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Tree Information

Tree Diseases

personal using chemicals around tree

After 30 devoted years of service to the Black Hills and to western South Dakota, the Johnson Tree Company (JTC) can accurately diagnose any tree’s disease or health problem, and then initiate a remedial course of action. We’re usually able to assist our customers immediately, using our own equipment and in-house treatment plans.

JTC chemical applicators are commercially licensed by the South Dakota Department of Agriculture. Our applicators are current and legal in all aspects of urban and rural pesticide and herbicide applications. All JTC chemical applications are applied in strict accordance with product labels regarding timeliness, environmental conditions, and application rates, coverages, and dosages.

JTC is certified by South Dakota and U.S. agencies to properly apply any curative chemical for South Dakota’s urban and forest trees. We can professionally and correctly identify and manage any health problem on any tree in the South Dakota landscape.

Nobody knows South Dakota’s trees as well as we do. And, we stand behind our work.

healthy Elm

Dutch Elm Disease

Dutch elm disease (“DED”) is a fatal disease of (primarily) the American Elm tree (Ulmus americana).* It is a fungal infection caused by an infestation of the elm bark beetle. Only elm trees are susceptible. Once an elm is infected with the fungus, it cannot be saved; it will not survive. Trees infected with DED must be completely removed.

The City of Rapid City, SD loses more than 200 elm trees annually because of this highly-contagious and killing disease. Very few old-age elms remain due to encounters with DED.

But not all hope is lost. JTC arborists can absolutely protect your elm for three full growing seasons. However, only trees that are currently healthy and disease-free are candidates for DED preventative treatment. The treatment is time-consuming and is costly — so treatment is usually reserved for specimen or high-value trees only.

JTC offers a proven — and guaranteed — systemic treatment for dutch elm disease. No company — anywhere — will stand behind their treatment of DED as firmly as we do (please see our Warranty section). JTC’s DED treatment covers your tree for three years, so contacting us annually is unnecessary. In fact, JTC specialists will contact YOU when the treatment is up for renewal. You won’t have to worry ever again about losing your majestic elm to the deadly DED fungus.

*Contrary to common belief, there are no “Dutch Elm” trees in South Dakota or any of the surrounding states. It is the grand old “American Elm” that catches the fatal dutch elm fungus. The fungus was first identified nearly 100 years ago in the Netherlands (hence its name) and it arrived in the U.S. on an imported pallet of infected timber in Ohio in 1928.

Nobody knows South Dakota’s trees as well as we do. And, we stand behind our work.

Elm chlorosis


Trees that exhibit yellowing leaves long before the routine autumn coloring are often suffering from a nutrient deficiency called iron chlorosis. Chlorosis is a serious tree-health problem where a tree has lost its ability to turn sunlight into its own food (sugars). Left alone, chlorosis leads to leaf-death, dieback of branches, lack of vigor, and eventually the death of the entire tree.

Initially, the problem may affect only a few branches, though it is common for the whole tree to take on a yellow-green hue. Trees will continue to deteriorate in following seasons.

In South Dakota and surrounding areas, iron chlorosis is most often a problem of maple trees (Acer) and is typically associated with our prevailing clay and high-alkaline soil conditions.

JTC treats chlorosis problems using systemic (trunk) injections that provide your tree with iron “fertilizer.” Because of the specialized equipment, chemicals, and procedures involved, your tree’s chlorosis problems can only be solved by a knowledgeable arborist.

healthy elm foliage
Foliage of healthy Silver Maple tree (Acer saccarinum), photo courtesy of NDSU

JTC has been conducting chlorosis experiments and research in conjunction with the City of Rapid City and the Rainbow Treecare Company from Minnesota. Over the past few years, the research has exhibited extremely positive results. JTC is at the forefront in rescuing Rapid City’s municipal and park trees from the slow death of iron chlorosis.

If you have a high-value or sentimental maple tree in your yard, and you wish to keep it alive and healthy, contact the arborists at JTC to keep it beautiful, alive, and wholesome for generations to come.

And, to learn even more about the signs of disease in your tree, visit the International Society of Arboriculture.