The Woburn Experiments on “ Potato Disease.” 
7 77 
young growth of the “ earlies.” — On the plots (“ Early Shaw ” and 
“ Village Blacksmith ”) where the tubers had been steeped in 
sulphate of copper or in the solution of sulphate of ammonia and 
nitrate of potash, only a stray plant appeared, the dressings having 
evidently destroyed the vitality of the tubers, for, on the corre- 
sponding untreated plots of both varieties the crop came up well. 
Dates of Application of Dressing and Appearance of Disease . — 
The first dressing with bouillie was done on June 30, the earlier 
kinds having grown sufficiently by then ; the other varieties were 
dressed for the first time on J uly 6 and 7, and the whole was finished 
before any sign of disease appeared. 
Tlie plants grew on, and by the middle of August the “early ” 
kinds were quite ready to take up, but still no disease came, so these 
crops, viz. “Beauty of Hebron,” “Myatt’s Ashleaf,” “Early Rose,” 
and “Early Puritan,” w^ere raised August 10 to 13, as also the 
“ Dalmahoy ” of the “ medium ” varieties on August 16. There were 
no diseased tubers in either of these crops. On August 24 it 
was noticed that the dressing had for the most part been washed oflf 
the leaves of the remaining plots, and directions were given that the 
plants sliould be again sprayed. This was begun on September 1, and 
the very same day (and before the spraying could be completed) 
disease began to make its appearance. Mr. Carruthers’s examination 
of some of the leaves sent to him confirmed the presence of the fungus 
{Fhgtophihora infestans). The varieties most affected appeared to be 
“Schoolmaster,” “Victoria,” and “White Elephant.” Thereupon 
not only were the previously dressed A plots (for early application) 
sprayed once more, but the B plots (for late application) were also 
treated. By September 9 all the A and B plots had been dressed. 
Bearing in mind that the A plots were those dressed early, before 
disease appeared, that the B plots were dressed late, on the appear- 
ance of disease, and that the C plots remained untreated throughout, 
the following notes, taken on September 3, may be given : 
“ White Elephant ” — A hardly attacked at all. 
B very badly diseased. 
Here a marked difference was seen between the A plot and the 
others. 
“ Reading Giant ” 
“Imperator” 
“ Schoolmaster ” . 
“ Victoria ” . 
“ Regent ” . 
“Champion” 
A and B hardly touched. 
C one large patch in centre of plot diseased. 
A and C, leaves slightly spotted. 
B rather more attacked. 
All plots slightly attacked; A less than the 
others. 
All plots slightly attacked; A less than the 
others. 
All plots slightly spotted ; no difference letween 
them. 
Hardly attacked at all ; only a few spots 
here and there; no difference between the 
plots. 
3 o 2 
