ISSUE 7   June 21, 2007


Lyme disease is vectored by black-legged tick (Ixodes scapularis), also known as deer ticks (I. dammini) and has increased ten-fold since 1991 in Minnesota! Fortunately, the black-legged tick does not naturally occur in North Dakota, but may be brought in from neighboring states. Some of symptoms of Lyme disease include: fever, headache, fatigue, muscle and joint aches, swollen lymph nodes. About 70-80 percent of infected people develop a circular or bullís-eye skin rash. In North Dakota, there are about 14 species of ticks. If you suspect that you are bitten by a tick, it is very important to always get the tick properly identified by an expert.

Blacklegged tick
Blacklegged tick
(photo by J. Occi, BugPics,

Ticks go through one inactive stage (egg) and three active stages (larva, then nymph, and finally adult) in their life cycle. It takes about 1 to 2 years to complete and the tick must take a blood meal at each active stage. Germs including the bacterium that cause Lyme disease may be present in their saliva and are transmitted as they feed on the person or animal.

The best way to prevent tick infestations around the home is keeping lawns mowed (height of 3 inches or less) and remove high grass, weeds, leaf litter, and undergrowth near home. Property that border woodlots typically present the most risk, with tick numbers generally declining as you move farther from the woods. Ticks require high humidity to survive and do not do well on lawns or fields that are routinely exposed to direct sunlight. Wild animals (deer, birds, mice) and pets can transport ticks long distances and into your yard or home. Chemicals (pesticides) that kill ticks can be applied to your yard as a last resort if large numbers of ticks are present. The critical point is the timing of application to target early life stages (nymphal/larval ticks), usually early June. This can help reduce the number of ticks later in the season. Some of the pesticides that are effective for controlling ticks by homeowners are listed below:

Carbaryl (Sevin): A commonly used garden inseciticde. Available as a spray or granule for ticks on turf and recreational areas.

Cyfluthrin (Tempo, other brands): Labeled for tick control on turf and ornamentals.

Deltamethrin (Suspend, DeltaGard G): Available as a spray or granule. Labeled for tick control in residential areas when ticks may be found.

S-fenvalerate (Zema Lawn Spray): Labeled for tick control on turf and ornamentals.

Permethrin (PermaKill 4Week Tick Killer): It is labeled for use against ticks on the lawn. Permethrin is highly effective as a clothing toxicant against ticks as a tick repellent.

Liquid formulations of pesticides will kill nymphs in spring, larvae in summer, or adults in the fall. Where as granular formulations of pesticides are more effective on nymphs that are overwintering in the fall or larvae that are hatching from in the early summer.

Remember to practice personal protective measures as well. Wearing long sleeves and long pants to prevent ticks from reaching your skin. Tuck your shirt into your pants and your pant cuffs into your socks or boots. Use an insect repellent containing DEET on any exposed skin. Permethrin can be spray onto clothing. Finally, be sure to check your clothing and body carefully for ticks when youíve been outdoors.



Birch trees in North Dakota provide beautiful accents to home lawns and other settings, and when these trees are planted in well-chosen sites that closely resemble conditions that the trees are best adapted to, they can thrive for many years.

The NDSU Plant Diagnostic Lab has not received samples with definite bronze birch borer injury in at least three years (since Iíve been here), but this pest still remains a problem on birch in North Dakota. Preferred hosts include European white birch (thought to be the most susceptible of birch), water birch, yellow birch, and the paper birch. Some cultivars of paper birch are thought to be more tolerant or resistant to the bronze birch borer, but this belief is based on observational evidence over many years rather than on inoculated studies. Darker-barked birch are also thought to be more tolerant to the bronze birch borer.


Symptoms of infestation typically appear as top dieback or dieback of individually infested branches. The adult beetle itself is small (almost Ĺ inch) and narrow. The larvae damage the tree by feeding just under the bark. If the feeding girdles a branch or trunk, the tree above that point wilts quickly and dies. If infestation by bronze birch borer is suspected, look carefully for D-shaped exit holes and raised ridges (tunnels calloused over with tree tissue), which are often associated with damage. Heavy, continued infestations can lead to tree death when the main trunk becomes girdled by larval feeding.

Keep Birch Trees Healthy and Free from Stress

One of the best defenses against the bronze birch borer is to keep birch trees healthy and free from stress. Since borer beetles typically are more attracted to stressed trees, planting trees in appropriate sites (to minimize stress) is the best management strategy available. A healthy tree can also better withstand an infestation.

Paper birch, a North Dakota native species, is best adapted to sites with shaded, moist soils and wih soil pH 5.0-7.5. These trees are sensitive to drought stress, so supplemental water is recommended during dry periods. Fertilizer applications are also recommended, and a well-balanced lawn fertilizer with a slow-release formulation of nitrogen, applied at the normal rate for lawns, may be sufficient.

Other Managment Strategies

Symptomatic limbs should be pruned out and destroyed when trees are still dormant. Suppression (rather than complete control) of infestation may be achieved with protectant insecticides, but these must be applied annually, with the first application occurring before eggs are laid. Multiple applications of protectant-type insecticides may be needed in a given year, and thorough coverage of the bark and crevices must be achieved to maximize efficacy. Efficacy of another type of insecticides, known as systemic insecticides (such as imidaclopryd), has not been clearly demonstrated. Systemic insecticides are thought to suppress the pest and so may be helpful, particularly for very young trees.

Links to websites listed below offer more information on bronze birch borer and birch species for North Dakota.  (Click on N.D. Tree Handbook in the submenu)  



Periodic reports of the NDSU Plant Diagnostic Lab are available at the following website:

Kasia Kinzer
NDSU Plant Diagnostic Lab
Telephone: 701-231-7854

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