Poplar trees can cause problems by reproducing easily

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Question: We had a 30- to 40-foot-tall cottonwood tree cut down in April. The stump was not removed. Now we have trees growing all over our yard from the roots of the original tree. We drilled holes in the stump and poured a stump killer on it, but we cannot get rid of all the new trees growing in our yard.

Answer: Just a quick note about cottonwood trees: we all have a tendency to call a tree that grows fast and has a leaf that is roughly triangular in shape a cottonwood tree. This is a problem when using common names for plants.

All cottonwoods are poplars, but not all poplars are cottonwoods. Cottonwoods are poplars that produce a lot of "cotton" in the spring, filling the air and covering the ground with white, cotton-like seeds from the female plant. All poplars, whether they are cottonwoods or not, have male flowers only on a male tree and female flowers only on a female tree.

The female tree produces seed and the male tree produces pollen. The seed gets fertilized from wind blowing pollen from the male tree to the flowers of the female tree. This makes male trees and female trees. The female trees produce the cotton since these are seeds. Male trees produce pollen, but no cotton.

One of the worst poplars you could plant is called the white or silver poplar, which could be mistaken for a cottonwood. The white poplar is distinctive because it has a leaf that is clearly green on the topside and white or nearly silver on the bottom. The leaf shape strongly resembles a cottonwood leaf.

Once planted, you can have a nightmare due to the sprouting of new plants from the roots once the tree is established. This only gets worse when the tree is cut down and hundreds of new plants, now released from the roots of the parent plant, sprout everywhere the roots are growing. I don't even want to tell you what they will do to septic tanks and sewer lines if they get in.

Once cut down, killing the stump will probably not help much. These new trees are "on their own" and not connected much to the parent plant any more. Plants with this type of characteristic evolved in places where survival from catastrophic losses due to fire, animals and other devastating events was important.

You should keep in mind that when these sprouts are growing rapidly, they are using food stored in the roots. Once these sprouts become established, they begin rebuilding the root supply to help other potential sprouts.

The only way you have of getting rid of these sprouts is to remove new growth that is using food stored in the roots frequently so that eventually, over time, you will begin to starve out the root system and exhaust their food reserves. When you start doing this, you will see the vast majority of shoots give up and not regrow. Shoots that have access to the most food will be more difficult to control and will take a longer period of time to kill.

Removal of sprouts should be done as soon as you see leaves and continuously through the year. Removal can be by hand or by spraying or painting the leaves with a weed killer with a label approved for that purpose. Actually, the easiest way for younger sprouts is with a sharp spade or shovel and undercutting the sprout and pulling it out.

The key in eventual control is to diligently remove the new sprouts before they have produced about eight new leaves. Once they have a full set of new leaves, they will begin to send surplus food back to the roots and the roots will be back to where they were. Control centers around removing new shoots as soon as they are seen.

Remove shoots as soon as possible and do that every week. Some of this can be done with mowing if it is in a lawn or using a line trimmer.

Q: I try to water my garden every morning before sunup so that way the ground is cool. I'm trying to grow watermelons and cantaloupes and so far, I have a pretty good crop. One problem that I have is that some of the melons are splitting open. What would be causing this?

A: Split melons may be caused by a number of different factors. These include the type of melon, irrigation practices, rain close to harvest time and not picking when ripe.

Some melons are more inclined to split than others. The Charentais melon has a heavy percentage that will split when mature. If you try to harvest too early to avoid splitting, the fruit is not a good quality and will not ripen off of the vine.

As the melon rind begins to set up as it matures, irregular watering practices or wet dry cycles can cause the melon to swell and split. In the same way, rain can cause the same thing to happen. Usually, they do not all split, but some percentage might, depending on the type of melon.

The best advice I can give you is to mulch the soil surface to keep soil moisture from cycling wildly between wet and dry. Irrigation practices that apply water evenly will help. Harvest when the melons are mature and don't let them get overmature. Grow melons with a low splitting percentage, such as the more traditional melons found in stores. Mulch can be an organic mulch, such as wood chips or plastic mulch.

Q: My squash is rotting before it fully matures. They will get about 3 to 5 inches long and then on the tip, where the flower was, start to rot. So far, out of six or eight squashes, I have been able to gather only four that were good.

A: Squash usually shrivel up and die if there is a lack of pollination. The fruit will get a few inches long and die just as you describe, shriveling from the flower end.

Squash and melons both are pollinated by bees. You may not have enough bees visiting your plants at the time when flowers are open. You can put plants close to the garden that attract bees during the same time your plants are blooming to encourage bee visits.

Or you can hand pollinate the flowers with a soft brush in the early morning hours, transferring pollen from the male flower to a female flower and do the work of a bee. Or you can construct some leaf cutter bee houses to encourage their presence for pollination.

For gardeners who are interested in expanding their skills, upcoming gardening courses offered include Winemaking at Home and Landscape Design With the Desert in Mind. The winemaking course is set for 6:30 to 9:30 p.m. Thursdays through Oct. 19.

Winemaking basics for making good wine will be taught, together with wine appreciation and wine blending techniques. The $50 class fee will include wine tasting and wine blending exercises. Contact me at 257-5509 or at Extremehort@aol.com if you want a registration form mailed or e-mailed to you.

Landscape Design With the Desert in Mind is planned for 6:30 to 9 p.m. Tuesdays from Sept. 5 through Oct. 24. Learn how to convert your water-guzzling, water-wasting yards into less thirsty, water efficient, energy saving and attractive landscapes that meet the needs and desires of those who live there. The class fee is $50. To register, call 257-5555 or e-mail mojavemel@aol.com.

Both classes will be held at Cooperative Extension Lifetime Learning Center, 8050 S. Maryland Parkway.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.