This is a public-interest archive. Personal data is pseudonymized and retained under GDPR Article 89.

Re: Brown spots on my tomatoes!

Hi Richard,

> Hi,
> Every night I cover my tomatoes with a plastic covered cage and every
> morning I remove the cage from my tomatoes so that they don't cook
> inside my little mini greenhouse during the heat of the day. I've been
> putting it on because it has been dropping into the 40's, low 50's at
> night and I wanted to help the plants stay a little warmer than they
> would if I left them exposed.

Warmer temperatures will increase growth rate, but your tomatoes are likely
hardened off to the cold now and should easily survive exposure to the nighttime
temperatures you describe (above 45F is considered "safe" for good sized tomato
transplants).

> Well, the other day I noticed that when I took off the cage the plants
> had dew on them. I thought nothing of this until yesterday when I
> noticed that one of the plants had brown spots on some of the leaves, I
> picked off the leaves and hoped for the best. This morning I noticed it
> was still on that plant and was also on two other plants! I was
> devastated!
> I always make sure that whenever I water I don't let any water splash on
> any of the leaves because I heard that this is how disease is spread
> onto the plants. Could the dew on the leaves also spread disease? I
> looked in the new Gardens Alive catalog and saw pictures of Early Blight
> and Septoria(sp?) leaf spot, and as far as I have noticed, the leaves
> haven't turned yellow they just get covered with more and more brown
> spots. I think it is early blight but I am no expert. Is there anything

Yes it sounds like the beginnings of early blight, supported by the combination
of dew on the leaves and the warm period in the morning before the plastic is
removed.

> that I can do to cure this? They sell something called Shield-All
> Organic fungicide that I can order but if someone knows a home remedy I
> would appreciate it. One last question, should I leave the cage off the
> plants from now on even though it is still pretty cold at nights?

Yes, because you are noticing it early on you can take measures to control it's
spread.  Early blight spores seem pretty ubiquitious, so best you can do is
create conditions less favourable to their development.  During rainy warm
periods it gets established but if followed by dry weather it's development
slows and may stop completely.

Your covers may be creating the warm and wet conditions the blight thrives in,
so you could stop using them if you want, your tomatoes will be just fine as
long as the temperatures aren't dropping into the lower 40's or upper 30's.  An
alternative to completely stopping thier use would be to open up the ends of the
cages so the enclosure isn't so complete.  This will allow more air flow,
hopefully lessening the dew forming (because of better evaporation with the air
moving through) and keeping the morning temperatures inside from climbing too
high while still providing a warmer microclimate at night.

We get a lot of summer rain here so I use large hoops of PVC pipe and vapour
barrier to cover an area of my garden in which I grow tomatoes, peppers,
eggplants, basil and melons - all plants which are susceptable to fungi problems
and which benefit from the warmer microclimate created by simply keeping the
rain and cooling breezes at bay.  It is kind of like a big umbrella for the
garden, protection overhead but with lots of air flow from the large open ends
and open bottom edges too.  If you're interested I can e-mail the plans, I've
posted them to the list before, or you can just make up something along the same
lines - rain protection while maintaining good airflow.

Beyond keeping the foilage dry here are a few other things you can try ...
  Pick and destroy infected tissue (within reason - a few spots is one thing
while a seriously infected and yellowed leaf is another - you don't want to
defoliate your tomatoes - if you have to go that far you might as well pull the
whole plant, it is too far gone).  Be careful not to spread the fungi to healthy
plants, wash hands and tools well after picking/pruning.
   A good layer of well-done compost (from a cool compost pile preferably) will
introduce many beneficial fungi and organisms into the topsoil layer and will
perhaps help displace the offending fungi while providing additional nutrition
to the tomatoes, bolstering their resistance.  Good nutrition goes a long way to
preventing this problem from becoming a serious crop destroying ailment.
  Feed and/or foliar feed (early in the morning) with compost tea and/or seaweed
fertilizer. These tonics will aid in the plants resistance.
    As a last resort you may want to spray with something.  You could try copper
fungicide, which is considered an organic treatment.  It is nonetheless fairly
heavy-duty stuff, being highly toxic to fish and acquatic invertebrates, toxic
to mammals (including us), irritating to skin and eyes and persisting
indefinitely in the soil.  I've never used it myself, having always opted for
the less extreme dry foiliage approach which has kept blight from developing
very fast on my tomatoes despite it's established presence on the plants and
inclement weather.

> Thanks,
> Richard
> Brooklyn, NY (zone 6)

Welcome, and good luck!  I think your plant will be fine, they have a good
caretaker watching over them. ;-)

   ____________________
  |                    |
  |     Bob Carter     | Kootenay Bay, BC, Canada
  |  bcarter@awinc.com | Zone 6b
  |____________________|


You are a completely unique individual, just like everybody else.

***************************************************************************
To unsubscribe, send to: listserv@umslvma.umsl.edu
the body message: unsubscribe sqft
See http://www.umsl.edu/~silvest/garden/sqft.html for archive, FAQ and more.
References:
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index