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Purdue Landscape Report: An unfortunate question I am sometimes asked is similar to this: “I lost my prized shade tree! What can I plant that will grow fast and give me shade?” While there is no instant fix to this scenario, let’s review a few trees that might be better choices here in northern Indiana.

One obstacle to consider is that many of the fast-growing trees are also fast-dying, meaning that, relatively speaking, they are not long-lived for trees. We’re already behind the 8-ball in our highly manipulated landscapes because we know that trees in landscapes tend to live much shorter lives than trees in their unmanipulated natural habitats.

That said, here are a few trees to consider. I would still encourage homeowners to invest some time in researching the trees that they are considering. There are pros and cons to almost every tree, and there isn’t room in this article to fully explore all the advantages and disadvantages of each tree. Additionally, I will not be getting into detail about all the cultivars available.

Let’s start with our state tree, the Tuliptree (a.k.a Tulip-poplar or Yellow-poplar). Tuliptrees can become quite large and offer a pretty yellow fall color. They prefer deep, rich, well-drained soils.

If maples are on your mind, a couple of options would be Red maple and Freeman maple (a hybrid cross of Silver maple and Red maple). Red maple has more moderate growth. The Freeman maple is a faster grower and has stronger wood than one of its parents, the Silver maple. These maples do best in well-drained, slightly acid soils, but will tolerate a variety of soil conditions.

Northern catalpa is a fast grower, but dealing with the fruit litter, a long seed pod, may be a deterrent for some locations. It has large, heart-shaped leaves. It would grow well in moist sites.

Common hackberry is a fast grower, but it is susceptible to galls on the leaves (from a n insect), and limbs can become susceptible to wind and ice damage. It tolerates a wide variety of soil conditions. Thornless honeylocust is widely adapted to different soil types. Honeylocusts in the wild produce large thorns. The Thornless honeylocust is adapted to landscapes and allows dappled sunlight to reach turfgrass, so that it thrives more than it would under a tree that provides heavy shade.

Sweetgum is also a fast-growing shade tree with brilliant fall colors. It has a star-shaped leaf. One drawback of sweetgum is the spiny seed capsule. This fallen fruit can make walking in the yard barefoot a painful experience.

Eastern cottonwood is the tree on record for the fastest growth rate of any tree native to the U.S. However, those with cottonwoods in their yard can tell you that the cottony seed mass shed in the spring sticks everywhere. It can be a mess. Plus, cottonwood can shed limbs frequently, especially after storms. This tree is commonly found along rivers and streams, so it not surprisingly prefers moist soils.

Also found along rivers and streams, American sycamore is a fast-growing tree in some landscapes. However, it can be a messy landscape tree, shedding bark, leaves, limbs, and fruit nearly year-round. The large fallen leaves can smother grass if not mowed or raked. It is also sensitive to a spring disease called anthracnose, which can cause defoliation and twig death.

Wild black cherry may be another good choice. Although it may not be available in some nurseries, it can be grown from seed. It prefers rich, moist, well-drained soils.

A couple of faster-growing oaks to consider are Pin oak and Northern red oak. Pin oak would be better suited to slightly wetter spots, while Red oak would work on a wider variety of soils, preferring rich, moist, well-drained sites. Pin oak is susceptible to iron chlorosis (yellowing leaves) on alkaline soils.

Finally, American basswood also prefers rich, moist, well-drained soils and is somewhat shade-tolerant. This tree can grow quite tall and provide excellent shade.

In your research, find out how large the tree you will be purchasing will get. One common planting mistake is locating trees too close to structures. Consider the mature size when placing it in the landscape.

Time your spring planting near Arbor Day, the last Friday in April.

Original article posted: Fast-Growing Trees for the Landscape.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Fifty Common Trees of Indiana
An Introduction to Trees of Indiana
Native Trees of the Midwest, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Tree Installation: Process and Practices, The Education Store
Wildlife Habitat Hint YouTube Playlist, Purdue Extension – FNR
Invasive Species YouTube Playlist, Purdue Extension – FNR
Report Invasive Species, Purdue Invasive Species
Find an Arborist video, Trees are Good-International Society of Arboriculture (ISA)
ID That Tree, Purdue Extension-FNR YouTube playlist
Purdue Plant and Pest Diagnostic Laboratory
Trees and Storms – The Education Store, Purdue Education’s resource center
Planting Your Tree, video, Purdue Extension
Subscribe Purdue Extension – Forestry and Natural Resources YouTube Channel

John Woodmansee, Extension Educator, Whitely County
Purdue Extension

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Purdue Landscape Report: Recently a homeowner in Hamilton County posted on the Indiana Native Plant Society Facebook page with concerns about aphids, mites, and apple scab in her maple and oak trees. She asked for a second opinion and treatment options for these pests. I reached out to the homeowner and requested permission to collect samples from the trees. Let’s look at what I found (or didn’t find) and discuss when and if these issues should be treated.

