I read a very interesting article a couple of days ago which was discussing the problems folks have if they have Black Walnut trees on the garden, or even close by, they apparently give off a toxin called Juglone which contaminates the gound and kills off other plants, even the nuts falling on the ground can do it.
What was really interesting is that this can also happen with Sunflowers in much the same way, they along with the Black Walnut are called allelopathic plants which simply means they can react with others nearby and cause trouble, the dead opposite of companions planting as I see it. The black seeds from Sunflowers seem to be the worse. If planted in numbers they can kill off much of the plants round about especially apparently some types of grasses.
I have looked for a posting I read here recently about couchgrass(cannot find it)
In this posting someone said they had planted a whole lot of Sunflowers and the following season all the couch grass had died.
Someone else had a similar experience with Jerusalem artichokes which are a member of the sunflower family.
I think this is very interesting and worth following on.
Have we stumbled on a couch grass cure???
Any comments anyone ??
XX Jeannine