Selecting trees for the Home Landscape

Choosing fast-growing trees to fill new home area

Bill Sevier: Ask a Master Gardener

Saturday, August 29, 2015

Q: I have just moved into a new home in an area with no trees. What would be some fairly fast-growing shade trees? R.W., Sand Springs.

A: This is a common question, especially with new homeowners whose homes were built on what was once open treeless prairie or pastureland.

Trees are commonly rated as slow, medium and fast growers. Their rate of growth is dependent not only on the genetic makeup of the tree but also the type of soil, amount of sunlight, availability of water and overall care the trees received.

As you start out with this project of planting new shade trees, and once the varieties are decided upon, always opt for the largest trees you can afford and are physically able to plant — then plant them correctly.

Unfortunately, many of the fast-growing trees are “weak-wooded” and tolerate wind and ice storms less well than others. Some of these have additional issues, making them less appealing. In this category are box elder, silver maple, weeping willow, Bradford pear, mimosa, mulberry, honeylocust, cottonwood and other poplars.

A few of the rapid growers have positive assets, which outweigh their negatives. Some of these are October glory and Caddo red maples, arborvitae, river birch, dawn redwood, tulip tree, Nuttall oak and lacebark elm.

The Caddo maple is a native of Oklahoma and is one of the most heat- and drought-resistant maples available. The dawn redwood is a rapidly growing deciduous tree (up to 50 feet in 20 years), which was once thought extinct. It looks and behaves similarly to a baldcypress. It is very hardy. Bald cypress and dawn redwood trees are great choices for a landscape.

Others in the medium- to fast-growing category which might be good choices for your new yard are water oak, Shumard oak, sawtooth oak, common hackberry, Japanese zelkova, Kentucky coffeetree and Chinese pistache. There are some varieties of ash trees that would normally be suggested, but a destructive ash insect, emerald ash borer, seems to be headed our way. It has destroyed most ash trees in areas where it is located.

Among the oaks mentioned above, the Nuttall is a good choice for a fast-growing shade tree. It is a variety of red oak, similar to a pin oak. However, unlike pin oaks, it thrives in a wider diversity of soil types and pH (acidity) ranges. It’s native to the south and is normally found in wet bottomland and heavy clay soils.

The above suggestions are just a brief list of what would be a good tree recommendation, there are many other acceptable ones. Consider going to the Master Gardener website and look at selecting trees in the “Lawn and Garden Help” section. At the same time, check out the information on “how to plant a tree.”

Garden tips

Always follow directions on the labels of both synthetic and natural pesticide products. Labels will always list where the product may be used and which pest it is certified to cover. If you spray pesticides, do it early in the morning or late in the evening after bees have returned to their colony.

If your tomatoes are too tall and gangly, now is a good time to prune the top of the plants by as much as 1/3 to ½, depending on the plant. This will stimulate new limb growth and new fruit production heading into fall.

Reseeding fescue is best done from mid-September through mid-October. If you plan on reseeding, begin scouting for good seed. There is no “best” variety. Purchase a fescue blend of three or more varieties, with or without Kentucky bluegrass. Read the label on the seed bag. A good blend will have 0.01 percent or less of undesirable “other crop” seeds.

Stinging Insects

Beware of stinging insects -- especially yellowjackets

Brian Jervis: Ask a Master Gardener

Saturday, August 22, 2015

Q: My husband has been stung by some sort of wasp while mowing the yard, twice now, both in the same area of the yard. It looked like a wasp, what can I do? L.M., Tulsa

A: There are several wasps and bees which may sting, some more so than others. The most aggressive insects are yellowjackets, paper wasps and Africanized bees.

According to records, Africanized bees are found in 40 Oklahoma counties in the southern and southwest part of the state but not in our area.

From your description of being stung in your yard and the fact they nest in the ground, the most likely insect to do this is a yellowjacket.

