The Importance of Being Furnaced

When the temperatures start to sink and the thermostats start to creep up, we get around to thinking about cozy night fires indoors or even outside.  And fires need firewood.  That begs the question: where should we get our firewood? 

Let’s start at the beginning: the tree.  After a tree is cut down, the wood is considered too “green” to burn. This wood does not burn well, if at all, and produces much smoke because of its high moisture content- after all, it was recently alive! Wet firewood is difficult to burn in home burners, fireplaces or fire pits, and prolonged use adversely affects the performance of these heating systems. For good combustion, firewood should have no more than 20 percent moisture content. For good burning performance, firewood must air-dry for one season or even longer. But there is a superior process other than letting wood dry for several months to several years. This is to dry out the wood in a kiln.


A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete the drying process. There is no standard for “seasoned” firewood sold by typical vendors. Generally, well-seasoned firewood has a moisture content of about 30 percent, but that can significantly vary upwards from dealer to dealer- especially well into firewood season when many vendors run out of their best wood and start to sell a less seasoned product. Firewood dried in a kiln reduces that moisture content to between 10 to 20 percent. Kiln drying firewood kills bugs and fungus and prevents disease, mold, or mildew from growing on the wood during the drying period. This quick and efficient drying process also provides additional benefits to you, specifically when it comes to storage and burning.

The Benefits of Nels Johnson Kiln-Dried Firewood

Kiln-dried firewood is the cleaner alternative to traditional firewood. Grocers, retailers and even brick-oven pizza shops prefer this method of dry, sterilized, firewood. Yes, it is bug free, but it also provides the following benefits:

  • Ready to burn the day you get it; ignites easily and burns efficiently

  • Can be safely stored indoors.  Kiln drying insures that insects, larvae, and mold are killed, making our firewood safe to store in your garage, porch, deck or living room.  Who wants bugs crawling out of the wood sitting next to your hearth?

  • Less flaking bark and debris for tidier indoor storage.

  • Cleaner burn because it produces less creosote, which means fewer chimney and indoor air quality problems. Kiln-dried wood also provides a higher BTU (heat) output because energy is not being wasted to boil out moisture – you’ve heard the hissing sound of burning firewood that was wet.

  • Produces less ash and less smoke when burning.

Now that you’ve learned about the benefits and superiority of kiln-dried firewood, and why you should make Nels Johnson Firewood the choice for your family’s health and enjoyment, give our firewood specialist, Lisa Johnson, a call to place your order.  We will deliver and stack your wood for you in preparation for all your warm and enchanting fires this winter.

Dormant Pruning

A question that we arborists commonly hear is: “When is the best time to prune my trees?” I always chuckle at this because to me there is a lot to unpack from this seemingly simple inquiry. There is no hard and fast rule- depending on site conditions, species, and pruning goals (among other factors), the answer can vary wildly. Generally speaking, you can prune whenever you’d like; however, there are bad times and absolutely a best time to prune most plants. Usually that timing would be winter, and we refer to it as dormant pruning.

Dormant pruning refers to pruning a tree/shrub during its most inactive period, and for the Midwest, that is always the winter season. While most trees (with notable exception- I’m looking at you, oaks and elms!) can be pruned during the growing season, there are good reasons to prune during the dormant season.

 You can readily see the structure of a tree in the winter when leaves aren’t filling out the canopy. This helps when making educated, minimal pruning cuts (and reduces the amount of work you have to do, too!). The strong convergent habit of this larch tree is easily visible.

You can readily see the structure of a tree in the winter when leaves aren’t filling out the canopy. This helps when making educated, minimal pruning cuts (and reduces the amount of work you have to do, too!). The strong convergent habit of this larch tree is easily visible.

1. During the winter, you can easily visualize the full structure of the tree. After fall leaf drop, there are no leaves to obscure the upper canopy of branches. This makes it much easier to decide pruning strategy (i.e. which limbs are being crowded) and to easily identify structural defects (like crossing branches, weak branch crotches, and dead/diseased limbs).

2. Contrary to common belief, dead/diseased branches are still easy to identify in the dormant season. While obvious signs of brown leaves may not highlight dead branches, an arborist can look for other cues such as sunken or shriveled branches, missing bark and saprophytic fungi. Leaves that died during the growing season, depending on the reason, also have a tendency to stay attached to the tree through the winter. It’s also easier to identify damage or defects that lead to branch death without leaves obscuring the view.

