[NAFEX] Allelopathic Sunflowers?

tanis grif tanisgrif at yahoo.com
Thu May 19 22:50:20 EDT 2005

My 2 cents (Hey Doreen, I was in J'svl this aft, but didn't see the tornado. 
Getting too old for that anyway!)

I'd be concerned that the sunflowers would grow tall enough to shade my new trees
too much.  The first couple years they really need all the sunlight they can get. 
Also, would the vigorous sunflower roots rob nutrients & water?  Secondary concern
would be allelopathic effects from the sunflower roots this year, especially if your
soil is not optimum (I keep seeing anecdotes and evidence that the better the soil,
the less the allelopathy.)  I definitely wouldn't worry about problems after the
sunflowers are removed.  Lift the fiberous root mass so there is less sunflower
plant left in the soil, and any allelopathic effects should fade fast.   

--- "Lon J. Rombough" <> wrote:

> I've been testing that theory by growing sunflowers in the same area 
> for three years.  As far as I can tell, the most they do is slow some 
> of the weeds.  If I don't weed, they are just as full of weeds as any 
> other area in the garden.  The shade they produce seems to have as much 
> effect in slowing weed growth as anything.  Of course there are many 
> kinds of sunflowers and it may be that other varieties or species will 
> have differing effects.  The person who would really know is Dr. Alan 
> Kapuler in Corvallis.  He breeds sunflowers and many vegetables and has 
> tried a range of varieties and species of sunflowers.
> -Lon Rombough
> Grapes, writing, consulting, my book, The Grape Grower, at 
> http://www.bunchgrapes.com  Winner of the Garden Writers Association 
> "Best Talent in Writing" award for 2003.
> On May 19, 2005, at 6:08 PM, Doreen Howard wrote:
> Dylan Ford wrote:
>   If my memory serves (which is ever less likely), it is a substance
> > in sunflower seed hulls that suppress the growth of some plants. Or so 
> > I've heard.
> Yes, the hulls are allelopathic, but the plant roots also secrete a 
> hormone that is allelopathic, especially for weeds.  That's a good 
> thing.  But, my concern is that if I grow sunflowers in ground I will 
> ultimately use for more dwarf fruit trees, will I create problems for 
> the trees.
> Doreen

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