There are many other insects — bees and wasps — with abilities to sting but rarely do so unless overtly provoked. Of the stinging insects, only the females sting; their stingers double as an egg-laying device. Wasps can sting multiple times, but all bees sting only once, losing their stinger and venom bag after the sting.

It is important to realize that most of these stinging insects help control undesirable pests, and some are important pollinators. They shouldn’t be killed unless there is a documented problem or foreseeable threat.

Yellowjackets come in three different varieties — Eastern and Southern yellowjackets and baldfaced hornet. The first two varieties are usually yellow and black and nest in the ground, in old logs or in voids inside the walls of buildings. Their underground nests are hidden but are similar to the baldfaced hornet nest, which is above ground and is a large cone-shaped paper-mache structure.

Yellowjackets also congregate around open garbage, old fruit or any wet sugar source such as open soft drinks where they may be a threat.

The ground nests may be difficult to locate, but if you watch for yellowjacket activities, you should be able to locate the hole, usually less than an inch in diameter.

Once located, use an insecticide — either spray or dust — into the hole then plug the hole with an insecticide-soaked cotton ball. Do this at night when they will all be home and less aggressive.

OSU fact sheet “Paper Wasps, Yellowjackets and other Stinging Wasps” has complete information about controlling wasps, which includes some do’s and don’ts about avoiding stinging insects:

·       Do not use sweet-smelling colognes, perfumes and hair sprays in wasp areas.

·       Do not wear bright-colored clothing; wear tan, khaki, and dark-colored clothes.

·       Do not picnic, sit, or stand near trash cans, fallen fruit, or other wasp feeding sites.

·       Do not swat or move rapidly when a wasp visits you or your food or drink; move slowly.

·       Do not approach a nest; if you do disturb a nest, run away from attacking wasps.

·       Do clean up food and drink refuse, clean trash cans, and fit them with a tight lid to reduce wasp visits.

Garden tips

§  August is a good month to start your fall vegetable garden. Bush beans, cucumbers and summer squash can be replanted for another crop. Beets, broccoli, carrots, potatoes, lettuce and other cool-season crops can also be planted at this time.

§  Discontinue deadheading roses by mid-August to help initiate winter hardiness.

§  Irrigated warm-season lawns such as Bermuda and zoysia can be fertilized once again; apply 1 pound N/1,000 square feet this month. Do not fertilize these grasses after the end of August. Do not fertilize tall fescue lawns in summer; fertilize in late September after it cools and again in November.

§  This time of the year is generally not the best time to prune, but if you have damage to trees and shrubs due to storms, prune out the damage now.

Grasshopper Control

Grasshoppers can be garden pests

Bill Sevier: Ask a Master Gardener  

Saturday, August 15, 2015

Q: Grasshoppers are eating all my flowers and vegetables. What is the best way to control them? J.W., Claremore

A: If you rate the difficulty of insect control from one to 10, grasshoppers will be an eight or nine. They are a challenge, but there are several ways to deal with them — including insecticides and landscape alterations

There is excellent detailed coverage of grasshoppers and strategies for control in OSU fact sheet EPP-7322, “Grasshopper Control in Gardens and Landscapes” available online.

Oklahoma has more than 130 species of grasshoppers, but only a few are pest problems. They are more prevalent in rural sites close to pastures or in urban areas which have land overgrown with weeds or other vegetation nearby. This is because grasshopper eggs are deposited in the soil under the cover of vegetation.

The eggs hatch in spring and look like tiny versions of the adult. They then go through five levels of development, called instars, and are mature 1-2 months after hatching. The small instars have no wings and stay close to the hatching area. However, the adults have wings and can fly for miles if the local food supply is depleted.

Grasshoppers feed on ornamentals and vegetables, as well as grass. They can be destructive, eating large amounts of foliage, when found in large numbers. Evidence of their destructiveness may be found in the biblical and current descriptions of “locust plagues.” The locust in these plagues are not locusts but grasshoppers and continue to be a significant problem in Northern Africa, the Mid-East and Australia.

