STINK BUG THRESHOLDS: EMPLOY AFTER 2% STINK BUG DAMAGED CONFIRMED IN BOLLWORM SCOUTING - PowerPoint PPT Presentation

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STINK BUG THRESHOLDS: EMPLOY AFTER 2% STINK BUG DAMAGED CONFIRMED IN BOLLWORM SCOUTING

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Stink Bug and Plant Bug. Management in North Carolina: Training ... Stink Bug Damage to Bolls: Bollgard vs. Conventional ... Current Stink Bug Thresholds ... – PowerPoint PPT presentation

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Title: STINK BUG THRESHOLDS: EMPLOY AFTER 2% STINK BUG DAMAGED CONFIRMED IN BOLLWORM SCOUTING


1
Stink Bug and Plant Bug Management in North
Carolina Training Module
Jack Bacheler NCSU
2
Bollgard Adoption in NC 1996 - 2004
( of total cotton acreage)
83.1
69.7
63.5
72.5
54.6
Bollgard Acres (x 1000)
20.2
12.6
2.8
3.0
Year
3
Insecticide Applications / Acre 1996 - 2004
Conv. 2.8 Bollgard 0.9
4
Insect Shifts with Bt Cottons
Bollworms Budworms Europ. Corn Borers
Thrips Cotton Aphids Early Plant Bugs
Stink Bugs Late Plant Bugs Leaf-footed Bugs
5
Undamaged Open Boll
Stink Bug Damage
6
Stink Bug Damage to Bolls Bollgard vs.
Conventional Cotton, 1996-2004
83
Damaged Bolls
64
55
20
72
70
13
Year
7
Almost all bug damage to bolls in NC is caused by
the following
Brown Stink Bug
Green Stink Bug
Plant Bug
8
Southern Green
Green
Brown
Common Stink Bug Nymphs
9
Plant Bug Adult
10
Plant Bug Nymph
11
Pre-bloom Square Loss to Plant Bugs Generally of
Little Consequence in NC
12
Post-bloom Plant Bug Damage
13
Late Season Plant Bug Thresholds
15 Dirty Blooms
10 Internal Boll Damage (also varies like stink
bug)
14
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15
Effect of Various Stink Bug Stageson Harvestable
Locks in NC
GSB Green Stink Bug BSB Brown Stink Bug
97
No SB
84
83
GSB 3rd
GSB 4th
Harvestable Locks
47
40
BSB adult
34
GSB 5th
GSB adult
Stink Bug Species and Instar
16
Scouting for Stink Bugs
  • Sample at least 50 quarter-sized bolls
  • Crush or cut open all bolls and examine lint
    and boll walls
  • Count warts and internal damage

17
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18
Scouting for Stink Bugs
  • Sample at least 50 quarter-sized bolls
  • Crush or cut open all bolls and examine lint
    and boll walls
  • Count warts and internal damage

19
Penetrations
Wart
Wart
Stained lint
Internal Boll Damage by Stink Bugs
20
Scouting for Stink Bugs
  • Sample at least 50 quarter-sized bolls
  • Crush or cut open all bolls and examine lint
    and boll walls
  • Count warts and internal damage

21
Current Stink Bug Thresholds in North Carolina
  • 10 damaged internally-damaged bolls (first
    3.5 wks. of bloom)
  • Then raise threshold based on proportion of
    bug safe bolls (see next slides)

22
When is a Boll Safe from Stink Bugs?
Answer at approx. 25 Days
23
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24
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25
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26
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27
Possible Boll Sizer?
Small-bolled lines 2nd positions 7-9 weeks
post-blm.
Large-bolled lines 1st position 4-6 weeks
post-blm.
28
Suggested Damaged Boll Thresholds for Stink Bugs
Boll Ratio
Safe (gt 1.25 dia.)
Susceptible (lt 1.25 dia.)
Threshold ()
10
0
1
15
0.5
1
20
1
1
25
1.5
1
30
2.0
1
35
2.5
1
A BollChecker may be helpful in determining
ratios. Boll diameter approximately 1.25
inches or larger.
29
Summary of Scouting Procedures
  • Conduct initial boll-sizing approx. 4 wks after
    1st
  • bloom.
  • Cut open or crush 25 to 50 quarter-sized
    bolls/
  • field and examine for internal damage
  • Count any internal damage except pin pricks
  • Try to determine ratio of brown or green stink
    bugs
  • If ½ threshold or more is reached, re-scout
    field
  • within a few days
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