Lawns, Gardens & Trees

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Lawns, Gardens & Trees

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Fireblight

A common disease of crabapples and other species. Learn about the cause and the multiple control methods.

Fireblight is a common disease of many Rose-family species in North Dakota.  The list of hosts includes apples, crabapples, hawthorn, mountain-ash, cotoneaster, pear and others.  Fireblight is caused by a bacteria that enters the tree via succulent tissue or through fresh wounds.  The recent storms that have been rolling through our region have resulted in perfect conditions for this disease to flourish.

The most common symptoms (see below) are dead branch tips with leaves still attached, curved over at the tip into a ‘shepherd’s crook’.  There is usually a sharp dividing line between living and dead tissue, and in some cases a sunken canker will be found here.  The bacteria can be found even further into the living tissue which is very important when treating the problem.

fireblight, crabapple, Valley City

A heavy infection of fireblight on a crabapple in Valley City, ND.

Dormant-season pruning is the best option for treating fireblight.  Locate the dividing line between living and dead tissue, and go back at least 8-12” into the healthy wood before pruning at a branch connection.  If there are just a few dead branch tips, they can be pruned out during the growing season but it is critical to sterilize the pruning tool between cuts to minimize the potential for spreading the bacteria to new wounds.  Pine Sol® or a 20% bleach solution can be used as sterilizing agents.  Both are corrosive to metal, so rinse and oil pruning tools when finished.  Chemical treatments in the spring can help prevent the disease from establishing, and copper-based fungicides as well as streptomycin are labeled for this purpose.  Follow all label directions and treatment recommendations.

fireblight, canker, margin, crabapple, Valley City

Canker margin on fireblight; living tissue is on the left and dead tissue is on the right.  Pruning should be at least 8-12" into living wood and should occur at a branch connection.

One additional way to prevent fireblight is plant resistant varieties of the host species.  Fireblight ratings of several edible apple varities can be found at: https://www.ag.ndsu.edu/pubs/plantsci/hortcrop/h327.pdf.  More information on the basics of tree pruning is available at:

https://www.ag.ndsu.edu/publications/landing-pages/gardens-lawns-trees/pruning-trees-and-shrubs-h1036

-Joe Zeleznik

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Spring Fever Gardening Workshops Set

Spring Fever Garden ForumsIf you want to learn about selecting trees or growing a productive garden, the North Dakota State University Extension Service's Spring Fever Garden Forums can help.

NDSU Extension is offering the series of workshops for gardeners across the state Monday and Tuesday nights, March 23, 24, 30 and 31, from 6:30 to 8:30 p.m. Central.

A team of 12 university experts will present information on timely topics in gardening and landscaping and then answer your questions.

Topics also include landscaping with flowers, pruning shrubs, attracting pollinators, growing fruits and herbs, and protecting plants from diseases.

The presentations will be made to a live audience in Fargo and delivered to more than 40 Extension sites across the state. Gardeners may attend at these sites or go online and participate in the live presentations on their home computer.

"More than 1,000 gardeners will participate in this mega-event," states Tom Kalb, Extension horticulturist. "It is a great opportunity to learn of gardening trends and see the latest research from NDSU."

The workshops are free of charge. For a full list of presentations and to register, go to http://www.ag.ndsu.edu/springfever.

Written by Tom Kalb, Extension Horticulturist. Edited by Ellen Crawford, Information Specialist.

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Gift ideas for gardeners

These gifts will bring happiness to your friends and family.

'Appleblossom' amaryllisThe holidays are here and so are the busiest shopping days of the year! Gardening is America’s #1 hobby and you can bring happiness to others by giving gardening presents. 

Amaryllis is a great holiday gift. It is showy and one of the easiest plants to grow. A quality bulb company can offer extra large bulbs that will bloom this year and in future years too. Always remember: the bigger the bulb, the better.

The following is a brief description of more gift ideas:

Lightweight gardening hoses are getting popular. Good pruning tools are always appreciated. A pocket knife is a handy gift. Solar-powered gardening pots are popular—they glow at night!

A new shovel, spading fork or hoe will be appreciated by a true gardener. A garden cart can help your friend move plants and tools around their yard.

Nitrile garden gloves are very popular. Hand scrubbing lotions will clean and moisturize our hands (the most important gardening tools). 

We all need to eat more veggies. A juicing machine can help us to get all the servings we need for a healthy diet. A dehydrator can convert our garden produce into nutritious snacks.

Thermometers, soil thermometers and rain gauges provide valuable information to a gardener.

Gnomes and other garden statuary are risky gifts, but sometimes these gifts bring the biggest smiles!

When all else fails, a gift certificate to a local garden center or a gardening catalog will put a smile on your friend’s face.

Happy holidays!

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. This article is an excerpt of a story published in the NDSU Yard & Garden Report, November 15, 2014. The photo was made available under a Creative Commons license specified by the photographer: Liz West.

