Thinning of Fruit Crops

New Zealand Journal of Agriculture, Volume 73, Issue 5, 15 November 1946, Page 424

Thinning of Fruit Crops

By

S. FREW,

Orchard Instructor, Blenheim.

ONE of the most important orchard operations during the next two months is the thinning of the fruit crop. In a normal season practically all classes of fruit trees will benefit from thinning, and attention to this work will result not only in increased crops but .in improved vigour and condition of the trees.

EVERY, season blossoming is suffici- ' ently heavyfor an excessive fruit set, but weather, frost injury, shybearing varieties, and the normal drop which usually occurs in late, spring or early summer often tend to. reduce the amount of thinning necessary. How and When to Thin Thinning should be started as soon as the natural' drop has taken place and after all/ danger of a late frost has passed. To judge correctly how much should be thinned off and how much should be left - requires ■ experience. For general purposes pip fruits should not be allowed more than two to a bunch, and stone fruit, should be spread singly not less than 6in. apart. Stone fruit can be thinned quite . satisfactorily by hand. .Clusters of pip fruit are often difficult to thin by hand without loosening the remaining fruits, so a pair of thinning shears 1 should be used. ' . ...

It is more satisfactory to do the thinning -in two stages, the first-or major thinning being followed about a month later by a more detailed operation* when the season has progressed and the orchardist is able to judge whether a further reduction in crop is necessary.

Aims of Thinning Primarily, thinning is the means of regulating the size of individual- fruits and their distribution on the tree, but its importance goes further than that. It is. one method by which the fruit grower can improve the quality of the crop, maintain the trees in good condition and . growth, and reduce < the tendency to biennial bearing—a habit which seme varieties, of pip fruits in particular are prone to. develop. . As the prime , reason for thinning is to ■ increase the, size of -the fruits, the overladen tree requires' first attention. An excessive crop means undersized fruit, and at all costs sufficient must be thinned off to ensure the remainder reaching marketable, size. A crop of small fruit,* even 'if up to minimum size, is not -always an economic proposition. It is -costly to handle; has a low market value, and the number' of fruit required to fill a box is greater. It is therefore a sound proposition to endeavour to increase the size of this fruit by further thinning. That does not necessarily mean a reduction in the

_ ' ; crop. The difference a slight increase in the''diameter of individual fruits will make to; the volume of the prop is /not . always realised. For example, to .fill a bushel case requires 288 apples of 2in. diameter, 234 of 2|in. diameter, 175 of 2|in. diameter, but only 125 of 2fin. diameter. If the - average diameter of fruits can be increased by Sin., half the number can be thinned with little difference 'in the quantity harvested. • .Thinning is supplementary to the work of spraying in disease control, 4 diseased or blemished fruit being removed. This type of thinning can be

attended to better' during . the second thinning. ■' • • ‘ . • • . '•*>■ ■ • ; Tree Conditioning Good tree growth is ■ easier-to maintain with moderate '. annual cropping. Blossoming and fruiting are exhaustive processes, and an overcropped tree will become retarded in its growth. Unrestricted cropping in some varieties will result, in the . development ‘ of biennial bearing. The maintenance of a reasonable annual tree growth is the best protection from this habit, which has often been considered an inherent trait, fixed and immutable in some varieties. A happy medium of growth condition, commonly described i. as vigorous, is usually - associated with maximum ' fruitfulness. Every fruit grower should endeavour to maintain this vigorous condition and its high productive standard. {

Thinning should be treated not merely as a means of growing better-sized fruit, but also as a long-range plan of tree maintenance •which is well worth. the practice.

Orchardists*Labour Saver . - Case End-Brander . .

'T’HE work of branding the registered “ mark on . case ends has been speeded up considerably by a Horotane orchardist who has constructed a stamping device. 'lt consists of an inking pad, , sunk into a , bed on which the case ends are inserted, and a movable arm which carries . the brand made of rubber.

On the first downward movement of the . lever the brand is brought into contact with ■ the pad and inked. As it is raised again, a case end is slipped into the bed and on the next downward 1 movement the impression is made. In practice the stamp is inked by the use of one hand- while the case end is being handled with the other.

From 750 to 800 ends can be stamped in an hour.

The equipment illustrated is . used only for ends of the' No. 6 case • (7in. x 7in. x 18in.). Should .it be desired to use it on other .sizes the guide pieces would have to be altered. For clean stamping two important points of construction should be noted. The rubber brand should be mounted on a resilient bed such as a layer of crepe rubber, and the stamp pad in the base y should be set at an angle to the horizontal x so that the brand will » press on it evenly.

A. R. GRAINGER,

Orchard Instructor, Christchurch.