7 

 experiment he sprayed tomatoes, thoroughly ten times with the 

 Bordeaux mixture, begining- when the hrst rough leaves were 

 formed and continuing until the ripening of the fruit. "The 

 treatment did not have the slightest effect in controlling the 

 disease." 



Our own observations on the use of the Bordeaux mixture 

 for the control of tomato rot have not always been of the most 

 encouraging nature. 



INVESTIGATIONS ON THE BLOSSOM END ROT OF 



TOMATOES 



Our observations on and investigations of the blossom end 

 rot of tomatoes under glass have extended over a period of six- 

 teen years and many series have been recorded. From the first 

 our observations and experiments were made on the influence 

 of moisture conditions surroundirig the plants, as it was believed 

 that the rot was associated with the moisture conditions of either 

 the soil or air, or both. 



Investigations concerning the particular organism causing the 

 rot were made by Miss E. H. Smith*, a former student, and her 

 work has been repeatedly verified in our laboratory and green- 

 house. 



That soil moisture is an important factor in the control of 

 blossom end rot in the greenhouse, as pointed out by A. D. Selby, 

 is shown in the experiments which follow, but it should be stated 

 that there are many factors, such as light, transpiration, plant 

 foods, etc., which play an important role and which may be of 

 sufficient importance if not properly controlled to overcome the 

 effects of sub-irrigation to some extent, at least. 



A liberal supply of soil moisture appears to cause the form- 

 ation of more perfect fruit, thus eliminating the possibility of 

 infection ; on the other hand, a plant not supplied with sufficient 

 moisture has a greater tendency to produce fissures and abnor- 

 mally developed tissue at the blossom end of the fruit, near 

 where the style breaks off, providing a suitable entrance for 

 germs. A large number of observations was made on top- 

 watered and sub-irrigated plants, and records kept of the corky 

 growths, irregular formations, fissures, etc., at the blossom end 

 of the fruit, with the result that the top-watered plants produced 

 a larger percentage of these irregular formations than those 

 grown in sub-irrigated soil. These cracks, etc., furnish a suit- 

 able entrance for the bacterial organisms which are largely 

 responsible for the rot, if not in all cases, and the occasional 



♦Mass. Agr. Exp. Sta., Tech. Bui. No. 5, 1907. 



