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The Best of the Rest Items of Interest from other Publications that Should not be Missed |
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Phenology Phenology is 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. In Wisconsin, 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 rigs. 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 with information.
High Tunnels for Winter Protection Researchers at 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.
Choosing Soil for Pond Plants The 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:
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