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Attack of the Japanese Beetles

Japanese beetle eating an Oenothera flower.

Japanese beetle eating an Oenothera flower at the Denver Botanic Gardens.

Gardeners around Colorado’s Front Range are coming face to face with a new foe in our landscapes. Japanese beetles have been a pest for years in U.S. gardens in the east, south and mid-west. It is only relatively recently that the feared invasive pest has made its presence known in Colorado.

The beetles (Popillia japonica) are believed to have entered North America via New Jersey in 1916, probably hitchhiking on ornamental nursery stock from Asia. They are voracious feeders, doing damage to trees, shrubs, perennials, annuals and turf grass. Some of the 300 favorite food plants of the adult Japanese beetles are roses, Virginia creeper, grape vines, raspberries, linden, elm and fruit trees. The sign of their destruction is skeletonized foliage and  flower petals that have been devoured. The adult beetles feed during the day, preferring hot and sunny days.

Popillia_japonica_on grape leaf at DBG 2

Japanese beetle on a “skeletonized” grape leaf at the Denver Botanic Gardens.

The beetle’s one-year life cycle seems tailor made for a traditional lush turf and shrub landscape. They spend winter underground as a grub, feeding on turf grass roots, creating dead patches in the lawn. In June they begin to emerge as adults ready to feed on the flowers and leaves of plants. The adults can be found feeding on plants as late as September. In addition to feeding on your landscape plants, they might be seen mating on those plants. After mating, females will move to turf grass lawns to dig into the soil to deposit their eggs. After depositing eggs, the females will resume feeding on host plants. The females will return to the lawn to lay more eggs. Up to 60 eggs can be laid by each female beetle during her 4-8 week life span.

Back in the turf grass soil, the eggs will hatch and the Japanese beetle larvae will emerge and move to the grass roots to feed. The larvae are most susceptible to drying out and dying when young if the soil dries out. That is one reason some experts advise against over watering lawns in mid to late summer. The larvae will develop rapidly, causing much damage to the turf grass roots, eventually killing some of the turf grass plants. The larvae feed on the grass roots until the temperature drops below 60 degree F. The larvae move deeper down into the soil to overwinter. Once the soil warms up in spring, the larvae move back up through the soil to resume feeding on the grass roots for about 4 to 6 weeks. After that, they begin to pupate. A couple weeks after pupation, the adults will emerge from the soil to feed on leaves and flowers, mate and start the cycle all over.

The worst damage caused by the Japanese beetles seems to be to lawns, where the larvae can cause dead patches. It appears the damage to shrubs and trees is mostly cosmetic, and will not kill those plants. However, this cosmetic damage can be significant and will upset most gardeners.

Unfortunately there is no magic bullet to control Japanese beetles in your landscape. If you discover them when they first arrive, using manual methods to collect them is a wise choice. Do not crush them, or the chemicals released upon squishing will attract more Japanese beetles to your yard. Try collecting them in a jar of soapy water. Traps are not recommended because they also attract more beetles to your yard. Pesticides may be effective at controlling the beetles. However some systemic pesticides have been linked to death of beneficial pollinating insects such as bees. For more information on the safe use of pesticides and other methods to control Japanese beetles, visit the Colorado State Extension webpage on the subject. Some experts advise the application of grub killing pesticides to lawns to kill the Japanese beetle larvae and keep your turf from being destroyed. The extension does say this about trying to control the larvae of Japanese beetles: “Some cultural practices can limit damage and applied chemical or biological controls may also be useful. However, control of Japanese beetle larvae in a yard will have very little, if any, effect on the number of Japanese beetle adults feeding on trees, shrubs and garden plants. The insect is highly mobile so that problems with adult beetles typically involve insects that have moved a considerable distance.”

As mentioned earlier, dry turf soil during the egg laying season (mostly in June & July) will keep some larvae from surviving to become adults. Some experts recommend drying out your lawn and letting it go dormant during the typical Japanese beetle egg laying time, and resuming watering after the eggs have been layed. This would seem a challenging approach to the problem as most people prefer a green, non-dormant lawn during the time of year when a lush lawn is much desired. The extension service does recommend that keeping lawns well watered after egg laying (and once the older larvae are present and most actively feeding) may help the turf survive root injuries caused by larval feeding.

It would appear that typical xeriscape plants are not usually favored by the beetles. This is yet another reason that a xeric and regionally appropriate landscape design is a good approach to follow in Denver and Colorado in general.

Let’s hope we can keep this exotic and invasive pest at bay, and not let it become an established nuisance.

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, click here.

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10 tips for Choosing the Best Plants for Commercial Sites

The landscaping on commercial sites may be low on a business owner’s list of priorities for their property. But you should not underestimate the positive influence an attractive landscape can have on potential clients. With this in mind, here is a list of ten issues to consider for choosing the right plants to keep your property’s landscaping looking and functioning at its best.

