How to Get Rid of Overwintering Pests (The Use of Dormant Oil and Horticulture Oil Sprays)

Posted on March 21, 2013 by Glenn

In a recent blog post, I talked about the fact winter’s colder temperatures, especially here in North Texas, do not necessarily kill all your lawn and garden pests – many live to fight another day. One way we battle these overwintering pests such as aphids, mites and scales before they become active in the spring is with dormant oil (sometimes called horticulture oil) sprays.

Dormant oils were originally developed to treat otherwise hard-to-control pest problems on fruit trees. These highly refined oils are sprayed on shrubs and the bark of trees during the winter months when plants are dormant (November through February). They kill difficult-to-eradicate microscopic pests
In a number of ways by either suffocating them or disrupting how they feed.

Dormant oils pose few risks to people and do not harm most beneficial insects. Toxicity is minimal, at least compared to alternative pesticides, and these oils quickly dissipate through evaporation, leaving little residue. Further, dormant oils also are easy to apply using proper spray equipment and can be mixed with many other pesticides to extend their performance.

That said, it is important to know what you’re doing when applying dormant oils, as improper application can lead to disastrous results. Dormant oils should never be applied to plants when there is a danger of freezing or when plants have emerged from dormancy. They should also not be applied to plants that are stressed out. In all of these instances, phytotoxicity can result (poisoning). Other plants such as pansies, bluebonnets and snapdragons growing under or near plants to be treated need to be completely covered and protected.

Recently, more refined oils have been developed that can be used for greater pest control during the growing season. Spider mites, whiteflies and young stages of scales are common pests that can be controlled by oils during the growing season.

Is a Cold Winter Good or Bad for Plants?

Posted on February 21, 2013 by Glenn

The short answer to this question is it depends on how cold, where you live and what types of plants you are trying to grow. In the Dallas area, our winters tend to be mild with cool temperatures interspersed with warm temperatures and a few freezes.

When is Cold Good?
Vernalization is a physiological process in some plants where the flowers or seeds must go through a prolonged period of cold in order to blossom or germinate in the spring. The amount of cold required by a plant is measured in “chill hours.” For many perennial plants, such as fruit trees, a period of cold is needed to break dormancy, prior to flowering. Peaches, for example, typically require 700 to 1,000 “chill hours” (below 45°F and above 32°F) before they break their rest period and begin growth. Nuts trees and berry bushes also have varying chilling requirements. That pretty much sums it up for cold = good.

When Cold Bad: Frosts and Freezes
To understand frost, you need to understand a little bit about dew point. Dew point is a water-to-air saturation temperature. When the temperature falls to the same temperature as the dew point, dew forms because that is temperature at which the air can no longer hold all its moisture. When the dew point is below freezing, frost forms instead of dew. Frost typically forms when the temperature drops to near or just below freezing and there is no wind. Frost can form when the temperature is above freezing, but frost is a sign that the plant tissues have dropped below freezing. When you see frost there has been a freeze at the point of the plant surface. The absolute low as well as the length of time frost conditions remain can affect how much damage is done to plants. Real damage occurs when the water in a plant’s cells freeze, damaging the cell wall.

When a plant is frost-damaged, growth can take on a translucent appearance or become limp, then turn black or brown and dry up. Frost problems can be worse where plants face the morning sun because they defrost more quickly, which ruptures their cell walls.

A freeze is a more extended period of below freezing temperatures and may or may not include wind. In the Dallas area, extended periods of freezing temperatures are rare. When they do occur, soil becomes frozen. Many people think that trees and shrubs “go dormant” in the winter. This is true, but the internal functions of plants do not stop, they just slow way down. As long as the soil is not frozen, trees, shrubs, and even some perennials will still be growing roots. When soil becomes frozen roots are unable to take up water and plants can die from lack of moisture.

