By Jon Trappe
Many plant enthusiasts have observed difficulty planting some plant species around black walnut trees. Black walnut trees naturally excrete chemicals into their environment to make themselves more competitive. This negative plant-on-plant interaction is known as allelopathy, and is more common in multiple plant species than was once previously thought.
There have been a few reports (Bertin et al., 2009; Bertin et al., 2003) of natural weed suppression in certain fine fescues (Festuca spp.).
Every year around this time I start receiving questions regarding when to apply preemergent herbicides for preventing crabgrass establishment in lawns. Crabgrass germination is driven by soil temperatures and because of this we cannot rely on a calendar date to tell us when to apply our preemergent products.
Yes, I said summer! With temperatures in the mid-80’s and dew points approaching 70 degrees, I think it’s safe to say that summer has finally arrived. With the arrival of summer, we also notice that many weeds are starting to show themselves in Minnesota lawns. The late winter (or cold spring…..whatever you want to call it) left many of us scratching our heads wondering if our turf would hav