Got Nature? Blog

Purdue Extension forester Lenny Farlee tells you a little about how to identify Silver Maple trees and differentiate them from other species of maple.

If you have any questions regarding trees, forests, wildlife, wood products or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
Investing in Indiana Woodlands, The Education Store, Purdue Extension resource center
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

Lenny Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources


Purdue Landscape Report: Hot, dry summers are not that unusual in the Midwest, but 2020’s hot dry spell started considerably earlier than usual, before summer even officially began! To make it a triple whammy, the hard freeze in early May caused some landscape plants to burn up more stored carbohydrate reserves to produce a second round of foliage.

(Figure 2) July Heat Map

(Figure 2) July Heat Map

I’m sure I don’t have to point out that most of Indiana is currently experiencing abnormally hot, dry conditions. Although recent rains have brought relief to some areas, any respite is sure to be temporary. Seasonal thunderstorms may deluge some landscapes with water while other areas, even those close by, may stay fairly dry. Much of the area has experienced highs in the upper 80’s to over 90º F over the past month.

Leaf scorch on trees and shrubs, appearing as a browning along the edges of the leaves, is very common in dry summers. While minor cases of leaf scorch are not very harmful, prolonged lack of moisture can spell disaster for landscape plants.

Leaf Scorch on Lilac

Leaf Scorch on Lilac

Hydrangea wilting

Hydrangea wilting

Young and newly established plants are most susceptible to the dry conditions, but even established plants may reach a critical point during prolonged drought. If the heat and drought continue this summer, branch dieback, combined with eventual root death, will make plants more susceptible to winter injury. Plants that were already under stress from other factors may succumb to severely dry soils.

The intense heat makes it difficult for plants to keep up with water and cooling requirements, even in areas where moisture is adequate. One of the ways that plants cool themselves is through transpiration, which allows water to evaporate from the foliage. Plant leaves have pores called stomata that can open and close to allow water vapor and gas exchange with the environment. During extreme heat and/or drought, stomata will nearly close, thus reducing transpiration and exchange of carbon dioxide and oxygen. The end result is seen as wilting foliage and leaf scorch. But not so obvious is that reduced water uptake and gas exchange also leads to reduced production of carbohydrates through photosynthesis and reduced uptake of soil nutrients, having longer term impact on plant health.

There is still plenty of summer yet to get through to see the further challenges ahead. Meanwhile, we can mitigate some of the stress by watering landscape plants as needed where feasible.

Resources
US Drought Monitor
Indiana – Purdue Rural Emergency Preparedness, Purdue Extension website
In Times of Drought, Indiana Yard and Garden, Purdue Consumer Horticulture
Drought? Don’t Forget the Trees, The Education Store, Purdue Extension resource center
Turfgrass Disease Profiles: Summer Patch, The Education Store
Iron Chlorosis of Trees and Shrubs, The Education Store

, Extension Consumer Horticulturist
Purdue University Department of Horticulture and Landscape Architecture


Join Purdue Extension forester Lenny Farlee as he introduces you to the Bald Cypress in the video below, one of two deciduous conifers in Indiana.

If you have any questions regarding trees, forests, wildlife, wood products or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources
Indiana Department of Natural Resources – Division of Forestry, District Foresters 
Forest Improvement Handbook, The Education Store, Purdue Extension resource center
Tree Appraisal and the Value of Trees, The Education Store
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
A Woodland Management Moment, Playlist

Lenny Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources


Figure 1. White oak slime flux

Figure 1. White oak slime flux

Purdue Landscape Report: Slime flux (also known as wet wood) is a dark, foul-smelling and unsightly seepage of sap from tree trunks (fig. 1). The disease is not usually a serious problem but the appearance can be alarming. Slime flux is caused by common surface-inhabiting bacteria or yeast fungi that enter the trunk through wounds associated with improper pruning, stem breakage, injections, cracks from freeze injury or weak limb crotches. The bacteria and yeast may live on sap nutrients within injured trees for many years without any outward evidence.

