HTIRC E-NEWSLETTER – December 2017

Volume 10 Issue 2

Articles in this issue:

Welcome to this issue of the Hardwood Tree Improvement and Regeneration Center E-newsletter. We have a new website and associated newsletter format that we hope you will enjoy and find useful.

The HTIRC is committed to enhancing the productivity and quality of Central Hardwood Region trees and forests for the economic and environmental benefits they provide. Scientists at the HTIRC are using conventional tree improvement breeding as well as molecular and genetic technologies to improve the wood quality, growth characteristics, and insect and disease resistance of trees like black walnut, black cherry, red and white oaks, butternut and American chestnut. Research in tree breeding, tree nursery practices, tree plantation establishment and management, and Central Hardwoods silvicultural systems is aimed at increasing the regeneration success rate for high quality hardwood trees and forests.

We invite you to read about some of our activities by visiting the E-Newsletter Page at:

If you wish to download the pdf version and your web browser is Internet Explorer, we recommend you first download Adobe Acrobat Reader DC at for the newsletter format to appear correctly on your screen.

Forestry Mulching Heads: A Powerful Tool for Invasive Shrub Control

By Graham Frank

By now, you’re probably well aware of the threat that invasive shrubs represent to forest regeneration and biodiversity in forest understories.  The easiest and least expensive way to control woody invaders will always be early detection and control, but populations of these invasive species can rapidly go from a handful of individuals to dense thickets in a few short years.  So, what is the best way to control mature populations of invasive shrubs when clipping or spraying scattered individuals is no longer a feasible option?

Many contracting companies have moved away from the “cut-stump” method, which involves cutting the shrub at the base and treating the stump with an herbicide, in favor of forestry mulching heads, which can clear dense shrub thickets in a fraction of the time.  However, many invasive shrubs resprout from pre-formed buds in the stump when cut, and the effectiveness of mulching heads at controlling this resprouting has been understudied.  There has also been concern that soil disturbance from mulching heads will harm existing native species and cause further invasive species to establish after shrubs are removed using this technique.  M.S. student Graham Frank, advised by Dr. Mike Jenkins, has been monitoring how understory vegetation responds to these two shrub control techniques when applied to mature Amur honeysuckle (Lonicera maackii) invasions.

Image of honeysuckle research plot
Figure 1. Forestry mulching head on a skid-steer grinding up Asian bush honeysuckle.

In the first growing season after honeysuckle removal, the mulching head promoted establishment of new honeysuckle seedlings and reduced the number of native tree seedlings in the understory, but both of these effects were temporary, and by the following year there were no differences in the vegetation responses to the two control methods.  Honeysuckle stumps also resprouted more vigorously when treated with the mulching head.  However, another experiment initiated the following year showed that applying the mulching head more aggressively (i.e. grinding the stumps down closer to or below the soil surface) could help to reduce resprouting, though responses of other vegetation to this more aggressive treatment have not yet been examined.

Image of Resprouting Honeysuckle Fecon
Figure 2. Asian bush honeysuckle re-sprouts.
Image of Fig 3 Nonsprouting honeysuckle fecon
Figure 3. Asian bush honeysuckle stem base with no resprouts following use of a forestry grinding head.

Mulching heads leave a layer of residual woody debris on the site, but mulch added onto some plots treated with the cut-stump method showed that it had no strong effects on the recovery of understory vegetation.

Forestry mulching heads are a promising technique for controlling invasive shrub species, particularly in areas that are generally flat, have widely-spaced trees, and are not very rocky.  Invasive shrub control is a multi-year process that requires vigilant follow-up treatments to take advantage of the initial reduction in shrub biomass, but the benefits for natural regeneration and understory biodiversity can be apparent after only one or two growing seasons.  More detailed information on the study will be available in a forthcoming scholarly publication currently in preparation.

Image of Fig 4 Trillrec and Allium
Figure 4. Trillium and wild leeks may return to sites following treatment of Asian bush honeysuckle.

Planning for Tax Time

By Lenny Farlee

Tree planting and timber management activities may provide some tax management opportunities for landowners preparing their 2017 income taxes. Several sections of the federal tax code deal directly or indirectly with expenses or income related to tree planting and timber management. Opportunities exist for eligible landowners to utilize these to manage their tax liability.

One example is the ability for taxpayers to deduct up to $10,000 of expenses related directly to reforestation or afforestation costs on areas of at least one acre planted in the US for commercial timber production. Expenses above $10,000 may be amortized as a deduction over 84 months. Trusts are eligible for amortization deduction only.

