Got Nature? Blog

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.

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.

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

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

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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.

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’s 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, Chapter Executive Director
Indiana Arborist Association

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Purdue extension forester Lenny Farlee introduces the red maple, a native tree to Indiana, known for its red to maroon foliage.

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
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

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This webinar titled “Tree Selection for the Landscape” by FNR Urban Forestry Specialist Lindsey Purcell talks about the tree selection process including the benefits of trees, urban tree planting, purpose for planting, environmental considerations, proper placement and utility considerations, along with many shared resources.

Please visit the Tree Selection 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 Appraisal and the Value of Trees, The Education Store, Purdue Extension resource center
Tree Selection for the “Un-natural” Environment, The Education Store
Tree Pruning Essentials, Video & Document
Tree Pruning: What Do Trees Think?, The Education Store
Mechanical Damage to Trees: Mowing and Maintenance Equipment, The Education Store
Tree Installation Process and Practices, 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

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Purdue urban forester Lindsey Purcell shares tips for tree pruning for the landscape, including knowing why you are pruning, how to prune and how to help the tree heal properly.

Please visit the Tree Pruning 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 Pruning Essentials, Video & Document
Tree Appraisal and the Value of Trees, The Education Store, Purdue Extension resource center
Tree Pruning: What Do Trees Think?, The Education Store
Mechanical Damage to Trees: Mowing and Maintenance Equipment, The Education Store
Tree Installation Process and Practices, 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

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Question: 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
Find an Arborist, International Society of Arboriculture

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

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Across the entire United States, and into Canada and Mexico, coyotes can be found just about everywhere. But what would you do if you encountered a coyote while out all alone? Would you feel comfortable knowing how to act? How about how to keep your children or pets safe in such an encounter? 

In our June 11th Ask the Experts series, “Coexisting with Coyotes,” Purdue researchers Brian MacGowan and Bee Overbey talked about these topics and more. As a keystone species in their ecosystem, coyotes play an extremely important role in maintaining population levels of other animals, such as deer, rabbits, raccoons, and voles. By keeping these populations in check, plants and trees are better able to grow, and this creates greater biodiversity and healthier habitat. And coyotes are not going anywhere! This resilient, intelligent species has learned to adapt around humans and every change that we bring.

Check out the video below to learn more about coyotes, how important they are to the lands where they are found, and tips on how to coyote-proof your property and keep yourself and your loved ones safe in coyote encounters. By working together, we can easily and safely coexist with this vital native species.

Resources
Ask an Expert, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Coyotes, IN DNR
Coyotes (PDF), Wildlife Conflicts, Department of Entomology, Purdue University
Coexisting With Coyotes, Wild Bulletin, Indiana Department of Natural Resources, Division of Fish and Wildlife
Urban Coyotes – Should You Be Concerned?, Purdue Extension – FNR Got Nature? Blog
Pets Disappearing? The Cause May Be Coyotes, Purdue Extension – FNR Got Nature? Blog
Question: Which is the correct species of coyotes I have on my land here in Indiana, coyote or coywolf?, Purdue Extension – FNR Got Nature? Blog
Permitted Wildlife Rehabilitators, Indiana Department of Natural Resources
Dealing with Nuisance Coyotes, Indiana Department of Natural Resources (IN DNR)-Fish and Wildlife
Urban Coyote Research Center, Urban Coyote Ecology & Management, Cook County, Illinois

Brian MacGowan, Wildlife Extension Specialist
Purdue Forestry and Natural Resources

Brande (Bee) Overbey
Purdue Forestry and Natural Resources

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Marking your property line can ensure you are receiving the full benefit of the property you own. Lenny Farlee, Purdue Extension forester, shares in the video below a new inexpensive way to mark your property line and has the same force of the law as no trespassing signs have.

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 
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
Woodland Stewardship for Landowners, Playlist
Investing in Indiana Woodlands, The Education Store, Purdue Extension resource center
Forest Improvement Handbook, The Education Store
Timber Harvesting and Logging Practices for Private Woodlands, The Education Store

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

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Purdue Landscape Report: Trees provide many benefits for our homes and properties. If a tree is found to have a defect such as dead branches or broken limbs from a storm; it can become a risk issue. It is important to understand that tree owners have a duty to inspect and maintain their trees. All property owners should take reasonable steps to protect themselves by involving a qualified consultant or certified arborist when needed.

All trees have some sort of risk involved with it. They are living organisms that are endangered by environmental impacts and pests. However, it is important to create a balance between the risk a tree may pose and the benefits provided by the tree. We don’t want to remove trees unnecessarily, but rather reduce the liability by Identifying, analyzing and evaluating the problem.

