[tomato] Red Plastic Mulch - results

William McKay (Tomato@GlobalGarden.com)
Mon, 01 Nov 1999 10:20:05 PST

This year I was taken with the idea of using plastic mulch to solve a number 
of problems I have been having.   Almost every year, many of my plants wind 
up with septoria leaf spot and I was under the impression that a plastic 
mulch would tend to prevent this.  Also, I use municipal water and the water 
rates in the Boston area are among the highest in the country.  I had also 
heard that red plastic mulch increases yields even over black mulch.  
Finally, I expected the mulch to cut down on weeds.  I wound up using red 
plastic mulch on the bulk of my tomatoes and black mulch on peppers and 
eggplants.  I left four or five plants unmulched as sort of a control.  
Tomatoes were almost entirely heirloom varieties, although I did two or 
three hybrids.

I laid down red plastic mulch on raised beds with soaker hose under the 
mulch.  The tomatoes were transplanted in mid may, a week or so earlier than 
usual.  In general, I was not satisfied with the results.

The good news was that the mulch worked extremely well keeping weeds down.  
However, a few passes through the tomatoes with a stirrup hoe would have 
done as good a job.  Other than that, I believe I would have been better off 
not using the mulch.

	One of the things I have started doing is using lightweight remay cloth 
over my transplants when they first go out.  The cloth provides a few 
degrees of extra warmth, but most importantly, protects them from wind and 
to some extent, excessive sun.  I couldn't use it in combination with the 
red plastic;  the few plants where I tried it burned up.

	While the plastic mulch may have saved me some water by preventing 
excessive evaporation, it also kept out any supplemental water from rain 
(not that we had a heck of a lot of rain during the spring and early part of 
the summer.)  Had I used grass clippings or ground up leaves as mulch, I 
would have saved even more water.

	The plastic mulch prevented the manure I had added in the spring from 
breaking down-the combination of plastic & soaker hose irrigation resulted 
in minimal moisture in the first four or five inches of soil.  This fall 
when I took off the plastic and turned over the soil, I noticed the manure 
had not broken down in the beds, although it had done so in the walkways 
which were uncovered.  There was a much larger worm population in the 
walkways than in the beds.

	I did not notice any significant difference in production between the 
plants under plastic mulch and the unmulched plants (all did fairly well).

	While the incidence of spetoria leaf spot was less this year than last, I 
still had it and a number of varieties did not survive much past mid August. 
   Only a few of the most resistent varieties made it until the first frost. 
  (Part of the disease problem, I am convinced, is due to my cultural 
practices.  I made my rows too close (4-4.5 feet).  Also, I have some tall 
trees on the west side of my garden which cut down significantly on sun.  
This winter I plan to visit them with a chain saw.  I also do not spray.

I am at a loss to explain my fairly dismal results given the generally 
glowing reports in the literature of the use of red plastic.  In addition, 
there is a very successful farmer down the road from me who has done 
considerable experimentation with red plastic and he is extremely 
enthusiastic about it.

I would be interested in the results of other folks who may have used 
plastic mulch, although I suspect there is nothing could convince me to use 
it next year.

Bill McKay in E. Massachusetts

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