Lawns, Gardens & Trees


Lawns, Gardens & Trees

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Worm-free Apples

How to trap apple maggot flies

Apple maggot
Apple maggots create tunnels in fruits. Traps may be used to monitor for the presence of the egg-laying flies.
Nobody likes wormy apples … but nobody enjoys spraying pesticides. What’s the solution?

Spray only when needed.

The apple maggot is the #1 pest of apples in North Dakota. The egg-laying flies begin attacking our fruits in early July. Now is the time to set up traps to monitor for the flies.

Apple maggot traps are available at major garden centers and online. These plastic spheres are coated with the sticky substance Tanglefoot and hung in trees. The flies are attracted to the red spheres and will get stuck when they land on them.

You can make your own 3-inch-diameter spheres out of wood and hang them using an eye screw and wire hook. Another option is to use bright red apples, skewer them with a thick wire (or coat hanger) and hang them up. Coat them with Tanglefoot.

Small trees need a couple traps and full-sized trees can use five traps. Hang them on outer branches, placing at least one on the south side and on branches facing brushy areas.

Check every week. If you don’t see any flies, you don’t need to spray.

If you do see flies, you have a choice to make: Spray to protect your fruits or get ready to make a lot of maggot-rich applesauce this fall.

Written by , Extension Horticulturist, North Dakota State University.

Source: University of Minnesota. Apple maggot. apple-pest-management/maggot/. Photos were made available under Creative Commons licenses specified by the photographers: E.H. Glass, New York State Agricultural Experiment Station,; Cornell University, jentsch/scouting-reports/.

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Tough Tree Gains Popularity

Japanese tree lilac has become one of the most popular trees in North Dakota.

Japanese tree lilac
Figs. 1–3. Japanese tree lilac is becoming one of the most popular trees in North Dakota. The trouble-free tree blooms in June and features glistening copper bark. ‘Golden Eclipse’ has variegated foliage in spring.
The Japanese tree lilac (Syringa reticulata) is one of the toughest and most trouble-free trees for landscapes. It offers year-round beauty with its showy blooms, emerald leaves and glossy bark.

Japanese tree lilac is hardy throughout the state and adapts well to our soils. It is one of the finest trees to grow along boulevards. The rounded canopy grows 25 feet tall and fits neatly under power lines.

When the spring blooms of crabapples and lilacs have faded, the Japanese tree lilac takes center stage with its late display of cream-colored flowers. The fragrance of the flowers is not very pleasing; but not stinky either. Some gardeners feel the flowers smell like privet. Less critical gardeners say the blooms smell like vanilla.

The glossy copper bark is a great feature that provides winter interest.

‘Ivory Silk’ has been the top variety since its introduction from Ontario in 1973. It is a sturdy tree with deep green leaves. It blooms at a young age and is known for its heavy set of blooms. First Editions Snowdance™ has similar features (Fig. 1), and it has sterile flowers that won’t create messy seedheads.

‘Golden Eclipse’ offers variegated foliage in spring, making this remarkable tree even more special. Its variegation fades over summer.


Written by , Extension Horticulturist, North Dakota State University. Photos were made available under Creative Commons licenses specified by the photographers: Bailey Nurseries, Inc.; Minnesota Tree Resources; and Mark Dwyer.

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Super Summer Lawns

Tips on caring for your lawn in summer.

Lawns require irrigation to stay green in summer.
Lawns in North Dakota hate the heat. The grass turns yellow and goes dormant as temperatures rise. 

It’s okay to let your lawn go dormant—it’s natural. But if you don’t like looking at golden grass, let’s talk about summer lawn care:

Water deeply. It’s better to give your lawn a big gulp of water rather than a series of sips. That’s because roots grow where the water is. If you give the lawn a big gulp and water deeply, you will develop a deep root system. On the other hand, if you only sprinkle the surface of the soil, you will create a shallow root system.

