Re: Red spots on Nepenthes

Date: Fri Apr 02 1999 - 19:55:45 PST

Date: Fri, 2 Apr 1999 22:55:45 EST
Message-Id: <aabcdefg1194$foo@default>
Subject: Re: Red spots on Nepenthes

In a message dated 99-04-02 18:57:51 EST, you write:

<< I have recently obtained a few Nepenthes with red blotches on alot of
  the leaves. I was told this was due to cold damage. Until this time I have
  thought these red spots to be the result of a fungus (rust) which other than
  being unslightly wasn't a threat to the plant. I had never heard of the
  markings due to cold temps. I sometimes get these dark red spots on plant
  leaves that have not been exposed to cool conditions.
       While at a bromeliad nursery the orchid grower had some N. x Coccinea,
  some had the red spots which he tried to tell me was a varigated leaf! But
  these plants did have damage due to cold.
       Could anyone offer comments on these spots?

Dear Mike,

I have noticed this red leaf spotting on Nepenthes for years and a friend had
leaves sent to the University of Florida at Gainsville for an I.D. As far
as they could tell these spots are caused by the systemic fungus Cercospora.
I do not by what means the fungi attacks plants, it may germinate in drops of
water on the leaves, enter by way of the sugar glands or perhaps by
mechanical or insect damage. It has been reported not only in cultivated
plants but on a N. stenophylla on Kinabalu as well, and this species seems
particularly sensitive to it. It will cause a weakening in Nepenthes and
even death in severe infections. The good news is that it is easily
treatable. There is a systemic fungicide, Clearies 3336 flowable that will
destroy it. I believe the concentration is 1 tablespoon per two gallons but
I have used it at 4 tablespoons per gallon as a test with no damage to N.
mirabilis, a thin leaved species. Also good to know is as far as they have
tested it, it is not a carcinogen and seems to be toxic only to fungi at
normal strengths. I have used it on Utricularia, orchids, Genlisea, all
Nepenthes, and Mexican Pings with no damage to the plant. Lower leaves that
are heavily infested with Cercospora may die off after a few weeks, but new
grow will be free of the fungus, at least until it re-infects the plant in
the future. I try to treat all my plants about twice year, overdoing it may
produce resistant fungi. One other thing of great interest to Nepenthes
growers, after treatment I have seen the leaf size of fungi-free plants
triple in size!

Clearies is available through V.J. Growers in Apopka, FL.


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