Growsafe Spray Application Techniques

Question 1

What is the recommended maximum wind speed for ground-based agrichemical spraying in New Zealand?

Accepted Answer

Up to 15 km/h, depending on the product and application method

Answer

In NZ, the general guideline for ground-based spraying is that wind speeds should not exceed approximately 15 km/h, though specific products and regional rules may require lower thresholds to minimise drift.

Question 2

What is calibration of spray equipment designed to ensure?

Accepted Answer

The correct volume of spray mixture is applied per hectare

Answer

Calibration ensures that the spray equipment applies the correct volume of spray mixture per hectare, which is essential for effective pest control and compliance with label rates.

Question 3

In NZ, what is an inversion layer and why is it dangerous for agrichemical spraying?

Accepted Answer

A weather condition where cool air is trapped under warm air, causing spray to hang and drift unpredictably

Answer

A temperature inversion occurs when cool air is trapped under a layer of warm air, preventing normal air mixing. Spray droplets can remain suspended in the still, cool air and drift long distances unpredictably, making it dangerous to spray.

Question 4

What nozzle type produces the coarsest droplets to reduce spray drift in NZ conditions?

Accepted Answer

Air induction (AI) or low-drift nozzles

Answer

Air induction (AI) or low-drift nozzles produce coarser droplets by mixing air into the spray, which significantly reduces the proportion of fine, drift-prone droplets. They are widely recommended in NZ.

Question 5

What is the purpose of adding a surfactant or wetting agent to an agrichemical spray mix?

Accepted Answer

To improve spray coverage and adhesion on plant surfaces

Answer

Surfactants reduce the surface tension of spray droplets, improving their spread and adhesion on plant surfaces. This is particularly important on waxy or hairy leaves where droplets might otherwise bead up and roll off.

Growsafe Practice Test

Growsafe Practice Test

Growsafe Spray Application Techniques