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Sparkling jewels

Crabapple fruits add sparkling color to the winter landscape.

Red crabapple fruit in winterCrabapple trees have dropped their leaves and most have dropped their fruit, too. This litter creates a mess. That’s unfortunate. These fruitless trees will look unremarkable all winter long. That’s really unfortunate.

Why not select a variety with persistent fruit? Some crabs hold onto their fruits through much of the winter, adding sparkles of red and gold in the landscape. These fruits will also attract songbirds, adding another dimension of life and color to your home surroundings.

Red Jewel™ is renowned for its display of bright red fruits during winter. ‘Donald Wyman’, Sugar Tyme®, ’Prairfire’ and Sargent are other outstanding red-fruited types.

If you are looking for something different, ‘Snowdrift’ and ‘Professor Sprenger’ have orange fruits and the yellow fruits of Harvest Gold® are absolutely fascinating.

The next time you look for a crab, don’t focus on its spring flowers—these last for a couple weeks. Instead, consider how the tree looks during winter—this lasts for five months. Consider a crabapple with persistent fruit.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, November 15, 2014. The photo was made available under a Creative Commons license specified by the photographer: Leah Grunzke.

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Know your manure

Know where your manure comes from and avoid contaminating your garden with herbicide.

Horse with manure in pastureMany gardeners add manure to their gardens in fall. Please be sure you know where your manure comes from. Some farmers spray their pastures with pyridine herbicides to control broadleaf weeds. These herbicides include Crossbow, Curtail, Forefront, Grazon, Milestone, Redeem and Surmount.

Manure from livestock feeding on pyridine-treated hay or pasture grass should not be used in gardens. The chemical passes through the animal without decomposing. When gardeners use this manure, they are literally adding a persistent herbicide to their soil. The hearts and hopes of many of the best gardeners in our state have been broken. 

Tomatoes, potatoes, peas and beans are extremely sensitive. Affected plants will stretch and curl, similar to damage caused by dandelion killers that drift onto plants. Pyridine can persist in manure for a few years—be very careful!

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, October 15, 2014. The photo was made available under a Creative Commons license specified by the photographer: Malene Thyssen.

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Preparing trees for winter checklist

A great summary of the steps needed to minimize winter injury to trees and decrease disease pressure, ensuring a great start to next year's growing season.

The following article was written by Aaron Bergdahl, Forest Health Specialist with the NDSU/North Dakota Forest Service.  It first appeared in the NDSU Extension Crop and Pest Report, September 12, 2013.

White ash - NDSU 2013

With the coming of fall it is important to remember to prepare your trees for the tough North Dakota winter. The following checklist serves as a reminder of the most important considerations for fall tree care and proper tree winterization.

  • Water trees weekly in late fall until freeze-up. Two gallons per inch of stem diameter is recommended, if the soil is dry at a depth of six inches. This will help minimize winter injury.
  • Rake up and remove/destroy fallen leaves. This is the best thing you can do to reduce the amount of fungal leaf disease next year because many fungal leaf diseases overwinter on leaf litter.
  • Prune dead wood to decrease overwintering sites for tree diseases and insect pests.
  • Wait until the tree is dormant (at least November) to prune living branches, always using proper technique.
  • Wrap the lower main stem of trees that have not developed thick bark to protect them from sunscald and rodent feeding damage.
  • Wrap burlap around smaller, high-value (landscape) conifers or set up a burlap sun/wind shield to help minimize the chances of winter burn.
  • Throughout winter, use caution when applying deicing products near trees and shrubs. Salts and other chemicals contained in some products may cause harm.

By completing this checklist you will be doing your part to maximize the chances that your trees will make it through the winter in good health and will be ready for a productive growing season.

For more information, please contact: Aaron Bergdahl, Forest Health Specialist, NDSU/North Dakota Forest Service. aaron.d.bergdahl@ndsu.edu (701) 231-5138

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Frosted apples

Apples will freeze at approximately 28°F. Use frosted apples quickly.

Frosted applesVery cold temperatures will sweep across the state tonight. Most apple cultivars freeze at approximately 28°F but can tolerate temperatures down to 25°F before suffering major damage.

If apples freeze on the tree, wait until they thaw before picking. Frozen fruits will bruise easily.

Frozen apples are edible, but will not store long. Eat or process the fruit quickly.  

Harvested apples should be kept cool (32–40°F is ideal). For small amounts, keep in perforated plastic bags in the refrigerator. For large amounts, the fruits can be stored in cardboard boxes.

Written by Tom Kalb, Extension Horticulturist. Photo was made available under a Creative Commons license specified by the photographer: Fredrik Alpstedt.

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Time to plant garlic

Plant garlic now and enjoy some amazing meals next summer!