Timber or landscape trees destroyed by events like hurricane, fire, tornado, or ice storm may be tax deductible. The amount of deduction is dependent on the type of property – private residence, business, or investment.

Sale of standing timber held as an investment is generally eligible for capital gains tax rates, as opposed to ordinary income. Income from selling cut logs is normally taxed as ordinary income, unless you are able to use some special elections in the tax code.

Timber property acquired by purchase, inheritance, or gifting may provide an opportunity to use the cost basis of the timber to apply against income from timber sales. Professional foresters can help you determine if you have a useful amount of basis available and what that basis is. Properties recently purchased or inherited may have a significant amount of timber value basis to apply against income from a recent sale of timber. If you inherited timberland, you are normally able to “step up” the basis of the property to the value at the time of inheritance. This provides an opportunity to sell appreciated timber assets and limit tax liability by using the stepped-up timber basis to reduce net taxable income.

The opportunities available to you are determined by your particular situation, so consult with your professional foresters and tax advisors about the best course of action for you. The following resources offer additional details on the topics listed here and several others related to tree planting and timber management. Also, be aware that tax law is subject to change, so work with your professionals and keep an eye on these reference sites.

The HTIRC publication Financial and Tax Aspects of Tree Planting:

Tax Tips for Forest Landowners for the 2017 Tax Year:

The National Timber Tax Website:

Is Nursery Production of Hardwood Species in Jeopardy?

By Carrie Pike

Our love of trees

Humans love our trees. In cities, trees are celebrated as icons of nature in our urban jungles. Cultivars, or plant varieties that are often vegetatively propagated, are commonly used in urban spaces because they are selected for traits with visual appeal, such as a certain branch angle, leaf shape or color. In rural areas trees are also valued for their wood and fiber, their ability to protect watersheds from erosion, and the habitat they provide for wildlife. Native species are generally favored for reforestation in woodlands, with innate levels of genetic diversity, so trees will have a myriad of traits to adapt to conditions at the site. Trees can be prolific seed producers, but sometimes planting is needed to supplement natural regeneration, to afforest areas where trees have not recently existed, or to control species make-up for specific management objectives.

Image of tree planting machine
Tree planting machine

Stock type 101

Tree nurseries supply most of the plant material used in reforestation across the US and territories. Nurseries come in two main forms: those that grow conservation grade (wild) stock for regenerating future woodlands, and those whose production focus mostly on cultivars.  (Some nurseries grow both types.) Cultivars and conservation-grade trees can be grown as one of two main stock types, either bareroot or containerized seedlings.

Bareroot seedlings are field-grown for one to three seasons – typically in long, narrow, sandy nursery beds. They are ‘lifted’ from the nursery beds, a process involving a combination of machine and human labor, to remove the soil from their roots, and facilitate storage and transport. The seedlings are graded to remove undersized, oversized, damaged, or diseased individuals, then they are bundled and shipped.

Containerized seedlings are sold with their roots in a container of soil (or soil-less potting media), ranging from small seedlings (the length of your hand) to trees in large pots or balled and burlapped, which may be in excess of 10 feet in height. Cost per tree varies by size, quality, and availability, but size largely dictates price: a 10 foot tree in a 10-gallon pot can cost 1000 times more than a small seedling that would fit in a planter’s bag.

Image of young seelings at vallonia
Young seedlings at Vallonia Nursery

Forests are regenerated with seedlings or seed supplied by public (state or federally managed) or private nurseries. Nursery operation is a challenging business because it is subject to variants in weather, and unpredictable supply/demand.  As such, stock at private nurseries consists largely of products that command the highest value, usually large stock (balled/burlapped trees, for example) or cultivars that are sold, often to house developers, in large quantities. Private nurseries also dominate markets for specialty products, such as Christmas trees or exotic trees, shrubs, and perennials. In contrast, rural reforestation projects in woodlands require millions of small seedlings, often less than 2 feet in height, planted across large geographic areas in a single season. In 2016, over 70 million tree seedlings were planted across the Northeastern Area (NA), a 20-state area from Maine-Maryland-Missouri-Minnesota (see this fall’s edition of Tree Planters’ Notes for the report). Most seedlings sold for reforestation, afforestation, and conservation planting cost less than $1 each, and nurseries must sell millions to reach a comfortable profit margin. Small, conservation-grade seedlings are the most widely planted of all stock types, and represent the dominant source of the genetic makeup of future forests. Public and private nurseries play a substantial role in supplying seedlings that constitute America’s future forests.

