Arizona Agricultural Experiment Station. 337 



with reference to any one plant disease, yet there are indications 

 that considerable injury is being done by a goodly number of 

 these pests in the Territory. The greatest amount of correspond- 

 ence results from root rots of various forms. 



The experiments conducted last year by Professor Tyler 

 have been continued the present year and preparations are being 

 made for still further investigations later in the season. The in- 

 vestigations of Professor Tyler were on the whole encouraging. 

 The plot upon which experiments were conducted with various 

 chemicals produced, according to reports of Mr. Grossetta's fore- 

 man, the best crop of alfalfa on the ranch. No distinction was 

 observable, however, in the effect of the different chemicals used. 

 The experiment is simply encouraging and does not indicate posi- 

 tive results because the treated plot received about four times as 

 much water as any other portion of the field. The successful 

 crop may be due entirely to the action of an abundant supply of 

 water. However, even if this is true the experiment is 

 valuable. 



Experiments are being conducted on Mr. Grossetta's ranch 

 again this year mainly for the purpose of determining the utility 

 of the ditching system and also for the purpose of ascertaining 

 whether areas over which the disease has passed can be success- 

 fully reseeded. 



Small plots of alfalfa have been planted on the University 

 campus with seed obtained from various sources. Inoculation 

 experiments will be conducted on these plots during the month of 

 August for the purpose of determining the communicability of the 

 disease under variable moisture conditions. 



ECONOMIC CACTI. 



The writing oh this line of investigation was quite exhaust- 

 ive in the last annual report. Being plants of very slow growth, 

 no special results can be expected for years to come. Many of 

 the plants which were set out last year have died ei .ht: from 

 drouth or depredations of animals. These have been replaced as 

 far as possible by other plants from the same source. 



