384 



Journal of Agricultural Research 



Vol. XIX, No. 8 



made as previously indicated. Typical yellow colonies of the blackchaff 

 organism, concentrically striated by oblique light, were readily obtained 

 in poured plates from blackchaff leaf lesions, which at this stage appeared 

 characteristically as brown, water-soaked linear areas, narrow and ex- 

 tending for various lengths along the edges or centers of the second, 

 third, or fourth leaves from the top, with clouds of oozing bacteria in 

 cut sections. Septoria was also found in the oldest leaves, distinguished 

 by wider lesions and characteristic black dots of pycnidia. 



Table XII. — Condition of experimental plots in May, ig20 



Locality and date. 



Abilene, Kans., 

 May 15, 1920. 



Hays, Kans., 

 May 22, 1920. 



Plot. 



Number 



of 



plants 



examined 



IKanred, untreated 

 Kanred, western area, presoak formalin 

 treated. 

 IKanred, untreated 

 Kanred, presoak formalin treated 

 Kharkoff, untreated 

 Kharkoff, presoak formalin treated. .. . 



312 

 386 



293 

 356 

 266 

 298 



Number 



with 



bacteria 



oozing 



from cut 



sections. 



87 

 26 



33 



72 



Percent- 

 age of 



fection. 



27.8 

 6.7 



33- 

 9- 



27. 



7- 



There is an evident increase in the amount of secondary infection 

 during April and May. It was also observed that most of the lesions 

 on leaves from treated plots were small, 2 to 8 mm. long, consisting of 

 from I to 3 spots on the second or third leaf from the top, and were 

 evidently fairly recent infections. Leaves from control plots showed 

 similar lesions but also a larger proportion of more advanced lesions up 

 to 30 mm. long on the older leaves. No lesions were observed in the 

 young heads, which were still inclosed in the sheath. 



EFFECT OP MODIFYING THE TREATMENT PERIODS UNDER FIELD CONDITIONS 



A shortening of the entire treatment period appeared desirable after 

 field experience with the method so far described, mainly for the purpose 

 of facilitating drying after treatment. Three greenhouse germination 

 experiments were made with Currell wheat seed, using a shorter presoak 

 time and a longer (varying) soak in formalin i to 320, followed by very 

 short periods during which the seeds were kept moist, the entire process 

 covering various periods from 5X to 8 hours as outlined in figure 7. 



Formalin treatments involving a soaking longer than previously 

 used — that is, of 15 to 30 minutes — followed by immediate drying or in- 

 volving a short moist period of i to 3 hours decreased the germination 

 considerably. The same treatments preceded by a 5-hour presoak (in one 

 case a 6-hour presoak) resulted in no injury whatever to germination 

 and in fact caused distinct acceleration. The effect of the various 

 periods upon germination was determined for infected wheat seed also. 



