Cooperative Extension
No. 8
Community-Wide Lygus Action Plan
The University of Arizona • College of Agriculture
Our action plan called for community-wide sampling of Lygus over multiple hosts. Much work remains in understanding the large dataset collected
during the past four months. Cotton production is
several weeks ahead of last year’s schedule. Seed
alfalfa production is even farther ahead of schedule. There were few, significant non-crop sources
of Lygus this year. Lygus were found mainly in alfalfa crops in the spring and early summer. Movement and distribution of Lygus are related to host
availability and adult preferences. We need your
input on what is now needed by this community of
growers and how, if at all, this project has helped
meet your needs this year.
Lygus Sampling Comes to an End
This small group of concerned growers and affiliated personnel put in action this community-wide
plan. Central to this plan was the organized, independent sampling of area fields for Lygus. Sampling concludes next week. We now have an objective source of data that will help answer questions about the distribution and abundance of this
shared pest.
Forage Alfalfa Host Management
Another aspect of this action plan was the planned
management of forage alfalfa host availability.
Lygus adults will preferentially move to or stay in
vigorously growing or flowering alfalfa. Conventional cutting of alfalfa forces adults out of these
fields and into more sensitive crops like cotton or
seed alfalfa. The MAC farm managed several large
fields of alfalfa using a bench-cutting strategy. This
practice was begun early in the spring season and
continues today. Cotton fields immediately adjacent to these hay fields have stayed nearly Lygusfree.
July 10, 2000
When alfalfa hay prices decrease during the summer, some growers elect to withhold water and discontinue cutting. These fields can remain green,
start flowering, and serve to produce large numbers of emigrating Lygus. Efforts are needed to
identify these situations early enough so that contingency plans can be made.
Communication
A goal of this group and this newsletter is to foster
better communication. In Cooperative Extension
we seek to deliver science-based, educational programs and to facilitate communication and crosscommodity interactions that enable our agricultural
clientele to compete globally. We welcome any
feedback about this newsletter, our action plan, or
other programs that relate to your interests.
Credit Where Credit is Due!
A project of this size or nature, planned and implemented so quickly, relies on the good faith efforts
of many different people. The sampling efforts
alone constitute the individual contributions of
several members of my staff in the field, but many
others have contributed, too. We hope it helps make
a difference. We also want to give credit where
credit is due:
Samplers: Francisco Borjorquez, Gilberto Castro,
Gloria Gomez, John Hawkins, John Huen, Curtis
Main, Sam Goodwin
Mapping: Larry Antilla, Mike Whitlow, Jerry Kerr,
Bill Tompkins, and the rest of the ACRPC Staff
Organization and Data Entry: Virginia Barkley,
Ghislaine Majeau
Newsletter Review & Distribution: Bob Roth, Jennifer Jones (Web), Lily Reyes (mail)
70
0 Lygus
35
Cotton (% of Fields)
Weeds
Hay
30
Sd Alfalfa
25
Cotton
20
15
10
60
40
30
20
7-Jun
7-Jul
30-Jun
23-Jun
9-Jun
16-Jun
2-Jun
26-May
19-May
5-May
12-May
28-Apr
21-Apr
0
7-Apr
0
14-Apr
10
31-Mar
≥ 10 Lygus
50
5
24-Mar
14-Jun
60
4-Jul
Weeds
50
Cotton
7-Jul
30-Jun
23-Jun
9-Jun
16-Jun
2-Jun
26-May
19-May
24-Mar
7-Jul
30-Jun
23-Jun
16-Jun
9-Jun
2-Jun
26-May
19-May
5-May
12-May
28-Apr
21-Apr
0
14-Apr
0
7-Apr
10
31-Mar
10
5-May
20
12-May
20
30
28-Apr
Cotton
Sd Alfalfa
21-Apr
30
40
7-Apr
Sd Alfalfa
Hay
14-Apr
40
Adults / 100
Hay
31-Mar
50
24-Mar
140
100
Weeds
90
Weeds
120
80
70
Total Lygus / 100
Hay
Sd Alfalfa
60
Cotton
50
40
30
20
Hay
100
Sd Alfalfa
80
Cotton
60
40
20
10
Peter Ellsworth, IPM Specialist1
Steve Husman, Area Extension Agent2
Dave Langston, MAC Farm Superintendent1
1
2
7-Jul
30-Jun
23-Jun
16-Jun
9-Jun
2-Jun
26-May
19-May
12-May
5-May
28-Apr
14-Apr
24-Mar
7-Jul
30-Jun
23-Jun
16-Jun
9-Jun
2-Jun
26-May
19-May
12-May
5-May
28-Apr
21-Apr
14-Apr
7-Apr
31-Mar
24-Mar
Figure 2: Number of Lygus per 100 ‘cotton-style’ sweeps in various crops
in the western Pinal County area. Each chart represents an average of
multiple sites in multiple fields each week. Due to differences in the
number of sites each week, these numbers are for general information
only. No sample was taken from seed-alfalfa on 28 March. Each site is resampled each week unless it has been recently sprayed, cut or otherwise
removed, or watered. Each chart shows the results for the entitled life
stage. Small Nymphs are instars 1–3; Large Nymphs are instars 4–5; All
Nymphs is the sum of these 2 nymphal categories; Total Lygus is the sum
of all stages of Lygus including adults.
7-Apr
0
0
31-Mar
Large Nymphs / 100
28-Jun
60
Weeds
All Nymphs / 100
21-Jun
Figure 1: Weekly percentage of cotton fields in the area (of those that we
sample) that had no (0) or ≥ 10 Lygus per 100 sweeps.
21-Apr
Small Nymphs / 100
40

Department of Entomology, Maricopa Agricultural Center, Maricopa, AZ
Pinal County Cooperative Extension Office, Casa Grande, AZ
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