Tulsa World: Green potatoes contain toxic substance

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Green potatoes contain toxic substance

Unluck of the Irish: The Master Gardeners recommend avoiding consuming green potatoes. Courtesy

By VIJA SEVIER Ask a Master Gardener
Published: 11/14/2009 2:19 AM
Last Modified: 11/14/2009 5:20 AM

Are potatoes that turned green in storage poisonous? — Phil S., Grove

Green potatoes do indeed contain a toxic substance called solanine and should be avoided.

Irish potatoes are a member of the nightshade family. This family also includes tomatoes, peppers, eggplant, Jimson weed, Belladonna, tobacco and others. Many of the leaves of these plants make chemicals called alkaloids that might be toxic. The plant makes these chemicals in defense against insects and animals. Solanine is an alkaloid produced by the green leaves and stems of the potato plant, but not normally in the potato.

However, the Irish potato is an underground stem which, when stored in light or at too warm temperatures, may begin to grow. This process involves developing chlorophyll — the green part of all plants — and is the reason for potatoes turning green.

If solanine is consumed, intestinal disturbances and dizziness are said to develop. Since it is impossible to know how much solanine is present in any green potato, common sense suggests avoiding them.

I have a large number of weeds in my lawn. Is it too late to use a herbicide? — John K., Tulsa

Many of the weeds in the "winter weed" group, such as henbit, have already sprouted. A pre-emergent herbicide applied in late August through early September would have prevented most of these.

However, all broad-leaved weeds (versus grassy ones) are very susceptible to post-emergent herbicides applied in October and November. This controls both new winter weeds and older perennial weeds, such as dandelion and wild strawberry.

Consider using Trimec, Weed-B-Gon or one of the other herbicide brands that contain 2,4-D and are labeled for broad-leaved weeds.

Glyphosate, a nonselective herbicide found in Roundup, will kill all weeds, but it also will kill your grass. However, glyphosate may be used on Bermuda lawns in January, when the grass is dormant. At that time, glyphosate will kill anything green in the brown grass. Roundup should not be used on zoysia grass, even when it is dormant.

The Tulsa Master Gardeners are trained volunteers who help provide information and support to home gardeners and the community. For more, go to tulsaworld.com/ mastergardener. If you have a garden-related question you would like the Master Gardeners to answer in a future column, call 746-3701 or e-mail Kim Brown at kim.brown@tulsaworld.com. By VIJA SEVIER Ask a Master Gardener

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