434 EXPERIMENT STATION RECORD. 



As to the comparative merits of acidulated and raw phosphate for 

 fertilizing cotton and the residual effects of the same, the summarized 

 results of all the experiments made under the direction of the station 

 and bearing on this point seem to abundantly' demonstrate the superi- 

 ority of the acid phosphate. 



The use of potash as a factor in controlling the black rust in cotton 

 is summarized as follows: "Not onl}^ kainit but other soluble forms 

 of potash, as the muriate, sulphate, and sili(^ate may, under suitable 

 atmospheric conditions, restrain the spread of black rust. The mini- 

 mum amount required to exert a notable rust-restraining influence is 

 not yet determined, but is between 50 and 100 lbs. of kainit per acre, 

 and apparentl}' nearer the latter figure." 



Results of experiments in composting such materials as cotton seed, 

 fine stable manure, cotton-seed meal, and phosphate, taken as a whole, 

 offer no arguments in favor of the practice. Fractional applications of 

 fertilizers have not proven advantageous. The best time for applying 

 fertilizers is believed to be before the seed is sown. The results of 

 cooperative experiments have shown that practically all the cot- 

 ton soils of Alabama, except the central prairie region, are greatly 

 benefited b}'^ the addition of acid phosphate. Cotton-seed meal is 

 desirable on nearly all soils in the State except new lands and soils 

 containing considerable vegetal;)le matter. Kainit is less frequently 

 needed than either acid phosphate or cotton-seed meal. It is most 

 needed in the southern part of the State and on soils especialh' liable 

 to black rust. Fertilizer formulas suitable for different sections of 

 the State are tentatively suggested. 



The section of the bulletin treating of diseases of cotton considers 

 the following subjects: Root knot, sore shin or damping off, cotton 

 wilt, rust, anthracnose of the stem, red rust, leaf blight, cotton mildew, 

 angular leaf spot, cotton-boll rot, anthracnose of the boll, and shedding 

 of bolls. Sulphur used at the rate of 16 lbs. per square rod seemed 

 to have no beneficial effect in freeing the soil from nematodes causing 

 root knot. In pot experiments injections into the soil of carbon 

 ))isulphid seemed to be beneficial for this purpose. ]>ut satisfactory 

 results were not secured with it in field tests. Unpublished investiga- 

 tions of C. F. Baker are given as showing that the probable cause of 

 the cotton-boll rot (at least in the case under investigation) was pri- 

 maril}- due to the puncture of the boll by one of the small hoppers, 

 known as "sharp shooters," after which it was attacked by various 

 species of saphrophytic fungi which fed on the broken-down tissue of 

 the boll. A number of these fungi were isolated, but inoculation 

 experiments with them during dry weather failed to produce the 

 disease. The bibliography of cotton diseases contains 47 references. 

 A list of 64 varieties and species of fungi, recorded as growing on 

 cotton, is also given. 