Plants are most vulnerable to freezing temperatures in the spring when periods of warm weather increase and suddenly there are several nights with temperatures well below freezing. A hard freeze can damage fruit and buds. Buds may freeze and drop off or fully opened flowers can turn brown or fall to the ground.

The Effects of Drought on Mature Trees

Posted on December 12, 2012 by Glenn

Sadly, as this year draws to a close we continue to see the effects of the prolonged drought the North Texas area has been experiencing. One of the largest casualties, both literally and physically, has been the loss of mature trees. Large mature trees are more easily stressed-out and damaged than established trees that are smaller and younger and we have literally been seeing them dying all over town.

Always remember, because trees take longer to grow and reach maturity, in times of drought and water restrictions, trees should be given priority over other landscape. A turfgrass lawn left unwatered will naturally go dormant for the season and turn brown, but it may turn green again when rain falls or irrigation is reintroduced. Even if reseeding or resodding is necessary, a lawn can often be reestablished in a single season—a large tree cannot.

What are the Effects of Drought?
Early signs of drought stress include wilted leaves and leaf scorching but drought can affect a tree in many other ways including:
• Buds, bark and root systems begin to decline
• Photosynthesis stops
• Growth slows and shoots dieback
• Susceptibility to diseases, insects and other pests increases
• Sensitivity to pesticides, insecticides, herbicides increases
• Vulnerability to high winds, other plant competition and pollution increase

Drought stress symptoms can persist for several years after the initial drought and the previous year’s drought damage may not become evident until spring when weakened limbs break due to strong winds and heavy rains. A tree can show declined growth for a year or two and that decline, along with the
tree’s reduced natural defenses, allows for the expansion of pest populations or diseases that take advantage of the tree’s weakened state.

Which Trees are Susceptible to Drought?
Some trees are more susceptible to drought than others. These include: our beloved red oak, trees with shallow roots such as maples and elms; trees that tolerate heavy clays such as bald cypress, honey locust and river birch; and trees that tolerate poor soil such as hackberry, hornbeam, catalpa and others

How Much Water Does a Tree Need?
A tree’s water demands vary depending on many factors including the age and size of the tree (and its leaves), ambient air temperature, wind speed, etc. When the temperature goes above 80 degrees, large, mature trees may need hundreds of gallons of water a week to sustain through a drought. Through the process of transpiration, up to 80 gallons or more of water can evaporate through the leaves of a single mature tree on a hot summer day.

Watering Established Trees
Established trees should be irrigated from the dripline (the edge of the tree’s leaves) outward. The distance will depend upon the size of the tree and the tree’s root system (a tree’s roots can extend more than three times wider than the height of the tree). A basic rule of thumb is to apply water in a circle that’s at least half as wide as the distance from the trunk to the dripline. Trees should be watered slowly and deeply. Since most of a tree’s water-absorbing roots are in the top 12 to 24 inches of the soil you’ll want to water the soil to a depth of two to three feet each time you water. Let the surface dry between waterings. Remember, deep watering encourages deep rooting—and deep roots are the best way for a tree to survive a drought. Irrigate established trees once every two weeks during the growing season and once a month during the dormant season.

Why Overseed Your Lawn

Posted on November 28, 2012 by Glenn

As the term suggests, overseeding is spreading grass seed over an existing lawn. There are basically two reasons for overseeding lawns. One is to maintain a healthy, thick lawn, which you do by keeping your grass young, and the other is to avoid an unappealing brown lawn during the winter. With these two different goals there are two slightly different approaches.

Overseeding Warm-Season Grasses with Cool-Season Grass
Because we are in Dallas, Texas our clients’ lawns have warm-season grasses, such as Bermuda grass, buffalo grass, St. Augustine grass or zoysia grass. In the winter when these grasses go dormant, they turn brown and unappealing. By overseeding a lawn with ryegrass, a cool-season annual grass, you can enjoy an attractive green lawn year-round. Another benefit of overseeding your lawn in fall is that it helps reduce weeds, crowding them out naturally, without resorting to chemical weed killers. Importantly, annual ryegrass will die back when the heat returns so that warm-season grasses can take center-stage again. It should be noted, however, that overseeding can also place stress on the primary lawn. In the spring when the warm-season turf is trying to come out of dormancy, the cool-season rye grass is still coming on strong, creating competition and slowing the primary grass growth. Especially in the shade, this can be detrimental for the warm season grass.