Lawns need about 1.0 to 1.5 inches of water per week, either from you or rainfall. If you have a clay soil, irrigate only once or twice a week. Sandy soils can’t hold a full inch of water. These soils should receive about 0.5 inch of water two or three times per week when needed.

Watering in the early morning is best. The grass plants are active and will absorb the water they need. Any extra water will evaporate, keeping the grass blades dry and preventing diseases. Watering during the middle of the day is not recommended since much of the water you apply will evaporate before the plants absorb it. Watering is the early evening is not recommended since the lawn will stay wet all night, leading to diseases.

Mow your turf tall—the taller the better. A tall turf will shade the soil, keeping it cool. A taller turf naturally develops a deeper root system, protecting your lawn against drought damage. The first lawns in the neighborhood that turn yellow are lawns that are mowed short.

Your grass will be healthier and less thirsty if you let your grass clippings fall to the ground. These clippings will shade the soil surface, keeping it cool.

Avoid using weed killers on your lawn in the summer. You will have better success at killing weeds in September. Herbicides add extra stress to lawns, which are already under stress from the heat. There is also the risk of the herbicide drifting into your garden, causing these plants to curl and/or die.

Don’t be too worried about grubs or other insects. Less than 5% of our lawns need treatments for insect pests. Before treating, make sure you actually have a problem.

Grubs are the most common pest. Dig a couple inches deep along the edges of emerging brown spots. The grubs, which are creamy white in color and the size of your pinkie finger, will be munching on the grass roots. A few grubs are normal; treatments are not recommended until you find three or more grubs per square foot.

Don’t burn the lawn with fertilizer. Heat-stressed lawns do not need fertilizer, but a light fertilization might be necessary if you irrigate all summer. Use about one-half the suggested rate. Organic fertilizers are especially useful in summer since they are less likely to burn the grass.

Whether or not you actively take care of your lawn in summer, expect the lawn to wake up when temperatures cool off. Autumn is the best time to reseed, kill weeds, fertilize and aerate the lawn.

Written by , Extension Horticulturist, North Dakota State University.  

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Memorial Day: A Great Time to Fertilize Your Lawn

Fertilize your lawn around Memorial Day to support its growth and reduce the stresses of summer.

Healthy lawn
Healthy lawn.
Did you fertilize your lawn yet? Don’t feel bad if you didn’t. The best time to feed your lawn in spring is near Memorial Day, not earlier.

The key to a thick, healthy turf is a strong root system. When your turf wakes up after winter, it naturally wants to develop roots and build up its energy reserves. If you fertilize early in spring, your lawn will skip this phase and immediately go to producing more grass blades.

Lawns fertilized early in spring may appear to be robust since they are mowed more often, but the individual grass plants are drawing from their limited energy reserves. This makes the lawn more susceptible to stress from diseases and summer heat.

Its better to wait until Memorial Day. Let your turf focus on root growth in early spring. Once temps warm up in mid-May, the plants will naturally change its focus to blade growth. A fertilization around Memorial Day will support this growth, maintain food reserves in the plants, and prepare the turf for the stresses of summer.

A few other quick points:

  • Use a lawn fertilizer that contains some slow-release nitrogen. Examples include isobutylidene diurea (IBDU), polymer-coated urea, sulfur-coated urea and organic sources. This will gradually feed the lawn for several weeks.
  • Irrigate your lawn after fertilizing. This increases the effectiveness of the fertilizer and prevents fertilizer from running off the surface after a thunderstorm.
  • Apply the fertilizer in two directions (for example, north/south and then east/west). This will give you more uniform coverage and prevent striping.
  • Lawns are generally fertilized at the rate of 1.0 pounds of actual nitrogen per 1000 square feet. Shady areas grow slower and require less fertilizer.
  • Follow the instructions on the bag.

Source: Rose, C.J., B.P. Horgan and R.J. Mugaas. Fertilizing lawns. University of Minnesota. Accessed online on May 25, 2018.

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Emerald Ash Borer - Treatments

Treatments for EAB are available, but aren’t recommended for North Dakota at this time because the insect has not been found in our state.

