280 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
[ September 23, 1880. 
no hesitation in supporting Mr. Muir’s recommendation of School¬ 
master, and in advising its use for a main garden crop. I fear we 
must be dependant on a field supply of Champion and Magnum 
Bonum for the latest supply, for they are certainly too rank in 
growth for an ordinary garden. 
Each season I have been obliged to give up the cultivation of 
some late varieties through disease, and if compelled to grow 
only three sorts would plant Rivers’ Royal Ashleaf or a kidney of 
that type, Schoolmaster, and Magnum Bonum ; the last in a field 
if convenient.—R. Crossling. 
If Mr. John Taylor will only procure a really good strain of 
Paterson’s Victoria he will find it to possess most if not all the 
high qualities enumerated by me. The very best form of it that 
I have met with is the Dunbar Victoria of commerce, every tuber 
supplied by Potato dealers being exceptionally large, full eyed, 
and of the true flat kidney-shaped type. The old tubers are still 
excellent in June, and you may dig up the young tubers as soon as 
they are large enough for cooking in July, and they will prove so 
white, mealy, and well flavoured as to obtain the especial approval 
of those who are critical in such matters, and I suppose we are all 
so in some degree. Let not the failure of this and most other 
good varieties last year induce us to give undue preponderance 
to the one or two points of merit in rampant-growing Champions 
and Magnum Bonums. Unfortunate indeed must be those persons 
with whom it is “a question of Champions or no Potatoes ” again 
this year. That it unfortunately is so I have strong reason to believe 
from the account I have received of water laying for weeks in the 
furrows between the rows in some districts. Under such circum¬ 
stances the stronger-growing sorts could alone flourish, and I 
suppose it is this fact which prompts so many to regard them as 
superior to more delicate varieties.— Edward Luckhurst. 
PETAS1TES FRAGRANS. 
Winter-flowering- plants are always valuable and scarce, 
and in the Petasites fragrans (sometimes known as Tussilago 
fragrans) we have a midwinter flowering perennial. The flowers 
are whitish, with a peculiar Heliotrope-like perfume, and are 
borne in a thyrsiform panicle. It can be grown almost anywhere, 
such as under the benches of greenhouses, in a cold frame, or even 
out of doors with a slight protection from frost. It was introduced 
from Italy about the year 180G, and has become so well naturalised 
in some parts, and especially in Cornwall, as to become a trouble¬ 
some weed. I think it is best to grow this plant in boxes. Its 
common name is the Winter Heliotrope.—W. R. 
FUNGI A CAUSE OF DISEASE IN PLANTS. 
“Why,” writes Mr. Luckhurst in your last issue, “does ‘ S.’ 
entertain feelings of regret that our opinions are entirely at 
variance ?” My reply to this query is that I suppose it is due to 
the fact, well known to all, that when a man of whose general 
accuracy of judgment we were previously assured expresses an 
opinion opposed to our own, it suggests either that his observations 
are not reliable, or the equally unpleasant alternative that we 
have ourselves been mistaken. This was my predicament when 
I read Mr. Luckhurst’s first communication on the subject under 
discussion, and it induced me to request him to state his reasons 
for such positive assertions, fully expecting in reply facts that 
would substantiate his views and subvert mine. In this, however, 
he has not been very successful, for with one exception we were 
already familiar with what is advanced ; and in my opinion it 
affords very dubious support to his statements. Taking these in 
the order he discusses them, the first to be considered is 
The Potato Disease .—Under this head your correspondent com¬ 
mences with a question to which he gives an extraordinary answer. 
