Description of the Pest
Adult Fuller rose beetles are brown to grayish snout beetles (weevils, family Curculionidae), about 0.36 inch (9 mm) long. Adults are all females, which lay eggs in clusters of several dozen in crevices on the tree or under loose bark. Larvae drop to the ground and feed on weed or tree roots, but larval feeding does not damage trees. Overwintering is as grubs that pupate beginning about June to July. Most adults emerge from June through October, but a few will emerge each month throughout the year. They feed for about 2 weeks before laying their first eggs. Feeding and egg-laying can continue into winter. There is one generation each year.
Damage
Fuller rose beetle is an occasional problem in young avocado plantings. It can also damage top-worked, recently grafted, or severely pruned trees that have relatively little mature foliage and an abundance of developing immature leaves. Fuller rose beetle usually is common only on avocado growing near citrus or other preferred hosts.
Fuller rose beetle adults chew leaf margins, causing a ragged, notched, or serrated appearance that is quite different from damage caused by other pests such as snails. Most chewed leaves are on lower branches because adults cannot fly and must climb trunks and branches to reach foliage. Leaf chewing on older trees with a well-developed canopy is not economically important. There is no evidence that root feeding reduces yield and research has not been done to determine if root feeding predisposes trees to infection by Phytophthora.
Management
During late winter or early spring, apply a sticky barrier to trunks to exclude weevils if they may be a problem. Encircle a smooth section of trunk with a flexible wrap or tape and apply the sticky material on top to prevent direct contact with, and injury to, bark. A parasitic wasp (Fidiobia citri, family Platygastridae) parasitizes up to 50% of Fuller rose beetle eggs in citrus. Parasitized eggs darken and may persist long after unparasitized eggs have hatched. This parasite's importance in avocado is unknown.
Starting in June, inspect susceptible young or top-worked trees for leaf notching made by newly emerged adults. Be aware that caterpillars, earwigs, June beetles, grasshoppers, and snails also chew avocado leaves. Larvae and pupae of the exotic Diaprepes root weevil (Diaprepes abbreviatus) resemble Fuller rose beetle and adults of both species chew leaves. Be certain to identify the cause of problems before taking action. If suspected Diaprepes root weevils are found, notify agricultural officials as prompt management action may be warranted.
| Common name | Amount per acre | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. 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. Always read the label of the product being used. | ||||
| A. | STICKY POLYBUTENE MATERIALS# | |||
| (Tanglefoot) | Label rates | NA | NA | |
| COMMENTS: For use on all varieties. Use polybutene-based products only. Do not apply sticky materials directly on the trunk; use a 6- to 18-inch wrap under the sticky material to protect the tree from sunburn. Exercise caution in applying multiple applications (more than 3 or 4); watch for symptoms of bark cracking. Apply the sticky band high enough to avoid sprinklers, dust, and direct sunlight. Reactivate periodically by rubbing with a stick to remove dust. Check to ensure that low hanging branches, sticks, weeds, etc., are not allowing ants access to trees. | ||||
| B. | THIAMETHOXAM | |||
| (Actara) | 4 oz | 12 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: For use on all varieties. Review and follow the California neonicotinoid regulations effective January 1, 2024. Application of this insecticide is prohibited if managed pollinators will be used during the growing season. The use of multiple application methods or neonicotinoid active ingredients affected may also be prohibited. |
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| C. | MALATHION | |||
| (Malathion 8) | 4.7 pt | 48 | 7 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Apply as a foliar spray. Use of this material will disrupt biological control of other pests such as scales, thrips, mites, and whiteflies and is not very effective against Fuller rose beetle. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. | ||||
| ‡ | 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. | |||
| # | 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). | |||
| NA | Not applicable. | |||