Re: detergent soap/leaf scorch
Just an uneducated guess here but if there severely damaged, I'd whack them
close to the vine, dust with sulfur and bury them.
Bob ......
bob johnson wrote:
> I am a first time grower learning the hard way. My two Giant Atlantic
> Pumpkins plants are in deep trouble. Some type of leaf disorder. I had been
> feeding the little guys with a fish emulsion. (Probably over feeding is more
> exact.) This attracted a lot of flies to the plants. I became worried about
> the flies being a vector for pathogens so I washed the plants with soapy
> water. (Ajax dish washing liquid.) The flies headed for the hills. The
> plants looked great. Several hours after their bath, however, the leaves
> closest to the stump started developing rusty/grayish blotches which quickly
> spread to newer leaves farther down the vine. The most seriously discolored
> leaves also began curling up at the edges. Prior to my Ajaxing 'em, the main
> vines on both plants were about 4-5 feet long with the biggest leaves a foot
> in width and all a beautiful healthy green.
>
> I found an image on the Texas A&M horticulture site of a cucurbit with a
> leaf disorder closely matching the appearance of the damaged leaves on my
> AGPs indicating the problem could have resulted from a pesticide injury.
> Somewhere in a Rodale organic gardening book I found a sentence about using
> "non-detergent" soap to clean leaves from invading pests. The soap I used
> was apparently a detergent soap, i.e., one that cuts grease and oil. My
> amateur guess is that the detergent may have been absorbed through the roots
> and possibly created the damage by acting like a broadleaf herbicide. Small
> amounts of residual herbicides apparently can cause leaf scorch, dwarf plant
> growth and reduce vigor. (See
> http://aggie-horticulture.tamu.edu/cucurbit/leaf/39.2.html for image and
> text.)
>
> This occurred several days ago. Since then, new growth appears to be
> unscorched or minimally scorched. Most scorched areas have dried up and
> turned gray in color. Don't know whether to prune damaged leaves or not. I
> am not even sure about my hypothesis that this event was caused by my use of
> a detergent soap.
>
> Any opinions and/or advice from listmembers are greatly appreciated.
> ______________________________________
> bob johnson
> holbrook, ma usa rjohnson@thecia.net
>
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