“ When are fungi perceptible in the Potato ? Before the plague 
spot appears, or afterwards ? Invariably afterwards.” If this be 
correct the matter is quite clear and indisputable ; but upon what 
is it founded ? If Mr. Luckhurst has microscopically examined 
the tissue of the Potato with the care and perseverance needed in 
such work, and has conclusively proved that when the “ plague 
spot ” appears there is no trace of fungus spores or mycelium in 
plant or tuber, then he is entitled to great credit for a discovery 
of considerable value very modestly announced. If it is not 
derived from his own observations who is his authority ? 1 have 
never seen the statement in any of the multitudinous treatises 
that have appeared upon the subject in recent years. But possibly 
much depends upon the interpretation of the word “ perceptible'” 
in the first sentence quoted ; for if this is only intended to signify 
what can be seen by the unaided vision, it possibly applies to the 
appearance of the fructification of the fungus on the surface of 
the plant, in which case I fail to see how it supports the argument 
that fungus is a result of disease. This portion of Mr. Luckhurst’s 
reply requires further elucidation, which undoubtedly he will 
willingly supply. As to the fungus continuing to spread, “no 
matter how hot or dry the weather may be,” I can only say that 
it is directly contrary to my experience, for hot dry weather most 
decidedly arrests its progress, and elaborate statistics have been 
published showing that heat and moisture are its chief require¬ 
ments. It appears to me unnecessary to seek imaginary causes 
of disease when those already known are sufficient to account for 
the phenomena. The Potato fungus is known to poison and cor¬ 
rode the tissue of the plant into which it penetrates, inducing de¬ 
composition by a positive action upon the living substance, where 
its mycelium is traced, and there only are the peculiar character¬ 
istics of the Potato disease found. Why was the disease we are 
familiar with unknown in this kingdom previously to 1845 1 Why 
was the Peronospora infestans then first observed here, though it 
had been previously known in America ? And if the Potato 
disease is not the effect of a fungus, what is it ? Can Mr. Luck¬ 
hurst answer these questions satisfactorily ? As to the experi¬ 
ments with Salus at Chiswick, they were simply undertaken to 
ascertain if it possessed any efficacy in preventing the disease ; but 
their success or failure had no bearing upon the relation of the 
fungus to the disease. 
Peach Blister .—A few years ago this subject wa3 discussed at 
length in the pages of the Journal, but the only evidence adduced 
in support of the view that the blister is not the result of a fungus 
attacking the foliage was the generally admitted fact that it is 
confined to trees occupying exposed positions. This is all that 
Mr. Luckhurst now advances, and yet it is by no means sufficient 
to satisfy an unprejudiced mind that his view is correct. In the 
first place the cold winds, which are alone said to give rise to the 
blister, do not, so far as my observations go, produce a similar 
effect on any other inhabitant of our gardens. The tendency of 
exposure to winds is to cause the foliage to shrivel in the majority 
of plants, and not to become inflated or blistered, which generally 
results from internal injury, as in the case of many leaf-burrowing 
insects. Secondly, the conditions which are claimed to produce 
the blister are exactly those that favour the production of the 
fungus, for at no other time does it appear ; and this fact, so far 
from confirming your correspondent’s opinion, is directly opposed 
to it, as if unhealthiness of a Peach tree was all that is needed to 
render it a suitable habitation for the Ascomyces deformans it 
would surely appear at other seasons, when the moisture and 
temperature are such as encourage the growth of fungi generally. 
It must, however, be remembered that fungi are very widely 
distributed, members of the order occurring in all parts of the 
world even where the cold is excessive, and many will only 
thrive when a particular temperature or moisture peculiar to 
the species or genus is provided. Again, whenever the blistered 
leaves of the Peach have been carefully examined by competent 
observers the tissues have been found to contain the mycelium of 
the fungus, and it is incumbent upon those who oppose the opinion 
that the blister is produced by the fungus to prove that they have 
similarly examined leaves in which no trace was present. 
Concerning the shanking of Grapes I have little to say. My 
opinions on the subject have hitherto been in accordance with the 
overcropping or exhaustion theory, and I should require some sub¬ 
stantial evidence to induce me to alter my views. Mr. Harrison 
Weir is, I believe, the first writer who has advanced the theory 
that shanking is due to a fungus, and at present his statements 
have not been confirmed by any other observer. 
With regard to the remarks concerning the analogy between 
plants and animals, Mr. Luckhurst should remember that it is 
only in the lowest forms that the two kingdoms approach each 
other. The most highly organised are widely different in structure 
and requirements, yet it was from the latter that he endeavoured 
to deduce his argument ; the analogy between a man and the 
Potato plant, for example, is not very striking. His argument in 
logical form was this : Delicate human beings are more subject to 
infectious diseases than those that are healthy ; plants are ana¬ 
logous to animals ; therefore an unhealthy Potato plant is more 
liable to be affected by the fungus Peronospora infestans than a 
healthy plant. The first proposition is inaccurate, and conse¬ 
quently the conclusion is illogical. Then the statement that 
“ similar conditions are necessary to health ” of both the plants and 
animals is scarcely correct. Plants possess the power of convert¬ 
ing various elements and chemical compounds into organised 
substance, animals can only assimilate that which has already 
been prepared either by vegetables or other animals; plants 
chiefly require carbonic acid gas in the atmosphere, animals need 
oxygen ; plants can live where animals would speedily die ; and 
further, the most luxuriant vegetation on the face of the earth 