Overseeding Cool-Season Grasses with the Same Type of Grass
Not every cool-season grass benefits from overseeding. Grass types that spread by the production of “runners” are not typically overseeded unless the lawn is damaged or diseased. Cool-season bunch type grasses such as fescue grasses, ryegrasses and occasionally bluegrass benefit from overseeding.

The reason to overseed cool-season grasses is to keep your lawn looking thick and healthy. The easiest way to do this is by keeping your grass young. To understand this, it helps to understand a little about how bunch grasses grow. As the name suggests, bunch type grasses grow in a bunch. The grass crown, at the plant’s center, has roots and blades. Grass plants expand as new grass blades or “tillers” develop and grow next to the original crown. A blade of grass has a lifespan of about six weeks and must continually produce new tillers or the grass thins out. Hundreds of new tillers can develop, each having its own crown, roots and blades. After several years, mature plants begin to slow down their reproduction rate. Since new growth must outpace dying grass, it is important to keep young grass in the mix that will produce tillers faster than older grass.

When to Overseed Your Lawn
Whether it’s for warm-season or cool-season grasses, the time to overseed is fall when soil temperatures are still warm (necessary for seed germination), air temperatures are cooler (better for grass growth) and there is more rain. Additionally, cooler temperatures reduce insect infestation and disease.

Green Gardening Flea Control with Nematodes

Posted on June 11, 2012 by Glenn

In the never ending quest to live more organically and naturally, there’s a new way to give your pets a break during the hot Dallas summer months. Treating your garden with nematodes (a type of roundworm) will help flea-proof your pets and your home. Nematodes happily munch on grubs, Japanese beetles, fleas, fly larvae and more than two hundred other pests without disturbing your unique eco-system with chemicals or pesticides.

You can find nematodes at home improvement stores, garden shops, or order them online. If you order online, the nematode container will arrive wrapped in cold packs to keep these helpful creatures alive when you introduce them into your soil. The beneficial types of nematodes (non-parasitic) are toxic to pests but safe for plants, animals and humans. They already occur naturally in soil and once they have completed their dining excursion they die off and biodegrade.

Application is a breeze. Simply spray nematodes on wet soil with a garden hose twice a year, during spring and fall. The nematodes will burrow in the ground, rooting out your flea population and devouring it. Over time, you’ll find your flea population is significantly reduced at an economical price (under $20) and your pets are scratching significantly less.

Mosquito Control Solutions for Your Yard

Posted on May 22, 2012 by Glenn

In February, I read about the Jumanji effect; hibernating animals were awakening earlier than usual due to warmer than usual temperatures. The article went on to talk about the unseasonably warm winter we had, and what we can expect this summer including more ticks (due to soaring deer populations that survived the mild winter) and more mosquitos (due, in part, to decreasing bat populations that have been plagued by a fungus). Deer and bats aside, we should expect more bugs simply because with this year’s unseasonably warm winter, they have managed to survive in greater numbers. So with an even buggier-than-usual summer on the horizon, what can you do to make being outside an enjoyable, less-than-pest-dominated experience?

DIY Natural Mosquito Control Solutions
The best thing to do is to minimize or eliminate any areas of open water in your yard that might be places for mosquitoes to lay and grow their eggs (they’ll either lay them on the water surface or on the ground next to it.) If your yard has a frequently-watered flower bed or you have any area that is poorly leveled and holds water after a rain, you have an ideal breeding area for mosquitoes. Larvae can live in very little water, even in wet foliage. Other obvious areas are flower pots, bird baths, roof gutters, rain barrels, streams and ponds, unused swimming pools and outdoor tubs.

