WEAR OR ret rule weer ache OI eo te el ts 
ty ag wi Boe + Wry Ly Sal ee iy cab cakes i or 
ve x we ‘ Me Tee RENE 
. Pte y 
570 Report or HorticuLTuURIST OF EXPERIMENT STATION. 
the differences in the results were less liable to be due to variation 
in the amount of the scab fungus in the soil, the zine sulphate 
treatment gave apparently the greatest freedom from seab fol- 
lowed by mercuric chloride and iron sulphate in the order named. 
Copper sulphate lessened the amount of the disease but also les. 
sened the yield. Eau Celeste, Bordeaux and ammoniacal solution 
of copper carbonate had little value at the strength used. 
Turning now to series B where the seed was simply soaked in 
the fungicides before planting, an average of all the experiments 
shows that zinc sulphate was apparently most successful, possibly 
dive in part to favorable soil conditions; but the results obtained 
at the Station alone where the soil conditions seemed to be more 
uniform indicate that iron sulphate was most effective followed 
by mercuric chloride, Bordeaux mixture and zine sulphate in 
the order named. There were some indications that Bordeaux 
mixture slightly injured the yield, and this was also noted in pre- 
liminary greenhouse experiments. Eau Celeste, copper sulphate 
and ammoniacal solution of copper carbonate had little or no 
effect at the strength used. These apparent discrepancies in the 
results may be due to the fact that the amount of the scab present 
in the soil or seed was not uniform in the different rows as shown 
by the variation in the amount of scab in untreated rows, 
These experiments and those of other investigators show that 
preventive treatment is in a measure successful; but it will be — 
necessary to investigate this subject further in order to determine 
what fungicide, cheap and easily applied, is most effective in 
preventing potato scab. 
It should be remembered that, as previously stated, these 
experiments were planned so as to give the proposed remedies the 
severest possible tests, therefore scabby seed was selected for each 
experiment and part of the experiments were conducted on badly 
infected ground. It is reasonable to suppose that much more 
favorable results in preventing scab could be obtained by avoiding 
infected soil, by selecting smooth seed, and by using all the pre- 
cautions mentioned on pp. 563-4. 


