Fielding Questions: Woodpecker damage, using sump pump water, asparagus harvest

Q: I’ve attached photos of our six-year-old Discovery elm that woodpeckers have been attacking. How serious do you think the damage is and do you have suggestions for protecting and saving this beautiful tree? – Loren L.

A: Holes like these are usually made by sapsucker type woodpeckers. The holes fill with sap, and the birds then drink the material. If they drill enough holes around a tree's circumference, the holes disrupt the flow of vital materials within. Trees can be killed if damage reaches a certain point.

To prevent continued injury, wrap the trunk with burlap, covering the area where the woodpecker has been working. When their habit is disrupted, the birds will usually go elsewhere. Some try aluminum foil, but burlap is less noticeable.

Another option is to coat the area of activity with sticky Tanglefoot, which is available at garden centers. Tanglefoot doesn't harm the tree, but birds don't want the sticky material on their feet.

Scare-type devices can sometimes work, such as Mylar balloons or aluminum pie tins suspended in the tree.

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There's nothing that can be done to remedy the past injury. Hopefully the tree will compartmentalize the wounds, often called "healing," and carry on.

Q: Would sump pump water be good for houseplants? - Connie C.

A: There are variables with sump pump water that allow it to be used safely for certain things, but not others. Houseplants tend to be sensitive to water sources because their root systems are confined to a small area, and the quality of water has great impact.

Sump pump water percolating along a house foundation might carry calcium or other material from the concrete or adjacent soil that could affect potted plants. I’m sure this varies by location, but for a general recommendation I’d be hesitant, and instead use rainwater, when available.

Sump pump water is generally safe to use on ornamental shrubs and perennial flowers in the landscape, if the water hasn't percolated down through a lawn that's been treated with herbicide. Sump pump water isn't recommended for vegetables or other edibles, because the quality and safety of the water are usually unknown.

Most sump pump water obviously doesn't kill grass during the growing season, since that's where it's commonly discharged. I’ve used the water successfully for years on roses, shrubs and perennials, but if the hose is running directly to plants, monitor and move as needed to avoid drowning.

Q: How long can we continue to harvest asparagus? I know there's a date that you’re supposed to stop. – John L.

A: July 4 is an easy date to remember to discontinue harvest of asparagus, and rhubarb also. Allowing the plants to grow naturally after that date without harvesting the stems and stalks lets the plants carry on their photosynthesis and build important internal strength.

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If we continued to remove the stalks of these perennial vegetables all summer, they wouldn't have the chance to recharge their energy. Asparagus and rhubarb are quite generous to gardeners, allowing us to pluck away their stems and leaves for the first half of the summer. We can repay their kindness by letting them grow naturally for summer's last half.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at [email protected] . Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.

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