Conifer vs hardwood

North America is home to hundreds of tree species that are cultivated and sold by nurseries. Conditions to store and germinate seed, and to cultivate seedling growth vary widely by species, and cultivar (within a species). Conifers, or evergreen trees such as pines and spruces, are generally easier to cultivate than hardwood, or broad-leaved trees, with a few exceptions. Conifer seed stores easily, germinates readily, and produces a rigid, stout, straight seedling with a balanced, or similarly sized, root system. Exceptions include difficult-to-germinate whitebark pine, for example, and slow-growing less rigid species such as eastern hemlock.

Hardwood species pose unique challenges to nursery managers. For one, the seeds are often recalcitrant, and cannot be stored more than one year before they germinate. Seeds of some species germinate prematurely before they are planted, with detrimental consequences. Hardwood trees also have a tendency for early, rapid growth, so seedlings tend to be much larger than their evergreen counterparts, with extensive root systems that can greatly exceed the above-ground biomass. Usually a one-year old hardwood seedling is large enough for most reforestation projects, in contrast to evergreens that are often grown for 2-3 years before they are large enough to plant. A healthy hardwood seedling has a large, fibrous root system that thrives in the open conditions of a nursery bed, as opposed to the confinements of a pot. Shipping and transporting containerized hardwoods becomes an expensive prospect: a healthy, one-year old containerized bur oak weighs upwards of 10 pounds, whereas a bareroot seedling of the same age weighs less than a pound. For large-scale reforestation of hardwood species, bareroot seedlings are far and away a better choice for most projects. Generally, bareroot seedlings are more commonly propagated at state, rather than private, nurseries.

Each year, the USDA Forest Service surveys all state and private nurseries to obtain an approximate number of trees planted across the 50 US states and territories. This year’s report can be found in fall edition of Tree Planters’ Notes, which will be available at the RNGR website later this fall, at The intensity of tree planting often tracks the availability of federal cost share dollars, increasing when environmental conservation programs are fully funded, and decreasing when they are not. Since the 2008 recession, production of hardwood trees has dropped almost in half, compared to conifers that dropped approximately one third. In 2016, more than 75% of trees planted in the Northeastern Area were conifers, compared to 25% for hardwood trees. While the recession had the greatest influence in the short term, long-term production of seedlings may never fully recover since four states closed their nurseries in response to the budget shortfalls in period following 2008: Louisiana, Texas, Oregon, and Ohio. Of these nurseries, Ohio predominantly grew hardwoods. Other nurseries consolidated their operations into one facility (Minnesota, Wisconsin), responding to reduced demand for their stock.  Private sector nurseries were also impacted but closures more difficult to track.

What’s the problem?

In 2016, a national survey was conducted by the NASF (National Association of State Foresters), and concluded that family forest owners were the most important customers of state nurseries. State nurseries grow seedlings speculatively, which means their buyers – mostly small private woodland owners – can order from the available inventory on demand. They must meet the minimum ordering size requirements, which varies by state, but otherwise trees can be ordered shortly before planting. While some private nurseries also sell speculatively, the vast majority of seedlings planted are grown on contract from commercial nurseries. In some states, state nurseries are the only vendor available for small woodland owners to purchase locally-sourced conservation-grade seedlings on demand.

State nurseries often are asked to validate their importance to their agency, especially as sales ebb and flow with the economy. Some states face intense scrutiny from private sector nurseries who argue that competition from state nurseries is detrimental to their business interests, an argument that gains traction where government is viewed with suspicion. The impact of the nursery on its taxpayers often exceeds its perceived value: seedlings are often given to school children, educational programs are hosted, and sometimes land is shared with recreational uses. A nursery closure impacts small private landowners to a greater degree than any commercial customer because they lose access to speculatively-grown, locally-sourced seed or a stock type that would optimize their tree planting efforts. Hardwood seedlings – that are predominantly cultured as bareroot seedlings – are especially vulnerable since state nurseries supply over half of all bareroot hardwood seedlings produced in the northeast. This places small landowners with few options in the event their state nurseries are eliminated, but legislative decisions about nurseries are often done with some level of secrecy. Even when nurseries are publicly debated, many landowners aren’t legislatively active or may not realize the impact until long after the nursery has closed.

