June 3, 1992

Cold Injury to Woody Ornamentals

We have been deluged with phone calls and samples concerning tree problems during the last three weeks. Symptoms vary widely, from leaf spots and blackened leaf margins on maple, to undersized and defoliating leaves on oak and ash, to complete failure to break bud in a few cases. Conifer problems include needle browning or yellowing, drying of emerging candles, and branch dieback. What's the explanation? The consensus of Extension specialists in plant pathology, horticulture, and forestry is that the vast majority of the problems are related to cold-temperature injury.

Insect Damage to Notice on Trees Now

Ash Plant Bug.
This common sap feeder on ash tree foliage causes discrete white speckles on the upper surface of the leaves. The leaf undersurface is marked with shiny black specks of excrement called varnish spots.
The feeding stipples are often clustered and in some severe cases, enough speckles accumulate to cause shriveling or browning of the leaves. Premature leaf drop is possible later in the season when the second generation has further stippled the same leaves. Control is seldom warranted except on stressed or newly transplanted trees.

Ground Beetle--Another of the Accidental Invaders of Summer

Ground beetles are very common "outdoor" insects that occasionally become pests by wandering into houses and buildings by mistake. They do not damage household structures or furniture and are harmless to people and pets.

There are hundreds of species of ground beetles commonly found in Iowa. Most of these are about 3/4 to 1/1/4 inch long though smaller species may be present. Most species are shiny black with few distinctive characteristics aside from the lines or ridges down the wing covers. A few species have brightly colored sections or spots.


Many gardeners are now enjoying the rewards of early spring planting. Lettuce, beet tops, mustard greens, spinach, and turnip tops are just a few of the leafy greens being eaten right now. Many greens grow best in cool weather and mature in a relatively short amount of time. Most greens can be planted just as soon as the soil can be worked in the spring or in August for a fall crop. Successive plantings are also recommended to extend the harvest season.

Misapplied Pesticides in the Home Garden

Every year someone will make a mistake and apply a the "wrong" pesticide in their vegetable garden or home orchard. It may be a canceled pesticide such as old, leftover chlordane or heptachlor that was used in the garden, or it may be a current pesticide that is not labeled for food crops that was applied. Misapplication of Orthene, Isotox and the corn rootworm insecticides are all-to-frequent examples of the latter problem.

Seedhead Development in Lawns

Seedhead development in home lawns has raised some interesting questions. Two of the most interesting questions have been: "What causes grass to develop so many seedheads?" and "Can a person allow the seedheads to develop and mature to overseed a thin lawn?"

Vorlex Lost to Re-Registration

NOR-AM Chemical Company has requested voluntary cancellation of two soil fumigant products, Vorlex Soil Fumigant and Vorlex 201 Soil Fumigant, due to the cost of re-registering the products as required under the FIFRA regulations. Active ingredients in both products include methylisothiocynanate (MITC) and 1,3-dichloropropene. Vorlex has been used to control disease, weeds, and insects for a variety of fruit, vegetable, ornamental, and greenhouse crops.