Inspect regularly: Trees should be assessed through inspections by a qualified arborist, preferably an International Society of Arboriculture Certified Arborist. It is especially important to inspect trees after major weather events. At a minimum, trees should be carefully checked out every 3-5 years.

Document and maintain records: Every inspection should be recorded and kept on file for future reference. Past evaluations can show how a tree has changed in its health and structure over the years. Also, these written evaluations could minimize liability if a failure occurs and a claim is filed against the tree owner.

Tree Inspections: For a tree to be considered a risk it must be defective and a target that is threatened.

A target is people, property or activities that could be injured, damaged or disrupted by a tree failure. Review everything in the target zone. This should include the area inside a circle around the tree, which is at least as wide as the total tree height.

Read the body language of the tree. Inspect each section of the tree including the crown, branches and root zone to check for signs of failure. These include:

• Dead, diseased, dying or broken branches.
• Thinning or poor canopy health.
• An unstable branching pattern overextended or weakly attached branches, or cracks in the stems.
• Cracks or decayed areas in the main trunk.
• Exposed or decayed roots, heaving of the soil, fungus growth or cracks in the soil around the root plate.

Among the characteristics to consider when conducting tree risk evaluations are:

• Decay, cankers, cracks and other positive indicators of weakness in the roots, stems and branches.
• Canopy size, shape and weight distribution. This is especially true in situations where a tree is exposed to windy conditions, is leaning or has a poor stem-to-canopy ratio.
• Crown architecture. Poor branching and similar characteristics can create high-risk situations in strong winds and other weather conditions.
• Plant health and vigor. This determines how a tree can overcome wounding or pest infestations.

What do you do when a defect is found?
The goal is to reduce the likelihood of failure. Most of the time pruning can improve risk situations. Perhaps cabling and bracing may be an option. Also, plant health care improves the trees condition which can reduce risk… the last option should be removal and that should be an informed decision.

Recurrent inspections to determine tree health and condition are important for sustainable, long-lived tree plantings. The most important factor for any tree owner is know when to contact an ISA Certified Arborist who understands tree risk assessment. They can help with the decision making for the tree if there are concerns about its safety and health.

For more information refer to Trees and Storms: Understanding Damage, Risk and Recovery from theGot Nature? Blog by Purdue Extension, Department of Forestry and Natural Resources (FNR).

Find a certified arborist in your area by going to Trees are Good.

Resources
Planting Problems: Trees Planted Too Deep, Video, Purdue Extension – Forestry and Natural Resources Youtube Channel
Planting Your Tree Part 1: Choosing Your Tree, Video, Purdue Extension Youtube Channel
Tree Planting Part 2: Planting a Tree, Video, Purdue Extension Youtube Channel
Tree Appraisal and the Value of Trees, The Educational Store, Purdue Extension resource center
Surface Root Syndrome, The Education Store
Iron Chlorosis of Trees and Shrubs, The Education Store
Tree Pruning Essentials, Publication & Video, The Education Store
Cold Injury to Trees, Got Nature? Post, Purdue FNR Extension

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

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Recently during an online program (video) I received a question about the risk of using toxicants for controlling moles in lawns. Specifically, the question was if animals (pets or wild animals) ate the moles that consumed the bromethalin “worms” or “grubs” would that harm them. I decided to do some digging (no pun intended) for more information so people can make informed decisions regarding their use.

What is bromethalin?
From the Purdue University Animal Disease and Diagnostic Laboratory:
“Bromethalin was developed and released in 1985 to combat a world-wide problem of rodent resistance to warfarin-like anticoagulant rodenticides. Bromethalin is not an anticoagulant but is a highly potent rodenticide that provides a lethal dose to rodents in a single feeding. Death occurs within 24 to 36 hours after ingestion. It is a pale, odorless, crystalline solid compound in the diphenylamine family. Its mechanism of action is to uncouple oxidative phosphorylation in the mitochondria of the central nervous system. This leads to a decreased production of ATP. Low levels of ATP inhibit the activity of the Na/K ATPase and lead to a subsequent buildup of cerebral spinal fluid and vacuolization of myelin. The increased CSF results in high intracranial pressure, causing damage to nerve axons, inhibiting neural transmission and leading to paralysis, convulsions and death. Signs of a sub-lethal dose include hind limb ataxia, depression, extensor rigidity, opisthotonus, lateral recumbency and vomiting. High doses may bring about severe muscle fasciculations, hind limb hyperreflexia, seizures, hyperthermia, depression and death.”

