226 THE FRUIT GROWER'S GUIDE. 



the sides at the top, about 6 inches long, to keep the ladder from injuring the trees. It 

 also ought to have an iron-shouldered rod, as before advised, at the lower end, middle, 

 and top to keep the sides in place. 



In the engravings (6 and 7, page 225) a form is represented which may be used as 

 steps or ladd er. It consists of two parts, one narrower than the other, and connected at 

 the top round by a slot (a), about 4 inches in length, which serves as a hinge. The ends 

 of the narrow part are cut, as in c, to the depth of 2J inches, and when the ladder is 

 opened out, the second round of the wide part fits into these notches, as at &, and the 

 ladder is then firm and available for wall trees and other purposes. It is capable of 

 modification, and its length may be increased both as steps and ladders. More steps in 

 the length are shown in 6 than 7. The steps are exceedingly useful in pruning pyramid 

 and other forms of dwarf trees, also in fruit houses. Two pairs of them, with a plank 

 between, form a stage for thinning grapes and many other purposes. They can be 

 made any height, and risk of their slipping at the foot is easily avoided by hooks on the 

 sides with a linked chain to regulate the straddle. 



Pincers for drawing nails are often required, and a screw-driver is indispensable in 

 the packing of fruit. 



DISEASES. 



Fruit-tree ailments are attributable to 1, excess or deficiency of temperature, mois- 

 ture, and light ; also impure air and defective soil ; 2, parasitic animals and vegetables. 

 Excessive heat excites and dilates the tissues inconsistently with healthy growth; 

 extreme cold (relevant to the subject) destroys the connection between the cells, frost- 

 bitten parts having their vesicles partly or completely isolated. Undue moisture pre- 

 judicially affects the tender tissues of the roots. Defective light hinders the chemical 

 changes necessary to the complete development of the chlorophyll, a gloomy season 

 being unfavourable to the health and productiveness of trees. A vitiated atmosphere 

 causes trees to sicken, the soot and dust of towns closing their pores, thus obstructing 

 respiration and evaporation, whilst sulphurous fumes are pernicious. Chemical changes 

 effected in soil by manures or cultural operations, when unsuitable, injuriously affect 

 fruit trees. Fertility of the soil depends chemically upon the presence in it of all the 

 ash-elements and nitrates in proper quantity and combination. Soils, however, may 

 be fully supplied with the nutritive elements, yet the trees be barren or unhealthy. 

 Certain physical conditions of soil, rendering it congenial to vegetation, are no less 

 indispensable to health and high productive power than an appropriate amount of 



