Protect your crop Part 2
Use the correct nozzles
G
ood crop protection starts with a good sprayer. Last month we discussed the parts of sprayers and what a farmer should consider when he buys a sprayer. In this issue we discuss different nozzles, and next month we compare costs of draw, hitch and selfpropelled sprayers.
Nozzle types
Various overseas companies manufacture a wide range of nozzles, each with its own purpose and application
Flat-fan nozzles
Flat fan nozzles are used on most farms for the broad cast or strip application of herbicide on well-prepared soil. Broad cast application with flat-fan spraying Flat-fan nozzles are mounted evenly on the spray bar. The spacing of the nozzles depends on the specific spray angle of the nozzle and the height of the spray bar from the ground. The spray bar must be placed at a specific height above the ground so that a 30% overlap is obtained on the sides of the spray patterns between nozzles. A code number on the nozzle indicates the spray angle and delivery volume of flat-fan nozzles. For example, the number 80 in the code number 8004 on the nozzle, indicates that the specific nozzle sprays out the mixture at an angle of 80°. The last two digits in the code, namely 04,
Compiled by JP le Roux
indicate the delivery of the nozzle which in this case will be: 4 US gallon per minute at a pressure of 40 pounds per square inch. Flat-fan nozzles with different spray angles and delivery volumes are available from suppliers. Strip spraying with flat-fan nozzles (Evenly) Code numbers on these nozzles are followed by an "E". This means that unlike the ordinary flat-fan nozzles, equal quantities of the mixture are delivered across the entire spray width of the spray pattern of a nozzle and therefore do not allow for overlapping with other nozzles. The whole spray width is uniformly covered by the one nozzle. The "E" type nozzles should not be used for broad cast applications.
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Cone type nozzles
Of the cone type nozzles, the following two are of great importance: Hollow cone nozzles As the name indicates, the spray pattern of this nozzle is in the form of a hollow cone. It is important to note the manner in which the nozzles should be assembled. Hollow cone nozzles are suitable for the application of fungicides and insecticides, and also for foliar feeding of plants. The fact that it sprays in the form of a hollow cone, results in different droplets reaching the target at different angles of incidence. In this way, better intrusion and covering are obtained in dense leaves. For example, hidden insects and fungi can also be targeted easier.
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