The Beaufort scale is a measure that relates wind speed to observed conditions at sea or on land. It can be used in place of a wind-measuring instrument to assess the suitability of the weather conditions for spraying.
Pest control operators need to be aware of wind conditions at the time of application as some conditions are not ideal for spraying pesticides.
Table 1 outlines different wind speeds and their corresponding Beaufort number, and how these conditions relate to pesticide spray application.
Wind speed and pesticide spray advice
Table 1: Beaufort scale and pesticide spraying conditions
|
Beaufort number
|
Wind speed
|
Description
|
Spray notes
|
|
0
|
<1km r="">
<1 knot="">
|
Calm: smoke rises vertically
|
Avoid fine sprays,
especially on warm, sunny days
|
|
1
|
1–5 km/hr
1–3 knots
|
Light air: wind direction shown by smoke drift, not wind vanes
|
|
2
|
6–11 km/hr
4–6 knots
|
Light breeze: wind felt on face, leaves rustle, wind vanes move by wind
|
Ideal spraying conditions
|
|
3
|
12–19 km/hr
7–10 knots
|
Gentle breeze: leaves and twigs in constant motion, wind
extends a light flag
|
|
4
|
20–28 km/hr
11–16 knots
|
Moderate breeze: raises dust and loose paper, small branches move
|
DO NOT
attempt to apply
pesticides under these conditions
|
|
5
|
29–38 km/hr
17–21 knots
|
Fresh breeze: small trees sway, crested wavelets form on
inland waters
|
|
6
|
39–49 km/hr
22–27 knots
|
Strong breeze: large branches move, umbrellas hard to use
|
|
7
|
50–61 km/hr
28–33 knots
|
Near gale: whole trees move, breaks twigs off trees,
difficulty walking against the wind
|
|
8
|
62–74 km/hr
34–40 knots
|
Gale: breaks twigs off trees, generally impedes progress
|
|
9
|
75–88 km/hr
41–47 knots
|
Strong gale: slight structural damage (e.g. chimney pots and roof tiles removed)
|
|
10
|
89–102 km/hr
48–55 knots
|
Storm: seldom inland, trees uprooted, considerable
structural damage
|