APPLICATION OF ORCHARD SPRAYS.

New Zealand Journal of Agriculture, Volume 54, Issue 2, 20 February 1937, Page 71

APPLICATION OF ORCHARD SPRAYS.

111. SPRAY NOZZLES— continued.

G. G. Taylor,

Plant Disease Division, Plant Research Bureau, Palmerston North

Depth of Penetration.

Depth of penetration refers to the distance to which spray is driven from the nozzles and serves to indicate the suitability of any nozzle for driving spray to the highest parts of trees and forcing it amongst the foliage, into bark crevices, bud-scales, &c. In order to eliminate the influence of wind' when making comparisons between different nozzles it was found necessary to take measurements under windless conditions, the maximum vertical height to which spray was driven being taken as an index of penetration. Thus measurements given in the following pages only indicate relative depths of penetration and cannot be taken as the actual distances to which spray would be driven under normal working-conditions. EXPERIMENTAL METHOD. . A pole, marked in feet and 25 ft. in length, was erected in a perpendicular position. Close to the base of the pole the nozzles were fixed so that they pointed vertically upwards. Measurements of penetration were taken from the maximum height to which spray was actually driven, any drift in excess of this height being ignored. Owing to variations caused by slight air-movements, tests were repeated on two or three different days and the average measurements taken. Nozzle-pressures were measured and adjusted, and the construction of different nozzle parts varied, by methods identical with those previously described for testing distribution and fineness of . spray droplets (see this Journal, Vol. 53, p. 68). RESULTS. Pressure. — Increase in pressure from 50 lb. to 300 lb. caused a marked increase in depth of penetration (Fig. 18). The rate of increase was greatest as pressures were increased from 50 lb. to approximately 100 lb. . Increase in penetration with increasing pressure was highest where disks having the greatest diameter of apertures were used (Fig. 18). Disk Aperture. — The depth of penetration increased as the diameters of the disk apertures were increased from in. to in. and - 6 ? T in. The rate of increase with increasing diameter of disk aperture was highest where whorl-plates with the greatest diameter openings were used (Fig. 19). Thickness of Disk. — Increase in disk-thickness from KT in. to in. caused a slight increase in penetration. Further increase in thickness to in. had no measurable effect. Depth and Shape of Whorl-chamber. —Increasing the depth of the whorl-chamber from approximately 0-08 in. to 0-24 in. caused only a slight increase in penetration. Alteration in the shape of the whorl-chamber by means of a |-in.diameter pin projecting 0-04 in. from the centre of the whorl-plate did not cause any appreciable variation in penetration. With the pin projecting 0-08 in. penetration appeared to be slightly reduced.

FIG. 18. ' EFFECT OF. INCREASE IN PRESSURE ON THE MAXIMUM HEIGHT OF CARRY r. UNDER WINDLESS CONDITIONS. The different curves show the effects produced when using whorl-plates and disks of varying construction, as follows: — Curve A : Whorl-plate with six openings of diameter in. at angle of 22-5° ; disk aperture in. diameter. ■ Curve B : Whorl-plate with six openings of diameter sJ,in. at angle of ■ 22'5° ; disk aperture in. diameter. Curve C : Whorl-plate with six openings of diameter in. at angle of 22-5° ; disk aperture in. diameter. Curve D : Whorl-plate with six openings of diameter in. at angle of 22*5° ; disk aperture in. diameter. Curve E : Whorl-plate with two openings of diameter in. at angle of •' 67-5° ; disk aperture in. diameter.

FIG. IQ. EFFECT OF INCREASE IN THE DIAMETER OF DISK APERTURE ON THE MAXIMUM HEIGHT OF CARRY UNDER WINDLESS CONDITIONS WITH A NOZZLE PRESSURE OF APPROXIMATELY 200 LB. The different curves show the effects produced when using whorl-plates of varying, construction, as follows : Curve. A: Whorl-plate with six openings of diameter %% in. at angle of 22-s°. . Curve B : Whorl-plate with six openings of diameter ■ in. .at angle of 22-s°. Curve C: Whorl-plate with six openings of diameter in. at angle of 22-s°. Curve D : Whorl-plate with two openings of diameter in. at angle of 67-s°. ' Curve E : Whorl-plate with two openings of diameter in. at angle of ’ " 67-s°. ■ .