Non-Invasive

Some very hardy plants would be great choices for commercial landscapes if not for their tendency and ability to invade and spread where they are not wanted. This may happen via seedlings or by creeping rhizomes (horizontal underground stems that can send out new roots and shoots). Luckily, here in Colorado and the Inter-Mountain West, our growing climate is challenging for many invasive plants that have ravaged milder climates in North America. However, there are some plants you should never allow to take root in Colorado due to their invasive nature. For a list of plants see: http://www.invasivespeciesinfo.gov/unitedstates/co.shtml; http://www.ext.colostate.edu/ptlk/2041.html

ArtGym-Grass-and-Lavender

Blonde Ambition Grama Grass and English Lavender

Disease Resistant

Nobody wants to spend extra money or time dealing with or replacing diseased or dying plants. Avoid choosing plants that are easily susceptible to attack from disease or pests.

Long Lived

Along the same lines of replacing diseased plants prematurely, nobody wants to spend time and money replacing plants that live short lives. The cost of purchasing and installing landscape plants is significant, so it is wise to choose plants that will stand the test of time.

Adaptable to various exposures

The location you are planting on your property may currently be in any degree of exposure from full sun to full shade. But conditions may change in the near future. Will a new building or new trees be placed on the neighboring property? Conversely is a structure or tree slated to come down, creating a new pocket of full sun? Picking plants with higher adaptability to various exposures will ensure success for your landscape.

Adaptable to various soils

The soils in my area are typically heavy in clay with a high (alkaline) pH. This is one more challenge to add to the list of issues that face landscape plants. For best success and longevity, choose plants adapted or adaptable to the soil conditions on your property.

Adaptable to variable moisture levels

You may be familiar with desert plants and you may be familiar with rainforest plants. These two extremes of ecology illustrate the wide variability of climate that plants live in. Your landscape likely falls somewhere in between these extremes. However, even in the most average commercial landscape, we might find wide degrees of moisture and irrigation levels. Having plants that can handle these extremes will help ensure your landscapes do well.

Drought Tolerant

Although nearly all municipalities require automatic landscape irrigation, it is good if the plants you specify for a site are truly drought tolerant.

But on the flip side, some plants that are considered very low water plants may be more difficult to establish on a commercial site due to over watering. Many but not all native plants fall in this category. They are more fussy about soils and drainage. They may need to be ruled out of the “set it, and forget it” situation that many commercial clients may seek. But if you have the time or the staff to work with some very low water plants during their establishment time, they can eventually become great components of your drought tolerant landscaping. The easiest plants to use in your landscape will be adaptable to varying soil moisture levels.

HD_perennials

A variety of perennials and shrubs adapted to Colorado’s climate.

Not messy or difficult to maintain

Your maintenance crew has enough on their plate with regular landscape maintenance. There’s no reason to increase their burden and your costs by having messy, difficult plants on your property.

Readily available from nurseries (not rare)

If you lose some of your landscape plants due to accidents, vandalism or bad weather, you will likely want to easily replace the missing vegetation. If the plant that needs to be replaced is hard to find, you might have to resort to replacing it with one that does not match.

Attractive/Interesting/Eye-catching

Attract eyeballs and attention to your business by choosing interesting trees, shrubs and flowering plants. Just as having aesthetically pleasing buildings or signage is good for business, eye-catching vegetation and other landscape elements makes good business sense. Choose Trees and shrubs with notable flowers or good fall color.

Crataegus - Hawthorn 2

A Hawthorne tree in spring bloom.

In Summary

If you are planning a new commercial landscape or taking an assessment of your existing commercial landscape, keep these guidelines in mind. They’ll help you avoid potential problems that might repel clients and customers from your property, rather than inviting them in. An inviting landscape on your commercial property is one of the first steps to achieving business success.

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, click here.

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Colorado Tree View

From time to time, we here at Outdoor Design Group like to hand over the reins of this blog to a guest writer. This allows us to peer over the fence into the realm of another business, and bring our readers new views on topics related to our field of work.

This week, T.J. Wood from Plan-It Geo (a company that Outdoor Design Group has collaborated with in the past on various projects) gives us a description of an application they developed for the Colorado State Forest Service. This online tool helps Colorado communities assess their public street and park trees locally to provide a statewide picture of tree diversity and health.

Introduction:

At Plan-It Geo, we specialize in “Trees and Technology.” A tree inventory combines both of these elements seamlessly by management of this important natural resource with use of mobile devices and technology in the field. The Colorado State Forest Service contracted Plan-It Geo to develop a web-based application that communities, campuses, and HOA’s can upload their tree inventories and view important state-wide tree data summaries. To access all of our web and mobile GIS software applications, click here.