Use Bacillus thuringiensis israelenis bacteria (Bti). This bacteria will infect and kill mosquitos, gnats and black fly larvae. Bti won’t harm anything else including other insects, fish, birds, worms or mammals. You can buy Bti as a dunk to submerge in standing water or buy the bacteria in bits that you can broadcast across your garden. It starts working within 24 hours.

Mentioned above, bats are one of nature’s most effective mosquito controls. Some bat species can eat 500-1000 mosquitos per night. Bats come out in the evening and sleep during the day so you’ll never know they’re around. Buy a bat house.

I won’t claim this to be a very effective approach, but there are a number of plants with repellant effects – their fragrance essentially blocks mosquitos’ ability to smell the things that attract them; these include marigolds, rosemary, and ageratum. Crushing some of the leaves when you are nearby to release fragrance can help. In the same vein, throw a bit of rosemary or sage on the fire when you barbeque. Marigolds are pretty “smelly” on their own so some claim just planting large beds of them helps. And, of course, there are always citronella products (made from citronella grass) such as candles or oil that can be burned in lamps and sprays.

Natural Mosquito Control – Professional Help
Landscaping companies such as ours also offer natural solutions for mosquito control. These natural solutions are repellants rather than insecticides and are effective for about 24 hours. Clients having a special occasion outdoor party often opt for this solution. Pyrethrin (used in natural sprays) is made from extracts of a chrysanthemum plant grown primarily in Kenya, Rwanda, Tanzania, and Ecuador. Natural pyrethrin is a contact poison that rapidly penetrates the nervous system of mosquitoes and other insects. (They are toxic to ants, roaches, silverfish, mosquitoes, wasps, spiders, crickets and basically all insects and garden pests.) Within a few minutes after pyrethrin is applied, mosquitoes are paralyzed and unable to fly away. In most cases, pyrethrin alone is not enough to kill mosquitoes, and it is gradually detoxified by the enzymes in the mosquito. Sunlight also degrades pyrethrin so your yard is left residue-free. Although pyrethrin comes from flowers, it is not completely correct to think of it as either “natural” or “organic” because it is highly refined and contains a man-made “synergist” that increases its effectiveness.

Garlic-based solutions are another natural option. Like chrysanthemum-based solutions, they are repellants rather than insecticides and their lifespan is limited, requiring more frequent spraying for ongoing efficacy. Spray systems (see below) designed for garlic-based solutions need to be high pressure, so the smell can be more intense, but the solution can be diluted with water and effectively used for cooling the air as well.

Mosquito Control Spray Systems
For homeowners who want to enjoy their yard throughout the summer and need consistent and reliable mosquito control, installing a spray system may be the answer. These systems feature inconspicuous nozzles and dispense a very fine mist. Bonick Landscaping offers the MistAway control system that uses formulations that are safe for both pets and people. MistAway has several advantages over other spray systems:

• Systems have the ability to agitate the contents to ensure a consistent blend of active ingredients in every mosquito mist.
• If the system is somehow damaged and a leak occurs, the system will automatically suspend operation until the leak can be repaired.
• Every system has an optional wind sensor. The controller is programmed to check the wind speed before each scheduled mosquito mist cycle. It will check the wind every minute for five minutes, and if the wind is above a predetermined speed, the unit will go into hibernation until the next regularly scheduled cycle.

A word of caution: it is important to use knowledgeable, professional mosquito mist installers you can trust to install your mosquito control system as improperly installed mosquito systems can damage and burn plants.

On a final note, with this past winter being the fourth warmest on record and insects emerging to find food earlier in the season than usual, OFF!® Insect Repellents ranked the top 50 American metro areas to identify which cities are most affected by mosquitoes and other biting bugs. Dallas ranked in the top 20 at #17. Are you feeling itchy yet?