Since EAB was discovered in the U.S., researchers have focused much of their efforts towards finding effective control treatments.  Experimental results are variable – some treatments are highly effective, but others are less so.  The latest research results can be found in the 2nd edition of ‘Insecticide Options for Protecting Ash Trees from Emerald Ash Borer’, which came out in 2014: summary is listed below. Note that new research results are coming out all the time, so recommendations may change is the future. As always, follow all pesticide label directions carefully.  

Spray-type treatments with traditional broad-spectrum insecticides have been the least effective at controlling EAB. Quite simply, EAB adults can be active through most of the summer, and the insecticides didn’t last long enough to provide enough control. Additionally, obtaining a thorough spray coverage is very difficult, especially with larger trees.

Tree injection system
Tree injection system.
Systemic chemicals, those that move within the tree, have proven more effective. Those with the active ingredients ‘imidacloprid’ and ‘dinotefuran’ have been researched extensively and are available in multiple formulations. Some formulations can be applied as a soil drench, a soil injection, a granular product applied to the soil surface, a bark-penetrating spray, or a stem injection (professionals only). These chemicals move through the tree to the tissues that EAB feed on. Control is not 100%, but these pesticides do a very good job of reducing the number of EAB larvae feeding beneath the bark.

The most effective insecticide treatment by far has been stem injections with the active ingredient ‘emamectin benzoate’. Test results have shown that this product provides better than 99% control of EAB larvae – and that level of protection lasts for at least two years. Many communities in the Midwest have found that a combination of insecticide treatments, along with timely removal of low-value trees, is incredibly useful in managing the ash trees in their urban forests.

Additional information about EAB is available from the ND Department of Agriculture at:  For more information about tree pests such as Dutch elm disease, gypsy moth, and others, please visit the ND Invasives website at:

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Emerald Ash Borer - Diversity/Replacement Trees

When we speak about financial investments, we often hear the recommendation to “diversify, diversify, diversify!” The same is easily said of the investment in our green infrastructure – the trees found in yards and communities.

Diverse tree planting
Diverse tree planting.
Many years ago, American elm was the most common tree species planted in urban areas of the Great Plains. In some areas, it was the only tree species. Then, Dutch elm disease came and wiped out the tree canopy. People searched for a new species to replace the elms, and they came up with green ash – a tall, fast-growing tree that is tough enough to handle the urban environment. Again, people relied on a single tree species and green ash was overplanted. With the approach of emerald ash borer, the importance of diversity in tree plantings cannot be overstated.

Many species of tall deciduous trees are available for conservation plantings as well as in urban areas. (Some, such as cottonwood or boxelder are probably better suited to conservation plantings.) The ND Tree Selector ( is an online tool that helps users choose tree and shrub species based on a variety of characteristics. Are you looking for something that is fast growing? Or a tree that is long-lived? Perhaps a species with pretty flowers?  The ND Tree Selector can help you find species to consider for your next planting.

And don’t forget to visit with your local professionals – city foresters, nursery owners and many others who have been planting trees for years can make recommendations about which species will do well – and those that won’t! 

Additional information about EAB is available from the ND Department of Agriculture at:  For more information about tree pests such as Dutch elm disease, gypsy moth, and others, please visit the ND Invasives website at:

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Emerald Ash Borer - Value/Cost

The economic impact of emerald ash borer is staggering. The city of Bismarck estimates that the removal of ash trees on their boulevards will cost over $5 million.

EAB-infested trees
Trees infested with emerald ash borer
The financial impact of EAB is incredible. Direct costs include tree removals (don’t forget stump grinding) and planting replacement trees. For those people who want to save specific ash trees, stem injections with the chemical ‘emamectin benzoate’ have been extremely effective – but they’re definitely not free. Indirect costs are also large – losing a prime shade tree can result in an increase in electric bills by more than 25%. That loss of shade has also resulted in an increase in water bills, as exposed lawns have needed additional irrigation. Property values have decreased in some communities as the overall tree cover has declined. One study even found an increase in heart and respiratory diseases in those areas that have been hardest-hit by EAB.