Garlic clovesMost gardens in North Dakota have been struck by frost. The natural tendency for gardeners may be to slow down, but there is still some great gardening weather ahead of us!

Think about growing garlic. It can add amazing flavors to your meals next summer.

Garlic types include hardneck, softneck and elephant. Hardneck types are hardiest and most suitable for us in North Dakota.

Get your cloves from a local garden center or an online seed company. There are robust varieties from all over the world, including Europe, the Middle East and Asia. The bulbs come in an attractive array of colors from pearl white to royal purple.

Garlic scapesGarlic grows best in a rich, well-drained soil. Add an inch of compost to the site and up to 3 pounds of 10-10-10 per 100 square feet. Work this into the soil.

Separate cloves from the bulbs a day before planting. Set cloves upright in the furrow, 4–6 inches apart and 2 inches deep. Space rows 18–30 inches apart.

Water deeply to activate the bulbs. The bulbs will push out roots and underground shoots this fall. Mulch with 4 inches of straw in November. This straw will insulate the soil and protect the sprouted bulbs.

The flower buds, called scapes, can be harvested in June (see bottom photo). They are mild in flavor and great in stir fries.

Harvest the bulbs in July. Then get ready for some of the most delicious meals you have ever eaten!

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photos were made available under Creative Commons licenses specified by the photographers: Felix and danbruell.

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Kill weeds now; feed lawn later

This is a great time to kill weeds but a bad time to feed the lawn.

Field bindweed in lawnNow is the best time of year to kill broadleaf weeds in lawns. This includes dandelions, thistles, clovers, black medic and field bindweed (shown). As days get shorter, these perennial weeds begin channeling their nutrients down into their roots to prepare for winter. This is great, because a herbicide sprayed on a weed at this time will be channeled down into the weed’s root system, killing the entire plant.

The most effective products include a combination of herbicides. Trimec formulations will include a combination of 2,4-D, mecoprop and dicamba. Dicamba is especially powerful, but the chemical can build up in the soil and damage trees, shrubs and perennials. Limit yourself to one application of dicamba per year; and now is the best time for it.

Now is not a good time to feed your lawn. The grass plants want to prepare themselves for winter. A fertilizer application now prevents this by promoting blade growth and delaying hardening. This makes the lawn more susceptible to winter injury.

It is better to wait until mid to late October to feed the lawn. This is after the grass blades stop growing and after you have stopped mowing. This application in October is the single most valuable time to fertilize the lawn—any lawn.

You will not see any immediate effects of this dormant application, but the fertilizer will develop a stronger root system this fall and generate new buds for blade growth next spring. Turf roots grow until the ground freezes in mid November.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. The photo was made available under a Creative Commons license specified by the photographer: Colin Jacobs.

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Normal fall needle drop in conifers

Conifers - pines, spruces and others - sometimes lose older needles during the fall. This is normal, and does not indicate a pest problem.

During autumn, deciduous trees like green ash and linden change color and lose their leaves. This is normal and expected. It happens every year and people are used to it. When evergreen needles turn brown and die, it’s definitely unexpected, but not necessarily abnormal. 

There are several species of evergreens or conifers that grow in North Dakota. Pines and spruces are most common. Pines have relatively long needles (two to nine inches), which are held in clusters called fascicles. These needles live for two to seven years and then die and drop during the fall. These are the older needles toward the center of the tree. Needles that are going to drop start turning yellow as early as late August. By mid-September these needles turn brown and begin falling from the tree.

Another common group of conifers are the spruces such as Colorado blue spruce and Black Hills spruce. These trees have shorter needles, about three-quarter to an inch long, and are attached to the stem individually, not in bundles. Spruce needles usually live longer than pine needles and may persist for up to 10 years. Just like pines, those spruce needles which are older and more shaded, will turn color and drop during autumn. In the photo, the ponderosa pine (background) is showing normal fall coloration, while the Colorado blue spruce (foreground) is not shedding any of its needles.

Ponderosa pine tree (background) that is showing normal fall needle drop.  Colorado blue spruce (foreground) is not shedding needles in this photo.

Some needle drop by conifers during the fall is normal. The exception occurs with larch trees (also called tamarack). Larch trees lose all of their needles every year because they are deciduous evergreens. Larch needles are one to two inches long and borne in clusters on short shoots or individually on long shoots. The needles are also very soft. Some larch trees are native to the swamps and bogs of northern Minnesota. A common larch that has been widely planted in North Dakota is the Siberian larch. Larch needles turn bright yellow and provide a golden rain during autumn.

Evergreen needles don’t last forever. Some needle loss toward the center of the tree during autumn is normal. Needle loss at other times of the year is not normal and may be due to an insect or fungal pest or the result of severe environmental stress. Larch trees, the exception to the rule, lose all of their needles every year. Enjoy the colors this fall.

-Joe Zeleznik

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