NOTES ON SCIENTIFIC RESEARCH. 67 
Tulasnei. Cracks are caused by it, through which Colletotrichum gloeosporicides (see 
before) enters and causes the death of the parts affected. Spraying with Bordeaux 
mixture is recommended. 
“Melanose” is another disease of the orange which has been reported from Florida, 
Cuba and Australia. It occurs on the leaves, fruit, and twigs, forming brownish-black 
elongated spots. The leaves fall rapidly, and the trees consequently cannot thrive. 
The fungus causing it has not been determined so far. 
Gloeosporium Pelargonii, Cke. et Mass., is known to attack pelargonium plants, 
but it does not seem to have been recorded as injurious to the scented species. It 
forms minute spots on the under surface of the leaves, which soon drop and wither. 
“Mint rust” is well known, as it often destroys whole beds of mint. It is due to 
Puccinia Menthae. The aecidium causes the stem to be swollen and distorted, and to 
become covered with orange-yellow spots. The summer or uredospores are developed 
as yellowish spots on the leaves, and the Puccinia or winter spores form blackish 
spots on the leaves. The mycelium of the aecidium stage is perennial in the under- 
ground stems, so that when once a plant is affected it can produce the disease every 
year. In the spring of the year, therefore, all peppermint plants with distorted stems 
and pale leaves should be dug up and burnt. The disease also affects wild mints and 
may easily be communicated from them to peppermint. Dry seasons are favourable 
to the disease. 
One of the most dreaded diseases of roses is the ,,rose mildew”, caused by 
Sphaerotheca pannosa (Erysibaceae). Roses with soft leaves are more subject to it than 
those with hard, shining leaves. There are two periods of attack, one in the spring, 
often following a check caused by late frosts, and one soon after midsummer, when 
the roots are suffering from drought. Spraying with a solution of potassium sulphide 
or dredging with flowers of sulphur is very effective. “Rose rust”, Phragmidium sub- 
corticium, Schrank (Pucciniaceae), forms orange-coloured patches of uredospores on 
the leaves and young shoots; later on the black teleutospores appear on the under 
surface of the leaves. The leaves that fall in autumn, bearing these black dots, should 
be burnt, and the plants that have been attacked should be drenched with sulphate of 
copper solution during the winter. ‘Rose canker” is due to Coniothyriwm Fuckelii, Sack. 
(Sphaerioidaceae), which is considered by some the conidial stage of Leptosphaeria 
Coniothyrium, Sacci. It appears first as reddish patches, scattered over the green bark. 
Minute cracks then appear, and an increase of cells causes the formation of swellings, 
on which the pycnides appear as black dots. The fungus is a wound parasite. It is 
recommended that in the early stage when red patches appear they should be painted 
with Stockholm tar containing creosote. 
Actinonema Rosae, F. (Sphaerioidaceae) causes “rose black spot”, the mycelium 
penetrating the whole of the leaf and causing premature falling of the leaves, in con- 
sequence of which the buds expand before their time. Fibres radiate from the centre 
of the circular dark purplish spots which characterize the disease, and black perithecia 
are attached to the fibres. As soon as the spots appear, the roses should be sprayed 
with potassium permanganate or potassium sulphide solution; all spotted leaves must 
be burnt. . 
Septoria Rosae, Desm. (Sphaerioidaceae), forms minute, yellowish-green patches on 
the surface of the leaf. They enlarge and change to a pale brown colour, bounded 
by a dark line. If the leaf is not full-grown, when attacked, the brown patches often 
fall out, leaving holes. Those that remain in fully-developed leaves become studded 
with minute black points of spores. It is a difficult disease to get rid of. The bushes 
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