How to Manage Pests
UC Pest Management Guidelines
Of the two species of katydids found in California stone fruit orchards, the forktailed katydid occurs most frequently. It is smaller than the angularwinged katydid nymphs and adults and also does not have the distinct humpbacked appearance of the angular winged katydid. Nymphs of both species have very long antennae that are banded black and white.
Katydids lay disk-shaped eggs throughout summer. If the eggs do not hatch before the end of August, they will overwinter. The eggs of the angularwinged katydid are 0.125 to 0.15 inch (3.2–3.8 mm) long, gray, and laid in two overlapping rows that form a long "tent" on the surface of twigs and branches. In contrast, eggs of the forktailed bush katydid are about 0.125 inch (3 mm) long, and inserted into the edges of leaves. Eggs of the forktailed bush katydid hatch in late March and April. Adult katydids appear in midsummer and continue to lay eggs during June and July. Some of these eggs will hatch in July and August (about 15%), whereas the rest will overwinter. The angularwinged species, however, emerges in late May and has only one generation a year, laying overwintering eggs during the summer.
Katydids occasionally become damaging pests in orchards where broad-spectrum pesticides were not applied or are under minimum tillage programs. High numbers of these pests may occur near raisin and wine grape vineyards, where the do no damage to the fruit.
Nymphs feed on leaves or fruit early in the spring as they climb from the ground to the tree. 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.
Look for katydid damage when monitoring for leafrollers in spring. From April to May, examine shoots in the center of the tree for the characteristic 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. Fruit damage will also be seen in May. 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. Treatments are most effective when applied to nymphs; best results have been achieved with late April and early May sprays.
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 (see FRUIT SAMPLING AT HARVEST). Record results (example form— ).
|Common name||Amount per acre**||REI‡||PHI‡|
|(Example trade name)||(conc.)||(dilute)|
|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.|
|(Altacor)||3–4.5 oz||0.75–1.125 oz||4||10|
|MODE-OF-ACTION GROUP NUMBER1: 28|
|COMMENTS: Do not apply more than 9 oz/acre per year or make more than three applications a season. Do not apply with less than 100 or more than 200 gallons water/acre.|
|MODE-OF-ACTION GROUP NUMBER1: 22A|
|COMMENTS: This product is highly toxic to bees exposed through direct contact. Do not apply or allow to drift onto blooming crops or weeds if bees are present. For best results apply when katydids are in the early nymphal stages. Do not apply more than 24 oz/acre per season.|
|(Delegate WG)||4.5–7 oz||1.125–1.75 oz||4||14|
|MODE-OF-ACTION GROUP NUMBER1: 5|
|COMMENTS: This product is toxic to bees for 3 hours following treatment; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. Apply in the late evening after bees have stopped foraging. Do not apply more than 28 oz/acre per year or make more than four applications per year.|
|(Entrust#)||1.25–2.5 oz||0.42–0.83 oz||4||14|
|(Success)||4–8 fl oz||1.3–2.7 fl oz||4||14|
|MODE-OF-ACTION GROUP NUMBER1: 5|
|COMMENTS: Do not apply more than 29 fl oz/acre per year of Success or 9 oz/acre per year of Entrust. Most effective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. Apply in late evening after bees have stopped foraging.|
|(Imidan 70-W)||2.125–4.25 lb||1 lb||7 days||14|
|MODE-OF-ACTION GROUP NUMBER1: 1B|
|COMMENTS: Acidify water to 5.0 or below before adding phosmet.|
|**||For dilute applications, rate is per 100 gal water to be applied in 300 to 500 gal water/acre, according to label; for concentrate applications, use 80 to 100 gal water/acre, or lower if label allows.|
|‡||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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.|
|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 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 website at http://www.irac-online.org/.|
|#||Acceptable for use on organically grown produce.|
UC IPM Pest Management Guidelines:
UC ANR Publication 3433
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
K. A. Kelley, UC Cooperative Extension, Stanislaus County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
PDF: To display a PDF document, you may need to use a PDF reader.