60 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
[ July 20, 1893. 
CANKER IN FRUIT TREES. 
Before replying to the articles on this subject by Mr. Kruse, 
“ A. D.,’' and Mr. Pendered in the issue of the Journal of Horticulture 
of June 22nd (pages 497 and 498), I desire to correct an error in my 
paper on “ American Orcharding ”—viz., the “ 3G bushels ” in the first 
.sentence of the seventh paragraph on page 437 should have been 
2| bushels. 
Mr. Kruse’s able description of the soils of the ragstone range of 
hills in Kent is interesting and valuable. A brief digest of the condi¬ 
tions of soil and environment disfavouring or countenancing canker in 
Apple and Pear trees on the Kentish rag formation will be instructive 
and useful. 
1, On the lower slopes of the ragstone range of hills the rock 
(calcareous sandstone) is nearest the surface, therefore well drained ; 
the ground is the richest from the rainwash or dehrh brought down 
from the higher parts of the range, and it is the lightest in colour, 
because it is nearest the rock, consequently contains more lime, and 
from the water percolating through it freely the iron has been eliminated 
or assimilated and taken up by the crops during an untold period of 
cultivation or carried off by the water passing through the soil. Under 
these conditions the Apple and Pear trees canker the least. This being 
30, and if parasites are not the cause of the cankerous affections, why 
do the trees canker at all ? 
2, At the top of the ragstone range of hills the subsoil is a red clay, 
water must pass through it slowly, or not at all, and this will, in a greater 
or lesser degree, irrigate the ground lower down, and enrich it with 
assimilible iron and other tree food ; the soil is also redder and less rich 
than on the lower slopes—this through air and rain not entering it 
freely so as to liberate and render its stores of nutrition so quickly 
available as where the soil is more open. Thus the trees are placed at 
a disadvantage, not only in respect of soil, but of climate, for it must 
be colder at the top than at the bottom of the range. Qn this part of 
the hills the Apple trees canker the most, and “ hardly any Pears will do 
well, the fruit of most varieties cracking so much as to be worthless, 
and the trees are unhealthy.” Mr. Kruse, it will be observed, makes a 
distinction between the canker of the Apple trees and the cracking of 
the fruit and ill-health of the Pear trees, and this shows conclusively 
that the diseases are different. That of the Apple trees may or may not 
be due to fungi. I have never stated, as “ A. D.” alleges, that the canker- 
fungus (Nectria ditissima) was the sole cause of cankerous affections on 
Apple or Pear trees. The evil may, and does result from several causes, 
and I have said and shown that trees may have many wounds without the 
fungus growing in them. But there is no question about the Pear trees ; 
they or their fruit are troubled with scab-fungus (Gladosporium or 
Pusicladium dendriticum var. pyrinum), which attacks the young wood 
and produces the cankerous, scaly condition of the bark, so well seen in 
Louise Bonne of Jersey Pear in far too many cases, especially on the 
Quince stock, in cold localities and heavy or wet soils. Is not the canker 
in the Apple trees and the cracking of the fruit and ill health in the 
Pear trees as much, if not more, due to the unfavourableness of the 
environment than to the soil ? The latter may be improved by drainage 
and cultivation, but who can alter the climate ? Nevertheless, the 
climate may be much improved for tree growth by attending to the 
sanitation of the soil, or, in other words, the trees so benefited by 
drainage and soil improvement as to resist the parasites which await a 
favourable opportunity to fasten and prey upon them. 
3, Midway between the top and the bottom of the slope of the 
ragstone range of hills, “the soil is a rich brown loam in a very good 
condition, owing to the abundance of ragstone d4bris, is neither too 
heavy nor too light, and is well supplied with the principal elements of 
plant food. Experience shows that these are in a sufficiently available 
form, for all kinds of vegetables can be grown of splendid condition, and 
fruits of high quality are cultivated.” Such is Mr. Kruse’s description 
of the soil of the slope on which he operates. In this “ rich brown loam 
in a very good condition,” and in a favoured situation of a county 
that produces the best using Apples in the world, “some trees of 
almost every variety canker. With some varieties there is only 
a tree here and there, and other sorts canker so much that it is im¬ 
possible to grow them except for a few years.” Mr. Kruse’s evidence is 
conclusive. It is not a question of soil so much as of environment and 
of the “ survival of the fittest,” for “ the higher the ground the more 
the Apple trees canker.” 
But Mr. Kruse still adheres to the soil theory, and thinks he would 
be benefited in his culture by an “ analysis of a good Apple soil in the 
Weald of Kent.” I cannot help him in this matter, and think it would 
not benefit him much if I could. After a careful study of the soils of 
these islands, and guided by nearly half a century’s experience, I am 
convinced that cultivators who pay the most attention to the natural 
adaptability of crops to the soil and position obtain the best results with 
the least expenditure of labour and manures. So with fruit trees. To 
secure healthy trees and profitable crops of fruit they must be suited 
alike to the soil and the location ; and to avoid disease—canker or any 
other—we must select those varieties best able to resist and throw oil 
the parasite producing it. This means finding out by experience or 
observation the varieties that succeed, and plant those only. This 
applies to all parts of the British islands, for there is not a spot in them 
up to 500 feet and more above the sea level that is not fitted for the pro¬ 
duction of some varieties of hardy fruits. With all due deference to 
soil theorists and the ransacking of all parts of the world for manures, 
I am satisfied that cultivation and selection of kinds and varieties are 
far more important. 
“A. D.,” page 498, commences by sheltering under Mr. Tonks’ 
mantle. I was under the impression that my views and those of Mr. 