The end-game: healthy forests

Challenges to the forest nursery industries are numerous. Public nurseries generally fill a niche that private sector nurseries can’t fill reliably because of low profit margins and vagaries of demand. However, private nurseries can benefit from the presence of a state nursery in states where public nurseries are permitted to sell seed or resell live seedlings. For example, public nurseries are often centers for seed procurement and many contain seed processing plants from which seed is sold, stored or grown. Private nurseries that purchase seed from the state are relieved from the burden of maintaining a seed processing facility, or relying on seed dealers, who either lack a local seed source or fail to disclose seed origin. Secondly, in some states, private nurseries are allowed to purchase bareroot seedlings from the state to line-out for production of larger containerized stock. This helps increase genetic diversity of native trees across woodlands or urban areas where larger stock is requested, and releases the private sector from the challenges of germinating seed. Forest landowners, who undertake tree planting, benefit from having their choice of stock type, species, and seed source for plant material that they purchase. A healthy nursery sector, with both public and private nurseries, provides the greatest prospect for restoring future forests that can endure on the ever-changing landscape.

Trees on the Move

From Dr. Songlin Fei’s interview with the National Public Radio Living on Earth Program – May 26, 2017.

Image of Songlin FeiTranscript

CURWOOD: Yes, we have another tale of trees, trees that are moving, though not as dramatically as the Ents in the Lord of the Rings epic. And not individual trees of course, but species that are migrating. A newly-published study confirms that 86 tree species of the Eastern U.S. are moving as the planet warms. But not just north: some are heading west. Songlin Fei of Purdue University is the lead author of the new study and joins me now. Professor Fei, welcome to Living on Earth.

FEI: Well, thank you, it’s very nice to be here.

CURWOOD: So, tell me what’s going on here? The Northward shift is not so surprising, since that’s mostly having to do with temperature and climate change certainly is warming things up, but why are trees also moving West?

FEI: Well, this is a very fascinating phenomenon. When we first looked at it, we have the exact same question that you do: Why the trees are moving westward? So, for climate change it means two things, often we think about temperatures warming up, but on the other aspect is that climate change is also causing precipitation pattern changes.

In our study area in the Southeastern US like in Georgia, in the Carolinas and part of Florida even, they have a significant drought. On the other hand in the western portion of the study area — primarily we’re talking about the Mid-western areas such as Missouri, Illinois — they have more water or precipitation overall compared to historically what they have. So, the main driving factor that we are seeing that trees move Westward is due to the responding to the changing of moisture availability.

CURWOOD: So, the way that the trees move, of course, is that trees don’t pick up and walk on their roots. Their seeds go in one direction or another, and the saplings have more success then in a particular direction or another.

FEI: Yes, so we are not only talking about addition of the new seedlings, but we are also talking about mortality that is also happening for the big trees, especially given the drought that we have in the Southeast. And so, you think about this as an example, say, a line of people lining from Indianapolis to Atlanta. Every individual in that line has not moved in a single inch, but there are more people joining the line, say in Indianapolis or in Lexington, and there are people dropping out of the line in Atlanta, and then what’s going to happen is the center of this line seems to have shifted.

CURWOOD: What kinds of trees are experiencing these shifts?

FEI: Well, so if we look at the groups that belong to certain families, what we find is that trees which are those flowering plants, broad-leafed plants, they are moving westward, so those are the oaks, maples, or the hickory species. But if you’re looking at the specifically evergreen tree group which are the pines and spruce and firs, majority of these evergreen trees are moving northward.

Image of Fig 1
Figure 1 Mixed conifer-hardwood forest in the Upper Peninsula of Michigan

CURWOOD: So, what’s the difference then between the pines and plants like them versus the broadleaf trees like the oaks and maples that causes this difference in movement? I gather one is more sensitive to water and moisture. Which one would that be?

FEI: Well, so in our analysis, we followed up by looking at the traits of the individual species. We looked at over a dozen of traits, and for those westward moving trees in general they are more tolerant to drought. They also have some unique ability in terms of the seeds.

CURWOOD: So, why did the broadleaf trees, the oaks and the maples, if they have more drought tolerance, why are they moving west? It seems that there is more water to the west?

FEI: OK, well so we need to put into context even though we say there is more drought in southeast and getting wetter in the Midwest, in reality Georgia and Florida they still get way more precipitation than in say, Missouri or Illinois. But compared to the historic average, they are starting to get more moisture and these other trees are able to take the advantages of more moisture availability in a relatively dry area.

CURWOOD: So, in other words, they can pioneer to places that were previously too dry for them but now with just a little more moisture, they can go there. So, to what extent have tree species shifted their range in the past?

