14 



MASS. EXPERIMENT STATION BULLETIN 351 



Four brands of cider vinegar were used in this work, and the results did not 

 differ significantly one from the other. Undiluted vinegar was worked into the 

 soil immediately before seeding, except as otherwise indicated. Some of these 

 soils had been inoculated with Pythium or Rhizoctonia and others were naturally 

 infested. The soils were well watered immediately after seeding. Results are 

 recorded in Table 6 in terms of percentages which damped-off and relative numbers 

 of plants which lived. 



Table 6. — Effect of Vinegar on Damping-off and on Final Stands 



Vinegar 

 cc. per 

 Square 



Foot 



Percentages which Damped-off 



22 49 



3 2 







Relative Numbers of Plants Which Lived 



100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 



117 312 • 



121 163 233 393 233 



167 133 — -280 307 



204 162 265 129 137 142 131 538 300 316 



600 229 



623 225 170 



129 



258 143 146 167 



196 637 318 343 



145 189 834 509 343 197 



Damping-off caused by Pythium and Rhizoctonia was usually well controlled 

 by 215 cc. vinegar per square foot, with better control by 235 cc. (about one-half 

 pint). Germination of most species, especially those like cress and beet which 

 are very susceptible to damping-off, was usually much improved also. Beneficial 

 effects on stands are illustrated in Figure 1. Vinegar in too small quantities to 

 prevent damping-off, down to 140 cc. per square foot, often improved germination. 



As may be seen from the following tabulation, the quantity of vinegar which 

 can be safely used immediately before seeding is not the same for all species. 



As compared with check plants infected by Rhizoctonia, growth was often 

 improved by 200 to 240 cc. vinegar. 



At present it does not seem wise to suggest the use of more than 237 cc (one- 

 half pint) of vinegar per square foot, to be worked into the soil immediately 

 before seeding; and lighter applications are sometimes sufficient in soils not too 

 heavily infested with fungi. Homemade vinegar may, according to Wyant 

 (101), have a higher content of acetic acid than the vinegar which is commonly 

 sold, and must, therefore, be used with extra caution unless it has first been 

 diluted to about 4 percent acidity. 