3. Pruning a tree often necessitates removal of live branches from the canopy. Removing these limbs during the growing season can lead to excessive resource removal. You lose both the limb AND the leaves when pruning just after the tree leafs out/pushes new growth. In the fall, trees pull the nutrient resources from their leaves to store in the root mass for the winter, hence the leaves turning color and dying. If we prune during the dormant period, we can avoid excessive loss of nutrients from the tree, and therefore reduce the amount of stress created when pruning. This is also why Arborists say that pruning in the spring- just after the tree used the stored resources to push new growth- should be done with caution.

 Winter can be a great time to scout for diseases and defects on plants. This black knot, normally obscured by the leaves of the shrub, can be easily spotted during the off-season. In the winter, you can safely prune out this diseased wood without concern of it spreading.

Winter can be a great time to scout for diseases and defects on plants. This black knot, normally obscured by the leaves of the shrub, can be easily spotted during the off-season. In the winter, you can safely prune out this diseased wood without concern of it spreading.

4. Every pruning cut can be thought of as an intentional wound made to a tree. These wounds are openings for diseases (mostly rots) to enter the tree until they callus over. There are no diseases around in the winter to infect trees through new fresh cuts. However, wounds are also subject to extra exposure from the cold temperatures of winter. This is why some more sensitive trees are recommended for pruning in late winter, after the coldest months are in the past. A Nels Johnson arborist can help you determine which trees are more sensitive to winter damage.

5. Similar to the last point, there are several high concern diseases that are moved around (called vectored) by insects during the growing season. These insects are attracted to the sap of the trees they reproduce/feed on, mostly because wounded or stressed trees are easier to inhabit. When pruning cuts are made during the growing season, flowing sap will naturally be extruded from the wound. The two best known diseases that infect through this method are oak wilt and dutch elm disease. This is why it is important to only prune oak and elm trees during the dormant season, when the beetles are absent and sap flow is reduced. This preventative practice is so effective at slowing the spread of disease that some municipalities forbid the pruning of oaks and elms during the growing seasons. Any reputable tree care company in Chicago will not prune oak and elm trees between April 1st and November 1, with deadwood removal and risk mitigation being the exceptions. If you must prune an elm or an oak tree during the growing season, wound dressings are recommended to stop excessive sap flow.

 Pruning trees in high traffic areas, or with special needs, can be very difficult during the growing season. These London Plane trees are located in the middle of an outdoor amphitheater, normally packing during warm weather. By pruning in the dormant season, time can be taken to properly pollard the canopies without having to jockey for workspace.

Pruning trees in high traffic areas, or with special needs, can be very difficult during the growing season. These London Plane trees are located in the middle of an outdoor amphitheater, normally packing during warm weather. By pruning in the dormant season, time can be taken to properly pollard the canopies without having to jockey for workspace.

6. An understated benefit for dormant pruning is that winter is when the rest of the landscape is also dormant. The ground is frozen, reducing any soil compaction from large machinery and concern about damaging annual and perennial plantings. Snow gives more flexibility of drop zones for large limbs, and cushions the plant material below. Loud machinery is less of a nuisance when families are bundled up inside staying warm. Additionally, there is less traffic in the landscape with routine mowing and landscape crews, reducing unintended run-ins and scheduling conflicts.

Dormant pruning provides many benefits over in-season pruning, including smaller factors not listed here. With some exceptions, winter pruning can be the best (and least stressful!) time to have your large trees pruned. If you’re interested in having your trees inspected, or are unsure if dormant pruning is right for your landscape, have a Nels Johnson Arborist schedule a site visit today! Give us a call at (847) 475-1877 to schedule an appointment now!

Late Summer Pests

Zimmerman Pine Moth

This insect has an extended life cycle in which it repeatedly bores under the bark of common pine trees to feed and overwinter.  There are two treatment windows timed for the larval stage of the insect; one in April and another in August.  Severe damage will cause branch and whole tree death.

  • What to look for:  The adult moths are nocturnal and difficult to see.  Look for characteristic pitch masses under large branch connections at the trunk.
  • Where to look: Preferred hosts are Scots and Austrian Pines, but also Mugo and White Pine

Spider Mites

Spider Mites fall into two categories: either cool-season or warm-season (relating to their active weather conditions).  Two-Spotted spider mites are a common, warm-season spider mite that thrives in hot and dry weather.  Individual insects require a magnifying loupe to see, but in heavy infestations look like fine sand collecting on the underside of affected leaves.

  • What to look for: A bronzing or stippling of leaves.  Severe infections have visible webbing on affected branches.
  • Where to look: This insect is a generalist and has over 180 preferred plant hosts!  Commonly seen on Arbor Vitae and Cotoneaster.