FEI: Trees are shifting its range all the time because of glaciation, or retreat of the glacier, and so there are studies in the New England area looking at how trees are tracing the changing temperature in the precipitation in the last several thousand years. But the differences among our study and what we’re seeing is that we are talking about a 30-year period, that we track trees shift between 1980 to 2015, and are seeing a big change that if only nature taking its course might take several thousand years that is happening.

CURWOOD: And how far over these three decades do these trees move? How far can they go?

FEI: So, on average, these trees have shifted about 15 kilometers per decade, so it’s roughly about 10 miles per decade, close to 50 kilometers during the study period.

Image of forest
Figure 2. Oak-hickory forest in southern Indiana.

CURWOOD: Songlin, if the maples, if the oaks, if the hickory are moving to the west, and yet the pines and the spruce and the firs and moving to the north this will change the whole ecological balance in a forest system. How are forest ecosystems coping with this divergent change?

FEI: Yes, this is really a great question, and we don’t really know yet because the current study we are looking at individual trees, but when we look at a forest this is really a composition of multiple species which in ecological terms we call a community. And so, we don’t know whether the community is currently vulnerable for break down because of the different direction of this shift by individual species. So, we are interesting in looking at how these communities are responding as a group. Are there certain community groups that are more vulnerable than the others? And so, this is really what we are interested to look at next.

CURWOOD: Songlin Fei is an Associate Professor in the Department of Forestry and Natural Resources at Purdue University. Thanks, Professor, for taking the time with us.

FEI: Well, thank you, it’s nice to be on the program.

Image of Fig 3 maps







HTIRC Research Projects Incorporate Advanced Techniques

By Shaneka Lawson

Research within the HTIRC has always been current but the latest projects will employ several cutting-edge methods for data extraction. The first technique, used most recently to identify differentially expressed genes in figured and non-figured wood is RNA sequencing (RNAseq). Image of figured koa This method required RNA extracted from wood samples to be sequenced before genes involved in wood formation could be isolated. Once isolated, expression levels of those genes could be compared in figured and non-figured samples of koa (Acacia koa), a high-value tropical hardwood species. An example of the process is shown in the schematic below for differentiation in male and female gene expression.

Image of Fig 1

Research outside of HTIRC with chestnut (Castanea sativa) in 2017 worked to determine which Septoria spp. cause leaf blotch infections1. Other work using RNAseq included examination of salt stress responses in elm (Ulmus pumila) in 20162 and drought stress responses in oak (Quercus lobata) in 20173. Recent apple (Malus domestica) research using RNAseq indicated that pale green lethal disorder in apple (Malus spp.) stimulates stress responses and affects senescence4. The variability in these research topics alludes to the plethora of various projects that could be initiated using RNAseq.

A second method, laser-capture microdissection (LCM), has been recently used within the HTIRC to isolate and analyze adventitious root cells from softwood cuttings of black walnut (Juglans nigra). This technique combines basic light microscopy with a low-energy laser beam and special films to excise specific cells from tissue samples while leaving all other cells untouched. Combining this procedure with simple staining can allow visibility of tissue specific gene expression. The example below shows how stained tissues in a stem cross section can be targeted and extracted for further study.

Image of Fig 2 LCM

This year, forestry publications from European scientists showed laser capture microdissection (LCM) could be combined with RNAseq to discover both the molecular and functional organization of pine (Pinus pinaster) tissues and specialized cells5. That work highlighted the relationships between tissue gene expression and function and could be used in HTIRC for numerous species of interest. A second European group used LCM and RNAseq in Norway spruce (Picea abies) and aspen (Populus tremula) to study cell-specific molecular events regulating wood formation in trees6.

A third method involves utilization of genome-wide association studies (GWAS) to relate a particular genetic variation to a specific trait. Widely used in grain crops, studies such as these exploit genome recombination events and pinpoint single nucleotide polymorphisms (SNPs) likely associated with traits of interest. There are current discussions among HTIRC scientists regarding use of these technologies for black walnut research studies but nothing concrete has been determined. An example below shows use of GWAS to examine tannin content in acorns as a trait of interest.

Image of Fig 3

To date, use of GWAS in forest tree species is almost non-existent however, GWAS in fruit trees species over the last few years has been much more common. The majority of those studies focus on traits that make these crops more appealing to consumers. Apple studies examined genetic relationships between skin color7 and texture and aroma8 while peach (Prunus persica) research elucidated relationships between genetics and fruit acidity9. Other studies in grain crops used GWAS to evaluate relationships between genetics and disease. A wheat (Triticum aestivum) study examined host resistance to Fusarium head blight (FHB), a significant disease worldwide10. A more extensive study in soybean (Glycine max) scanned SNPs in one bacterial disease, five fungal diseases, two diseases caused by nematodes, and three viral diseases for a study using the USDA Soybean Germplasm Collection11.

