The herald., 1896-07-18
THE FURROW TRENCH

oranges &C. nobilis) are occasionally
affected, but the damage is not usually
very great. The sour orange &C. bigara
dia) is apparently almost wholly free
rrufH Inai-uI- gururrao. rhe .pyritere car
ried on careful search for the disease
on this species, but succeeded in finding
only two unQuestionable cases. The sour
orange used as stock for budding re-
mains free from attacks. and in Florida
its use for this purpose is almost sure
preventive of the disease. 1t is prob
able that the disease occurs on the lime
&c. limetta) and citron &C. medica) also,
but no cases have as yet been observed
in Florida.
Cause-Mal-di-go has been stud
led extensively by many investigators
but as yet the cause of the disease is not
surely known. 1t is thought by many
to result from the attacks of some para
site organism, and Prof. Briosi describes
and names fungus (Fusisporium lin
onO which he finds always accompany
ing the disease. He is inclined to consider
the fungus the cause of the trouble, but
Is in doubt as to whether 1t is the primary
cause. He says, however: Il do not
believe there can be any doubt that its
presence accelerates the disorganization
of the tissues and aids in extending the
disease"
The manner in which the disease
SP'NesNS' appealing at ullleIeHl QdtcS
first in one country and then in another,
and extending gradually from grove to
grove, strongly indicates that it is con-
taglous, being caused or at least greatly
aggravated by some parasitic organism.
Some investigators also think that the
disease is due to physiological derange-
ments, for instance, imperfect aeration
or the roots. The most effective treat
ment known is based largely on this sup
position.
Observation has shown that the dis
ease Is most common where any of the
following conditions exists Improper
drainage; planting the trees so close to-
gether that the ground Is continually
shaded and kept moist; continuous use
OF organic fertilizers; excessive cultiva-
ton; continuous excessive irrigation,
which keeps the soil Yater-soaked, and
deep planting,
Trees badly affected with the disease
frequently recover If transplanted to
some other location, on apparently SINH
lar soil. and given plenty of room. A
remarkable instance of this was seen by
the writers in case where forty acres
were planted out some five years ago
with large trees affected with foot rot.
After three years every tree of the sew
eral thousand transplanted to this grove
seemed to have fully recovered.
Treatment-Very many attempts have
been made, both in Europe and in the
United States, to find remedies for this
malady. One Of the most important dis
coveries Is that it can be prevented by
using immune or resistant stocks 1t
was early noticed that the sour orange
and trees on sour orange stocks were al
most absolutely exempt from the mall
ady By using this stock in setting out
young groves the disease can be effect
ually prevented. On high, dry soils, not
suited to the sour orange, grape fruit
stock can be used, as it also is quite re-
sistant.
Many curative treatments prove more
or less beneficial, and this has led to
conflicting claims as to which is the
sufficient to simply dig away the earth
plains why so many different applica-
tions made to the roots seem to benefit
the tree. The very act of opening the
soil and exposing the roots to the air of
itself tends to effect cure. AS the dis
ease Is probably caused by parasite,
1t is important that no wounds be made
on healthy roots in removing the soil.
II Is desirable to cut away all infected
park and wash the scars with some anti
septic solution, such as sulphurous acid,
carpolic acid or sulphur wash. Where
trees are cosely planted it is usually
necessary to remove and transplant a
part or them TO give light and air free
access to the roots and trunk. The use
OF nighly organic heterogeneous fertilizers
snouid be avoided, and also excessive
or deep cultivation.