Diameter of Whorl-plate Openings. — Penetration was increased when the diameter of the whorl-plate openings was increased from in. to in- to in. This effect was most marked where disks having the greatest diameter apertures were used (Fig. 20).

- G. 20. EFFECT OF INCREASE IN THE DIAMETER OF WHORL-PLATE OPENINGS ON THE MAXIMUM HEIGHT OF CARRY UNDER WINDLESS CONDITIONS. WITH A NOZZLE . PRESSURE OF APPROXIMATELY 200 LB. The different curves show the effects produced when using whorl-plates and disks of varying construction, as follows : ’ Curve A : Whorl-plate with six openings at angle of 22-5° ; disk aperture in. diameter. ' Curve B ; Whorl-plate with six openings at angle of 22-5° ; disk aperture . 1 in. diameter. Curve C : Whorl-plate with two openings at angle of 67-5° ; disk aperture in. diameter. , - Curve D : Whorl-plate with two openings at angle of 67-5° ; disk aperture in. diameter. Angle of Whorl-plate Openings. — Increase in the angle of the whorlplate openings from 22-5° to 45 0 and 67-5° decreased penetration in those cases where whorl-plates with apertures in. and in. diameter were used. With whorl-plate . apertures of in. diameter the effect of increase in the angle of the openings on the depth of penetration was not significant (Fig. 21).

FIG> 21. EFFECT OF INCREASE IN THE ANGLE OF WHORL-PLATE OPENINGS ON THE, MAXIMUM HEIGHT OF CARRY UNDER WINDLESS CONDITIONS WITH A NOZZLE PRESSURE OF APPROXIMATELY 200 LB. The different curves show the effects produced when using whorl-plates and disks of varying construction, as follows : Curve A : Whorl-plate with two openings of diameter in. ; disk aperture in. diameter. Curve B : Whorl-plate with four openings of diameter in. ; disk aperture A in. diameter. Curve C : Whorl-plate with two openings of diameter in. ; disk aperture K B f in. diameter. Curve D : Whorl-plate with two openings of diameter in. ; disk aperture •sk in. diameter. ; ,

Number of Whorl-plate Openings. The depth of penetration was increased by increase in the number of whorl-plate openings from two to four and six (Fig. 22).

FIG. 22. EFFECT OF INCREASE IN THE NUMBER OF WHORL-PLATE OPENINGS ON THE MAXIMUM HEIGHT OF CARRY UNDER WINDLESS CONDITIONS WITH A NOZZLE PRESSURE OF APPROXIMATELY 200 LB. The different curves show the effects produced when using whorl-plates and disks of varying construction, as follows : Curve A : Whorl-plate with diameter of openings in. at angle of 22-5° ; disk aperture in. diameter. Curve B : Whorl-plate with diameter of openings in. at angle of 45 0 ; disk aperture in. diameter. Curve C : Whorl-plate with diameter of openings 6 y in. at angle of 45 0 ; disk aperture f. { - in. diameter. Curve D : Whorl-plate with diameter of openings /y in. at angle of 45 0 ; disk aperture in. diameter.

Strainer. — The use of a strainer had no measurable effect on the depth of penetration. GENERAL OBSERVATIONS. The maximum height of carry was varied considerably by wind, being reduced 50 per cent, by even a light breeze. It was noted that the effect of wind was greatest where nozzles having the poorest penetration were used. Some of the spray tended to fall before reaching the maximum height, thus only a portion of the total volume of spray delivered by the nozzle had maximum penetration. (To be continued.)

The production of superphosphates in 1935-36 reached a new record high level (322,522 tons), being 5,542 tons, or 2 per cent., greater than the 1934-35 figure. Pedigree Grass and Clover Seeds. With a view to further improving the pastures of the Dominion, the Division early in 1935-36 had harvested some Government pedigree grass and clover seeds. Such seed, which will be produced during each succeeding year, has been grown on contract from seed especially raised at the Plant Research Station at Palmerston North. The production of such seed is considered to mark a further advance in the already high standard of the Dominion's certified seed. Pedigree stock seed is intended for sowing down areas to be devoted to the production of certified pedigree seed. No difficulty whatever was experienced in the disposal at remunerative prices of the 800 bushels of Government pedigree stock perennial rye-grass seed and several hundred pounds of pedigree whiteclover seed. Annual Report, Director of the Fields Division.