Apple Scab on Maples?
First, we can eliminate the concern about apple scab because maple and oak trees are not hosts for this pathogen. Apple scab is caused by the fungus Venturia inaequalis, and hosts include apples, crabapples, hawthorn, mountain ash, firethorn, and loquat. There are other fungal diseases which cause leaf spotting in maples, such as Anthracnose, tar spot, and Phyllosticta leaf spot. To diagnosis these diseases, homeowners can submit a sample to the Purdue Plant & Pest Diagnostic Lab, or hire a certified arborist to assess the tree. However, all these diseases are primarily aesthetic issues. A healthy tree will not die from these pathogens and does not require treatment. You can find more information about maple diseases in this publication: Diseases in Hardwood Tree Plantings. You can also find a previous article on Tar Spot in Maple in the Purdue Landscape Report (Issue 18-12).

Spider Mites
The next pest concern on these trees is spider mites. Out of the dozens of leaves I collected, I found only two immature mites on a couple of maple leaves I examined. This is a very small mite presence, and it is not recommended to treat for spider mites unless the populations threaten the health or appearance of the tree. Limiting pesticide usage will conserve the natural enemies, which are vital to keeping mite populations in check. In fact, improper pesticide applications can kill these important natural enemies and worsen mite infestations.

When do you know if the mite population is large enough to merit intervention? Check your trees for signs of heavy feeding damage, such as leaf stippling (Fig. 1), or dense webbing on the leaves. Mites can also be monitored by placing a sheet of paper (8.5×11”) beneath a branch and striking the limb. Chemical treatments should be considered when you count ≥24 mites per strike. You can find detailed management recommendations and a full list of pesticide options in this Purdue Extension publication: Spider Mites on Ornamentals.

Aphids
The aphids I found on the homeowner’s maple trees are Drepanaphis acerifoliae, or the painted maple aphid (Fig. 2). This species only feeds on maple trees, and is not a threat to the oak tree on this homeowner’s property. Painted maple aphid is a very common aphid in our region. I found only a few aphids on one of the maple trees I sampled, which is not enough to require treatment. In addition, one of the aphids was a “mummy”, or a carcass left behind from a parasitoid wasp. This indicates that natural enemies are already at work managing the aphid population. Aphids may rarely require chemical control if their numbers grow large enough to produce significant amounts of honeydew, which can result in sooty mold outbreaks.

Tussock Moth
The only insect I found on the oak tree was a white-marked tussock moth caterpillar, Orgyia leucostigma (Fig. 3). This is the likely culprit for the minor feeding damage I noticed. These are not significant pests and do not require treatment. Don’t touch them, though! The setae of this caterpillar are irritating and may cause allergic reactions.

Overall, the pests I found were minimal and non-threatening to the trees. It’s normal to find some insect pressure in the landscape. Knowing when and if to treat requires accurate diagnosis and monitoring of pest levels. Check out PurduePlantDoctor.com for an easy-to-use diagnostic aid and treatment recommendations.

Original article posted: Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Large Spots on Maple Leaves that Look Like Tar, Purdue Extension News
Find an Arborist, International Society of Arboriculture
Diseases in Hardwood Tree Plantings, The Education Store, Purdue Extension’s resource center
Fifty Common Trees of Indiana
An Introduction to Trees of Indiana, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Tree Installation: Process and Practices, The Education Store
Forest Improvement Handbook, The Education Store
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
ID That Tree, Purdue Extension-FNR YouTube playlist
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources

Alicia Kelley, Cooperative Agricultural Pest Survey (CAPS) Coordinator
Purdue Extension – Entomology

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Purdue Landscape Report: The past two months have been relatively wet and cool to warm. This prolonged period of overcast conditions, high humidity, and light to moderate rainfall is perfect for some of our foliar disease issues.

“April flowers bring May Leaf spots” doesn’t have the right ring to it, but we are seeing quite a bit of leaf curl and leaf blister. These are two disease issues caused by Taphrina spp. fungi. Like the common names of their diseases, the symptoms caused by a Taphrina infection include leaf deformation.

In the case of Peach, the leaves turn light yellow, bright pink, or red where tissue puckers and twists leading to curled leaves. In oak, leaves develop localized blisters that are light green early in the season and are easy to miss since the color is not very different from healthy tissue.

However, the blisters will turn brown later in the season which makes them more noticeable. Maples also get a disease caused by Taphrina, but it does not cause as much distortion as it does on oak or peach. Severe maple leaf blister can lead to leaves becoming slightly contorted, but the primary symptom is brown necrotic lesions.

With cool wet weather over an extended period of time, we have been seeing more foliar disease issues than in the last few years.

Since disease problems can take time to develop, Taphrina is likely just the harbinger for some other disease issues we may see in early summer if moderate conditions continue. If the weather dries out as it heats up, it will halt many of these foliar problems in their tracks.

Original article posted: Purdue Landscape Report

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Learn How to Support Oak-Hickory Ecosystems, Purdue Extension – Forestry and Natural Resources (FNR) Got Nature? Post
“The Nature of Oaks” Webinar, Indiana forestry & Woodland Owners Association
How to Find an Arborist Near You!, Purdue Extension – FNR Got Nature? Post
Diplodia Tip Blight of Two-Needle Pines, The Education Store, Purdue Extension resource center
Boxwood Blight, The Education Store
Disease of Landscape Plants: Cedar Apple and Related Rusts on Landscape Plants, The Education Store
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store, Purdue Extension Resource Center
Native Trees of the Midwest, The Education Store

John Bonkowski, Lead Extension Administrator
Purdue Department of Botany and Plant Pathology

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