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UC Pest Management Guidelines


Forktailed bush katydid.

Plum

Katydids

Scientific names:
Angularwinged katydid: Microcentrum retinerve
Forktailed bush katydid : Scudderia furcata

(Reviewed 5/06, updated 4/09)

In this Guideline:


DESCRIPTION OF THE PESTS
Of the two species of katydids found in California stone fruit orchards, the forktailed katydid occurs most frequently. Angularwinged katydid nymphs and adults have a distinct humpbacked appearance. The forktailed bush katydid is smaller and is not humpbacked. Nymphs of both species have very long antennae that are banded black and white.

Katydids lay disc-shaped eggs in fall. The eggs of the angularwinged katydid are 0.125 to 0.15 inch long (3–6 mm), gray, and laid in two overlapping rows that form a long "tent" on the surface of twigs and branches. Forktailed bush katydid eggs are about 0.125 inch long (3 mm) and are inserted into the edges of leaves. Eggs of both species hatch in April and May. Adult katydids appear in midsummer and lay eggs in fall.

The angularwinged katydid emerges in May and has only one generation a year. Forktailed bush katydids emerge about a month earlier than the angularwinged species. Eggs are laid in June and July. Some of these eggs will hatch in July and August, whereas the rest will overwinter.

DAMAGE

Katydids occasionally become damaging pests in orchards that have not been treated with broad-spectrum pesticides. High populations of these pests also occur in cycles, and they may cause damage one year and not the next.

Nymphs feed on leaves or fruit. Katydid nymphs tend to take one bite out of a fruit before moving on to another feeding site. Hence, a few katydids may damage a large number of fruit in a short time. Feeding wounds heal over and enlarge into corky patches as the fruit expands. The most serious damage occurs when katydids feed on young fruit, which become severely distorted as they develop. Nymphs and adults also chew holes in foliage. Smaller nymphs feed in the middle of the leaf, creating small holes, whereas larger nymphs and adults feed on the leaf edge. Damage to fruit and foliage resembles that of green fruitworms.

MANAGEMENT
Look for katydid damage when monitoring for leafrollers in spring. From April to May, examine shoots in the center of the tree for feeding damage. Early in the season when katydids are small, they create small holes in the center of the leaf, whereas cutworms and other leaf feeders will be feeding on the leaf edge. If you find feeding damage, look for nymphs. Shaking foliage onto large beating sheets may be helpful; nymphs can be difficult to see on the tree because they jump readily when disturbed.

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. SPINOSAD
  (Entrust)# 1.75–2 oz 4 7
  (Success) 6 oz 4 7
  MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Apply to young nymphs (1st and 2nd instars).
 
B. AZADIRACHTIN#
  (Neemix) 4.5 0.25–1 pt 12 0
  MODE OF ACTION GROUP NUMBER1: 18B
  COMMENTS: Moderately effective on immature katydids. Must be contacted by spray so good coverage is essential.
 
C. PHOSMET
  (Imidan) 70WP 4.25 lb 3 days 7
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Effective against nymphs and adults. Apply with a buffer to lower solution pH to 5.0.
 
D. ESFENVALERATE*
  (Asana XL) 10-12 fl oz 12 14
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Pyrethroid residues remaining on leaves and bark will continue to affect mite predators long after application, increasing potential for spider mite infestations.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for use on organically grown produce.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
* Permit required from county agricultural commissioner for purchase or use.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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