38 BULLETIIs^ 1329^ U. S. DEPAETMEXT OF AGEICULTUEE 
species attacking certain bamboos of the Phyllostachys group was 
first noted in the United States four or five years ago and so far 
seems to be confined to Florida and one place in Georgia. The 
disease attacks the leaves, causing numerous brown powdery spots 
on the under surface with correspondingly yellow discolorations on 
the upper side. When badly aifected the leaves shrivel and dry up. 
The powdery dustlike material on the under surface of the leaves 
forms the spores, or reproductive bodies, of the fungus. While at 
Brooksville, Fla., in 1921, the teleutospores, or winter form, of the 
fungus were found by the writer on old leaves that had fallen to the 
ground. A few weeks later the uredo, or red-rust form, began to 
show on numerous plants. It is this form that causes most of the 
injury. The life history of the fungus has not been studied, so noth- 
ing is Imown as to its life cycle. Whether intermediate stages occur 
on other host plants, as is the case with certain grass rusts, remains 
to be determined. The effect of the rust is to check growth by injury 
to the leaves, many of which are shed prematurely as a result of the 
disease. 
In view of the present limited distribution of the rust it is im- 
portant to exercise every care to prevent its spread. To this end 
care must be taken in propagating only from rust-free stock. If the 
disease appears the rusted leaves should be raked up and burned. 
It may even be desirable to cut all plants back to the ground and 
when the brush is dry burn it. This has been done in some cases, 
using a blast torch and oil to aid in the burning. Plats burned over 
in this way early in spring soon recover their growth, and if there 
is no infectious material near by the plants are likely to remain free 
from rust for a time at least. There is no experimental evidence to 
show that the rust can be completely eradicated by the burning 
method, but even where infectious material is near, cutting and burn- 
ing greatly aid in holding the disease in check, being particularly 
applicable to the small-growing Phyllostachys. 
MELANCONIUM CULM DISEASE 
A disease which has been noted for several years at the Barbour 
Lathrop bamboo grove, near Savannah, Ga., shows on large culms 
when these are 40 to 50 feet high and 2 to 4 inches in diameter. The 
internodes near the ground become discolored, turning purplish black 
and sometimes brown. The discoloration is not sharply defined and 
gradually extends around and upwards until the whole joint is af- 
fected. The culm eventually dies and the leaves dry up. The wood 
of the discolored part is found to be permeated with mycelium 
threads. These threads constitute the vegetative parts of a fungus 
found penetrating the tissues of the wood. When poii:ions of the 
diseased wood are cut out under properly safeguarded conditions 
and placed in a moist, warm, sterile chamber large quantities of 
mycelium soon develop. This gives rise to quantities of spores. 
A similar disease has been reported from Italy {H) as attacking 
several kinds of bamboo. The fungus causing the Italian disease 
has been identified as M elanconiurn hamhnscf-e^ and the one occurring 
here appears to be the same. It is doubtful whether these fungi 
attack liealthy plant tissue. The culms at Savannah may have been 
previously weakened in some way. 