These techniques described above are only a portion of options HTIRC faculty and students have available for use to find answers to research questions involving hardwood tree species. These versatile techniques allow myriads of comparisons to be tested, are fairly new to field of forestry, and help ensure that HTIRC continues to conduct superior research. Visit the HTIRC webpage ( often to learn more about our exciting hardwoods research.

Reference material:

1Yousefzadeh et al. (2017) J For Res 28(4): 661-670. doi: 10.1007/s11676-016-0363-6;
2Zhu et al. (2016) Forests 7(12): article318. doi: 10.3390/f7120318;
3Gugger et al. (2017) Tree Phys 37(5): 632-644. doi: 10.1093/treephys/tpw122;
4Orcheski et al. (2017) Tree Gen Genom 13(1): article9. doi: 10.1007/s11295-016-1097-5;
5Canas et al. (2017) Plant J 91(6): 1064-1087. doi: 10.1111/tpj.13617;
6Blokhina et al. (2017) Frontiers Plant Sci 7: article1965. doi: 10.3389/fpls.2016.01965;
7Moriya et al. (2017) Euphytica 213(4): unsp78. doi: 10.1007/s10681-017-1864-x;
8Farneti et al. (2017) J Exp Bot 68(7): 1467-1478. doi: 10.1111/nph.14154;
9Wang et al. (2016) Euphytica 210(3): 413–426. doi:10.1007/s10681-016-1709-z;
10Arruda et al. (2016) Plant Gen 9(1): 1139–1151. oi:10.3835/plantgenome2015.04.0028;
11Chang et al. (2017) Phytopath 106(10): 1139–1151. doi: 10.1094/PHYTO-01-16-0042-FI

Large Seed Crops are a Regeneration Opportunity

By Lenny Farlee

A heavy seed crop on black walnut and other large-seeded hardwood trees has been noted in several areas this year. This heavy crop, sometimes called a masting event, provides an opportunity to regenerate some desirable trees naturally, or with some help from human hands. Some rodents, particularly squirrels like gray and fox squirrels, will naturally scatter seed by burying them across the area they inhabit. If the seed crop is abundant, they may not need to recover all those buried seed, leading to some potential new trees. I say potential because the tree seedling needs to be in a spot where it can obtain the appropriate amount of sunlight, space, water, and nutrients to develop and compete with surrounding vegetation. For example, black walnut seeds planted where they will not be shaded by other trees have a chance to grow quickly and compete successfully for space and resources. If the same seed ends up planted in the shade of the forest, it has little chance for survival, unless the competing trees and shrubs are removed.

image of black walnuts
Black Walnuts

If you don’t trust the squirrels to plant your seed, you could collect seed and plant them yourself. There are a variety of approaches to take. Perhaps the easiest is to collect seed and plant it this fall. This may be as simple as collecting seed on-site and moving to your planting site shortly after collection and planting it where you would like it to grow. Be aware that squirrels and other seed predators may pilfer some, and some cases nearly all, of the seed if you are near where they search for seed. A heavy seed crop may help you get more seed past the predators.

You can also collect seed of some species like walnut, butternut, red oaks and hickories and store them over winter in a cooler, refrigerator, or outside in a stratification bed. Many seeds, including those mentioned, require a cool, moist period, called stratification, of several weeks to break seed dormancy and allow for germination the next spring. Storing seed at the appropriate temperature and humidity for the appropriate time will break the dormancy. Seed storage can be tricky, so it may be best to use the next best thing to the natural process that happens over the winter in the forest – An outdoor stratification bed. This bed can be made with a raised-bed, containers, or a pit in well-drained soil areas. A high proportion of sand makes a good medium for soil drainage and easy recovery of seed. Bury seed in the soil medium after collection in the fall. Seed can be closely-packed since you will recover the seed in the early spring for planting before they germinate. Be sure the bed can be protected by screen or other barriers to prevent rodents from pilfering the seed. The soil medium should be moist, but not saturated. You can mulch over the top of the seed and soil to help conserve moisture and insulate from rapid temperature changes. Pull the seed out of storage in early spring and plant it where you want it to grow.