Many North Dakota communities’ urban forests are comprised of more than 50% ash trees. In one study of four North Dakota small towns, the cost of removal-and-replacement was estimated from $22,000 to more than $163,000; that study was completed 5 years ago and costs increase every year. Insecticide injections provide an alternative to removals-and-replacements, and may be a cost-effective option for managing the urban forest. The EAB Cost Calculator from Purdue University allows users to compare the costs of different management alternatives:

Technical and financial assistance for developing community-level management plans is available from the ND Forest Service. Contact Gerri Makay at 701-652-2951 or for more information. 

Additional information about EAB is available from the ND Department of Agriculture at:  For more information about tree pests such as Dutch elm disease, gypsy moth, and others, please visit the ND Invasives website at:

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Emerald Ash Borer - Firewood

On its own, EAB travels about ½ mile per year. With human help, it travels 55 miles per hour or even more! Please, don’t move firewood.

Campground managers, foresters and many others are encouraging their clients “Don’t move firewood” this summer and throughout the year. Movement of infested firewood has been one of the main methods of long-distance dispersal of emerald ash borer (EAB). The legal regulations regarding firewood movement can be rather confusing, with some examples listed below. In order to avoid the hassle, simply “Buy it where you burn it.”

  • A federal quarantine is in place around all of the known EAB-infested areas of the U.S.  Moving firewood and other ash products out of the quarantine area is illegal unless very specific, highly detailed rules are followed.
  • ND Forest Service – prohibits out-of-state firewood at their campgrounds, but they will provide a free bundle of firewood for each paid campsite.  Additional firewood is available for $3.00 per bundle.
  • US Army Corps of Engineers – at campgrounds in North Dakota, firewood must originate within 100 miles of the campground, unless it has been officially certified as pest-free.
  • MN Department of Natural Resources – in Minnesota, regulations were amended in December 2017 regarding firewood use on DNR lands including state parks:



Firewood Alert - flier developed by ND Forest Service.  Urging all campers and others, "Don't move firewood", and "Burn it where you buy it."



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Emerald Ash Borer - Signs/Symptoms

How do you determine if EAB is attacking your ash tree? Learn the signs and symptoms of Emerald Ash Borer

EAB galleries
Emerald ash borer galleries.
The signs and symptoms of EAB are varied: dieback of the branches in the crown, new branches sprouting from the stem, D-shaped exit holes from the adult insects.  And eah one of these can be caused by something other than EAB.  Correct diagnosis and confirmation of the true cause of problems in ash trees is difficult but it’s critically important – treating for the wrong problem is a waste of time and money.  At the other extreme, missing an opportunity to treat a problem is equally as bad.  The first step in determining if EAB is killing a tree is to confirm that it is actually an ash –  For more information on the actual signs and symptoms of EAB, go to:

EAB is tricky to diagnose for those who are not been trained.  If you think that your ash tree has Emerald ash borer, please contact one of the following people.

Lezlee Johnson, ND Forest Service –, 701-231-5138

Joe Zeleznik, NDSU Extension Service –, 701-231-8143

Charles Elhard, ND Department of Agriculture –, 701-239-7295

Additional information about EAB is available from the ND Department of Agriculture at:  For more information about tree pests such as Dutch elm disease, gypsy moth, and others, please visit the ND Invasives website at:

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Emerald Ash Borer - Summary/Reiteration

Thanks to everyone who contacted us this week and participated in EAB Awareness Week. Our main messages remain the same – let’s keep our guard up and continue to search for EAB. For firewood, the message is “Buy it where you burn it”. And let’s continue to diversify our tree plantings, both in our communities as well as in our windbreaks and shelterbelts.


Additional information about EAB is available from the ND Department of Agriculture at:  For more information about tree pests such as Dutch elm disease, gypsy moth, and others, please visit the ND Invasives website at:

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