Let me start by saying, I'm not proud of my home lawn. The 75 acres of turf that comprises Highlands CC is a greater source of pride for me. Plus, my yard has way too much shade to ever be nice. However, it is a textbook lesson of how turf responds in poor environments. Let's start above...the thin turf is simply wear from foot traffic that doesn't recover because the side of the house shades it, as you can see. This traffic is caused from me walking through the yard once, every other day if even that often. Think of a golf green if a club does 200 rounds a day! Below shows just how dramatic the shade can be! I tried for a moss yard with no success. I would love a moss yard. Our two Westies seem to have a preference for neither grass nor moss.
Last week, I decided to round up some of the yard. The reason? That's a story for another day. As a couple days went by, I noticed something interesting. Round up, is a systemic herbicide that is taken up through the stomata (tiny holes in leaves) and is systemically translocated throughout the plant. This is why if you buy the original Monsanto Round Up, it takes 10 days or more for you to see death. Newer versions of Round-Up are sometimes mixed with another herbicide, Diquat. Diquat is a contact aquatic herbicide; it's meant to spray in water. A contact is opposite of systemic...meaning it only kills the very tissue it touches. However, it's a very fast "burn-down." Sometimes it takes as little as 12 hours to see the weed wilted and on its death bed. Let's face it, we all know that is satisfying and the original Round-Up is frustrating because we want instant gratification and instant results. The round up that is quick to kill and advertised as, "weeds won't come back" is actually a 3 way mix of Glyphosate (Round Up active ingredient), Diquat and finally a pre-emergent chemical known as, Prodiamine (Its trade name is Barricade). This is like the atom bomb of chemical mixes and pretty much overkill. Prodiamine is the same chemical that will give you up to 3 months of preventative crabgrass control in home lawns. Anyway, it apparently sells.
Back to my point: In order for Round-Up to work, the plant/weed/grass must be actively growing so the chemical can translocate through the plant's vascular system as if it were nutrients. A plant that isn't actively growing for whatever reason, may be injured by it but may or may not die. We know shade and grass don't get along. The shade is holding back the potential of my back yard. The grass in full sun is further on its journey to death because the healthier grass is actively moving the nutrients through the plant and cell walls are dissolving left and right, ultimately turning the grass to mush. The shaded turf, which can't efficiently use nutrients (and Round-up in this case), is still pretty green. Eventually it will die, but it will be far behind the grass that was growing in sun. This whole explanation is counterintuitive. You probably thought the weak turf would be easier to kill. However, by understanding the mode of action of different chemistries, this isn't the case. The faster the Round-up moves through the plant, the faster it dies.
One last point and I will go away...I recommend avoiding the Diquat/Round-up mix. Given what you learned, if you burn a plant to the ground in 24 hours, the Round-Up will have no time to translocate and you just wasted money. In that case you should have sprayed straight Diquat, which is sold under the trade name, Reward. Final lesson: if you are spraying weeds throughout a bed of desirable plants, stick to Diquat. Contact herbicides will only kill what they touch. Therefore, if you have spray drift get on a good plant, it won't kill the entire thing. In theory, a little but of drift from Round-Up can be quite devastating due to its systemic activity in all plants. Remember, both are non-selective.
On more thing...if you are the organic type of person that is deathly afraid of chemicals because you might believe the extensive media coverage, particularly of Round-Up, consider this. Some folks use a mix of salt and vinegar to kill weeds. To me, this is bazar but I'm not one to judge. However, know this...that concoction is more toxic in regards to the LD50 value compared to Round-Up. If you want to learn more about LD50 values, read my early post from today! In addition, if you want to destroy a healthy soil, till some salt into it.
The argument some people make about plant protectants is summed up perfectly in this meme:
