Atlizctra Agricoxturax Experiment Station, T68 



oF the disease by the use of nursery stock obtained from ques- 

 tionable sources and by neglect to completely destroy all trees 

 that have succumbed to the disease, as well as knots trimmed from 

 those which it is hoped may be saved by treatment. All Arizona 

 fruit-growers will do well to observe the warnings and instruc- 

 tions urged upon them in this bulletin for the sake of checking 

 'the ravages of a disease that is becoming so destructively preval- 

 ent. 



Three of the series of l< timely hints'^ published during the year 

 have also come from the pen of the botanist; namely, No. 5, The 

 Crown-Gall; No. 8, What to Plant on Arbor Day.; No. 18. Graz- 

 ing vs. Irrigation. 



ALFALFA ROOT-ROT. 



Investigations have also been in progress upon the foot-rot 

 of alfalfa concerning which complaints and inquiries have been 

 received from time to time from various sources in arable parts of 

 the Territory. A plat was staked off in October, 1899, on the 

 ranch of Mr. A. V. Grossetta near Tucson where this disease has 

 gained a footing. The area marked off includes one of the typi- 

 cal circular spots of dead plants and 'those weakened by the des- 

 truction of the tap-root by the rot, as Well as unaffected portions of 

 the field. This area has been divided into sub-plats, eight within 

 and eight bordering upon the affected spot. The sub-plats have 

 been treated with several approved fungicides used in the normal 

 strength as applied to soils, one plat within and one bordering 

 upon the spot being similarly treated. The fungicides used were 

 copperas, blue-stone, Bordeaux-mixture, amraoniacal copper car- 

 bonate, corrosive sublimate, sodium carbonate and creolin. Plats 

 numbered 8 and 8a were reserved and treated as a check. The 

 plats within the spot were reseeded to determine whether the dis 1 

 ease would again become active upon an area already traversed 

 by it. About one side of the spot, also> a trench was dug forty 

 feet in length and increasing from one to three feet in depth 

 at a distance of seven and a half feet from the border, in order to 

 make possible observations upon trenching as a means of pre- 

 venting the spread of the disease. 



With a view to determining the relative resisting power of 