Symptoms
The main symptom is the appearance of the dark sap oozing on the trunk exterior which happens when gasses produced by growth of the bacteria and yeast cause the internal pressure of the sap to become high enough to force the sap out through cracks in the bark. The dark streaks usually turn light gray or white upon drying. Oozing sap may be frothy and white at the point of exit. Airborne bacteria, yeasts, and fungi often colonize the wet oozing material, which ferments and releases a foul odor. Slime flux may delay wound healing (callus formation).

Slime flux is extremely common on mature elms (fig 2), oak (fig 3) and mulberry; and is seen less frequently on maples (fig 4), paper birch, sycamore, and walnut.

Figure 4. Silver Maple

Figure 4. Silver Maple

Figure 3. White Oak

Figure 3. White Oak

Figure 2. American Elm

Figure 2. American Elm

Prevention
There is no control or treatment for slime flux. Inserting a drain tube into the tree to relieve pressure and drain infected sap was once an accepted treatment, but is no longer recommended and may do more harm than good. Boring holes in affected trees causes internal spread of the bacteria within the tree and may allow entry of wood decay fungi.

To reduce the chances of susceptible trees developing wet wood avoid unnecessary wounding of the trunk and branches. Proper pruning techniques, HO-4-W, will allow branches to heal more rapidly. Make sure susceptible trees receive good general care; including irrigation when needed and mulch to conserve moisture and keep mowers away from the trunk. Avoid excess traffic in tree root zone to prevent soil compaction and root injury.

The first and most important step for managing a tree disease is to accurately diagnose the problem. The best approach to diagnosis of tree problems is to start by submitting photos of the tree via the digital upload tool on the Purdue Pest & Diagnostic Lab (PPDL) website. In the case of slime flux it is impractical to collect the type of physical sample needed for confirmation so photos are the best alternative.

References
Sinclair, W. A. and H. H. Lyon. 2005. Diseases of trees and shrubs. Cornell University Press, Ithaca, NY. 660 pp.
Stipes, R. J. and Campana, R. J. (eds.) 1981. Compendium of Elm Diseases. APS Press, St. Paul, MN.

Resources
Diseases in Hardwood Tree Plantings , The Education Store, Purdue Extension resource center
Iron Chlorosis of Trees and Shrubs, The Education Store
Surface Root Syndrome, The Education Store

Tom C Creswell, Clinical Engagement Professor – Plant & Pest Diagnostic Laboratory
Purdue University Department of Botany and Plant Pathology

Lindsey Purcell, Urban Forest Specialist
Purdue University Department of Forestry and Natural Resources


blue spruce needle castQuestion: I have a blue spruce that is 40-years old and very tall. It is dying up the middle. I have read about the Needle Cast problem. Also read about Spectro 90 copper based fungus control. I can only spray so high. Is there a chemical that can be placed on the ground to be absorbed by the tree?

Answer: Thank you for contacting us regarding your tree issues. Rhizosphaera needle cast (Rhizosphaera kalkhoffii) is a foliar disease of spruce trees. It is most common in trees growing outside of their native range. It starts on the inner and lower growth and progresses upward through the tree. It can take up to 15 months for the needles to show visible symptoms after the initial infection. Young trees may be killed by this disease, but usually branches die off after 3-4 consecutive years of defoliation, causing trees to look disfigured.

Early identification of Rhizosphaera can prevent major damage to individual trees and prevent the spread to nearby trees. Protecting new growth as it emerges is very important. For best effectiveness, fungicides should be applied when the emerging needles are half elongated (1/2 to 2 inches in length). Needle cast diseases can be effectively controlled with fungicides containing chlorothalonil. For Rhizosphaera needle cast, two properly-timed applications per year for at least two consecutive years, and sometimes three years, is required for control. Heavily infected trees may require several years of fungicide applications but should be sprayed, soil drenches are not effective. Also, clean-up of any infected needles and branches will help reduce the spread of the disease.