A screen shot from CO-Tree View

A screen shot from CO-Tree View

Colorado Tree View:

Project Profile: Colorado Tree View

Project Title: Colorado Tree View – Statewide Inventory and Ash management Application

Client: Colorado State Forest Service

Timeframe: February 2015 – Present

Description: Tree inventories provide critical information for cities, neighborhood associations, and other entities to proactively manage their urban and community forestry resource. This project provided a tool to help diversify the planning and planting of tree species. It also provided a first-time statewide view of the structure of Colorado’s urban forests. The tool is a starting point for a long-term strategy and provides substantial new technical support to communities.

Outcomes: A statewide web-based application was created for Colorado. This application has the built-in ability to “crosswalk” a wide variety of inventory data into the application. The main fields collected are species, dbh (diameter breast height), condition, and location of each tree. The application has a hierarchy of log ins based on city and user approvals with different functionality at each level. A customized dashboard was created for the state to view important number and population statistics on each community or organizational inventory.

A screen shot from CO-Tree View

A screen shot from CO-Tree View

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, click here.

 

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Is Your Tree Next to Die? How Emerald Ash Borer Will Affect Our Urban Landscape, and What You Should Do About It

Green_ash_killed_by_Emerald_Ash_Borer

Green Ash tree killed by Emerald Ash Borer

2013 brought tragic news to urban tree enthusiasts in Colorado. In September 2013 the emerald ash borer was found in Boulder County. This find means that thousands of trees along Colorado’s Front Range could be decimated by this pest. And as Colorado State University Professor of Entomology Whitney Cranshaw tells us, the spread of the emerald ash borer (EAB) is dependent upon human activity. It is likely that EAB came to the United States via humans transporting contaminated wood crates from Asia, and it probably reached Colorado through contaminated firewood.

 

The emerald ash borer, Agrilus planipennis, is a beetle native to Asia. It is small, about the size of a grain of rice. Being a non-native insect in North America, it has no predators to keep its population in check. And unlike the Ash trees in Asia, our native Ash trees don’t possess the natural insecticides that control EAB. Adult borers eat leaves of Ash trees, then mate and lay eggs in crevices in the bark. The eggs hatch, releasing larvae which burrow beneath the bark, which disrupts the trees nutrient and water supplying layers. The tree becomes riddled with tunnels the larvae leave behind. The larvae then hatch in spring, burrowing their way to the surface, where they repeat the cycle of feeding on the leaves, breeding and laying eggs of new generation. They kill the canopy of the tree, limb by limb, with the entire tree dead in 3-5 years.

Adult_eab_on_a_penny

Adult EAB on a penny.

Colorado’s department of Agriculture estimates that there are 1.45 million ash trees in just the Denver Metro area alone.  The costs to spray so many trees will quickly mount.

Tree and insect experts agree that there is no point in spraying your Ash tree unless the tree is currently infested. “Since most EAB treatments provide control for one year or, at most, two years following application there is no benefit in treating a tree prior to when EAB is present”, Cranshaw writes in a recent report from Colorado State University.

In other words there is no treatment that will stop the EAB from attacking your Ash tree. Spraying before the tree is infested only wastes money and needlessly adds dangerous chemicals to the environment. In fact, many entomologists warn that even spraying an infested tree may have lethal impacts on beneficial insects such as bees and butterflies, and won’t completely rid your tree of EAB, and would probably only buy you a few extra years of life of an infested Ash tree.

If we take a serious look at the situation, spraying at all is mostly a futile and dangerous endeavor. Spraying gives tree care companies extra income but endangers the life of beneficial insects, could possibly have harmful effects on people and is very unlikely to ultimately save your Ash tree. As CSU’s Cranshaw has said, he expects in 5-10 years all Ash trees in the Metro Denver area to be infested by EAB.  Furthermore, Cranshaw writes: “Once established at a location emerald ash borer can be expected to survive in the area as long as any ash trees remain. Therefore some management of emerald ash borer will be required for as long as one wishes to maintain the tree”. It is our opinion that a better strategy to dealing with EAB is planning for the eventual replacement of your Ash tree, rather than treating your ash tree with toxic chemicals, year after year.

What can we do to slow the spread of EAB to the rest of Colorado?

1.)    Do not transport any ash wood in or out of your area.

2.)    Do not plant more Ash trees in Colorado.

If you have an Ash tree, you really should consider planting a replacement tree now. If you are unsure about what type of tree would be a good alternative to Ash, contact your local nursery, arborist, or contact us and we can help you with that decision.

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, click here.

 

 

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How Long Should You Run Your Lawn Sprinklers During the Drought?

Despite the recent rain across Colorado, much of the state remains in a drought.

The watering restrictions that Denver Water put in place for this year remain in place, having gone into effect on April 1st.

You may be aware that watering restrictions mean you can only water two days per week, but how long should you run your lawn sprinklers on those days?  Denver Water recently released this chart, which includes recommended watering times for different types of spray irrigation.  Note that due to the drought, these watering times have been reduced from their standard recommendations.

2013 Recommended Watering Times

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, click here.

 

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