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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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Collecting Rainwater No Longer Illegal in Colorado

Starting on August 10, 2016, it is no longer illegal for homeowners to collect the rain (or other precipitation) that has fallen on their roofs. In May 2016 Governor John Hickenlooper signed a law (House Bill 16-1005) that allows residential properties and multifamily residences with four or fewer units to use up to two rain barrels, located above ground, with a combined storage capacity of 110 gallons.

Rain barrels can only collect precipitation from rooftop downspouts, and the collected water can only be used on the same property from where it was gathered. The collected water can only be used for outdoor purposes, such as watering outdoor plants. Collected water in rain barrels can not legally be used for drinking or indoor uses.  Additionally, it should be known by rain barrel owners that operating a rain barrel does not constitute a water right. There is language in the bill that the State Engineer “may curtail rain barrel usage” if a water right holder can prove that the use of rain barrels has impacted their ability to receive their entitled water. In fact, in the bill it says the State Engineer must report to agricultural committees in the legislature in the year 2019 and 2022, on “whether the allowance of small-scale residential precipitation collection pursuant to this article has caused any discernible injury to downstream water rights.”

If you would like to learn more about rain barrels. check out Colorado State University Extension for more information.

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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Dog Tuff African Dogtooth Grass: The Best Turf Grass for Hot & Dry Sites

Do you love having a lush lawn, but hate the idea of wasting water? Do you have dogs who leave unsightly dead spots in your lawn where they’ve urinated? If you answered yes to either of these questions, then Dog Tuff African Dogtooth Grass (Cynodon ‘PWIN04S’) may be the best choice of turf grass for you. Dog Tuff is drought tolerant, resistant to dog urine, thrives is full hot sun, and is soft underfoot. Dog Tuff is a sterile variety of Bermuda grass, so it won’t spread via seeds. Dog Tuff grass was developed by respected Colorado horticulturalist Kelly Grummons. Kelly is working with High Country Gardens, and Plant Select to market this product. Watch this Plant Select video to see Kelly discussing this wonderful product:

 

Kelly has been working on bringing Dog Tuff to market for over ten years. The original parentage for this grass is native to South Africa, where a lush patch of it was found on a ranch. Dog Tuff is a “warm-season” grass, so it does not green up as early as blue grass. However, as Kelly mentions in the video, Dog Tuff needs only a fraction of the water to survive as compared to bluegrass. Dog Tuff grass will grow in many soil types, but it does need full sun (6 or more hours of direct sun). Dog Tuff is rated hardy to USDA zone 5.

We recently provided design services for a public park in Arvada, Colorado, where we incorporated Dog Tuff grass into an area the park. It was planted last year and is doing well. We are excited to have this as part of a park where people can visit and see the grass in person.

If you are planning a new lawn, or if you are thinking about replacing your current lawn with a more drought tolerant type of grass, you should consider incorporating Dog Tuff African Dogtooth grass in your home landscape.

This is the official blog of Outdoor Design Group, Colorado Landscape Architects.  For more information about our business and our services, please visit our website at odgdesign.com.

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10 Trees that are Better for Colorado

Tree Diversity Conference

Attendees in the lobby of the Denver Botanic Gardens where the Tree Diversity Conference was held.

This past Spring, tree enthusiasts from around the region gathered at the Denver Botanic Gardens to listen and learn from various presenters on the theme of Tree Diversity for Colorado. It seems recent crises such as the discovery of Emerald Ash Borer infestation in Boulder has revealed the urgency for members of the Green Industry to seek out more hardy and appropriate tree species for our region. There are other reasons to seek out trees better adapted to our climate. As climate scientists continue to inform us, it is likely that Colorado’s climate will get warmer and drier, providing even more challenging growing conditions for trees. Also, biotic mixing will continue to increase as more people move goods and materials far and wide across the globe. That is the most probable scenario of how EAB was found in Boulder: it was brought there in a wooden crate shipped from Asia. What far-flung exotic pest will next appear in our area?

This year’s conference was the second occurrence of such a gathering in Denver. Several new tree species were presented to the audience, along with some old stand-bys, with a discussion of each tree’s merits.

Although there were several genera that are represented in the group of trees, the two genera with the most candidates are Maples and Oaks. The other genus with multiple species that should get wider consideration for planting in our area is Ulmus (elms). While most elms have been looked over because of Dutch Elm Disease and also the invasive nature of Siberian Elm (Ulmus pulmila), there are a few cultivars that we should consider planting in Denver.

Here are ten trees that were discussed at the conference (out of many others) that you might consider planting in Colorado and the surrounding region:

Acer grandidentatum ‘Manzano’ – Manzano Bigtooth Maple   Ht: 20-30’ Wd: 20-30’

Large shrub or small tree with rounded form. The Manzano is a more tree like form of bigtooth maple. Once established, the bigtooth maples are drought tolerant.

Acer miyabei ‘Morton’ – State Street Maple   Ht: 50’ Wd: 35’

Rough corky bark and leaf shape are similar to Hedge Maple, but its stronger growth rate and ascending branch habit result in a larger mature size. Excellent drought and cold tolerance. Very adaptable.

Acer saccharum ‘Collins Caddo’ – Collins Caddo Sugar Maple   Ht: 45’ Wd: 40’

This maple provides red fall color, but unlike a red maple like Autumn Blaze (Acer x freemanii), the sugar maples are more adapted to the alkaline soils of Colorado’s Front Range urban corridor.

Acer tataricum ‘JFS-KW2’ – Rugged Charm Maple   Ht: 28’ Wd: 15’

Compact oval form. More upright than the popular Hot Wings Tatarian maple.

Quercus macrocarpa ’Bullet Proof’ – Bullet Proof Bur Oak   Ht: 50-80’ Wd: 50-80’

This large oak sports a massive trunk, deeply furrowed, that supports corky ridged twigs on spreading branches that makes for a broad and rounded canopy. This variety is more resistant to the galls that can affect other Bur Oaks.

Quercus muehlenbergii – Chinkapin Oak   Ht: 40’ Wd: 40’

A durable and adaptable oak with narrow lustrous glossy dark green leaves and an open, irregular, rounded habit. Prefers well drained soil.

Quercus robur x alba ‘JFS-KW1QX’ – Streetspire Oak   Ht: 45’ Wd: 14’

Dark green leaves of this narrowly columnar tree are mildew resistant. Turning red in autumn, they fall to reveal stiffly upright branches. Similar to Crimson Spire, but does not hold brown foliage through the winter

Ulmus davidiana – David Elm   Ht: 40’ Wd: 30’

Medium sized tree, with vase shape. Resistant to Dutch elm disease.

Ulmus propinqua ‘JFS-Bieberich’ – Emerald Sunshine Elm   Ht: 35’ Wd: 25’

Grown from seed collected in China, this sturdy, upright-growing elm was selected for superior performance on the hot, arid, windswept plains of western Oklahoma. Handsome, deeply corrugated leaves emerge coppery-bronze and mature to glossy green.

Ulmus japonica x wilsoniana ‘Morton’ – Accolade Elm   Ht: 70’ Wd: 60’

Arching limbs and a graceful vase shape (similar to the American elm) characterize this hybrid elm selected and tested at Morton Arboretum. Glossy, dark green foliage changes to yellow in the fall and is resistant to elm leaf beetle feeding.

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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