August 2, 2009

How To Control Your Neighbor’s Passion (vine)

Dear Arboretum Plant Information,Last year our neighbor planted passion fruit vines on his side of a retaining wall that separates our properties.  They’ve been very prolific and are constantly climbing over the top of the wall and onto our side. We politely asked him to keep the vines trimmed, which he did, but our problems still weren’t over. Early this month we noticed a few young shoots popping up on dry hard compacted dirt on our side of the wall & in the cracks of a bricked patio floor which is flush against the wall.  I tried using Roundup Weed & Grass killer a few times (streamed & foamed during some 80-mid 80 degree sunny weather) & later noticed that they were still growing (i.e. green & thriving).  Initially the portion above soil seemed to die, but after a week, the shoots came back.  I haven't sprayed any more since then & am waiting to let them grow long enough to match the growth on our neighbor's side. How do I get rid of these plants? Signed,  Passionate in PasadenaDear Passionate,What’s probably happening is that the vine is sending out shoots from its roots. Spraying Roundup seems like a good idea, but it does present some problems:

Treating the shoots may kill your neighbors vine. Since the shoots that you are spraying are basically the same plant as your neighbors, spraying an herbicide like Roundup that is absorbed by the entire plant before it starts to work could result in not only the shoots you are spraying dying, but your neighbor’s entire vine dying as well.

Roundup takes a couple of weeks to show results. You’ve just sprayed these plants, give the Roundup some time to work.

Applying Roundup when it’s too hot will result in the plant’s tissues burning. Scorched plant tissue does not absorb Roundup, so the plant does not perish. You should apply roundup when the temps are below 85 degrees F.  Preferably in the early morning when temperatures are low and any breezes are at a minimum. Errant exposure to Roundup spray can cause plants like roses to become deformed; even from minute amounts of Roundup.

Treating expanding shoots with Roundup can be futile; this is because the flow of nutrients in the plant (Roundup has to be taken up into the nutrient stream to be effective) should be in a direction towards the roots for Roundup to be effective. A newly expanding shoot has little capacity to make food, its expansion fueled by a nutrient flow with a net direction towards the tip of the shoot. So what you need to do is allow the shoots to grow until they are about a month old, and then spray them when temperatures are below 85 degrees F.  This is because after a month the ability of the plant to make food for the plant is much higher than when it first started expanding and therefore an effective dose of Roundup will be delivered to the entire plant…which, like I mentioned above, may include your neighbors plant too.  

So, how do you get rid of the shoots if you have decided you don’t want to kill your neighbor’s passion and not to use Roundup? Simply snap off the new shoots as soon as they appear.