Aeration is the key to summer lawn preparation

Regarding lawns in Las Vegas, there are a few things you can do about the upcoming heat if you haven't done so yet. First aerate. Aeration will help get the roots down deeper and improve your lawn's ability to withstand drought. Actually this should have been done earlier but if you haven't done it yet then it should be done. Aeration is particularly needed if you see any standing water, runoff or on slopes or heavy traffic areas.

Lawn areas should be aerated in preparation for the heat. Aeration can be done safely anytime of the year while dethatching is best done in the late fall. Get the mowing height up now for a deeper root system.

Follow aeration with a fertilizer high in phosphorus and potassium. I normally recommend a fertilizer high in nitrogen and low in phosphorus and moderate in potassium. But following aeration is a great time to get phosphorus into the root zone. And since phosphorus doesn't move through the soil easily it will help to apply it after aeration.

Phosphorus also improves root growth, which is why you are aerating now. The potassium is to help in drought stress. If you haven't fertilized for quite awhile then give yourself a high nitrogen fertilizer as well.

The last thing you want to do preparing for the heat is to get your mowing height up to 2 and one-half inches or higher. It will encourage the roots of the grass to go deeper, particularly if it's done after aerating and fertilizing.

There is a lot of wind damage to leaves on trees and other woody plants. When soft, leaf tissue first emerges from the leaf buds it is very susceptible to mechanical damage. The new leaves have not yet developed a toughness required for resistance to abrasion and tearing. High winds cause these new leaves to twist, whip and rub against the branches which causes them to tear and look ragged.

It's easy to confuse this with damage insects might cause when chewing. While the older, damaged leaves will be ragged; the newer leaves emerging will be in good shape since the wind is gone when these emerge. This can help tell if the damage was due to wind or not.

There were some questions that came into our office about the proper distance to plant trees and large shrubs from walls or foundations. A general rule of thumb when planting near the home is never plant trees closer than half the distance of the spread of the mature canopy.

When planting near a wall or sidewalk or driveway, the distance can be closer but should take into consideration the tree's mature height, it's rooting habit -- does it commonly have shallow roots? -- and the soil type. I certainly wouldn't want a tree closer than six feet to a wall or sidewalk. If the tree is a large tree with possible surface roots, then it should be further away.

Small side shoots or sprouts can be seen coming from the trunk and larger limbs on many small trees now. Should they be removed? Unless they are a nuisance or must be removed because of appearance, I would leave them on. This is for two very good reasons.

Small shoots coming from the trunk or large limbs produce leaves. These leaves produce sugars for the plant. The area closest to the leaves receives the most sugars from these leaves. These small shoots contribute greatly to the diameter growth of the trunk and large limbs. This type of growth on the trunk and large limbs makes the plant much stronger and more capable of withstanding strong winds and stand on its own without staking.

These small shoots also help to shade the trunk and limbs from our extremely intense sun. This sun can scorch and kill young wood exposed to it directly. Remove small shoots when they reach the diameter of a pencil. Think about these points first before removing these small shoots or suckers.

The cool wet weather of spring caused some other problems for us as well. Bees don't like to fly during cool wet weather. If bees aren't flying then there will be poor pollination. Look for the results of poor pollination on fruit and nut trees as well as your vegetable garden.

The results of poor pollination will be early, sudden fruit and nut drop before they can mature. Since the bees did not pollinate the fruit and nuts then the seeds cannot mature inside the fruit or nuts. Most fruits and nuts need seeds to develop because the seeds send chemical "signals" to the fruit and nuts that allow them to develop and mature. Of course there are exceptions such as the seedless grapes and watermelons. But for most fruits and nuts, even though small fruit or nuts may form, they will not continue to maturity since the seeds inside were never formed.

The same is true of vegetables that result from a pollinated flower. Vegetables such as tomatoes, peppers, squash, cucumbers, melons and the like all result from pollinated flowers. Even if the vegetable flower is not pollinated, a small vegetable "fruit" may result. But, like the fruits and nuts mentioned above, it will not contain seeds that can take this "fruit" to maturity.

Soon after this vegetable "fruit" begins to develop and the gardener sees and gets real excited, this fruit withers and dies. The natural response is to think it was a disease or blame the nursery for selling bad plants or your neighbor. When things like this happen, stop and think. What was the weather like a few weeks before this happened? Without bees, all of our gardens would fail.

Question: We have a Fan-Tex Ash in our backyard that is doing very poorly. The leaves curl up over a period of about 48 hours and then drop off. New leaves come out ... but only last a couple of weeks before they, too, curl up and drop off. There is no discoloration of the leaves and no sign of pests. The drip irrigation in these beds goes for 15 minutes, four times a day.

Answer: Leaf distortion and leaf drop could be physiological, damage from weed killers being sprayed in the neighborhood on a windy day or a possible insect problem. Although I couldn't see any traces of them on the photos, I think you had an early infestation of ash whitefly. There are very few pests of ash here in Las Vegas. The two principal ones historically are ash flower gall mite and ash whitefly. The ash whitefly has been in Las Vegas for many years now, coming most likely from California growers, but has never successfully set up housekeeping here. I can only speculate but perhaps the climate is too harsh for it to get a good foothold here.

Usually you would see traces of the whitefly on the leaves earlier in the season. The ash whitefly will feed on the leaves on the underside of the leaves usually leaving some sweet sticky honeydew excrement dropping on the leaves. Sometimes this honeydew will turn black from sooty mold growing on it. The other characteristic, early leaf drop, is very characteristic of ash whitefly. Ash whitefly does not handle our heat very well so usually it subsides during hot weather. The curling of the leaves can be caused by their feeding as the leaf is developing.

Unfortunately there is no chemical control recommended. There is a small wasp that can be released for biological control but is not available commercially. If you want to pursue this biological control I can try to obtain permission to release some in Las Vegas. To my knowledge this has not been done here. It has worked very well in California and would benefit the entire community.

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