THE CUBA REVI E W. 25 



The two unstenhzed beds became affected with pudricion almost as soon as the 

 plants were up the fungus showing in all parts of both beds. In 17 days from sowing 

 nearly all of the first plants to come up had been killed by the fungi and in some 

 pJaces a second growth was coming up. 



In the two beds treated with the standard formalin solution there appeared to 

 be no fungus at all at first and growth was excellent. Later a spot appeared in one 

 of the beds and spread gradually, and when the untreated beds described in the 

 previous paragraph were practically destroyed, this spot was 8 inches broad and 

 several new ones had appeared near it. They continued to spread and practically 

 killed all the tobacco plants in this bed before they were large enough to set in 

 the field. 



The second bed treated with standard formalin also showed several spots which 

 spread gradually, and it looked as if the bed would also be destroyed, but many of 

 the plants became large enough to resist the pudricion when it reached them. 



In the remaining bed which was treated with double strength formalin, a few 

 spots likewise appeared very early and spread precisely as in the sterilized beds 

 described above and in 18 days the whole bed seemed likely to be destroyed. 



Second Experiment. 



A set of 5 seed-beds_ treated like the 5 described labove, but fertilized with com- 

 post instead of commercial fertilizer, gave precisely the same results, except that, as 

 the weather had grown steadily drier, the humidity in the beds was not as great and 

 the pudricion did not develop vigorously. 



It might be said here that the formalin stock used was found to be only 26% 

 instead of 40%. 



The long vvait for the formalin to dry out and the danger of introducing soil 

 fungi while sowing the bed or by some accident is a serious practical inconvenience. 

 We tried, therefore, the effect of sowing the seed just before applying the solution, 

 thus sterilizing soil, seed-bed, and all at once, reducing the danger of reinfecting the 

 soil and avoiding delay. In both described tests tobacco seed grew satisfactorily in 

 beds treated with a much stronger solution of formalin then is necessary for steriliz- 

 ing the soil. When made four times as strong the seed was all killed. 



Standard strength • solution of formalin on tobacco plants which were damping 

 off badly resulted in the killing of the plants, but tobacco seed which was in the 

 soil germinated nicely afterward. 



Remedies for Pudricion. 



The soil sterilizing already described is a preventive, but if the pudricion gets 

 started, it progresses just as rapidly as if the' soil had, not been sterilized. In 5 

 different beds at 4 different times during the past winter we tried a remedy and found 

 that in every case the pudricion was stopped from spreading more than an inch after 

 the treatment and the remaining plants made a very rapid and healthy growth. 



This treatment consisted in thoroughly soaking the bed with a strong Bordeaux 

 mixture, 2 gallons of which were applied to four feet square (16 sq. ft.) of seedbed. 



To Make Good Bordeaux Mixture. 



Have a lime paste made by slaking good quicklime with water. Lime air-slaked 

 and dead is not suitable for making Bordeaux. The paste can be kept in a wooden 

 tub or barrel until needed but keep it covered with water. Copper sulfate should 

 be secured and kept in a dry place. For a test solution, a few ounces of the yellow 

 prussiate of potash (potassium ferro-cyanide) should be put in a clean bottle and 

 this filled with water and plainly marked "Poison." 



To make 50 gallons of Bordeaux, put about 30 gallons of water in a barrel. Put 

 6 pounds of the sulfate in a piece of sack, and suspend it just below the surface until 

 the sulfate all dissolves. Take about 15 pounds of the lime paste, put it in about 

 10 gallons of water and stir it up to a smooth lime milk. Dip this lime milk out and 

 mix it with the solution of copper sulfate, stirring as rapidly as possible. When the 

 mixture turns bright, deep blue, add a drop of the test solution. If a brown color is 

 formed, add more lime and stir until no dark color is formed by adding the test 

 solution. The Bordeaux is now neutral, but to make sure that it is perfectly safe, a 

 half more lime milk than that put in to neutralize the copper should be added. Now 

 add water to make 50 gallons and stir thoroughly. 



The Bordeaux may be applied to the seed-beds with a sprayer or a sprinkling 

 can. If successfully made, it will not injure the young tobacco. 



Notice. — The copper sulfate solution alone, if appHed to the seed-bed, would kill 

 every plant. If not sufficiently neutralized with lim^ it will also kill the tobacco. 

 Therefore, never apply any treatment like this to your whole crop. Treat a small 

 part and, if this is successful, after one or two days treat the rest in the same way. 

 Bordeaux leaves a whitish coating on the leaves and the sprayed plants might not 

 sell well, although they are in no way injured. 