Each tree species has particular requirements for best seed germination results. An excellent resource for seed collection, handling, germination and planting instructions is the Woody Plant Seed Manual produced by the US Forest Service:

A good guide specifically for black walnut is Propagating Eastern Black Walnut:

New Tool Detects Oak Wilt Fungus Faster and More Accurately

From 2017 NRS Research Highlights Report

Jennifer Juzwik, NRS-10 Biological and Environmental Influences on Forest Health and Productivity

Oak wilt is one of several significant oak diseases threatening oak health in the United States and is a potential threat worldwide. Accurate and timely laboratory diagnosis is critical to controlling the disease. A Northern Research Station scientist and collaborator have developed and validated two molecular-based diagnostic tools that greatly exceed standard isolation methods in time required and accuracy.

Caused by the fungus Ceratocystis fagacearum, oak wilt is causing crown wilt and death of oaks in 24 U.S. states; it has been particularly destructive in the Upper Midwest and Texas. If left unmanaged, the disease can dramatically alter urban and natural ecosystems. Effective disease management relies on accurate and timely diagnosis of the disease. Working with a University of Minnesota graduate student, Jenny Juzwik, a Northern Research Station scientist and HTIRC collaborator on other projects, has modified molecular protocols for effective and routine use by plant disease diagnostic laboratories. Fungal DNA was extracted from drill shavings taken from the sapwood of red, bur, and white oaks in different stages of oak wilt development. Amplification of the DNA was completed using either nested or real-time polymerase chain reaction methods. Resulting levels of pathogen detection were compared with rates of detection using standard isolation methods. The molecular protocols were superior in detection frequencies compared to isolation for samples from actively wilting bur and white oak trees. The pathogen could only be detected in 1-year-old dead branches (bur, white) and main stems (red) of oak species using the new techniques. The molecular assays can be conducted in fewer than 2 days compared to 10 to 14 days incubation required for isolation. University and state agency diagnostic laboratories are using the methods, particularly for problematic samples.

Additional Information on oak wilt:

US Forest Service Northeastern Area oak wilt site:

HTIRC publication Diseases in Hardwood Tree Plantings

Dr. Paula Pijut Retiring in December 2017

Dr. Paula M. Pijut will retire after 29 years with the USDA Forest Service including 17 years with the Hardwood Tree Improvement and Regeneration Center (HTIRC).

Paula is a Research Plant Physiologist with the Northern Research Station, HTIRC, and Adjunct Associate Professor in the Depts. of Forestry and Natural Resources, and Horticulture and Landscape Architecture at Purdue University. Paula received her B.S. in Medical Technology from Maryville College of the Sacred Heart, her M.S. in Horticulture from Murray State University, and her Ph.D. in Horticulture from The Ohio State University.

Her research program focused on plant cell, tissue, and organ culture for tree improvement, production, and conservation. Dr. Pijut developed protocols for in vitro selection, somatic embryogenesis, adventitious shoot regeneration, rooting, micropropagation, genetic transformation, induction or control of flowering, clonal propagation, and vegetative propagation of hardwood tree species. Paula conducted research on black walnut, northern red oak, black cherry, butternut, white oak, and green, white, pumpkin, and black ash.

In addition to her research, Dr. Pijut was an editor for four scientific journals, and advised numerous graduate students who are now contributing to science; extending her research legacy beyond her own career.

A more complete list of her research publications and accomplishments can be viewed at: and

We wish Paula the very best in her retirement!

Announcements, Publications, and Events

James Jacobs successfully defended his PhD dissertation on July 13, 2017. James has a position with the USDA Forest Service, Northern Research Station as a Plant Pathologist.

Kyle Earnshaw Rose (Former van Eck Scholar) accepted a new position as Assistant Professor at New Mexico Highland University (Las Vegas, NM) beginning in Fall 2017. He will work alongside Dr. Joshua Sloan (Purdue FNR PhD in 2011 and former van Eck Scholar).  Dr. Owen Burney (Purdue FNR PhD in 2011), Assistant Professor with NM State University) directs a forestry center and experimental nursery 45 minutes away, present opportunities for research synergies.

Nick LaBonte successfully defended his PhD dissertation on Thursday, August 3. Nick accepted a position as adjunct professor at Eureka College located in Illinois.

Micah Stevens accepted a Lead Scientist-Director at ProTree Nursery LLC, MicroPlants Division located in Brentwood, California (Former van Eck Scholar).

Jun Hyung Lee successfully defended his PhD dissertation on November 2, 2017. Jun has accepted a Post-doctoral position at the University of Tennessee-Knoxville where he will join Dr. Neal Stewart’s lab group.

