Mature cactus pads make propagation easy

: I have two Indian fig cacti that grow exceptionally well. My question is about how these cacti reproduce. Mine form little stubs on the leaves and flower quite heavily in the spring. The petals drop off in a few weeks. Later, the little stubs drop off. Are these seed pods? If I planted one, would I get another cactus? Or, do I cut a leaf off and pot that to start a new plant?

A: From your description it sounds like the cactus is one of the Opuntia type cacti, sometimes called prickly pear cactus.

They are very easy to propagate. You simply remove a fully mature pad from the mother plant, making sure it is cut precisely at the joint that connects the mother plant to the pad. Put this pad in the shade for seven to 10 days and allow the wounds to heal.

When planting the pad, make sure the hole where the pad is to be planted has been modified or amended with about 25-50 percent compost. Prepare a deep hole. Bury the bottom third of the pad in the amended soil and water it once a week to initiate roots. You will know when roots have begun because you will see new little pads starting to form on top of the planted mature pad. In fact, they may form even before roots begin to grow.

Some of these cacti are used to produce fresh vegetable (young pads that are eaten) and fruits that Mexicans call tunas. Some of these tunas are sweet and delicious while others are not, depending on the plant.

You will know if your cactus has sweet tunas because the birds will demolish them. If the birds do not bother the tunas on your cactus, they are probably not very good to eat.

You can start the cactus from seed but the pads are so much easier. Good quality cactus pads and fruits are produced if the cactus is given frequent watering, watering in midsummer about every two weeks.

Q: We have a pine tree in our backyard; it is surrounded by grass and close to the brick wall that separates our property from our neighbor’s. A friend told us to get rid of the tree because it is a yard killer. He said that the roots would start to knock down the wall and that the needles just kill the grass, which has been true of ours; the grass is dead underneath the tree.

I love the late afternoon shade that the tree gives to the yard and I would like to keep it if it won’t cause damage to the wall or if there is some way to keep the grass alive. Do you have any suggestions?

A: It is more likely that the grass is dying because of the shade rather than the pine needles. We use pine needles as part of an organic mulch at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas and have had no problems with it. If you are using a mulching mower on your lawn, which you should be anyway, the mulching mower will cut up the pine needles and return it as mulch and not damage the lawn.

Hopefully you are not bagging your lawn clippings. But if you are, the lawn mower will pick up the pine needles and remove them from the lawn.

If the tree is too close to the wall, let’s say closer than 6-8 feet, it could pose a problem but not necessarily. Roots travel where there is water. If water is applied in areas away from the wall, they will stay away from the wall. They will not go in search of water in a neighbor’s yard unless your neighbor is overwatering.

If the pine tree is watered with shallow irrigations, the roots are more likely to be close to the surface. If pine trees are watered deeply and infrequently, their roots are more likely to grow deep. Trees growing in a grassy area will tend to have shallow roots because of the frequent irrigation needs of the lawn.

It is very clear that the shade provided to the walls of your hot south and west exposures will save you a considerable amount of money in electricity, perhaps somewhere between 10-20 percent during the summer months. That has been demonstrated by research. Removing the tree will increase your energy consumption during the summer.

Before you remove the tree, you might want to consider having the soil on your side of the wall trenched about 2 feet deep to sever any roots that might be growing under the wall. Leave the trench open for 24 to 48 hours to allow the roots to begin healing before you put the soil back in.

As far as shading the lawn and causing it to die, yes, that is going to be a problem. You cannot grow a lawn in dense shade. Most lawns need about 50 percent sunlight on them sometime during the day.

Q: My almonds are losing sap and some have dimples and fall off of the tree. I discovered an insect with a long tube that it inserts into the almond. How do I get rid of them? What are they? This was the best almond crop we have had and they are now gone.

A: Thank you very much for sending me pictures. They were extremely helpful, particularly the last one showing the insect.

This insect is the leaffooted plant bug. You are very observant. You are exactly right. This insect has a long tube for a mouth, about half as long as its body. When feeding, the insect takes this tube and inserts it into green almonds. Because the tube makes a hole in the almond and the almond has sap in it, the sap oozes out of the hole in a squiggly curl.

For fruit growers, these insects are evil. They attack and feed on green almonds, green peaches, pistachios and pomegranates. The dimples occur a few days after feeding while the almond continues to grow around the damaged area.

At this point in time, all I can tell you to do is use a traditional pesticide spray for fruit trees as the fruits are developing. I would look for a pesticide that contains one of the synthetic pyrethrins or pyrethroids such as permethrin or resmethrin. Make sure it is labeled for the fruit and nut trees you are considering spraying.

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 extremehort@aol.com.