How to Manage Pests
UC Pest Management Guidelines
Katydids are becoming a more common pest of pomegranate. There are two species of katydids found in California orchards, the angularwinged katydid and forktailed bush katydid. The forktailed bush katydid occurs most frequently in pomegranate.
The forktailed bush katydid is smaller and is not humpbacked. Nymphs have very long antennae that are banded black and white. Disk-shaped eggs are about 0.125 inch long (3 mm) and inserted into the edges of leaves. Forktailed bush katydids emerge in April, about a month earlier than the angularwinged species. By midsummer, adults can be found. In June and July, oviposition begins, and continues through the summer and fall. Some of these eggs will hatch in July and August, whereas the rest will overwinter. There may be one or two generations of forktailed bush katydid per year.
The nymphs and adults of the angularwinged katydid have a distinct humpbacked appearance. Nymphs have very long, uniformly green antennae. Disk-shaped eggs 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. The angularwinged katydid emerges in May and has only one generation a year. Adult katydids appear in midsummer. Oviposition begins in June and July and continues throughout the summer to fall.
Katydids occasionally become damaging pests in orchards that have not been treated with broad-spectrum pesticides or where tillage is not used. High populations of these pests also occur in cycles, and they may cause damage one year and not the next. The angularwinged katydid is typically less damaging because it is less common.
Both nymphs and adults feed on leaves or fruit but the adults are the most damaging. Katydids tend to feed on a small section of a fruit (about 0.5 inch wide and 0.25 inch deep) before moving on to another feeding site. Hence, a few katydids may damage a large number of fruit in a short time. Katydids will feed on any size fruit. Feeding wounds heal over and enlarge into corky patches as the fruit expands. Damage to a young fruit can cause it to become severely distorted as it develops. 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.
Look for katydid damage in the spring. Also, use a sweep net to detect populations in the orchard cover crop or in weeds outside the orchard such as vetch, Brassica, and Malva. It is important to treat populations early in the season if they have been a problem in the past and are detected in the orchard. Adult katydids migrate readily from adjacent orchards, and late season fruit is particularly susceptible to late season feeding.
No research has been conducted on parasites of katydids in pomegranate. In citrus, parasitic wasps will attack katydid eggs. However, the wasps typically do not reduce katydid numbers enough to prevent damage.
It is unknown whether katydids migrate in from other neighboring crops or stay within the pomegranate orchard. If eggs are observed in pomegranate leaves, it may be helpful to shred leaves on the orchard floor in early spring to destroy forktailed bush katydid eggs.
From April to May, examine leaves on 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. Look at 50 trees throughout the orchard and examine each tree for 30 seconds. If you find feeding damage, look for nymphs by shaking foliage onto large beating sheets; nymphs can be difficult to see on the tree. Generally, treatment may be necessary if any of the foliage examined has feeding damage and katydid nymphs are detected.
Examine fruit on trees every other week starting in mid to late May to detect any developing problems in the orchard and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program.
|Common name||Amount per acre||R.E.I.‡||P.H.I.‡|
|(example trade name)||(hours)||(days)|
|The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.|
|(Delegate WG)||4–7 oz||4||1|
|MODE-OF-ACTION GROUP NUMBER1: 5|
|MODE-OF-ACTION GROUP NUMBER1: 28|
|(Lannate SP)||1 lb||48||14|
|MODE-OF-ACTION GROUP NUMBER1: 1A|
|COMMENTS: Disruptive to natural enemies of mealybugs, caterpillars, soft scales, aphids, and other pests. Use of this material may result in outbreaks of these pests.|
(0.45–0.83 oz/100 gal)
|MODE-OF-ACTION GROUP NUMBER1: 5|
|MODE-OF-ACTION GROUP NUMBER1: un|
|COMMENTS: Moderately effective on immature katydids. Must be contacted by spray so good coverage is essential.|
|‡||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 R.E.I. exceeds the P.H.I.. The longer of two intervals is the minimum time that must elapse before harvest.|
|#||Acceptable for use on organically grown produce.|
|*||Permit required from county agricultural commissioner for purchase or use.|
|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 ("un"=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.|
UC IPM Pest Management Guidelines:
UC ANR Publication 3474
D. R. Haviland, UC Cooperative Extension, Kern County
D. Carroll, Bio Ag Services, Inc., Fresno
W. J. Bentley, UC IPM Program (emeritus) and Kearney Agricultural Center, Parlier
V. Walton, Horticulture, Oregon State University (filbertworm)