Magnolia Scale

One of the largest and easiest to identify scales, this insect is a menace to magnolia trees.  Magnolia scale is a soft-bodied scale, and can be found in large clusters along woody stems.  Frequently these insects become a nuisance due to their excessive secretion of honeydew, which causes sooty mold to coat anywhere it lands.  Systemic treatments are highly effective, as well as well timed spray treatments in the late summer.

  • What to look for: Look on the underside of branches for large, whitish/cream colored bumps.  Also look for blackened leaves caused by sooty mold growth feeding on the honeydew secretions.
  • Where to look: Most Magnolia species are susceptible to some level.


Aphids (and most piercing-sucking insects) are at their peak levels right now.  There are a wide range of aphids species that look very different.  These insects will rarely kill their host, but heavy infestations can weaken plant defenses to more serious pests.  Additionally, excessive honeydew production can cause surfaces below to be covered in sticky residue and sooty mold.  Some more serious pathogens (bacterial and viral) have evolved to move from host to using by hitching a ride on these insects.

  • What to look for: check low branches for physical signs of the insects.  Commonly the infestation is made apparent by heavy sooty mold presence on underlying surfaces.
  • Where to look: Aphids come in a wide range of flavors and prefer a wide range of hosts


     Characteristic pitch mass forming under branch whorl of mugo pine.

    Characteristic pitch mass forming under branch whorl of mugo pine.

     Webbing formed by two-spotted spider mite on Cotoneaster

    Webbing formed by two-spotted spider mite on Cotoneaster

     Dried magnolia scale will remain attached to the tree after treatment and subsequent death.

    Dried magnolia scale will remain attached to the tree after treatment and subsequent death.

     Aphids come in many shapes and sizes, including differences between life stages of the same species.

    Aphids come in many shapes and sizes, including differences between life stages of the same species.

    Plant Healthcare and Disease Prevention

    Be on the lookout for these regional spring/summer tree and plant diseases! Click to learn more and contact a certified arborist at Nels Johnson Tree Experts if you have any questions about your own trees and plants. 

    Diplodia Tip Blight


    Diplodia tip blight is a fungal disease that kills the tips of the branches of pines, and less frequently spruce and firs. In the blight stage, it can cause severe dieback and the fungus can grow into the stems and main trunk where it becomes a canker disease. 

    • Where to look: Austrian, ponderosa, mugo, red, and Scots pines
    • What to look for: A few brown needles at the tip of the current season's growth is the first evidence of tip blight.

    Boxwood Blight 


    Boxwood blight is a serious fungal disease that kills boxwood trees and shrubs. The blight typically spreads when people acquire infected bushes or trees and then plant them alongside or in place of their existing, healthy boxwoods.

    • Where to look: Boxwood 
    • What to look for: Spotted leaves, stem cankers and defoliation. The spots usually appear as light- or dark-brown, circular lesions that are often surrounded by a large yellow halo.

    Apple Scab


    Apple scab is a disease of apple and ornamental crabapple trees that attacks both leaves and fruit. Severely infected leaves become twisted and puckered and may drop early in the summer.

    • Where to look: Apple and crabapple trees
    • What to look for: The fungal disease forms pale yellow or olive-green spots on the upper surface of leaves. Dark, velvety spots may appear on the lower surface.

    Cedar-apple rust


    Cedar-apple rust is a fungal disease that requires juniper plants to complete its complicated two year life-cycle. From year to year, the disease must pass from junipers to apples to junipers again; it cannot spread between apple trees.

    • Where to look: Junipers, apple and crabapple trees.
    • What to look for: Pale yellow and orange pinhead sized spots on the upper surface of the leaves shortly after bloom. Heavily infected leaves may drop prematurely. Junipers experience large stem cankers that ooze when wet.

    Important Questions and Helpful Tips for Selecting and Applying Fungicide

    The spring season is a usually frustrating time for farmers and agriculturists.

    During this time of the year, erratic temperatures are usually witnessed. This unfavorable temperature condition wreaked havoc on plants, thus, affecting their growth and development. The worst part is that they also aid the development of pest.

    Another thing notable during the spring season is an increased amount of rainfall, thus, an increase in the amount of spruce and pine diseases. However, this record high precipitation makes applying foliar fungicides quite difficult.

    Choosing and rotating your fungicide of choice can be quite challenging. Nels Johnson Tree Experts, your professional tree and plant health care company, brings you a couple of questions and tips to keep in mind while choosing and applying Fungicide during the spring season.

