May 26, 1995
Since ancient times, scholars have suspected that walnuts have harmful effects on nearby plants. In the 1880s, scientists isolated a compound called juglone from the fruit of walnuts. They demonstrated that injury and sometimes death result when this phytotoxic material interacts with susceptible plants.
Carpenter ant nests are very common inside trees, especially older trees that are hollow or have a significant amount of dead limbs and branches. The nests are usually in rotted, decayed wood, although some nests may extend into sound heartwood in the center of the tree.
European pine sawfly larvae have already been reported in several parts of Iowa, and NOW will be your last chance to discover any defoliation in time to treat effectively. Defoliation of pine trees and shrubs by clusters of European pine sawfly larvae is a common problem during the month of May. Full grown larvae that are usually present by Memorial Day weekend, may be a little later this year. Look for 1-inch long grayish-green larvae with 2 light stripes and 1 dark stripe on each side of the body and shiny black legs and head.
It's the time of year when noses and eyes are directed to the beauty and fragrance of certain plants. A genus of plants well known for both is Syringa, known commonly as lilac. Lilacs offer gardeners a large variety of plant shapes, sizes, and flower colors. The parade of lilac flowers begins in late April and early May and continues through mid-June. Hybridizers have worked extensively with the common lilac resulting in over 1000 different varieties. Some lilac species to look for include:
Deformed peach leaves have been arriving in the Plant Disease Clinic. These leaves showed a thickened, puckered appearance with a pink-red color. Later in the season infected leaves turn gray and fall from the tree.
The fungus that causes peach leaf curl, Taphrina deformans, overwinters on bud scales and twigs. Infection occurs during the spring just as the buds begin to swell. Spring rains wash spores of the fungus to newly emerging leaf tissue. Cool, wet conditions favor the disease.
PAT 13, "Personal Protective Equipment for Agriculture: Sources of Protective Apparel and Gear."
This popular pesticide applicator reference was revised and updated as of April, 1995. Twenty-one Iowa and adjacent state companies that specialize in providing respirators, gloves, goggles and other pesticide applicator safety equipment are listed. Please discard old versions.
IC 472, "Household Insect Pest Management."
The U. S. Department of Agriculture has announced a delay in the effective date of the pesticide recordkeeping amendments from May 11 to August 1, 1995. The requirement to keep records of federally restricted use pesticides, that was originally effective May 10, 1993 are still in place and only the amendments to the original regulations have been delayed. The delay will allow farmers and producers more time to learn about the new recordkeeping procedures. Private applicators will not have to make adjustments in their recordkeeping procedures during this busy planting time.