24 
continue in a fruit-bearing condition for several years, and even carry 
heavy crops; but with the progress of the diseasé the fruit becomes 
gradually reduced in size, and at length the power of maturation is 
lost. In the last stage the tree becomes almost leafless, yet still 
develops flowers, although the pollen is usually abortive, and the © 
ovaries do not become fertilized. It may linger in this condition for 
several years. . 
The disease commences with the decay of the minute fibrils of the 
root ; the fibres are next affected, and the decay extends to the larger 
arms ; the epidermis peals off in flakes or rots away, when the decay 
spreads to the woody parts, and, after attacking the bark of the collar, 
makes its appearance above ground, ascending the stem fora foot or 
more, the decaying bark emitting a nauseous odour, and falling away 
in pieces ; even before it falls, and while apparently sound, it may be 
rubbed off by the fingers. The bark is sometimes attacked by fungi, 
but their inroads are simply due to the progress of the disease, which 
has prepared a suitable nidus for the parasite, and must not be mis- 
taken for the cause.* 
- If the decay of the bark is confined to one side of the stem the 
plant may continue to produce fruit for years, but if the entire 
circumference is affected, so that the outer layers of tissue are 
destroyed, death speedily ensues. 
Healthy trees produce masses of matted rootlets immediately 
beneath the surface of the soil; every minute fibril being clothed with 
root-hairs near the tip. In diseased trees the branches of the root are 
almost naked; but few fibrils having escaped decay, and they are so 
much affected as to be almost destitute of root hairs. 
CausEs. 
Foot-rot is chiefly caused by the rootlets penetrating into a cold 
retentive subsoil; ‘deep planting; earthing-up, whether with wood- 
ashes, stable-manure, or with earth; excessive manuring, &c.; in some 
cases by excessive autumn pruning, leading to a late growth, and 
consequent development of unripened wood. Young plants that have 
been kept so long in pots as to become “ pot-bound” are peculiarly 
liable to be attacked. 
PREVENTION AND CURE. 
Excessive autumn pruning, the application of manure late in the 
season, or any cause tending to stimulate root-action shortly before 
the approach of winter must be avoided, on account of the risk 
attending a sudden arrest of growth.+ 
The degree to which remedial measures may fairly be expected to 
prove successful must depend to some extent upon the stage of the 
disease ; as a general rule, so long as decay has not encircled the stem, 
recovery may be hoped for. The soil must be thoroughly drained, 
*In this stage Ihave seen a trunk clothed on one side with a dense growth of Hirneola 
polytricha, the fungus so much in demand amongst the Chinese. 
tAt the Bay of Islands, in June last, oranges and lemons in active growth were severely cut by 
frost, while trees which had completed the season’s growth were uninjured. 
