September 16, 1994
The presence of a white, dusty mildew on infected plant partsmakes powdery mildew easy to diagnose. Late in the season, tinyblack fungal fruiting bodies may appear on the mildewed surface. Powdery mildew can occur on leaves, stems, buds, and flowers. Ornamental plants that commonly show signs of powdery mildewinclude lilac, viburnum, crabapple, phlox, rose, zinnia, begonia,and turf.
Powdery mildew is favored by cool nights followed by warmdays. The disease is most common in shaded areas and in siteswhere plants are crowded and air circulation is poor.
Are you tired of replacing your hybrid tulips every few years?Would you like a tulip that naturalizes well? The answer lies inthe selection of species tulips.
Species tulips are different than hybrid tulips. Theyperform best in rock garden-like locations. They require full sun,and well-drained, almost gravelly soils that drain quickly betweenrains. When preparing the site, amend the area several incheswider and deeper than the bulbs will occupy with sand or gravel. Planting on a gentle slope or in a raised bed assures gooddrainage. Plant the bulbs 5 to 8 inches deep.
An April 1994 Gallup survey sponsored by the Professional LawnCare Association of America and the Associated Landscape Contractors of America found that 9 out of 10 households recognizethe value of a well-maintained lawn and landscape. According tothe survey most households value an attractive, healthy lawn andlandscape because it enriches the neighborhood, provides abeautiful place to relax with family and friends, reflectspositively on the people living there and enhances property values.
The black walnut (Juglans nigra) is one of the most valuabletimber trees in Iowa. It is also a valuable nut tree.
The fungicide Captan has long been a mainstay of disease-control programs for growers of apples, small fruits, and berries. Sevral years ago, EPA put Captan went through its Special Reviewprocess to better assess its health risks as well as its benefits. Captan emerged from Special Review with a new restriction on itslabel: a 4-day reentry interval. The reentry interval meant thatworkers could no reenter a Captan-sprayed field for 4 days unlessthey wore protective clothing (long-sleeved shirt, long pants, andnonabsorbent boots and gloves).
A new report released by the EPA indicates that pesticide usein the U.S. equaled about 8.8 pounds per capita, relatively stableat about 2.2 billion pounds of pesticide active ingredients. Thetitle of this new report is "Pesticide Industry Sales and Usage,1992 and 1993 Market Estimates," and was assembled by EPA's ArnoldAspelin. Conventional pesticide use remained at about 1.1 billionpounds of active ingredient. Wood preservatives and disinfectants(non-conventional pesticides), pushed total U. S. pesticide use toabout 2.2 billion pounds of active ingredient.
This is the time of year we begin to notice activity by one ofour most common ant species, the larger yellow ant (LYA). LYA isfound throughout Iowa and because of its prevalence next to housesis also called the "foundation ant." Normally, these ants liveoutdoors in old logs and stumps and under stones. During the latesummer and fall, however, entire colonies may move toward buildingsand try to enter through cracks or gaps in the foundation. Swarmsmay be seen either outdoors or inside the house.
The Plant Disease Clinic has been receiving evergreen samplesshowing seasonal needle loss. (Many people panic at this time ofyear when they notice needles yellowing and falling from theirtrees.) Fear not, evergreens do not keep their needles forever. The older, inner needles eventually turn yellow or brown and fallfrom the tree.
Geraniums are popular bedding plants, blooming freely from May to frost. However, the first hard frost doesn't have to be the end for your geraniums. They can be overwintered by potting up individual plants, by taking cuttings, or by hanging the plants upside down in a cool, dry place.