612 HORTICULTURE, FORESTRY, FLORICULTURE 



great losses by reason of the presence of these undesirable types dur- 

 ing every season in which the seed was used. This breaking up of 

 type is due to the effect of the change of soil and climatic conditions, 

 resulting in striking variation in the plants grown from the imported 

 seed. The variation is particularly marked where southern seed is 

 taken to northern tobacco districts. 



Experiments have shown that if the seeds from typical and 

 desirable plants in these crops are saved under bag, and thus pro- 

 tected from cross-fertilization, the plants produced from such seed 

 will be uniformly like the parent plants. The second season it is a 

 good plan to increase the area of plants grown from seed saved under 

 bag, and from the most desirable plants in this crop selections of 

 seed can be made for future general crops. If the crop during the 

 second season shows uniformity of a desirable type, it is advisable to 

 save a large quantity of seed under bag if possible, sufficient to plant 

 several succeeding crops in order to provide for a possible failure 

 of seed production in future seasons. Inasmuch as tobacco seed when 

 properly cared for will retain its vitality for from 10 to 20 years, this 

 seed can be safely used, if necessary, for 5 years. The best practice, 

 however, is to save the seed for the following year's crop every sea- 

 son unless some accident should greatly injure the crop. 



The grower of all new varieties of seed should test them on a 

 small area before using them for his entire crop. In some cases new 

 seed, when grown under conditions different from those under which 

 the seed was produced, develops plants which are subject to fun- 

 gous diseases or insect enemies in the new conditions. Therefore it 

 is a wise plan to grow a small area of tobacco the first season and 

 observe the plants carefully in respect to the presence of fungous or 

 other diseases before using them in large fields. In other cases cer- 

 tain fungous diseases are present in the soil, which attack and destroy 

 the varieties imported from other regions. In most cases resistant 

 plants can be found in fields affected by these diseases. The struc- 

 ture or habit of growth of these resistant plants is such as to make 

 them immune to these attacks. The seed of resistant plants 

 should be saved under bag and used for the next year's planting. In 

 this way resistant strains of tobacco which will prove to be immune 

 to the attacks of the various diseases may be secured. 



' In selecting seed plants several important facts should be taken 

 into consideration. All the plants in the field should be carefully 

 studied and observations made on the shape of the leaf of the dif- 

 ferent plants, on the variations in size and color of leaves, and on the 

 time of maturity of individual plants in the field. 



The number of leaves and the number of suckers should be 

 counted on many plants in the field from which seed is to be saved, 

 in order that an accurate idea may be gained of the extent of varia- 

 tion in the variety as regards these points. As a rule, there is a great 

 variation in all of the important characters which go to make up the 

 type of plants, and individual plants will be found which have desir- 

 able shape, size, and color of leaf, which mature early and have an 

 extra large number of leaves and few suckers. The grower should 