    Helpful Tips for the Application of Fungicide:

    Start Applying Foliar Sprays Early

    Start applying foliar sprays for anthracnose on plants and trees such maple, ash, and oaks at a very early stage, precisely at a quarter leaf development. When applying treatment for anthracnose, lay more emphasis on the lower two-thirds section of the canopy. This will go a long way in reducing symptoms later during the growing season.

    Cover New Growth with Spray

    As we enter the growing season, the new growth of conifers will soon become rampant. This infers that the time to spray for botryosphaeria, rhizosphaera, and various other needle diseases will become necessary. For this reason, it is important to pay special attention while applying the spray. Ensure that all new growth getting are completely covered with the fungicide or spray.

    Watch out For Lecanium Scale

    Another disease that characterizes the spring season is lecanium scale. During the next couple of weeks, begin to watch out for this disease. Fortunately, lecanium scale can be managed by applying Transtect. As a result of the water-soluble nature of Transtect, it is very effective when used as a systemic treatment on scale insects. Transtect penetrates the plant quickly and distributes efficiently, thus, providing the most efficient way to treat scale insects systemically.

     Important Questions to Ask When Choosing Your Fungicides:

    • Will my work be able to support creating a single spray tank or route by making use of a single material or will do I have to mix different kinds of materials throughout the day?

    • Are there buildings, lawns, patios, or other hardscapes which require exceptional care while spraying materials made with copper?

    • What is the intensity of the pest infestation or disease on the tree, neighbors, and generally all over the region?

    • Will tank mixing a miticide be necessary?

    There you have it! The above are some of the questions and helpful tips that need to be considered when selecting and applying a fungicide. Regardless of the type of plant, these questions and tips will guide you in choosing and applying fungicides perfectly.

    For more information or professional helpful tips for choosing and applying fungicides for your plants, get in touch with us today at Nels Johnson Tree Experts. Our dedicated team of experts will be available to respond to you and provide a suitable response to your questions and concerns.

    It's time for dormant pruning

    Deciduous trees and shrubs are plants that drop their leaves generally during autumn or winter, and enter a dormant state. This is done mainly to conserve water that the tree needs to survive. Leaves contain small pores called stomata that allow for gas exchange to occur between the tree and the surrounding atmosphere, a process that is necessary for photosynthesis. However, these stomata also allow for a large amount of water to escape from the tree. By dropping its leaves, a deciduous tree or shrub can limit the amount of water that escapes from the plant during winter, allowing it to survive.

    Trees can benefit from tree care services all year round. Procedures done during winter can lead to a healthier tree come spring. For example, applying a wide and evenly spread layer of mulch around a deciduous tree in early winter can help that tree bloom earlier and grow faster in spring. The layer of mulch acts as an insulator to the soil and roots of the tree, which remain active even in the winter. This extra layer of insulation reduces dramatic temperature changes in the soil, which can be harmful to roots.

    Winter months also give arborists and tree care professionals a window of opportunity to perform dormant pruning. As the name suggests, dormant pruning is trimming that occurs during autumn or winter months (November – March), when deciduous trees are in their dormant state. With no leaves on the tree, arborists can easily examine the shape, structure, and condition of the tree’s branches. Contrary to what most homeowners think, dead wood is actually much easier to spot during winter. With no leaves to get in the way, dead wood can be easily spotted by changes in branch color, any cracks on the branch, fungus growth, or other symptoms such as the presence of buds. Once dead wood is identified it can be easily removed making the tree healthier and the property safer.

    Not only does dormant pruning allow for easy identification of dead wood, it also allows for the overall structure of the tree to be examined. Professional pruning is more than the simple act of cutting out dead wood. Good tree care professionals shape the tree with pruning, providing long term health benefits. For example, if left alone or not pruned properly, trees can grow crossing branches in its crown. These crossing branches compete for the same space and resources in the crown, and by removing them a tree care profesional can increase both air flow and sunlight exposure to the crown as a whole. Proper dormant pruning can also improve the overall appearance and structural integrity of the tree.

