Sycamore doesn’t grow well in desert

I will present a class on the basics of fruit tree pruning at the Las Vegas Springs Preserve Saturday at 8:30 a.m. There will not be a class on pruning at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas; pruning classes at the orchard will resume Jan. 15 with a session on how to prune pomegranates and nut trees, including almond and pistachio.

Q: Our board of directors decided to cut down all the sycamore trees in our community. They claim some of them are sick and need to be cut. They are also planning to cut other sycamore trees that are healthy. They claim that even though they are healthy they will get sick in the near future and that's the reason that they will be cut. These are 20-year-old trees that are nice and give a lot of shade. Several members of the community do not agree with the board. Can you advise me about the sickness of these trees? Could you also inform me about any ecological societies or organizations in Las Vegas that may stop them from cutting those trees, particularly if they are healthy?

A: Sycamore is not a good choice for our area. They are large trees, consume considerable amounts of water compared to desert-adapted trees, do not tolerate our soils all that well, usually develop considerable iron chlorosis and leaf scorch as they get older, and can die back and become unsightly. It was a mistake to put in these trees, particularly in the number that you are talking about, in the first place.

The trees could be improved for iron chlorosis with soil treatments or trunk injections of iron. Your association is caught in a dilemma. The treatment of these trees, if it works, will be quite expensive. They will probably require more pruning maintenance as they get older.

Perhaps your community could promote a program where those who want to preserve these trees can adopt them for treatment and care. In the meantime, replacement trees could be planted and given a chance to get some size before the older trees are removed.

Q: I have two problems I have not encountered before. First, about half of my kohlrabi are splitting almost in half, from top to bottom. They are 1 to 2 inches in diameter. Others in the row are OK. Secondly, some of my red beets want to grow above ground. The portion above ground appears woody. If I plant the seeds too deep, they don't germinate.

A: When I first read your e-mail I thought the rain and all the soil moisture might have caused the splitting. But if this was the case, then they should not be woody. That is an age issue. Kohlrabi should be smooth and green with no apparent fissuring on the swollen part of the stem, which should be above ground.

I have always liked kohlrabi because the vegetable was above ground, which avoided some pests like wireworms and maggots, and is not as pungent as turnips. It is tasty as a starch addition in stews.

If the kohlrabi or beets are woody, this is usually an indicator that they are too old and should have been harvested earlier. Poor soil conditions or soil that has not been fertilized might have caused them to be smaller than optimum. Uneven wetness also causes splitting, but if they are woody, then they are most likely too old.

Beets normally will grow so that the swollen portion, part of the stem, is above ground when they are ready to harvest. This is normal for beets as well as radishes and most root crops. This is an indicator that they are ready or near-ready for harvesting. The top of the swollen stem emerges from the soil regardless of how deep the seed is planted as long as it is not too deep. Most root crops are more tender and sweeter if harvested when they are smaller.

Of course you are right that if small seeds are planted too deep, then the tiny plant emerging from the seed will not make it to sunlight and the seed will die. A general rule of thumb is that the planting depth is no more than two to four times the width of the seed. If soil drying is a problem for small seeds, then use a surface mulch to help keep the soil moist between irrigations.

The size of the kohlrabi depends on the variety and soil conditions but should be about 3-4 inches in diameter. There are varieties like Gigante that can be much larger.

Q: My wife and I are recent transplants to Pahrump. We have been reading your column/articles in the Las Vegas Review-Journal and I'm wondering if there an archive of your writings somewhere on the Internet? I find your gardening articles very interesting and useful, and would like to collect past writings.

A: They should be archived at our University of Nevada, Reno website and can be found at www.unce.unr.edu/areas/southern/newsletters.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.