RUST-RESISTANT VARIETIES OF WHEAT 



37 



In the case of the former the plants grown in pots to which barnyard 

 mauure had been added were most severely attacked, while there was 

 little difference between those grown in loam and those manured with 

 both barnyard manure and bone meal. Khapli plants grown in soil 

 fertilized with both manure and bone were fairly successfully infected. 

 Areas of the leaf, one centimeter in length, were sometimes infected, 

 and pustules as big as a pin head were developed. There was little dif- 

 ference between the other pots, the infection being somewhat milder 

 than in the heavily fertilized ones 



It is quite probable that there was available in the rich loam very 

 nearly all of the plant food the plants were capable of utilizing. This 

 would account for the fact that the differences were not always greater. 

 On the whole it might be concluded that very heavy fertilization is 

 somewhat conducive to increased severity of attack on very resistant 

 varieties as well as on susceptible forms. 



Since the check plants in the trials just described were grown un- 

 der such favorable conditions, it was determined to grow the checks in 

 poorer soil in the next series. Therefore they were planted in mod- 

 erately fine sand (S) (see table below) to which but a very slight 

 amount of leaf-mold had been added. Nitrogen (N) was added to 

 another series in the form of calcium nitrate, to a third was added cal- 

 cium phosphate (P), and the fourth received both calcium phosphate 

 and calcium nitrate (P and N). The salts were applied in water. The 

 plants were watered three times with distilled water containing the 

 proper salt or salts, at the rate of 3 grams per 500 cc. The same varie- 

 ties were used as were used in the preceding series. 



Observations on results gave the following order of virulence, the 

 first being most virulent and the others arranged on the same basis. 

 Two observers took notes with the following results : 



EFFECT OF FERTILIZERS ON VIRULENCE OF RUST ATTACK 



The somewhat conflicting results suggested the desirability of an- 

 other trial. Four series were arranged as follows: Pure sand (S), 

 ordinary field soil (O), sand plus nitrogen (N), and sand plus phos- 

 phorus (P). The nitrogen and phosphorus were added as in the pre- 

 ceding experiment. Three persons working independently made ob- 