Several insecticides are recommended for use when grasshopper damage rises to the level when treatment is needed. A list of insecticides, their characteristics and effectiveness are listed in the OSU fact sheet mentioned. It is clear that the small instar grasshoppers are sensitive to these insecticides but the mature adults less so.

One of the problems with insecticides is that most of them are degraded by heat and sunlight, so there is no prolonged effect. Once the current crop of grasshoppers is killed, many others may move in from local weed patches and thrive due to degradation of the insecticide.

Other strategies include closely inspecting the surrounding weed patches looking for concentrations of young grasshoppers, then dealing with them. You may have to get cooperation from you neighbors for this to be effective.

Floating row covers can be used as a barrier to the insect, especially with vegetables (unless the vegetable needs pollinators).

Lastly, there is biological control, a fungus lethal to grasshoppers, which is available as a bait. It has 3 percent to 40 percent effectiveness at best.

Garden tips

During peak heat of summer is a bad time to use post-emergent broadleaf weed killers such as those containing 2,4-D. Weeds need to be growing to be susceptible to these chemicals. Weeds will start to grow when it cools.

The birds need a handy source of water, as well as food. Put out a big saucer of water and watch them not only drink, but also take baths to cool off and remove parasites. Another saucer of water filled with stones and sand will be a watering hole for butterflies and other beneficial insects.

If you are seeing scattered tips of limbs on trees turning brown with some falling to the ground appearing to be broken off, this is likely cicada damage. We experienced a hatch of 17-year cicadas earlier in the summer (the larvae have been in the ground for 17 years). The adults dig into the bark of a stem about 6 inches from the tip and lay eggs. The limb tip usually dies and may fall to the ground. It commonly involves oaks but others as well. The amount of damage is so low to be of little consequence.

Drought Tolerant Turfgrass

Choose the right grass for your specific lawn needs

Brian Jervis: Ask a Master Gardener | Posted:

Saturday, August 8, 2015 12:00 am

Q. I don’t have a sprinkler system, and my lawn is mostly sunny. What lawn grass can survive with the least amount of water? Bobby, Sand Springs

A. The turfgrass grown in Oklahoma that is most drought-tolerant is buffalograss, a native prairie grass, a grass that fed the herds of buffalo and was used by settlers to make the “sod” of sod roofs.

Oklahoma sits in a transition zone between warm-season and cool-season grasses. Our warm-season grasses are Bermuda, zoysia and buffalograss. The cool-season grasses are tall fescue and Kentucky bluegrass. These groups of grasses are named after the season in which they grow best. Warm-season grasses love hot summer; cool-season ones do best in spring and fall.

All turfgrass, like most plants, needs water to survive. However, the warm-season grasses generally can perform well on about half the amount of water needed by cool-season ones.

In summer, most of the cool-season grasses will die of heat and disease without irrigation. However, established warm-season grasses will simply turn brown and go into a protective summer dormancy when hot and dry. During this dormancy, if water becomes available, they usually green up and survive. They also predictably turn brown and go into a protective winter dormancy when cold weather arrives.

Of the warm-season grasses, buffalograss seems to be the best choice for a full-sun area with limited irrigation. Zoysia and Bermuda are the next most drought tolerant.

Native buffalograss can make an attractive lawn but is a little less appealing than the others. It has a blue-green tint, not deep green. The grass requires much less mowing, and some people don’t mow it at all, allowing it to grow to mature height of 4-8 inches, depending on the cultivar. However, mowing will stimulate deeper roots and above-ground spread by stolons.

Buffalograss also requires less fertilizer than other turfgrasses. Because it is a native prairie grass, it can do well with no fertilizer; however, it will look better with some fertilization.

Local sod farms have cultivars of buffalograss that are more attractive as a lawn than the native species. The cultivars are greener, shorter growing and more dense.

