Master Gardeners debunk pear trees and soil testing quandaries

Q. I noticed these white flowering trees or bushes along the roadside around the edge of town. The flowers look like Bradford pears. Is that what they are?

A. Unfortunately, these are wild degenerates of the Callery pear, of which Bradford is one selection. Callery pears are native to China and Taiwan and have been a hot landscape tree for a few decades. They have some very desirable characteristics - fast-growing, glossy leaves, dense foliage, pleasant shapes and spring flowers (by the way, they don't smell very good). They have also been criticized for weak branches, of which Bradford is one of the worst, but new selections have come out that corrected this. They also were considered resistant to most diseases, including fire blight, which can cause a lot of the branch ends to become brown and unsightly.

But any of these negative traits pales in comparison to what's happened with its reversion to wild types. The cultivated types were considered to produce sterile fruit, which are about pea-sized, hard and turn a tannish-brown when ripe, generally in July or August. The problem that has become apparent is that when different forms are planted in an area, they can cross pollinate, and the fruit that develops can have viable seed. Of course, any fruit like that will be eaten by some birds, and so it is spread. To make matters worse, some of these "off types" are also thorny. (Just an aside: pears, apples and roses are all from the same family, so "thorny types" are in the genes of apples and pears - mankind has just selected away from that trait, not surprisingly).

The Missouri Department of Conservation has a fact sheet on this matter advising a number of native trees to consider instead of Callery pears. This tree has gone from the "wanted list" to the "wanted poster" in a very short time frame. Because this tree is not native, you will typically notice the escapees around the roadsides of cities and towns. Many trees often grow close to each other in this situation, forming a thicket. Time will tell how problematic these wild types are in spreading further into natural areas.

Q. Will a soil test tell me why my lawn doesn't grow well or my vegetables did poorly last year?

Maybe. What it will tell you is how available the major nutrients are and what the pH is. If the pH is much too low (acidic) or high (alkaline), then this is likely to be the source of the problem. If one of the major nutrients is deficient, this could also be the source of the problem. A regular soil test does not tell the nitrogen level because it is quite mobile in the soil. Instead, it estimates nitrogen based on the organic matter level. Based on this, it will give nitrogen recommendations.

My experience is only a minor percentage of dissatisfied gardeners find their problem answered by a soil test. Nonetheless, we recommend it highly, as it does allow us to rule out poor fertility as a problem or complicating factor. Often, through follow-up discussion, one of these issues becomes the likely culprit:

• Not enough sun (too shady for the application, especially vegetables).

• Root competition from neighboring trees and bushes (especially vegetables).

• Compacted soil (especially lawns).

• Disease problem (especially lawns).

That said, just last week, we had one lawn soil sample come back where the pH was quite low and a likely culprit for the weak lawn growth. And many of the results on vegetables indicate organic matter is too low, so efforts should be undertaken to increase it. Temporarily, this can be remedied by adding nitrogen fertilizer more frequently.

Soil tests cost $16, and the soil samples can be brought to our office on business days from 8 a.m.-4:30 p.m. We do have a tool we can loan to make taking a sample easier, and can answer questions at 634-2824.

Q. When does the Master Gardener hotline start again? And when is the Master Gardener plant sale?

A. The hotline will begin again May 10. It will be open Tuesday and Friday afternoons from 12:30-4:30 p.m. through September. At that time you will also be able to submit questions via email to [email protected] for inclusion in the News Tribune's weekly "Ask a Master Gardener" column.

The Master Gardener plant sale is May 7, with doors opening at 7 a.m. As in the past, it is at the Jaycees Fairgrounds.