DISEASES OF PLANTS. 307 



pletely controlled ])y the application of a 2 per cent solution of 

 Bordeaux mixture. The influence upon tlie plant is shown by the 

 following- points: (1) The structure of the leaf shows a slight increase 

 in thickness and in strength ; (2) the chlorophyll content was increased ; 

 (3) the transpiration was constantly greater than in the unsprayed 

 plants; (4) the assimilation by the leaves was very much greater; (5) 

 the duration of the leaves was greater in the case of the sprayed ones; 

 and (6) the tuber production and the starch formation in the tuber 

 were considerably increased. 



The authors found that some kinds of potatoes are, through unfavor- 

 able conditions, sometimes injured by ai)plications of Bordeaux mix- 

 ture. 



The question having been raised as to whether it was the lime or 

 copper that was beneficial to the plant, the authors assert very 

 positively that it is the copper, the lime having little or no intiuence 

 upon the plant. 



Sugar cane disease in Trinidad, '1. II. Hart {Bot. Dept. Trinidad^ 

 Circiihtr Xote 11).— Dwrmg 1803 experiments were carried on to inves- 

 tigate the supposed necessity of the intervention of insects in spread- 

 ing cane diseases. A healthy growing cane i)lant w^as infected with the 

 microconidia of Trichosphccria sacehari by inserting some of the spores 

 in broken places in the midrib of the leaf. The cane continued to grow 

 apparently unaffected until it reached a heigh^f about ft., when it 

 assumed an unhealthy appearance, and finally dried away, proving 

 that the fungus is capable of destroying the cane without the aid of 

 any insect agency. Specimens of the diseased cane were sent to Kew 

 for examination, and the report made is as follows: 



"The following phases in the life cycle of Tricliospliaria saccharl are present in the 

 cane: 



"Conidial tonditiou. — (1) Melanconimn stage, (2) macroconidial stage, (3) CoUeto- 

 trichum stage. 



^'Ascigerous condition. — In small quantity and accompanying it, perithecia formed 

 of purple polygonal tissue and iuclosiuglarge brown 1-septate spores not produced in 

 asci- or stylospores. These structures have also been observed united with the 

 ascigerous form on canes sent from Barbados, and complete the usual setiuence of 

 phases in the life cycle of species allied to Trichosphuria sacehari." 



Experiments with fungicides, L. H. Pammel (Iowa Bui. 24, pp. 



,985-990). 



Synopsis. — The author reports on Ihe use of fungicides for the prevention of oat and 

 wheat rust, the treatment of spot disease of currants, and experiments in treat- 

 ing oats with dift'ereut chemicals and hot water. 



Spraying to prevent oat and lolieat rust (pp. 985-987). — Experiments 

 were conducted during the past season with Bordeaux mixture and 

 animouiacal copper carbonate for the j)revention of the rust of wheat 

 and oats. It was intended that applications should be made every 10 

 days, but owing to rains the average time between applications was 

 less than 10 days. 



