67 
The Effect of Weeds upon Cereal Crops. 
sowing or with Papaver ; apparently competition had not yet come 
into play. By the end of the second month the thickly sown plants 
were not so large as the others, but those with the poppy still looked 
full size. By harvest time, however, the latter plants seemed to 
have fallen very much behind the single sown plants, and were 
very poor indeed. The double sown wheat appeared on the whole 
very much like the single sown, but close inspection showed that 
while the total development was similar, the individual plants 
were much smaller The dry weights absolutely bore out this 
latter observation, but curiously enough the average weights of 
the plants grown with poppy was somewhat higher than that of 
the double sown wheat, although the latter seemed to be so much 
poorer at the time of cutting. 
For some long time the development of the poppy was much 
the same in all the pots, but by July a difference could be seen 
The plants with wheat were rather smaller than those grown alone, 
while the total development was comparable in both single and 
double sown pots. The impression was certainly not given that 
twice as much seed had been sown in the latter case. The presence 
of the wheat had a harmful effect on the poppy, so that the average 
dry weight with wheat was considerably below that of the double 
sown poppy, i.e., the competition of wheat with poppy is greater 
than that of poppy with poppy, but the competition of poppy with 
wheat is less vigorous than that of wheat with wheat, suggesting 
that in this case a certain balance of competition has been struck. 
Wheat and Spergula. 
Wheat associated with Spergula made a good start but soon 
began to fall behind, and by the end of the first month it looked 
decidedly unhappy. By harvest time the plants were very poor 
indeed, as they were practically smothered by the weed. In fact, 
the wheat made less growth in this case than in any experiment 
carried out along these lines. 
The Spergula made excellent growth, that with wheat being 
nearly as strong as that in the single sown pots all the way through 
the experiment. The thickly sown crop looked very little heavier 
than the thinly sown, and this was corroborated by the dry 
weights. In this case the tables were turned, and the weed got 
the upper hand of the wheat, the depreciation of the latter going 
on pari passu with the improvement of the weed, so that the 
development of the spurrey approached within measurable distance 