The grass can be established using sod, plugs or seeds. Most of the sod sold is composed of female plants — the males have undesirable tall seed heads. The seeds sold are actually small burs and are somewhat difficult to use. They also contain undesirable male plants.

On balance, some people will find buffalograss to be a good choice for dry areas, and after successful establishment, the need for less maintenance is a big appeal.

Garden tips

Fertilization of warm-season grasses can continue if water is present for growth. Do not fertilize Bermuda or zoysia lawns after the end of August. Do not fertilize fescue lawns until it cools off in September.

Establishment of warm-season grasses such as Bermuda and zoysia by sodding or sprigging should be completed by the end of July to ensure the least risk of winter kill.

Mowing heights for cool-season turf grasses should be at 3 inches during hot, dry summer months. Gradually raise mowing height of Bermudagrass lawns from 1½ to 2 inches.

Cucumbers may be bitter this time of year and vines quit producing. This is due to the heat. If you are able to get the vines through the summer, after it cools, they will be fertile again and the taste of the cucumbers will improve.

Fall Vegetable Gardening

Get tips on what and when to plant for fall vegetable garden

Bill Sevier: Ask a Master Gardener

Saturday, August 1, 2015

Q: My vegetable garden I planted in spring didn’t do so well due to the rain and I would like to plant some fall vegetables. What can I plant and when is the best time? T.M., Tulsa

A: OSU has an excellent fact sheet, HLA-6009, "Fall Gardening", available on the Master Gardener web site — that offers what, when and how guidance to plant a fall vegetable garden. It also lists average time to maturity of each vegetable.

Several vegetables may be planted from now through September. Some will tolerate a few frosts and are termed as “semi-hardy”; the others can’t handle frosts and are termed “tender” vegetables.

The tender group of plants include bush, pole, lima and cowpea beans, as well as sweetcorn, cucumber, eggplant, pumpkin, summer and winter squash, and tomatoes.

The semi-hardy vegetables to plant now or later in summer are beets, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, collards, Irish potato, radish, green peas, Swiss chard, turnips, parsnips and leaf lettuce. One should wait until September to plant garlic, kale, kohlrabi, mustard, spinach and onions.

Some of these vegetables are planted as seed, others as seedling plants. Seeds left over from previous plantings should be viable for use if they have been kept in a refrigerator or freezer.

The major obstacle in starting a fall garden in summer is the challenge of hot soils and rapid water evaporation. Some seeds will not germinate at high soil temperatures, which in summer may be in excess of 140 degrees.

There are some work-arounds to cope with the summer extremes. One method is to plant both seeds and transplants in the bottom of a furrow a few inches deep. The bottom of the furrow is cooler, and a furrow also makes it easier to irrigate. After planting, either in a furrow or on top, shading the soil is desirable. One can use a straw mulch or garden shade cloth to help cool the soil. These cloths are available in most garden centers.

All plants in the fall vegetable garden will need to be watered until rains begin in fall. The best way to do this is to use drip irrigation. This type of irrigation is relatively cheap and easy to install for most homeowners. You may refer to OSU’s fact sheet for commercial drip irrigation, BAE-1511, “Drip Irrigation Systems” . The companies that manufacture irrigation products, such as Rainbird, also have useful manuals with instruction directed toward homeowners.

There are many possible approaches to a fall vegetable garden, all of which result in produce that some people would argue is even tastier than spring-grown. In addition, some of the semi-hardy vegetables may be harvested into the winter months, especially if a cold frame is used.

Garden tips

Divide and replant crowded hybrid iris (bearded iris) after flowering until August. When planting, take care not to plant the rhizomes too deeply. Cover them with an inch of soil or less. Do not mulch iris.

Water all plants deeply and early in the morning. Most plants need approximately 1 to 2 inches of water per week. Rather than watering daily, water less often and more deeply.

Some trees such as sycamores and river birches lose large numbers of leaves in the heat of summer. Trees do this to reduce water loss from their leaves. It is a coping action by the tree; it is not dying.