Roundup Application Time of Day Farmers and - Agronomy

17 Pages·2008·4.09 MB·English

Roundup Application Time of Day
Farmers and applicators claimed
(cid:131)
reduced weed control with early
morning or late evening
applications of Roundup.
Does light or dew effect Roundup
(cid:131)
performance?
Roundup Application Time of Day
Material and Methods
Roundup rate: 1 pt/A
(cid:131)
Application Stages:
(cid:131)
P: 4-8 inch velvetleaf and Palmer
(cid:190)
amaranth
LP: 6-12 inch velvetleaf and Palmer
(cid:190)
amaranth
Application time of day:
(cid:131)
6 am, 10 am, 1:30 pm, 5 pm, 9 pm
(cid:190)
Early Postemergence Application Information
Time of Day: 6AM 10 AM 1:30 PM 5 PM 9 PM
Date -------------------August 19-----------------
Temperature 57 F 73 F 79 F 83 F 68 F
Humidity 70% 55% 45% 42% 80%
Dew Yes No No No No
Palmer amaranth ----------------1 to 8 inches-----------------
Velvetleaf ----------------1 to 4 inches-----------------
Sunrise/Sunset 6:42 am-----------------------------8:20 pm
Late Postemergence Application Information
Time of Day: 6AM 10 AM 1:30 PM 5 PM 9 PM
Date -------------------August 23-----------------
Temperature 64 F 78 F 86 F 89 F 64 F
Humidity 96% 67% 59% 33% 81%
Dew Yes No No No No
Palmer amaranth ----------------4 to 12 inches---------------
Velvetleaf -----------------2 to 8 inches----------------
Sunrise/Sunset 6:45 am-----------------------------8:18 pm
The influence of application time of day on
Roundup performance, Manhattan, KS, 1999.
Application Palmer amaranth Velvetleaf
Time of Day Post LP Post LP
--------------(% control)-------------
6:00 am 96 85 96 47
10:00 am 99 100 99 99
1:30 pm 100 100 99 99
5:00 pm 100 99 97 97
9:00 pm 99 88 95 47
LSD 3 9
Postemergence – 6am
Postemergence - 10 am
Postemergence - 1:30 pm
Postemergence - 5 pm
Postemergence - 9 pm