How to Manage Pests

UC Pest Management Guidelines

Citrus orchards provide food and shelter for vertebrate pests that can cause significant damage by feeding on fruit and on tree bark and shoots, which can stunt growth or kill trees. Some pests will chew or destroy flexible irrigation lines and emitters. Other pests will dig holes through the soil surface, thereby channeling surface irrigation water to undesired areas. Food safety also becomes an issue if pest residues come into contact with the fruit. The major vertebrate pests are pocket gophers, California ground squirrel, and black-tailed jackrabbit. Occasional pests include coyotes, voles, roof rats, wild hogs, deer, and starlings.

Manage your orchards in order to keep pest populations at low levels so that significant damage does not occur.

• Before planting, remove vertebrate pests and destroy habitats (such as burrows) within the orchard boundaries. Preventive measures cost less and are more successful before planting when one can easily see the pests or their habitats.
• Be aware of the orchard's location, as vertebrate pests can easily reinvade if the orchard is adjacent to rangeland, water ways, or unmanaged areas. It is much easier to manage vertebrate pests by implementing controls on the orchard's perimeter versus inside the orchard.
• Baiting, fencing, fumigating burrows, shooting, and trapping are easier and usually more effective if employed before you plant the orchard instead of after.
• Where feasible, deep plow and disc to destroy burrows, disperse or kill resident populations, and reduce the risk of reinvasion by pocket gophers, voles, and (to a lesser extent) ground squirrels.

Management programs for vertebrate pests involve 4 basic steps:

1. Correctly identify the pest species using damage signs, burrows or habitat, tracks, feces, etc.
2. Alter the habitat where feasible to make the area less favorable to the pest species.
3. Implement appropriate control for the orchard and time of year, taking early action and using due consideration for the environment and non-target species.
4. Establish a monitoring system so as to detect re-infestation and help determine when additional control measures are needed.

A successful pest management program requires good records and regular monitoring. Some vertebrate pest populations can easily "explode" because of high reproductive rates and abundant food. Keep a record of the management procedures you use and their effectiveness. Good records will help you plan and improve future control strategies.

For most vertebrates, there is more than one control option for reducing populations and damage. The following table summarizes the various control measures appropriate for the common vertebrate pests of citrus. Details on how to use these controls are given in the individual pest sections.

Pesticides Available for Controlling Vertebrates. Follow label directions carefully and understand the hazards when using fumigants. Contact your county agricultural commissioner for current product registrations and the latest information on legal pesticide use, including current information on restrictions that apply to pest control activities in order to protect endangered species.

Endangered Species Guidelines. Many citrus orchards are located within the range of one or more federally or state-protected endangered vertebrate species. Species likely to be of concern when using traps or poison bait include the San Joaquin kit fox and several species of rare kangaroo rats. If you use burrow fumigants in the San Joaquin Valley and the surrounding foothills, the blunt-nosed leopard lizard is a concern as this insect feeder seeks shelter in rodent burrows.

Special guidelines apply to the use of certain traps, fumigants, and toxic baits for vertebrate pest control in these areas. Modification of ground squirrel bait stations to exclude protected species is one common practice. Other typical guidelines restrict broadcast applications of bait, limit the percentage of active ingredient in baits, prohibit fumigation at certain locations or during some times of the year, and require that applications be supervised by someone trained to avoid harming endangered species.

Contact your county agricultural commissioner for the latest maps that show the ranges of endangered species and for current information on restrictions that apply to pest control activities in your area. More information on endangered species regulations is also available at the DPR Web site.

IMPORTANT LINKS

• Photos of vertebrates and their damage

PUBLICATION

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Vertebrates
M. W. Freeman, UC Cooperative Extension Fresno County
R. E. Marsh (emeritus), Wildlife, Fish and Conservation Biology, UC Davis
T. P. Salmon, UC Cooperative Extension, San Diego County

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