IN THEIR RELATION TO HORTICULTURE. 77 



drought, it may frequently be prevented by copiously watering the 

 soil, by which means Mr. Knight prevented this disease from attack- 

 ing his late crops of Peas. The rust in corn crops is produced by a 

 fungus in the same manner as the mildew ; but as it chiefly concerns 

 the agriculturist, we refer the reader to Professor Henslow's Report 

 on the Diseases of Wheat, ' Jour. Agr. Soc. Eng.,' vol. ii. p. 1, and the 

 Rev. Edwin Sidney's little work, ' The Smut of the Wheat.' 



Hoiiey-dew is a sweet and clammy exudation from the surface of 

 the leaves of plants during hot weather, and it is supposed to be occa- 

 sioned by the thickening of the circulating fluids in the leaf, which 

 being unable to flow back into the bark with their accustomed 

 rapidity, the sugary parts find their way to the surface. The disease 

 is common in the Oak, Beech, Thorn, and in many other plants. 

 Hitherto no remedy has been applied to it in general cases, as, though 

 it weakens plants, it seldom kills them. When, however, it appears on 

 plants in a state of high cultivation, for instance, in a peach-house, 

 or on a peach-wall, no time ought to be lost in applying the syringe 

 or garden-engine, and even rubbing it off the leaves if necessary, 

 otherwise the shoots or branches affected will be apt to be destroyed. 

 Some persons suppose the honey-dew to be occasioned by the aphides, 

 as the exuvia? of those insects are often found on leaves affected with 

 this disease. This view of the case has recently been confirmed by 

 writers in the ' Gardeners' Chronicle ' for the year 1869. It has also 

 been proved that ants are useful as antidotes to honey-dew. They 

 eat both the honey -dew and the aphides, and in this way consume 

 cause and effect together. 



Blight is a term which is very generally applied to plants when 

 under the influence of disease, or when attacked by minute fungi or 

 insects. Any sudden disease or death of a plant, or part of a plant, is 

 likewise termed a blight. Blight is often atmospherical or electrical ; 

 in some cases the continued action of dried air, and cold frosty winds, 

 preventing the flow of the sap, may bring on a disease which might be 

 called blight, exclusive of either the action of insects or of fungi or of 

 electricity ; but by far the greater number of instances of what is 

 called blight are produced by these three causes. In general the fungi 

 may be destroyed by the application of powdered sulphur, and the 

 insects by some of the different means that have been already pointed 

 out ; but we have no panoply against the lightning, nor security against 

 sudden changes of temperature. 



Flux of Juices. Under this term are comprehended the bleeding, 

 or flow of the juices of the vine and other plants, when accidentally 

 wounded, or pruned too early in autumn, or too late in spring ; and 

 the discharge of the descending sap, or the cambium, in a putrid state 

 between the bark and the wood, which frequently happens in elm- 

 trees, and is incurable. The flux of the rising juices seldom does 

 much injury, and may generally be prevented by pruning before the 

 sap is in motion, or after the leaf is fully expanded. 



The accidents to which plants are liable are chiefly confined to the 

 plants being broken ur bruised, and the general remedy is amputation 



