Re: Question for Dr. Grewal


Bill,

I replied to a very similar question yesterday.  I hope you got the answer 
to your question.  The nematodes become active soon after the plants start 
sprouting. Due possible injury (phytoxicity) to young plants, I would wait 
spraying until early May.

Parwinder

At 02:16 PM 01/08/2002 -0500, you wrote:
>Another thing most people seem confused about is when in the spring they
>become active. Because symptoms do not show in hosta until midsummer, it is
>impossible to tell without a microscope if a plant or bed is infested. This
>causes most gardeners to think in terms of beginning control measures at
>that time. When do nematodes come out of dormancy in the spring, and when
>should treatment begin?
>                                                             .........Bill
>Meyer
>
>
> > Yes, the rate of spread is about right and it depends mainly on the soil
> > type, slope and water.
> >
> > No nematicide provides 100% control of nematodes, but there are no reports
> > on the development of resistance in nematodes under field
> > conditions.  Furthermore, the mode of action of ZeroTol is such that
> > resistance development is not really possible.
> >
> > Regular applications of ZeroTol to infected plants will reduce spread of
> > the nematodes in a garden.  Plucking of infected leaves as soon as the
> > symptoms of nematode infection become clear followed by a thorough
> > clean-out in the fall can substantially reduce nematode spread.
> >                 - Parwinder Grewal
> >
> > At 01:13 PM 01/08/2002 -0500, you wrote:
> > >Hi Dr.Grewal,
> > >              Thank you for answering. From what I've seen, they seem to
> > >spread at a rate of about ten feet a year in all directions, more if
> > >downhill. Would this seem about right? Your findings indicate that
>ZeroTol
> > >kills about 80% when plants are in the ground, if I remember right. Would
> > >this make it likely that a resistant strain would develop? Also would
>using
> > >ZeroTol regularly control the spread, or would they continue to spread
> > >through the rest of the garden at more or less the same rate?
> > >
> > >.........Bill Meyer
> > >
> > >
> > > > Hi Bill,
> > > >
> > > > I know that most effective nematicides are no more available to
>control
> > > > foliar nematodes and there are many restrictions the use of other
> > > > chemicals.  In our research, we have discovered that ZeroTol, which is
> > > > currently used as a general sterilant/fungicide, is an effective
> > >nematicide
> > > > against foliar nematodes.  This chemical can be applied by home
> > > > owners.  Our findings on ZeroTol and other chemicals to
>control/suppress
> > > > foliar nematodes were published in the Spring issue of Hosta Journal
>in
> > > > 2001.  There are also other useful tips and preventive measures
>described
> > > > in that article.
> > > >
> > > > Yes, foliar nematodes can eventually kill hosta plants if they are
>ignored
> > > > for long.  Overtime nematode populations build up on plants and in the
> > >soil
> > > > around plants.
> > > >
> > > > Parwinder Grewal
> > > > Assistant Professor
> > > > Department of Entomology
> > > > OARDC
> > > > The Ohio State University
> > > > 1680 Madison Ave
> > > > Wooster, Ohio 44691, USA
> > > > Phone (330) 263-3963
> > > > Fax (330) 263-3686
> > > >
> > > >
> > > > At 11:31 AM 01/08/2002 -0500, you wrote:
> > > > >Hi Dr. Grewal,
> > > > >           A question that is commonly asked on the lists is what can
>the
> > > > >average gardener who does not have access to restricted chemicals
>like
> > > > >Nemacur do about foliar nematode infestation. Because of changes in
>the
> > > > >pesticide laws, many of us find ourselves with these pests running
> > >rampant
> > > > >and we are not permitted to use the chemicals that best control them.
> > >What
> > > > >would you say is the most effective treatment we could use?
> > > > >           Another somewhat related question is ------What would you
>say
> > >the
> > > > >long-term effects on hosta are of untreated or poorly treated foliar
> > > > >nematode infestations? Can they kill plants eventually?
> > > > >
> > > > >..........Bill Meyer
> > >
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