GARDENING: Spring brings puff mushrooms, pests

We have a great new composted dairy manure out of Amargosa Valley. It is one of the best composted manures I have seen. Pick-up loads are available to the general public for $30 each Saturday morning on a cost recovery basis for the master gardener orchard. The orchard is located east of the corner at Decatur Boulevard and Horse Road in North Las Vegas.

Our office has been getting calls now on mushrooms appearing in lawn and shrub areas. These are not the typical mushrooms that you normally see, but fleshy balls that burst from underground leaving holes in the soil about the size of an egg. These puffball mushrooms are white when they are underground but turn grey or brown once they mature and are ready to release their spores. Once the underground puffball bursts it releases thousands of spores into the air, its way of propagating itself. You usually won't see it unless it does rupture, leaving that hollow, fleshy depression in the soil the size of an egg.

Peach twig borer, the worm that gets into mid- to late-season peaches and the hull of almonds, can be controlled with sprays of Bt -- the bacterium spray usually labeled as Thuricide or Dipel. You will spray the tree as soon as you see the color appearing in the fruit buds and through bloom time until petal fall. The Bt spray will not hurt bees, only insects that turn into moths or butterflies.

Dormant oils can be applied now and all during the spring but avoid trees in bloom. This would include oil sprays like Ortho's Volck Supreme and others that are similar. The dormant oil spray is used to control aphids, mites and scale insects that can be troublesome later in the season.

Grapes should be pruned late in the spring, just before new growth or as new growth is starting to emerge. This will help to minimize the bleeding that occurs at the time of pruning.

Question: I would like to plant pampas grass this season. Is it appropriate for this area? The grass will be planted in full sun. I like the graceful plumes and plan to place them by a fence. Is it too early to plant now?

Answer: Pampas grass does very well in the Las Vegas climate and is appropriate if you have a large yard. Pampas grass can get to be 20 feet tall and 20 feet across, so it needs lots of space and it is difficult to cut back. The leaves have a saw-tooth edge that causes light scratches that typically draw blood if it is drawn across the skin.

It is a nightmare to keep trimmed. Frequently, people are told not to trim it but let it continue to grow from the base year after year. It can look quite messy after a while growing like that. There are forms that are variegated and there are dwarf forms that are supposed to get only 5 or 6 feet tall and are prolific bloomers. You may want to look for a dwarf form if you have a smaller yard.

Once established, the grass is very difficult to kill. In some communities with more rain than us it can be invasive.

Q. Does a young dwarf Bearss Lime tree -- about 4 feet high and put into ground last August and with most leaves lost to the wind and cold -- need to be pruned or cut back prior to spring? And if so, by how much?

A. Citrus trees usually need little pruning except to remove dead or weak branches and to thin twiggy growth, removing dead, injured, diseased and crossing branches, suckers and branches growing downward. Pruning should be done to remove water sprouts or suckers or to remove freeze-damaged material from the tree.

Shoots from below the head (scaffold limbs), whether on the rootstock or the scion, should be removed as soon as they are noted. You also can cut back long branches at the tips to promote shoots nearer the center of the tree. Never remove more than one-fourth of the tree at one time. Excessive pruning at one time may set back growth and fruiting.

Q. I have not been able to find information on pruning of ornamental grasses (deer grass). Is it necessary to cut back this grass now? Do they require plant food?

A. The ornamental grasses are mostly what we call bunchgrasses. That is, they get larger by sending out side shoots called tillers from the crown of the plant. These can be tillers that come directly from the stem of the plant or they can be on short runners called rhizomes if the runners are below ground or stolons if they are above ground. As the plant gets older, the older leaves die and remain in the center of the plant where they can look unsightly if you are expecting a lush plant free of debris every year.

In nature many of these plants may be renewed by fire or animals that may graze on them. In the case of deergrass, much of its charm is in the combination of brown and green growth signaling different times of the year. But it does need to be pruned periodically. It is best not to shear the plants.

However, it does need to be fertilized and spring is the time to do that in concert with many of the other plants. Use a turfgrass fertilizer to do this and sprinkle it at the base of the plant near the drip emitter if you are using drip. If it is overhead irrigation, then anywhere within a foot of the plant will do. Nitrogen is the fertilizer key to new growth but the other elements are needed for good health of the plant.

Deergrass really isn't pruned. It is left natural. If it becomes overgrown then you could replace it or cut it back close to the ground and let it regrow. Fountain grass, on the other hand, can be pruned by pulling the dead stems out of the bunch.

Q. I have a tall fescue lawn and it has a thick thatch layer. Is now the right time to remove the thatch?

A. Thatch results from the accumulation of dead grass stems and roots. It does not result from grass clippings.

A small layer of thatch can actually be beneficial. You don't want more than one half inch of thatch to accumulate in a lawn.

Thick thatch layers can result in poor water penetration, runoff, disease problems, insect problems, poor heat tolerance and other problems. Poor management practices can increase the production of thatch.

Heavy fertilizer applications, particularly nitrogen, frequent shallow irrigations and too much water also will stimulate thatch production.

Some grasses are heavy thatch producers and others are not. For instance, hybrid bermudagrass and Kentucky bluegrass can be heavy thatch producers. Tall fescue is not a heavy thatch producer. Be sure it is thatch that you see and not something else.

Airborne dirt blows across yards and the grass causes the dirt to fall onto the lawn.

This dirt, over time, builds up. As the soil level rises, the grass sends out new roots into this deposited soil and the lawn rises.

The lawn may be several inches above the sidewalk. This could appear as if a thatch layer is causing the lawn to get higher. As the lawn rises the irrigation heads become sunken into the lawn.

If it is thatch, then remove the thatch layers with a power rake or dethatcher. Remove no more than one half inch at a time.

A thick thatch layer is removed slowly over a period of a few years. This can be done in the spring or the fall, but the fall months are better.

There are fewer weeds that can become problems in thinned lawn areas in the fall. Dethatching in the spring opens up the lawn at just the time when crabgrass, spurge and the majority of our other lawn weeds become a problem for us. Aerating or coring the lawn will help to reduce thatch layers over time as well.