April 14, 1993

A Guide to Buying Healthy Trees and Shrubs

For many people, selecting a healthy tree or shrub is a game of chance. Sometimes you win, occasionally you lose. By following the suggestions listed below, the odds of selecting a healthy tree or shrub can be shifted in your favor.

Has the Crabgrass Germinated?

Spring is just around the corner; birds are singing, tulips have emerged, trees are budding out, and the turfgrass is greening. Last year at this time I was getting ready to apply a preemergence herbicide to control the crabgrass in my lawn. But, does this mean now is the time to apply a herbicide this year? No!, even though spring fever has hit everyone, including myself, restraint is necessary, because we are experiencing a late spring warm up.

When Should You Apply a Preemergence Herbicide?

Unlike last year, soil temperatures have remained rather cool for this time of year. Therefore, an application toward the end of April or first part of May should be early enough for most of Iowa. Another way to tell if soil temperatures are near the range for crabgrass germination is by looking for other plants to give us a clue. Crabgrass seed germination usually coincides with the time when forsythia blossoms start to fall. If you do not know where a forsythia bush is growing, perhaps you can find a redbud tree or a lilac bush.

Test Plantings of Scab-immune Apple Cultivars in Iowa

One of the most exciting prospects for reducing pesticide use on apples has been the recent emergence of apple cultivars that are immune to apple scab and also possess desirable horticultural characteristics. Many of these cultivars also have good to excellent resistance to cedar-apple rust and fire blight. Their potential is at least as exciting for home orchardists as for commercial growers. Among the named scab-immune cultivars to come from the Purdue-Rutgers-Illinois (PRI) breeding program over the last few years are Redfree, Jonafree, Liberty, Dayton, and Williams Pride.