Shrivelling
A condition met with in immature fruit on plants growing in unfavourable conditions. The fruits, after being properly set, so far as can be judged from their appearance, begin to wither, and finally shrivel and fall off without ripening, so that the yield of fruit is frequently much lessened. The cause of this condition seems to be deficiency in the supply of water to the fruit, which usually shows no evidence of any disease due to parasitic Fungi or insects. Shrivelling is quite distinct from the fall of the fruit known as "Windfalls." This latter results from the presence in the fruit of insects, which eat the seeds and cause premature and imperfect ripening, with early separation from the plant. Such "Windfalls," on being cut open, will show clear traces of the cause of injury in the interior, round the seeds. The deficiency of water to which Shrivelling is ascribed may result from various causes: one of the most frequent is dryness of the soil or of the atmosphere, which causes evaporation from the green parts at a more rapid rate than that at which the roots can supply the fluid. Another cause of such deficiency is the luxuriant growth of leafy shoots on plants in sheltered, warm situations: evaporation goes on from them in excess of the power of the roots to supply the full amount needed by leaves and fruits. Poor soil and insufficient nourishment have been suggested as causes.
Remedies must be selected according to the cause, which must first be carefully sought out. If the soil is poor, manure should be supplied; if it is too dry, it must be watered. Any excess in green shoots must be pruned away. Ringing the fruiting branches--i.e., the removal of a narrow ring of bark from their bases--has been found very useful in diminishing the loss by Shrivelling; it tends, besides, to improve the quality of the fruit, and hastens the period of ripening. It acts by preventing the passage downwards, through the bark, of the food formed in the leaves of the branch, so that all the food is retained for the nourishment of the products of the branch itself. This method is applicable only to Dicotyledons with a distinct bark; but these include all the fruit-bearing plants of the colder temperate regions. Some plants bear the operation well; but, in general, it should only be performed as a last resort, as the branches are apt to die above the ring, or to snap off at it, and the parts below the ring do not get enough nourishment, owing to the obstacle interposed by it to the descent of the elaborated sap. The roots, too, suffer if many branches are ringed, and the whole plant is thus weakened and may die from the effects. There is also danger of parasitic Fungi or insects obtaining entrance into the tissues before the wound produced by ringing the branch has been properly healed.