There's a reason this grass can rapidly invade lawns
"Fielding Questions" columnist Don Kinzler also answers questions about how long grass seed will last and if young trees should be fertilized this fall.
Q: Attached is a photo of a grass that’s invading my lawn. Do you know what type it is? — Eric.
A: I see several clues to the grass’s identification. It appears to have slowly spread outward into the surrounding lawn, because I see scattered spears arising beyond the densest clump. This makes me believe it’s a perennial grass that’s arising from a winter-hardy root system and underground structure, instead of an annual grass that sprouted from seed just this spring.
The blue-green color is also a clue, since some grasses have a lighter, yellow-green tint. If one could see the point at which the grass blades attach, additional clues could be revealed.
All things considered, I’d say this looks like quackgrass, which is a perennial grass that spreads throughout lawns by underground rhizomes. Digging a clump would likely reveal the white rhizomes in the root zone by which quackgrass spreads so readily.
Unfortunately, there are currently no products registered that will selectively kill quackgrass without harming Kentucky bluegrass lawns. Glyphosate, as found in original Roundup and other brands, can be used to spot-kill the largest areas of quackgrass, followed by reseeding.
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Q: If I purchase some grass seed this fall, will it still be good next spring? How long does grass seed last, and what’s the best way to store it? — Bill S.
A: Kentucky bluegrass seed will remain viable with little or no decrease in germination for at least 12-18 months from the test date on the label if stored properly. If stored improperly in a garage during summer’s heat and humidity, the germination rate can decline markedly.
For longest seed life, store in a dry area with good air circulation. Storage temperature is extremely important, with the preferred being between 40 and 50 degrees Fahrenheit.
A reduction in germination can be expected the longer grass seed is stored, with a 10-20 percent decrease every year. To compensate for a decline in germination, a slightly higher seeding rate can be used. Under proper storage, grass seed can last up to three years and still be useable.
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Q: Can we fertilize young spruce and maple trees in the fall? — Duff M.
A: Both evergreen and deciduous trees are best fertilized in spring if the trees are of average health. Most research universities recommend spring fertilizing, with some suggesting a slow-release fertilizer in fall only if trees are nutrient-stressed.
If trees are under drought stress, they definitely shouldn't be fertilized in late summer or fall. July 4 is an easy-to-remember cutoff date for fertilizing trees and shrubs. Fertilizing after that date can stimulate lush growth that doesn’t have time to “harden off” or toughen up before winter, increasing the chances of winter injury and dieback.
If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at firstname.lastname@example.org. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.