Resources
Needle cast in Colorado Blue Spruce, Purdue Landscape Report
Blue Spruce Update, Purdue Landscape Report
Why Spruce Trees Lose Their Needles, Purdue Extension
Blue Spruce Decline, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension
Tree Installation: Process and Practices, The Education Store, Purdue Extension resource center
Tree Planting and Urban Forestry Videos, Subscribe to our Purdue Extension-FNR YouTube Channel

Lindsey Purcell, Urban Forestry Specialist
Purdue University, Department of Forestry and Natural Resources


Purdue sustaining hardwood extension specialist Lenny Farlee talks about identifying invasive plant species in the webinar below.

Don’t forget to fill out the Invasive Plants Threaten our Woodlands Part 1, Identification survey after watching video to share your suggestions, other forest topics you would like to see and to help us learn more about you.

Resources
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
Invasive Species, Playlist
Woodland Stewardship for Landowners, Playlist
Invasive plants: impact on environment and people, The Education Store, Purdue Extension resource center
Woodland Invaders, Got Nature? Blog
Hardwood Tree Improvement & Regeneration Center (HTIRC)

Lenny Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources


In this Tree Installation for The Landscape Webinar, urban forestry specialist Lindsey Purcell shares information regarding research finds and current best management practices for tree installation.

Please visit the Tree Installation for the Landscape Survey after you watch the video so we can learn more about you and feel free to share your suggestions for future topics.

Resources
Tree Installation Process and Practices, The Education Store, Purdue Extension resource center
Tree Support Systems, The Education Store
Tree Pruning Essentials, Video & Document
Tree Appraisal and the Value of Trees, The Education Store
Tree Pruning: What Do Trees Think?, The Education Store
Mechanical Damage to Trees: Mowing and Maintenance Equipment, The Education Store
Tree Planting Part 1: Choosing a Tree, The Education Store
Tree Planting Part 2: Planting Your Tree, The Education Store
Planting Problems: Planting Too Deep, Video, Purdue Extension – Forestry and Natural Resources Youtube Channel

Lindsey Purcell, Urban Forestry Specialist
Purdue University, Department of Forestry and Natural Resources


Do you know what’s “bugging” your trees? There are several exotic insects which may be attacking our trees that you should be on the lookout for. Some have already arrived in Indiana, and others are still beyond our borders but have a risk of showing up here in the future.

Dr. Elizabeth Barnes, exotic forest pest educator with Purdue Department of Entomology, and Liz Jackson Purdue extension forestry specialist, describe these exotic insects, symptoms to watch for in your trees, and discuss what some of the biggest future pest concerns are in this Facebook Live session from June 18, 2020.

Resources
Purdue Report Invasive website
Indiana Department of Natural Resources Division of Entomology & Plant Pathology
Don’t Move Firewood
Purdue Plant and Pest Diagnostic Lab
Indiana District Foresters
Indiana Consulting Foresters
Planting Forest Trees and Shrubs in Indiana (pdf)
Purdue Landscape Report
Insect specific sites:
Thousand Cankers Disease (black walnut)
Asian Longhorned Beetle Information (from APHIS)
Spotted Lanternfly (Penn State Extension)
Emerald Ash Borer Information from Purdue
EAB University: Invasive insects and pathogens webinar series

Elizabeth Jackson, Manager Walnut Council/IN Forestry Woodland Owners Association (IFWOA) & Engage Specialist
Purdue University Department of Forestry and Natural Resources

Elizabeth Barnes, Exotic Forest Pest Educator
Purdue University Entomology


Are you noticing more birds in your backyard recently since sheltering at home? Do you wish you knew how to identify what you are seeing? Do you know what kind of food to put out to attract different species?

