Change Site
Growers
Go Search
cancel
cancel
Thank you for signing up for eNews and/or creating an Almond Profile.
Your sign-up is complete.


 Categories



Recent Issues
[+]  July 2014
[+]  June 2014
[+]  May 2014
[+]  April 2014
[+]  March 2014
[+]  February 2014
[+]  January 2014
[+]  December 2013
[+]  November 2013
[+]  October 2013
[+]  August 2013
[+]  July 2013
[+]  June 2013
[+]  May 2013
[+]  April 2013
[+]  March 2013
[+]  February 2013
[+]  January 2013
[+]  December 2012
[+]  November 2012
[+]  October 2012
[+]  August 2012
[+]  July 2012
[+]  June 2012
[+]  May 2012
[+]  April 2012
[+]  March 2012
[+]  February 2012
[+]  January 2012
[+]  December 2011
[+]  November 2011
[+]  October 2011
[+]  August 2011
Past Issues
Search:

Seasonal Timing Determines Best-Management Tactic for Ground Squirrels

A proactive, year-round strategy is the best approach for managing ground squirrels in almond orchards. UC IPM Wildlife Pest Management Advisor Roger Baldwin reported at The 2012 Almond Conference that almond growers need to take a season-long view and plan for what control tactics work best at certain times.

Start After Harvest

Growers can start thinking about ground squirrel control immediately after harvest, using bait to knock down populations going into the winter and following up early the next spring with burrow fumigation.

“After harvest is not necessarily the time to forget about squirrels, and is actually a good time to put together an integrated management plan,” Baldwin said.

There are some important facts to consider when putting that plan together:

  • Squirrels hibernate and will not be controlled with fumigation or bait during periods of inactivity in the winter.
  • Squirrels have seasonal eating habits, so control strategies should be timed to coincide with those preferences.

Fumigation

After winter hibernation, ground squirrels move above ground and begin actively feeding on surface vegetation. Burrow fumigation works well during this period in early spring and anytime enough soil moisture is present, either through precipitation or irrigation, to hold gases in the burrow system.

Aluminum phosphide is the most effective, least costly material registered for ground squirrel burrow fumigation, providing efficacy rates of 97% to 100%. As a restricted material, however, there are several hurdles that must be cleared before applying aluminum phosphide. Newer restrictions on aluminum phosphide include increased buffer zones around occupied structures and new 48-hour posting requirements after application. Gas cartridges, which primarily produce carbon monoxide, provide 75% to 80% efficacy, with fewer restrictions.

“If you just have a few burrow systems to treat, it is easier to use gas cartridges, but if you have a lot, the cost and efficacy benefits of aluminum phosphide will outweigh the negatives,” Baldwin said.

Late Spring Baiting

By late spring, as vegetation begins to senesce, ground squirrels switch their diet to eating seeds, and bait becomes a more logical control choice. Baiting should be done before nuts fill on trees, as they provide a preferred food source to baited materials.

Setting out bait stations should be done before nuts fill out;
otherwise, the nuts become the preferred food source. Photo
courtesy of Roger A. Baldwin, Ph. D.
Anticoagulant baits must be consumed several times over a three- to five–day period, and it can take up to two weeks before a lethal dose is consumed. They are also now a restricted-use material. Anticoagulants do, however, provide the advantage of good bait acceptance.

Zinc phosphide can yield poor bait acceptance and is only registered for a single application per year, so Baldwin suggested growers do prebaiting prior to applying zinc phosphide to see if squirrels will accept the bait.

Share this article
Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01 Image 01
Warning: This link connects to a third party website not associated with the Almond Board of California. The link has been provided solely as a convenience to you and The Almond Board of California assumes no responsibility for the accuracy, quality, safety, or nature of the content on the linked site.
Click Agree to continue to the requested site, or click Decline to return to your most recently viewed Almond Board page.
agree decline