70 HATCH EXPERIMENT STATION. [Jan. 



are so weakened that it looks questionable whether they 

 will ever develop into anything of value. 



We have previously attempted to show that the outbreak 

 of the uredo spore stage in this State bears a direct relation- 

 ship to the water retentivity of the soil ; that is to say, 

 during a season of drought, soil capable of holding a small 

 percentage of water becomes exceedingly dry, and it is on 

 these soils that plants suffer. There has been nothing 

 observed to disprove this idea, as we still find the uredo 

 or injurious stage of the rust usually occurring on those 

 soils which are light, and we do not get this stage on plants 

 grown on other soils. We have made a great many addi- 

 tional analyses of soils of the State during the past two 

 years, and the results obtained from such analyses bear out 

 these conclusions. It is also noticeable that in those regions 

 where the soil is lighter and more porous the uredo spore 

 infection shows itself earliest each season, and where the 

 soil is heavier and more compact infection is later, hence 

 doing less damage. Beds situated in regions where the 

 latter conditions prevail have not been damaged nearly so 

 much in the last five years as those situated in the lighter 

 and more porous soils. 



The foundation of the idea of the relationship existing 

 between the soil and the uredo outbreak is based upon vigor. 

 In seasons of drought plants become very much weakened, 

 hence they become infected ; while those plants grown in 

 neighboring towns, which are characterized by much heavier 

 soil, never have anything but the teleuto spore stage occur- 

 ring in September or October. The teleuto spore stage ap- 

 pears to be widely distributed in the State, and has been so 

 from the very first. The question naturally arises, Why do 

 these teleuto spore infected beds not have a summer stage ? 

 There are certainly plenty of beds which do not have it, and 

 their distribution is wide. All the theories re latino- to the 

 influence of such factors as dew, elevation, points of com- 

 pass, shelter, utterly fail to account for a lack of uredo 

 spore infection on these beds. The principal and most 

 important difference found in these beds which are subject 

 to the summer and fall infection is the one of soil text- 

 ure and water-retaining capacity, which enables the plants, 