Tonks and other earnest inquirers were identical—namely, that sound 
cultivation is the prime agent in securing healthy trees and profitable 
crops of fruit. It is as well to be disillusioned in this case. “ A. D.” says, 
“ Canker is a product of starvation in respect of the particular variety 
affected, or in other words, it is a disease caused by the absence in the 
soil of the elements which are essential to the healthy maturation of the 
wood.” This is a remarkable statement, and shows that he has nothing 
in common with Mr. Tonks, who did not advise different kinds of foods 
for various varieties of Apples, but a complete food for all the Apple 
family wherever situated, subject to variation according to the require¬ 
ments of different soils as ascertained by analysis. “ A. D.” does not see 
this, but asks, “ How is it that of two varieties of Apples or of Pears 
growing close together, . . . under absolutely the same conditions, yet 
one is healthy beyond all question, the other cankers badly, and hardly 
ever ripens annual growths?” He then answers, “The reason is 
obvious. One sort finds all that it needs in the soil, the other does not.” 
How does “ A. D.” prove this ? Where is the “ obvious reason ? ” I 
see no description of the soil or an analysis, no specifying of the varieties, 
and “ A. D.” sees nothing but soil starvation to account for the difference. 
What about constitutional hardiness in different varieties t Here is a 
chance for “ A. D.” to tell us why the Calville Blanche Apple requires to 
be grown under glass in this country, and the Hunthouse thrives at 
elevations in North Yorkshire over 500 feet above the sea level. Will 
“A. D.” oblige by naming the “predisposing cause,” the reason for the 
difference in hardiness between two varieties of Apples, perhaps raised 
from two pips taken from the same core of the parent Apple, and why 
one has a better constitution than the other. Until an answer is given 
to this I must decline to accept “A. D.’s” preconceptions of predisposing 
causes ; but at the same time he adduces evidence in support of my 
contention that the reason why all Apples and Pears do not suffer 
equally from canker is more a question of constitutional hardiness and 
adaptability to position than of soil. This is shown in the second para¬ 
graph of his critique as follows :— 
“ Trees growing together side by side for forty years, Kibston, 
Alfriston, Wellington [Dumelow’s Seedling], cankering badly ; Waltham 
Abbey Seedling, Cockle’s Pippin, and Beauty of Hants doing splendidly. 
All on Crab stocks, soil a deep and not very sweet clay. Again, of Pears, 
Alexandra Lambre, Thompson’s, Nouveau Poiteau, and Williams’ Bon 
Chr&tien do wonderfully well, planted twenty-two years on the Pear 
stock. Beurr6 Diel and Beurr(5 d’Amanlis canker very badly, fruit 
split and spotted, comparatively worthless; others [what varieties?] 
fruit perfect, clean, and delicious.” Then follows the question, “ Why 
is the canker?” and “A. D.’s” answer is, “Because of predisposing 
causes.” These “are deficiency of tree food, the lack of essentials to 
health ; in other words, of the formatien of perfectly sound ripened 
wood.” 
Now let us recognise established facts. Ribston Pippin has its home 
in the rich, deep, porous soil of the great Vale of York, where it has a 
different climate to that over a “ deep, and not very sweet clay.” It 
cankers to death on hot sands. Alfriston deserves a better fate than a 
lingering death on a sour bottom ; so also does Dumelow’s Seedling, 
which, however, will not thrive in the warm soil of Sandy in Bedford¬ 
shire. Waltham Abbey Seedling, Cockle’s Pippin, and Beauty of Hants 
do well in all fairly good Apple soils, even as far north as the North 
Riding of Yorkshire in lightish soils. The soil theory, therefore, breaks 
down along the line, and the selection of varieties suited to different 
soils and localities marches on as it has done in all time to victory. As 
for the Pears, it is certain that they are similarly influenced by location, 
and the hardiness or otherwise of their inherent constitutions. The 
Beurre Diel and Beurrfl d’Amanlis Pears had not the fruit cracked by 
soil influence, but by scab-fungus, and the susceptibility or otherwise 
thereto is more due to climate than to soil. In the north the trees 
are healthy and the fruit without speck or blemish, fruits of Beurr^ 
Diel often weighing 1 lb., and sometimes over 2 lbs. in weight. 
Among other things “ A. D.” says, we get rid of the canker by taking 
the head of the tree clean off and replacing it by grafting with scions 
from a variety that thrives well on the soil. The head is not “ re¬ 
placed ” but a new one provided of a variety suited to the climate, for 
the roots are in the same soil as before. Sir Walter Raleigh said 
“ beheading is a cure for all diseases,” and it is often the best for Apple 
trees afflicted with canker. But it is not Mr. Tonks’ plan, for he cured 
his cankered trees, not one variety in particular, but all, with the same 
generous regimen. I have not the least doubt that Mr. Tonks cured 
his trees of what he considered to be canker, and I am equally certain that 
those trees had not canker-fungus (Nectria ditissima) growing in them, 
for the parasite, once seated in a shoot, sooner or later if not destroyed, 
compasses its destruction. Lift fruit trees and improve the soil by all 
means, apply manures and attend to all the cultural requirements, 
but rest assured that none of these will avail against canker or gum caused 
by fungi, for the diseased limbs will remain so unless the parasite is 
destroyed or removed by incision or amputation. 
Trees injured by frost, as described by “A. D.,” clenches my argu¬ 
ment. They did “ splendidly for many years ” before the frost played 
havoc with them. Yes, the spores of the canker-fungus took possession 
of the wounds. He will not allege, I hope, that the frost would per¬ 
manently affect the constituent elements of the soil. What then becomes 
of his soil theory ? The soil had clearly nothing to do with the conse¬ 
quences in that case. 
I could say much more in reply to “ A. D,,” but I am encroaching. 