    Different styles and techniques of dormant pruning should be used depending on the condition of tree or shrub and the desired effect of the trimming. There are three main types of dormant pruning for trees and shrubs: selective pruning, renewal pruning, and rejuvination pruning. Selective pruning is the method most commonly used on trees. It is used to control the size and shape of the tree, as well as remove dead wood. First, obvious dead wood is removed. From there on, pruning is done branch by branch, removing branches that are not in healthy condition, or present a strucutral problem to the tree. Branches in trees should be removed at their base points, where they branch off from the trunk or another branch. If the branch is large or heavy enough, a 3-cut method should be used  to avoid any bark from being torn away with the branch. This method works by first making an upward cut about 1 or 2 feet away from the base of the branch. A downward cut is then performed, again 1-2 feet away from the base, intersecting with the first cut, effectively leaving a 1-2 foot branch stump, alleviating most of the weight of the branch. The final top-down cut can then be performed on the branch stump with no fear of torn bark or further damage to the tree. When conducting selective pruning, especially on shrubs, it is important to take breaks and step back from the plant, evaluating the effects of the pruning taking place, and when to stop.

    Renewal pruning is performed most commonly on shrubs. Old shrubs with large branches and old growth can quickly become thickly overgrown, looking gnarly and unshaped. The goal of renewal pruning is to eliminate this old growth over time, and replace it with new growth. This is done in stages by cutting the oldest, most overgrown branches down to the ground, removing no more than a third of the plant at a time. In spring, new branches will grow to replace that third. Over a period of three years, removing a third of the old growth down to the ground each year, all of the old growth will be removed, and replaced (or renewed) with new, healthy growth.

    Rejuvenation pruning is a drastic measure used only when a shrub is vastly overgrown or dense. In early winter the shrub is cut back entirely, to within an inch or two to the ground. The result may be surprising, but in spring new growth should begin to grow back, and within a few years the shrub will recover with new vigor. It should be noted that this method of pruning should be done only by professionals or after consultation by a professional, as not all decidous shrubs can survive the process, and the ideal timing of the pruning varies between species.

    Boxwood blight confirmed in Illinois

    Published January 23, 2017

    URBANA, Ill. - Boxwood blight, a serious fungal disease, has been confirmed in Illinois. According to a University Diagnostic Outreach Extension Specialist, two boxwood samples were submitted to the University of Illinois Plant Clinic in late 2016. The samples came from Lake and Cook Counties in northeastern Illinois. Both were from recent landscape additions.

    Although the characteristic leaf spots were not apparent on the samples, defoliation and stem cankers were noted,
    — Diane Plewa

    The samples were quarantined and, after sufficient incubation, fungal spores consistent with the Calonectria spp. fungi were recovered. The Illinois Department of Agriculture was notified, and samples were sent to the United States Department of Agriculture Animal Plant Health Inspection Service Laboratory in Maryland, where the genus identification was confirmed. Species identification is ongoing. 

    “To our knowledge, the infected plants where not from Illinois production facilities,” Plewa adds.

    Symptoms of boxwood blight include leaf spots, stem cankers, and defoliation. Leaf spots usually appear as light or dark brown circular lesions, often surrounded by a large yellow halo. If the infection occurs near the margin of the leaf, the lesion may be semi-circular or V-shaped. 

    Stem cankers are easiest to see on new, green stem tissue. The cankers are dark brown or black, and are often linear or diamond-shaped.

    “Defoliation occurs as the final symptom,” says Suzanne Bissonnette, director of the U of I Plant Clinic.

    “Because these symptoms can be similar to other, common fungal and environmental problems on boxwood, we strongly suggest submitting samples to the U of I Plant Clinic for confirmation. We recommend scouting boxwood and pachysandra plants, especially those that were installed in the last few years or plants that are near host plants that were planted recently.”

    Boxwood blight is a potentially devastating disease affecting members of the Buxaceae family. The disease has been found on boxwood, pachysandra, and sarcococca. The disease is caused by the fungi Calonectria pseudonaviculata (syn. Cylindrocladium pseudonaviculatum and C. buxicola) and Calonectria henricotiae. To date, C. henricotiae has not been found in the United States.

    Bissonnette adds that boxwood blight was formerly federally regulated, but is now regulated at the state level. “Although it can cause widespread death of hosts in the environment, the spores of the pathogen do not appear to travel extensively, reducing its overall impact. However, in production facilities where equipment can be contaminated and expose hundreds or thousands of plants, the pathogen is a much larger concern.”

    The pathogen was identified for the first time in the United States in 2011, and has since been found in 18 states. Most are located in the eastern part of the country, though confirmations have been made in Missouri and Ohio.

    News Sources: Diane Plewa, 217-333-0519, Suzanne Bissonnette

    News Writer: Debra Levey Larson, 217-244-2880

    Image Sources: Adobe Stock & Rutgers Plant and Pest Advisory - Rutgers University