Letter: Landowners, keep an eye on your black walnuts

To the editor:

Indiana’s hardwood forests are experiencing wave after wave of attacks from invasive insects and pathogens, including Asian Longhorned Beetles, Gypsy Moths and Emerald Ash Borers (which have caused the decimation of hundreds of thousands of ash trees in Indiana).

Thousand Cankers Disease, the most recent of these invasions, has serious implications for Brown County. In the West, where the disease was first identified in 2007, black walnut trees were experiencing a 60 percent mortality. Since then, the disease has moved east into the black walnut’s native range, which includes Brown County.

In 2011, Purdue University and the United States Forest Service began a surveillance program for TCD in Indiana, including a black walnut plantation in Yellowwood State Forest in Brown County. The results of that first testing for Thousand Cankers Disease, released to the public in 2014, were notable: while the Walnut Twig Beetle — which until then was the only known insect carrier for the fungus that causes TCD — was not found in the Yellowwood State Forest traps, a weevil found in those traps was discovered to be carrying the TCD fungus.

Although this was not a “classic” case of TCD, in 2014, the state entomologist declared that Indiana had joined other states with TCD, and, as a result, in 2015, several states quarantined the movement of black walnut logs, lumber, nursery stock, etc., into their state from Indiana.

There are significant economic consequences to being declared a TCD-infested state. This is especially true for Brown County, because of the large volume of black walnut trees growing in our forests, the economic importance of walnut to the hardwood industry, and the quarantine-related issues pertaining to movement of walnut within, into, and out of the state.

Forestland and walnut plantation owners and the timber industry alike could be affected by a flood of black walnut stumpage onto the market, which would seriously destabilize prices. At the same time, the export of black walnut timber from the state could be further curtailed, both within the U.S. and in foreign markets.

Economics aside, the ecological impacts of a loss of Indiana’s black walnuts would be as devastating as the financial. Black walnut plays a significant role in Indiana’s hardwood forests as an important source of food for wildlife; leaves also help maintain soil health. And it is an iconic tree for Brown County residents who mark the seasons by the tree, from greening in the spring to walnuts dropping in the fall.

In 2010, Indiana’s state entomologist said, “We have much to lose from the spread of TCD. It is crucial that we avoid its introduction into Indiana.”

Now, a mere six years later, we have failed to avoid this disaster. In 2016, State Entomologist Phil Marshall stated that he “doesn’t expect widespread mortality from TCD anytime in Indiana in the near future.” Forestland owners and managers know that they don’t manage their forests for the “near future,” and that timely information and advice is essential to making good management decisions.

Sadly, it doesn’t look like they are going to get those from the state of Indiana. An analysis of DNR press releases going back to 2010 concerning Thousand Canker Disease, invasive insect identification programs and other public outreach, quarantines, etc., reveals only a paltry four news releases (from 2014 to 2016) concerning the arrival of TCD in the state, and only one article (6/24/2015) offering free training for the public on forest pest detection. This is out of well over 200 press releases per year listed on the state site.

As far as TCD goes, there may be reason for “guarded optimism,” according to a recent USDA U.S. Forest Service article on the disease:

“Results of studies to date have led to guarded optimism that TCD will not be another chestnut blight in the eastern United States. It may behave more like oak decline, which requires stress events to predispose black walnut to the complex of insect attack and canker disease development.” (emphasis mine).

While this may be somewhat encouraging news for private forestland owners, who, to some extent, can avoid and mitigate stress on their woods by careful management and pest control (although obviously they can’t mitigate the effects of pollution, periods of droughts caused by global warming and other aspects of climate change) — it is not good news for Indiana’s publicly-owned state forests, which are facing incredible stresses from the state’s irresponsible and unsustainable logging practices, including an increase of 1,000 percent over previous quotas.

And because a stressed forest, like Yellowwood, itself becomes a vector for insects and diseases that then can percolate slowly before spreading to healthy forest stands, this mismanagement becomes a major problem for all the forests in Brown County.

In any case, private landowners can monitor their black walnuts for early signs of the disease, realizing that detection is difficult until the damage is well underway and crown symptoms begin to appear.

Look particularly for smaller trees in poor sites that are already stressed. In spring and early summer, leaves in upper branches will turn yellow, wilt and die. Branches die back gradually from the upper crown downward. Browning leaves often remain attached to twigs. New sprouts may grow from the tree roots or trunk, giving the tree a bushy appearance below dead branches.

If you think you may have a black walnut tree that is suffering from Thousand Canker Disease, please notify the Indiana Department of Natural Resources, Division of Entomology and Plant Pathology, by calling 1-866-NOEXOTIC (1-866-663-9684) or by sending an email to depp@dnr.in.gov or Phil Marshall@pmarshall@dnr.IN.; 317-232-4189. Please include your contact information, a description of the symptoms you have observed and the location of the suspect tree.

Linda Baden, Friends of Yellowwood

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