a study of the influence of climate on those activities that living
organisms undergo on a recurring annual basis, such as bud break
after winter, or the germination of successive crops of seed of
a species. Thomas Christopher reminds us, in Martha Stewarts
Living of March 2001, that this is ancient knowledge, that has
given rise to the timing that many farmers employ as a matter of
course. Native Americans, understanding that corn sown into cold
ground would rot, but that waiting too late to plant would lower
the yield, developed the guideline that the corn would be planted
when the young leaves of oaks were the size of a squirrel's ear.
Many growth patterns
of plants are influenced by the number of days that have had a temperature
above a certain level for a given number of hours (called "degree
days" for convenience). The bud break in oaks and the growth
of the leaves is controlled by temperature, and the number of degree
days that it takes to bring the leaves out to this size is also
enough of a warming trend to have raised the soil temperature to
the right level for rapid growth of a corn seed. This is not controlled
by the calendar: a warm spring would accumulate the degree days
early, a cold spring would set the process back later.
If more than
one organism needs the same number of degree days to trigger some
activity, then both will respond on the same day. This knowledge
is now being used in studying insect life cycles to develop the
optimum timing for control measures on those which attack plants.
Karen Delahaut, an Integrated Pest Management (IPM) Outreach Specialist
has been working with the squash vine borer, an insect that can
devastate a crop. Farmers had become accustomed to needing numerous
pesticide sprays to keep the vines poisonous to the insect. However,
it is now known that the moth that lays the eggs is only active
for two weeks in Wisconsin, and a single spray, applied at the right
time is enough to give control. But what is that right time? Not
a particular calendar date, but timed by observation of the roadside
weed chicory (Cichorium). When the cobalt-blue flowers appear,
the moth is ready to hatch, and it is time to roll out the spray
The same success
is being obtained with controlling the gypsy moth, an invader that
has stripped many forests as it spread across the northeastern states.
A common bacteria, Bacillus thuringensis, is very effective
against the first wave of attack in the spring if applied when the
caterpillars are small. And what is the clue to their appearance
as the moths become active? The appearance of flowers on redbuds
(Cercis canadensis) and Shadbush (Amelanchier xgrandiflora).
This knowledge is cutting the cost of control, but perhaps more
important, is reducing later sprays of chemicals that may be toxic
to many organisms.
These new applications
of an old knowledge are a critical part of many IPM control programs.
They don't work, for the most part, in areas like South Florida
where many pests are active year round, but the new name of phenology
for the study has given a new legitimacy to a country wisdom in
many temperate area of the world.
For the full
story see Martha Stewart Living for March 2001. This is a
remarkable publication for gardeners, beautifully produced and packed
for Winter Protection
Penn State University are beginning a five year study of the high
tunnels which have been used for many years in Europe and Japan
for winter cropping. Drs. Lamont and Orzolek are enthusiastic about
the possibilities for year round production of some vegetables,
and bringing considerably earlier crops to market with others.
The high tunnels
are car-sized tubular frames covered with plastic. Three sheets
are used along the length of the tunnel, allowing the side walls
to be lifted or removed for ventilation. End walls have a door or
detach in one piece for easy entry. The structures boost soil and
air temperatures using the sun's energy. In fact, these low-tech
structures do much that a greenhouse would but at a considerably
lower installation cost. Commercial versions 96 ft long, 17 ft wide
and 9 ft high cost about $1,800 to $3,000 per acre to install, where
greenhouse costs would be $15,000 to $20,000.
Many uses are
visualised, following the European lead, including low tunnels inside
the structures for additional protection, floating row covers and
thermal reflective covers which trap heat around he plants.
For the full
story, see the February issue of Greenhouse Product News
from which this brief report has been extracted. GM Pro returned
to the story in the April 2001 issue.
for more information
for Pond Plants
medium for potting aquatic plants should supply anchorage
and fertilization. It should be odorless and should not make the
water muddy. The best choices would come from the following list:
- Clay - While this gives
support and holds nutrients, it may make the water muddy
- Cat litter - The type
made from calcined clay is best. It has been heat-treated after
being mined and processed. It holds nutrients and gives some support,
and will not muddy the water or float up if disturbed
- Pebbles and Pea Gravel
- Good in terms of support, but with no nutrient-holding ability.
Very good for filtration plants
- Cocoa fiber - The woven
appearance of the fibers allows water to flow through. It is not
heavy enough to support plants without additional weighting down
- Sand - Little nutrient
holding capacity, and tall plants tend to fall over, but very
good for creeping types
- Potting soil - A bad
choice because of the organic material included: as this decomposes
it releases compounds which may be harmful. If the mix has vermiculite
or perlite, these will float to the top
The author, C. Greg Speichert, and his wife, Sue, own Crystal
Palace Perennials in Cedar Lake, Indiana They wrote this article
for the April issue of Fine Gardening, from which this
report is extracted. The magazine's website is at www.finegardening.com
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