Monday, January 31, 2005

Oxalis - Gopher Connection confirmed

Today (31 January 2005) I personally confirmed my theory that gophers are significant dispersal vectors for the bermuda buttercup, a serious invasive exotic weed, put forward in the article Oxalis -- Bermuda Buttercup Dispersed by Gophers.

I was working in a Saratoga garden infested with both Oxalis pes-caprae -- bermuda buttercups -- and botta pocket gophers. In a couple of places there were unnaturally dense aggregations of Oxalis about a foot in diameter. Digging them the shovel went in easily, as through gopher tunnelling. In each case bulbs and roots were packed tightly in a mass without soil around them -- they obviously had been packed into a chamber of the gopher tunnels.

I believe when the animals spread the weed by bringing it with them as a portion of their food cache to their newly dug burrow systems, thus spreading the weed.

A few years ago before I ever saw this yard, it had been rototilled. No doubt cultivation helps spread Oxalis around also; many orchards are infested. I stopped to talk to a neighbor and showed him the little bulblets that form along the roots later in the season, some close to the surface of the ground -- they seem to begin to form when the plant is flowering or more readily on stressed specimens, especially those trodden upon. Thus it really pays to go after this weed early in the season. The later in the season one pulls it up or cultivates soil it occupies, the more little bulblets one tends to leave behind or spread around! Pulling it up earlier puts one more firmly on the road to eradication.

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