Spring is here; at least it was today. No matter when it finally
arrives, there are a few indicators that should be obeyed when it does.
For me, small dead roaches in a cup of water said it was. Empty cups are
left on benches among plants and moved around each week to be sure that
my watering is thoroughly soaking pots and media. It is surprising how
often I find a portion of a bench that seems to be neglected when it
comes to water. The drowned roaches, however, indicate that some insects
are beginning to hatch and become active, thanks to warmer night
temperatures.
If you follow this column you may remember that the large roaches,
“Palmetto Bugs”, that rule Florida have been my worst enemy since moving
here five years ago. An old friend, Karen Tobiassen, suggested that I
try Orthoboric acid. Sold in a fine granular form, the product was
initially scattered around on benches especially where I had either seen
roaches during one of my late night “roach hunts” or seen roots eaten by
what I suspected were roaches. Some was also applied on the surface of
extra orchids to be sure there were no negative effects on my orchids.
Initially, I was disappointed because there was no pile of roach corpses
scattered under benches. After a couple of weeks, I noticed fewer
damaged roots near areas where the Orthoboric acid had been placed and
dead roaches nearby. Most important was the fact that these dead roaches
were terminal larval stages that are the most destructive because they
live in the bottoms of orchid pots. They were often found during
repotting and very hard to kill with pesticides while hiding in the pot
among the medium and crock or Styrofoam peanuts. Better still was the
fact that the orchids and their roots in pots saturated with the stuff
looked just fine when I removed these from their pots. An application
throughout the greenhouse in early fall seemed to eliminate these pests
all winter.
Their return was not surprising, given the fact that there is lots of
nature outside the greenhouse that sneaks in during winter. A spring
application will begin this month even though I have seen no apparent
damage yet.
There is a mystery that has long intrigued me with respect to orchids
and disease. There are number of commercial growers and friends from
whom I receive orchids where I expect problems. It is not the quality of
their orchids, but the fact that plants from them develop more than a
normal level of diseases once in my growing area. Why? I have examined
these plants carefully, looked at nutrients in their tissues that are
usually high, and not found satisfactory answers. Conversely, my orchids
as well as those from some other growers rarely have these problems even
though they are growing side by side.
My suspicion was that my own plants had some type of immunity or at
least resistance to many diseases that these other orchids did not have.
While plants do not have circulatory systems where disease fighting
cells will move to diseased areas, they do have an immune response. The
immunity is stimulated by previous attacks from pathogens and
communicated around the plant via plant hormones called auxins. Even
more interesting is the fact that some auxins can be passed from plant
to plant via the air, even to plants of different species.
A new product that attempts to stimulate Systemic Acquired Resistance
(SAR) is now being marketed for various vegetable crops and is reputed
to boost the plants immune system, increase plant growth and flowering
and even decrease the incidence of Botrytis. Will such a product work on
orchids that grow slowly and are members of a distinctly different plant
family? Pesticides that confuse insect molting cycles seemed like wild
ideas at one time, but are now part of my pest control. Who knows what
this new product will do? Only time will tell.