with the development of toxic 

 properties through the action of molds, is an important source of 

 loss. Work on the effect brought about in deteriorated maize by 

 several species of molds has l)een carried on by Dr. C. L. Alsberg and 

 O. F. Black, with the result that a number of metabolic products 

 have been isolated, some of them actively toxic to higher animals. 

 The possible relation of products of this type to diseases usually 

 associated with the consumption of spoiled corn gives unusual inter- 

 est to these results. The physiological properties of the substances 

 produced by these organisms in the grains or grain products will 

 continue to receive attention. 



PiiYSTOLOGiCAi, STUDY OF PLANT FEEDING. — The relation of plant 

 growth to a proper balance of the available inorganic salts has been 

 studied by Mr. II. H. Bartlett and Dr. 11. H. True, the balance be- 

 tween magnesium and calcium having been given special attention 

 in its relation to peas, asparagus, beets, and other plants. Important 

 relations have been shown to exist, and the surprising effectiveness 

 of minute quantities of these common soil constituents in determining 

 plant growth has been demonstrated. It has also been shown that 

 plants differ greatly in their demands on the soil. It is believed 

 that fundamental studies of the requirements of plants is an im- 

 portant line of investigation which underlies the production of farm 

 crops, and such a series of investigations, undertaken and carried out 

 with regard to the modern teachings of plant pliysiology, and with 

 the help of the newer laboratory methods, is to be actively pressed. 

 The efforts of the coming year are to be toward cultivating this most 

 important field. It is probable that as faulty nutrition conditions 

 are corrected many diseases of crops may in the end disappear. 



