Ground Squirrel Control in Avocado Groves

According to the UC Integrated Pest Management website, avocados are particularly vulnerable to California ground squirrels and although squirrels hibernate in cold winters they tend to be active year-round in avocado growing regions.  Besides eating the fruit, the squirrels can cause damage to groves by girdling trunks, eating twigs and leaves, burrowing around roots and gnawing on sprinkler heads and irrigation lines.

While ground squirrels look similar to tree squirrels, the easiest way to identify the ground squirrel is by noting where they flee. If the squirrel retreats to a burrow, it is a ground squirrel.

The burrows, which can damage roots and cause damage to equipment, are usually within two to three feet of the ground surface. In general, squirrels are most active during the daytime, but during the hottest times of the year, adults tend to rest in their burrows.

In order to control squirrels, it’s important to understand their behavior. Primarily herbivorous, they tend to eat greenery in the winter and spring, and eat seeds in the summer and fall. They tend to forage in the later afternoon or early evening when it is not as hot outside. In summer and fall, it is best to bait with treated grain. If growers plan to use fumigation, they should do so in spring or when soil moisture is high as this helps contain the gas within the burrow system. Trapping is also considered a control option if populations are low to moderate. Box traps and tunnel traps are recommended and should be placed on the ground near burrows and baited with almonds, walnuts, oats, barley or melon rinds. Ground squirrels are not repelled by chemical or physical means.

It is worth noting that squirrels can carry bubonic plague, which can be transmitted to humans and other animals. If growers find large numbers of dead squirrels in their groves, they should notify a public health official and not handle the squirrels themselves.