Please Help me,
My name is Kurt Deifel and I am the Research and Development
Officer for a large farming co-operative here in the Darling Downs
in Queensland, Australia.
The problem that we have at the moment is with the residual effect
of pre-emergent selective herbicides in our Lettuce and Celery
Transplants. The active constituent that we are having trouble
with is Pendimethalin mixed in a Liquid Hydrocarbon Solvent. It
is sold under the name of Prowl(R), Accotab(R), Go-Go-San(R),
Herbdox(R), Sipaxol(R), Wax-up(R) and sold under Stomp 330E(R)
here in Australia. It is manufactured by the American Cyanamid
Company in the United States. The chemical belongs to the
Dinitroaniline family and is originally a orange/yellow
crystalline solid soluble in most organic solvents hence being
mixed with the Liquid Hydrocarbon.
The problem is that we have been using this product quite
successfully to control certain weeds in our Lettuce and Celery
for about 15 years and have had excellent results. Until last
season when we started to find some abnormalities in our Lettuce
resulting in this seasons Lettuce having catastrophic problems.
Lettuce transplanted into blocks sprayed have very poor
establishment figures ranging from 10-50% of the transplants
dying. Once these Lettuce transplants had started to grow they
soon became very uneven. With the plants appearing to be about
two weeks different in the same blocks. Once they came to
harvest only about 30-50% of the Lettuce could be harvested with
the rest being either too small or not forming hearts. At first
we thought that it was something else such as nutrition or
insufficient irrigation but when we sprayed different blocks with
different treatments then this soon told us the real story.
Blocks that were not sprayed with this product had an excellent
establishment, over 99.9% with about 60-70% of the Lettuce being
harvested. Although this was still a disaster this was a large
improvement on the blocks sprayed with Stomp 330E(R) with only
30-50% being harvested. We also applied another herbicide,
active constituent Propyzamide or Pronamide under the trade name
of Kerb WP(R) manufactured and released by Rohm and Haas Company.
This appeared to have no effect on the establishment or growth,
in fact it appeared to be better than the control where no
herbicides were applied. There is such a large difference in the
stunting that the rate of growth between a treated block and an
untreated block is quite large, if you didn't know that they were
both planted on the same day you would swear that there was
7 to 10 days difference in the two blocks. This results in the
treated blocks being harvested almost two weeks later than the
untreated block. All of these trials were replicated and the same
results appeared pointing to the Pendimethalin being the problem.
It appears that if applied this season to blocks it will result
in killing plants and reduce yields by over 80%. And with the
residual or background levels in the soil it will severely effect
the growth and still result in massive reductions in yields. We
have been applying the product according to the label and at the
rate of 2.5 litres / hectare with the recommended rate being from
2 - 4 litres / hectare, and been more then generous with the
minimum interval time and the 2-7 days required with holding
period from spraying to transplanting. At the moment we are
loosing $40,000 to $50,000 dollars Australian and will go broke
very quickly if we cannot find a solution.
If you know anything about this product or know anybody that might
be able to help me please let me know. At the time being I would
like to find out as much as possible but am very interested in
- I can take tissue and/or soil samples and send them to a
laboratory to be analyzed to see if there has been any significant
difference in the levels of Pendimethalin between the treatments
and other farms or is the active constituent not translocated into
the plant or does it simply effect the root system.
- Do different varieties of Lettuce get effected differently by
- Is there an indicator plant that I can use such as a grass
species or other to tell us that concentrations are still toxic
in the soil so we will know very roughly what level is in the
field. I have read that some grass species are susceptible to
this so that may work.
- Is there any crop, element, chemical or technique that we can
use to so called soak up or reduce the effects of the product in
the ground, i.e. can I grow a certain crop species that will
absorb the chemical in stolens or tubers or other plant part and
use these to trap and store the product so we can dig this crop up
and remove the Pendimethlin from the field.
- Does this product have a history of having such a problem as
remaining in the soil, does it have a long half life to break
down or does it not break down, can I accelerate the natural
- Could it be another product or product reacting with the
Please help we with my quest for information and possible
contacts, your time and knowledge will be greatly appreciated,
and maybe I can even help you with some of your own problems.
Please E-mail and post your reply so I can get answers as soon as
possible because we have to try and find a solution very quickly.
I will answer all letters.
Thankyou very much in Reply,
Mr. Kurt Sepp Deifel
Research and Development Officer
for Story Farms Pty. Ltd.
E-mail address <kurt at tmba.design.net.au>
Snail Mail - F1/311 Bridge Street, Toowoomba,
Queensland, 4350, Australia.
Phone - (076) 361911 Fax - (076) 362216