From the Merk Veterinary Manual:
“Bromethalin, a nonanticoagulant, single-dose rodenticide, is a neurotoxin available as bars (blocks), pellets, seed, and worm. Mole baits are sold as worm containing 0.025% bromethalin, whereas rat and mouse baits contain 0.01% bromethalin. Bromethalin and its main metabolite desmobromethalin are strong uncouplers of oxidative phosphorylation. This results in intra-myelin fluid accumulation, leading to long nerve demyelination and intra-myelin cerebral edema. The net result is cerebral and spinal edema and increased CSF pressure, leading to neurologic dysfunction. In toxicity trials, the oral toxic dose of bromethalin when used as part of bait appears to be much lower than the dose administered as a technical grade agent. For example, in dogs, an average lethal dose of technical grade bromethalin is reported to be 4.7 mg/kg but 2.38 mg/kg in bait. Young dogs (<1 yr old) appear more sensitive; death has been reported at dosages of ~1 mg/kg in bait. Dogs are more commonly involved. Cats are 2–3 times more sensitive than dogs.”

 

 

 

 

 

 

 

 

What is the risk with mole baits?
The level of risk of any pesticide depends on a combination of toxicity and exposure. Anytime you are considering using a toxicant or other pesticide, first read the label in its entirety. Labels will contain information on how to apply a product safely, under what circumstances, and any precautions you should take. However, labels also contain other information that can users determine if they should use a product. This information is key in preventing pesticide exposure to people and the environment. In fact the label is a legal document. The pesticide user is bound by law to follow all label directions. Label directions for mole baits instruct users to keep pets out of treated areas and not to use the product above ground. Bait must be applied directly into moles’ tunnel systems. Following these directions will greatly reduce, or even eliminate, the exposure risk to pets. What might be the consequences if your dog or a neighbor’s dog mistakenly entered your yard and went digging around in a treated area?

To determine this we can calculate how much bait a dog would have to consume to reach the average lethal dose. The more technical term is the LD₅₀ dose which is the individual dose that kills 50 percent of a population of test animals. A single worm mole bait weighs approximately 5g since a package of 20 worms has a weight of 100g.  With 0.025% active ingredient, each worm would contain 1.25 mg of bromethalin. Thus, an 11lb (5kg) dog would need to consume 18 to 19 worms to reach the average lethal dose using the 4.7 mg/kg level for technical grade bromethalin, or 9 to 10 worms for the 2.38 mg/kg level in bait. Recall, these rates were listed in the Merk Veterinary Manual. The amount of bait consumption would be more for larger dogs. The average lethal dose is just that – an average. Some dogs would die with lower dosages and some with higher dosages within a specified timeframe.

It would be extremely unlikely that a dog could find, dig up, and consume the number of worms to reach or even approach the average lethal dose. Consider the following:

• How many worm baits will you use? According to label directions, worm baits are placed underground every 5 to 10 feet in active subsurface runways. Worms may be placed in the deeper underground runways. Limiting their use to only active runways reduces the amount of product applied. The label directions outline the procedure for identifying active runways.
• Applying the product according to label instructions (in underground active mole tunnels) helps minimize the risk of accidental ingestion. However there are additional strategies to prevent accidental ingestion of the bait, including: applying the product in areas inaccessible to pets or installing barriers, covering the application sites with pavers, and supervising the pet’s use of the yard (especially important for dogs that like to dig). Allow at least two weeks (or longer under dry conditions) for breakdown of any uneaten worms.
• Toxic baits placed in runways breakdown over time. That is, a treated area is not treated forever. This is a direct quote from one manufacturer, “Uneaten worms typically remain intact up to 14 days in mole runs. The amount of time it takes for the Mole Killer worm to degrade depends on soil type and the weather. Frequent and heavy rain or high temperatures may accelerate worm degradation. The active ingredient takes longer to degrade.”
• Toxic baits may be combined with other methods. For example, you may choose to limit use of toxic baits only in areas where the soil type or tunnel structure make trapping difficult.

In the end, it is up to the individual user on whether or not they choose to use toxic baits to get rid of moles in their yard. If you do choose to use them, read the label in its entirety. In the case of mole toxicants, the label clearly states that pets should not be allowed in treated areas. If you are not confident this is possible, then alternative control options are likely a better option for you.

Resources
Pesticides and personal safety (pdf), Purdue Pesticide Program
Pesticides and wildlife (pdf), Purdue Pesticide Program
Moles, The Education Store, Purdue Extension resource center
Adjuvants and the Power of the Spray Droplet: Improving the Performance of Pesticide Applications, The Education Store
Purdue Extension – FNR: Ask An Expert, Video, Purdue Extension –  Forestry and Natural Resources YouTube channel

Brian MacGowan, Wildlife Extension Specialist
Purdue University, Department of Forestry and Natural Resources

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