R. S. DUNHAM 203 



the unsprayed, while that of unsprayed Minerva was higher than that 

 of sprayed. The authors conclude that this formulation at the dosage 

 used "is not detrimental to the value of the flax crop." 



Further investigation has been completed recently by Dunham and 

 Robinson. Koto flax sown in rod rows was sprayed in the 2-inch stage, 

 the prebud stage, the late bud stage, and the full bloom stage with 

 4, 8, and 24 oz. of the sodium salt, the amine salt, and the ester of 

 2,4-D. The data for the sodium salt are reported in Table 3. It is clear 

 that the relatively tolerant Koto variety was adversely affected by the 

 treatment since differences in percentages of oil were significant at the 

 I per cent point and in iodine number at the 5 per cent point according 

 to the t test. 



Largest reductions in oil percentage resulted from spraying in prebud 

 and late bud stages, the first stage representing the approximate end of 

 vegetative growth. Differences from the 4 oz. treatment may not be 

 significant except in late bud and full bloom stages, but there is a reduc- 

 tion in all instances. 



Likewise the iodine number was adversely affected in general. The 

 two exceptions among 12 paired comparisons are the 4 oz. and 24 oz. 

 applications at prebud. 



In the 1948 variety test at Minnesota the percentage of oil in Minerva, 

 Victory, and B5128 was reduced 2.37 per cent, 0.56 per cent and 0.91 

 per cent respectively with only 1.3 oz. of 2,4-D acid supplied as butyl 

 ester per acre. 



To the pure-seed producer the effect of 2,4-D on germination of seeds 

 produced on sprayed plants is of vital concern. Buchholtz (5), Derscheid 

 (12), and Goodwin et al. (24) report the viability of oats unhurt. Elder 

 (17) reports no injury to winter wheat seed. Helgeson et al. (25) stated 

 that "germination of grain (hard red spring and durum wheats) was 

 reduced by ester treatment in the boot stage only." Dunham and 

 Robinson sprayed corn at five stages of growth and oats and barley at 

 two stages each without injuring germination of the resulting seed. 

 Tandon's (45) data show "that not even those varieties (of flax) which 

 were susceptible to 2,4-D in other respects showed any reduction in the 

 viability of seed." Further work at Minnesota found this to be true 

 only when the flax was sprayed before late bud stage. Marth et al. 

 (35,36) report no injury to the viability of Kentucky bluegrass or 

 timothy seed from treated plants. 



