ANNUAL REPORT, 1936 31 



the fungus Ceratostomella ulmi (Swartz) Buisman, was present in the State. 



As the name implies, the Dutch elm disease was first observed in the Nether- 

 lands in 1919 and thousands of elms there and in other European countries 

 have been killed by the disease. Reports from Europe indicate that the disease 

 exists throughout the extensive range of climatic and soil conditions included 

 in the following countries: Netherlands, France, Italy, Austria, Belgium, 

 Switzerland, Germany, Poland, Czechoslovakia, Balkan States, and Great 

 Britain. In the last-mentioned country, the disease is widely distributed. 

 Recent reports indicate that diseased trees are found within thirty miles of the 

 Scottish border. 



In America, from 1930 to 1932, the known cases of the disease were limited 

 to less than a dozen trees in Ohio. During the last three years, however, more 

 than 21,780 cases of the Dutch elm disease have been found in New Jersey, 

 New York, and Connecticut. Isolated cases have been found in Virginia, 

 Maryland, and Indiana. Destruction of all affected elm trees is the aim of the 

 present control program in the United States. 



Up to the present writing (December 1936), the disease has not been found 

 in Massachusetts. Nevertheless, the threat of the disease here is imminent 

 since the malady is known to occur within forty-five miles of the southern 

 border of the State, in Connecticut and New York. Also worthy of attention 

 is the fact that the earliest known American infestation of the principal carrier- 

 insect of the disease, the smaller European bark beetle {Scolytus multistriatus 

 Marsh), was discovered in Massachusetts in 1909. 



Since the organization of the shade tree disease survey in June 1935, approxi- 

 mately 5,000 specimens have been studied in the laboratory. During 1936, 

 the specimens were collected by four field men from the laboratory, scouts from 

 the State Department of Agriculture, and citizens throughout the Common- 

 wealth. This year, sixty-two diseases of thirty-one hosts were reported, in- 

 cluding thirteen diseases of elm. 



A detailed study has been made of the State-wide distribution of elm wilts 

 associated with species of Cephalosporium and Verticillium. The occurrence 

 of either or both organisms in 123 cities and towns is shown. 



Experiments on potted elms of several species have been conducted in the 

 greenhouse with the vascular fungus parasites of elm known to be present in 

 Massachusetts. 



In 1935, considerable assistance was rendered the survey by the organization 

 of an F. E. R. A. project. Since September 1936, a W. P. A. project has helped 

 in the laboratory work. 



Moist Mats for Clay Pots. (L. H. Jones.) A clay pot should always be 

 used on a moist surface. The root system in such containers is next to the wall 

 of the pot, and should the pot wall become dry, a drought hazard would exist. 

 Capillary moisture, pulled up from below the pot, is sufficient for the protection 

 of the roots. This is easily accomplished in greenhouses where moist bench 

 surfaces of soil, cinders, and sand are practical, but in homes and offices a sub- 

 stitute is necessary. The testing of various materials has resulted in the de- 

 velopment of a mat which will absorb water and transmit it to the clay pot 

 resting on the surface of the mat. The mat is featured by recesses that not only 

 provide reservoirs for free water, but also serve as drains to lead away any free 

 water about the base of the flower pot. 



Mats of wood pulp, wood fiber, and leather waste are suitable. Metal forms 

 filled with cotton or woolen cloth, sphagnum moss, peat moss, and absorbent 



