53 
LEMON BARK BLOTCH. 
(Ascochyta corticola , n. sp.) 
Symptoms . — On 30tli September, 1897, a grower in the 
Goulburn Valley wrote as follows :—“I am sending you a Lemon 
tree, to see if you can make out the cause of the trees dying. 
You will see that the bark of the tree is gone black about 6 inches 
from the ground. Its first appearance is a black spot, then it 
works all round the tree, and the tree dies. There are a great 
many trees affected in the orchard in the same way.” (Plate IX., 
Fig. L) . , 7 
Cause. — From the collar upwards, for about 6 or 8 inches, the 
stem was found to be shrivelled, and studded with little brownish 
thickly-clustered punctiform bodies, which burst through and 
slightly elevated the epidermis or corky layer. (Plate IX., Fig 2.) 
Each little pustule represented a spore case, and contained 
innumerable microscopic colourless spores. This fungus was 
found to be Ascochyta corticola , n. sp. The trees wore not planted 
too deeply, and they were carefully cultivated, but there had been 
two successive dry seasons in the district. 
While visiting the district in the same month of 1898, I found 
a Lemon tree dying, or dead, about 15 miles distant from the first 
orchard (Plate X.). On the stem there were several different 
fungi, and the question arose as to which was the primary cause 
of the disease. On examining the stem rioar the collar, I found a 
species of Gibberella ,» and, thinking this might possibly be a 
complete stage of Ascochyta , I examined a portion of the stem 
higher up, and found Ascochyta corticola, the same as in the first 
specimen. The pustules of Gibberella and Ascochyta were 
similar to the naked eye, only the latter wore a little higher up 
the stem. Later, I found a species of Fusarium associated with 
these fungi, which produced conidia, or naked spores. It is well 
known that a large number of fungi pass through different stages 
in the course of their life, some of which are so unlike each other 
that they were formerly regarded as distinct species, and named 
accordingly. Now, this may be merely a case of association, and 
not of genetic connexion, which can only be certainly proved by 
means of cultures ; but there are similar cases which give support 
to the conclusion that there is genetic connexion, that the one is 
a stage in the life history of the other. 
The " Strawberry Leaf Spot” is only too well known in these 
colonies, and it is due to a fungus known as Sphaerella J'ragariae 
Sacc. Sphaerella would represent Gibberella, the one merely 
having uni-septate spores, the other having three, or multi-septate 
