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[Fwd: Efficacy of hot water on weeds]



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Marsupial Landscapes Pty Ltd.
mailto:marsup@ozemail.com.au
Ph: 61-2-99056844
Fax : 61-2-99056244


Please find attached a letter providing and requesting information on
hot water control of weeds.  As a new-comer to the web I am not sure
wether you may have already received the mail as a cc.  Please advise me
if you do not receive the contents of the attachement.

Many thanks 

Jeremy Winer
SYDNEY AUSTRALIA.

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-- 
Marsupial Landscapes Pty Ltd.
mailto:marsup@ozemail.com.au
Ph: 61-2-99056844
Fax : 61-2-99056244


I have been browsing the web for other persons interested in the use of
hot water for controlling weeds.  I have been looking at alternatives to
the use of biocides for the control of weeds in the built environment ie
open public space.  There appears to be one or two companies world wide
who have developed apparatus for the application of hot water to weeds. 
The apparatus as they stand at the moment have a few major flaws.  

- They use in excess of 4 litres per minute of water therefore requiring
a cumbersome amount of water to be transported and a continual time
consuming refill on avearge every 1 to 2 hours.

- The heat exchanger is deisel fuelled; being costly, energy inefficient
noisy and potentially polluting.  If we are looking for sustainable and
non polluting alternatives a cleaner energy source is required.

- The consequential size of the apparatus make them unable to
unobtrusively operate in the public domain and the volume of water
consumed and consequentially out poured causes excessive runoff on paved
areas and floods garden beds.

-Tractor mounted apparatus are unable to apply control to the crop rows.
 
Trials I have carried out have shown that Hot water at tempertures in
excess of 75 degrees C will cause permanent cell collapse within 5
seconds on a majority of soft tissued plants above ground.  Controlling 
more persistant stoloniferous, rhizomateous, corm and bulb weeds
requires heating the soil to temperatures in excess of 65 degrees C.  To
do this the hot water must have time to penetrate the rhizosphere and be
of an application temperature high enough to still be of effect at the
required depth ie upto 75mm (3").

There is some concern for the other organisms present in the
rhizosphere, but worm counts a few days following application are
encouraging, probably due to their feeding on resultant dead tissue. 
Microflora counts have not been done.

Mr Hawkins, you mention in correspondance that you are familiar with hot
water treatment of weeds.  I would be pleased if you could refer me to
any published articles, preferably prior to 1991, on the method.  I am
running overtime on research and would be greatfull for an early
response.

Jeremy Winer
Sydney.

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