io 6 
Journal of Agricultural Research 
Vol. XXI, No. t 
EFFECT OF COPPER SULPHATE AND FORMALDEHYDE ON MOLD IN¬ 
FESTATION OF WHEAT IN STORAGE AND IN BLOTTER 
GERMINATIONS 
The observations which follow were made for the most part in con¬ 
nection with experiments on seed-treatment injury; but, as they are suf¬ 
ficient to show certain facts very conclusively, it seems worth while to 
report them here. 
Formaldehyde of the strength recommended for smut disinfection— 
i part of commercial formaldehyde solution in 320—is also an effective 
fungicide for the spores of Rhizopus and Penicillium. The latter is 
especially sensitive to it. When seeds with scratched testas dusted with 
Rhizopus spores were dipped into a 1 to 320 solution for 10 minutes and 
sown on sterile blotters, they grew almost without infection. The controls 
which were not treated and were germinated on the same blotter were so 
badly attacked that very few seedlings developed, and the sample was 
quickly overgrown with masses of fluffy white mycelium. 
It has been maintained by some that treatment with formaldehyde 
solutions renders wheat and barley more susceptible to subsequent 
fungous attack. Our own experiments failed to confirm such an assertion 
but disclosed a possible explanation of its origin. Whenever seed was 
injured or killed by being stored dry following formaldehyde treatment, 
it was very badly infected with Rhizopus if sown on a nonsterile blotter. 
Seeds treated in the same way but remaining uninjured because not allowed 
to dry germinated in the same blotters practically free from infection 
(PI. 19). In germinations of treated wheat and barley stored in atmos¬ 
pheres of different humidities, Rhizopus appeared only on those samples 
which were injured, and even those from the damper atmospheres 
escaped infection almost entirely. Also, in experiments to show that 
washing with water removes the cause of injury upon drying, the same 
fact was shown by the invariable appearance of Rhizopus on the unwashed 
injured seeds and its absence on the washed, uninjured ones (PI. 20). 
That these are not cases of stimulation of fungous growth by formalde¬ 
hyde, with subsequent death of the seeds from the Rhizopus infection, 
can be easily shown by sterilizing the seeds with mercuric chlorid before 
germinating in sterile blotters. The injured seed lots appear just as 
evident as before, although in the absence of the fungus a higher per¬ 
centage of gennination usually is obtained. Thus, our experiments 
did not show any increase in susceptibility because of formaldehyde 
treatment but rather because of lowered viability of the seed. As 
explained earlier in this report, low viability, no matter how induced, 
always renders seeds susceptible to invasion by fungi. 
That this relation between formaldehyde injury and fungous attack 
is not often illustrated by the development of Penicillium is due to the 
latter’s peculiar sensitiveness to this chemical. On the other hand, if 
seeds are injured by copper sulphate, it is Penicillium, not Rhizopus, 