Graham Frank (van Eck Scholar) successfully defended his MS dissertation on November 21, 2017.

2017 Research Publications

Origin of adventitious roots in black walnut (Juglans nigra) softwood cuttings rooted under optimized conditions in a fog chamber (PDF 582 KB) 2017. Stevens, M.E. and Pijut, P.M. New Forests 48:685-697.

Adventitious Shoot Regeneration from in vitro Leaf Explants of Fraxinus nigra (PDF 1MB) 2017. Lee, J.H. and Pijut, P.M. Plant Cell Tissue and Organ Culture 130:335-343.

Genetic diversity of Persian walnut (Juglans regia) in the cold-temperate zone of the United States and Europe (PDF 268 KB) 2017. Ebrahimi, A., Zarei, A., McKenna, J.R., Bujdoso, G., and Woeste, K.E. Scientia Horticulturae 220:36-41.

Isolation and characterization of a floral homeotic gene in Fraxinus nigra causing earlier flowering and homeotic alterations in transgenic Arabidopsis (PDF 344 KB) 2017. Lee, J.H. and Pijut, P.M. Plant Gene 10:17-25.

Pollen gene flow, male reproductive success, and genetic correlations among offspring in a northern red oak (Quercus rubra L.) seed orchard (PDF 397 KB) 2017. Alexander, L. and Woeste, K. PLOS ONE 12(2): e0171598. doi: 10.1371/journal.pone.0171598.

Combining Biodiversity Resurveys across Regions to Advance Global Change Research (PDF 535 KB) 2017. Verheyen, K., De Frenne, P., Baeten, L., Waller, D.M., Hedl, R., Perring, M.P., Blondeel, H., Brunet, J., Chudomelova, M., Decocq, G., De Lombaerde, E., DePauw, L., Dirnbock, T., Durak, T., Eriksson, O., Guilliam, F.S., Heinken, T., Heinrichs, S., Hermy, M., Jaroszewicz, B., Jenkins, M.A., Johnson, S.E., Kirby, K.J., Kopecky, M., Landuyt, D., Lenoir, J., Li, D., Macek, M., Maes, S.L., Malis, F., Mitchell, F.J.G., Naaf, T., Peterken, G., Petrik, P., Reczynska, K., Rogers, D.A., Schei, F.H., Schmidt, W., Standovar, T., Swierkosz, K., Ujhazy, K., Van Calster, H., Vellend, M., Vild, O., Woods, K., Wulf, M., and Bernhardt-Romermann, M. BioScience 67:73-83.

Response of spring flora to nearly two decades of deer exclusion and resurgent woody understories within exclosures (PDF 220 KB) 2017. Webster, C.R., Rock, J.H., and Jenkins, M.A. Journal of the Torrey Botanical Society 144(1):1-14.

High-quality genetic mapping with ddRADseq in the non-model tree Quercus rubra (PDF 886 KB) Konar, A., Choudhury, O., Bullis, R., Fiedler, L., Kruser, J.M., Stephens, M.T., Gailing, O., Schlarbaum, S., Coggeshall, M.V., Staton, M.E., Carlson, J.E., Emrich, S.,Romero-Severson, J. 2017. BMC Genomics (2017) 18:417. DOI 10.1186/s12864-017-3765-8

Development of novel genic microsatellite markers from transcriptome sequencing in sugar maple (Acer saccharum Marsh.) (PDF 800 KB)Harmon, M., Lane, T., Staton, M., Coggeshall, M.V., Best, T., Chien‑Chih Chen, Liang, H., Zembower, N., Drautz‑Moses, D.I., Yap Zhei Hwee, Schuster, S.C., Schlarbaum, S.E., Carlson, J.E., Gailing, O. 2017.  BMC Res. Notes (2017) 10:369. DOI 10.1186/s13104-017-2653-2

Practical strategies of black walnut genetic improvement — An update (PDF 592 KB) Rink, G., Van Sambeek, J.W., O’Connor, P., Coggeshall, M.V. 2017. Walnut Council Bulletin. 44(2): 1-3, 10-11.


Central Hardwoods Conference is May 15-17, 2018 in Bloomington Indiana. May 15-16 is concurrent sessions and May 17 is a field tour to the Hardwood Ecosystem Experiment.
The event website is

Walnut Council National Meeting will be held July 29-August 1, 2018 in Dubuque, Iowa, with tours in Wisconsin. The Walnut Council Events webpage is

HTIRC-Working the Forests for the Future – YouTube Video

Click here to view the video