Dr. Barny Dunning, professor of wildlife ecology, and Purdue extension wildlife specialist Brian MacGowan offer advice on birdwatching for birders of all skill levels, including how to bring species to your yard, what apps you can use to identify them and other resources to help you learn more in this Facebook LIVE Ask the Expert session from May 21, 2020.

Resources
Sibley Guide to Birds app
Merlin Bird App
Audobon Bird Guide App
Cornell University Ornithology Lab website
Migratory Bird Treaty Act
ProjectFeederWatch from The Cornell Lab
Nesting Box Information – National Wildlife Federation
Project Feeder Watch
Indiana Audobon Society
Sycamore Audubon Society
Attract Hummingbirds to Your Yard, Video, Purdue Extension YouTube Channel
Birds and residential window strikes: Tips for prevention, The Education Store, Purdue Extension Resource Center
No room at the inn: suburban backyards and migratory birds, The Education Store
Size Does Matter – Nest Boxes for Wildlife, The Education Store

John B Dunning, Professor of Wildlife Ecology
Purdue Forestry and Natural Resources


On May 5th, we held a Facebook LIVE: Ask an Expert with several FNR specialists and one of the questions that came in is a question I receive often.

One of the many benefits of interacting with farmers and land managers is I learn about the problems you face. A question came in around the 17:30 minute mark of how to deal with vole damage problems in their 3- to 5-acre pumpkin patch.  I didn’t have an answer regarding registered pesticides (including taste repellents and toxicants) that are labeled for voles in pumpkins. Doing a broad search on the internet is helpful but it is hard to figure out what you can use in your state. Pesticides are often labeled for use in one state but not others. Luckily, anyone can search for registered pesticides online at on the National Pesticide Information Retrieval System. Most states, including Indiana, are included. You can search by EPA registration number, product name, company name, or active ingredient.  A particular search can still yield many choices but this is a helpful way of finding out what is available. Each product has a link to the EPA website that includes product labels.

PumpkinPatch

Since our program last week, I did some checking and found a product registered in Indiana labeled for voles in pumpkins as well as many other crops. Millers Hot Sauce is a taste repellent with an active ingredient of capsaicin (2.5% by weight), which is an irritant to animals, but one some people enjoy in hot peppers. Per label instructions adding an anti-transpirant film former or a sticker may prolong the effectiveness of the product.  Mix the product and additives with water according to label instructions. For heavy damage, start treatment after first true leaves appear and continue treatment every 7 days.  If applying to transplants, start application one week after transplanting and continue every 7 days.

Always read the label completely before applying any pesticide. The efficacy of any repellent depends on a number of factors including animal population size and density, available food, and availability of cover. With voles, the year can be key because their populations tend to cycle. Combining other methods with repellents can often increase success. For example, soil cultivation within plant rows and in adjacent habitat can help reduce the habitat quality for voles. Cultivation can also directly kill some voles. There are of course tradeoffs and every situation is unique. Soil cultivation would not be an option in some cases (e.g., adjacent to water, steep slopes). I was unable to find a toxicant registered for voles in pumpkins. But depending on what the land cover is adjacent to the pumpkin patches, some of these may be appropriate in those areas.

With face-to-face Extension programs on hold for the foreseeable future, look for more live Q&A sessions and other programs on Facebook (PurdueFNR) or Twitter (@PurdueFNR).

Resources
National Pesticide Information Retrieval System
Midwest Fruit Pest Management Guide 2019-2020, The Education Store, Purdue Extension resource center
Hops Production in Indiana: Integrated Pest Management Guide for Hops in Indiana, The Education Store
Turfgrass Insects: Managing Black Cutworms in Turfgrass, The Education Store
Applied Research in Field Crop Pathology for Indiana – 2019, The Education Store
Managing Alfalfa Autotoxicity, The Education Store

Brian MacGowan, Wildlife Extensions Specialist
Purdue Forestry and Natural Resources


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