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Gardening Information (www.extension.umn.edu/gardeninfo) is a one stop information hub for Minnesota gardeners. The multitude of resources on this site will answer your gardening questions and introduce you to new and creative ideas about caring for the plants in your life! What’s included?
Not only is the current Yard & Garden News prominently posted on the Gardening Information website, a searchable archive of the past 8 years of this publication is also available.
Find specific information for your flowers.
Diagnose problems, plants, and insects with the diagnostic tools.Find Information on:
Publications containing research based information are available on a wide variety of topics including Flowers, Fruits, Houseplants, Diseases, Insects, Landscaping, Lawns, Soils & Composting, Trees & Shrubs, Vegetables, Weeds, and Wildlife. These publications contain practical Minnesota based gardening information and are written by the University of Minnesota Extension faculty and staff.
Diagnostic Modules
One of the cornerstones of the Gardening Information web site are the Diagnostics galleries, What’s Wrong with my Plant?, What Insect Is This?, and Is This Plant a Weed? These are user-friendly pages to help gardeners, landscape workers, and others diagnose all types of garden and yard problems. Each site starts with a series of broad categories that get progressively more specific as you make decisions applicable to your case. The specific problems are well illustrated to help make identifications easier. Links to further information about biology and management of the pest are included.
Questions?
Still stuck? Some plant questions and problems require assistance from the professionals. On the Gardening Information website, you can find information about how to contact the Master Gardener volunteers in your county. These University trained garden enthusiasts are happy to provide you with all the information you need to keep your yard and garden beautiful. In addition you can post an online question at the nation wide ‘eXtension - Ask a Master Gardener’ site.
Get Involved
If you are interested in participating in a gardening workshop, shopping for plants at a Master Gardener run plant sale, or bringing a problem plant to a Master Gardener diagnostic clinic, check out the ‘Upcoming Workshops’ section at the bottom of the page. This section lists all of the University of Minnesota Extension sponsored classes and activities.
Quick U Links
The Gardening Information site will also connect you to many of the great University of Minnesota resources available to gardeners. Find out how to have your soil tested through the University of Minnesota Soil Testing Lab. Send a sample to the Plant Disease Diagnostic Clinic. Connect to the Minnesota Landscape Arboretum and other great Minnesota public gardens. Use the PlantInfo site to search for nurseries that carry a specific variety of plant.
Don’t ever guess at gardening again. Find out all you need to know at the University of Minnesota’s Gardening Information website!
Plants of ‘PJM’ rhododendron gracing the entrance of a home. David Zlesak
Flowers and foliage of ‘PJM’ rhododendron are richly colored. David Zlesak
'Olga Mezitt' Rhododendron. John Eustice
Shining in the landscapes of Minnesota and other Northern tiered states for decades, the glowing purple/pink blooms of ‘PJM’ Rhododendron are an easily recognizable and much welcomed addition to the spring landscape. Out of all the rhododendron choices for Minnesota, ‘PJM’ is arguably the most widespread, hardy, and adaptable. Due to minimal or no seed set, it tends to set abundant flower buds and blooms prolifically each year. It performs well in partial shade to full sun and has a wide tolerance to soil conditions, although, like most rhododendrons and azaleas, it prefers cool, acidic, well-draining, soils high in organic matter.
History of ‘PJM’
The name comes from the initials of Peter J. Mezitt, founder of Weston Nurseries in Massachusetts. ‘PJM’ is a cross between two rhododendron species- Rhododendron carolinianum and R. dauricum. In 1939, Peter Mezitt heard of some particularly beautiful specimens of R. dauricum in the mountains of China from some visiting missionaries. He arranged to receive some seedlings and among them was a particularly nice plant that was more faithfully evergreen than the others. Peter’s son Edmund worked at the nursery with his father. Using a camel’s hair brush, Edmund put pollen of the select R. dauricum seedling onto R. carolinianum (this was the first cross Edmund ever made). The seedlings were planted out and a few years later, in May of 1945, Peter and Edmund noticed their spectacular blooms, even as young plants. They knew from the beginning that these plants were very special because of their vigor, compact habit, attractive foliage, and beautiful floral display.
Multiple forms of ‘PJM’ Rhododendron exist
Since seedlings are relatively uniform from this cross, what is sold as ‘PJM’ is sometimes derived from recreating the original cross and raising seed. However, some variability exists among the seedlings for flower and foliage color, growth rate, and plant habit. Selections with unique features have been made and are clonally propagated. Some of the clonal selections include ‘Elite’ (little bit later flowering and more upright than typical ‘PJM’), ‘Victor’ (earlier flowering, more compact, and less vigorous than typical ‘PJM’), and ‘Regal’ (vigorous selection with a spreading habit).
Two other hardy cultivars of note from Weston Nurseries include ‘Olga Mezitt’ (sometimes called just ‘Olga’) and ‘Aglo’. They are similar in growth habit and hardiness to ‘PJM’, but the flower color is more pink. Both are named after Peter Mezitt’s wife, Olga. Both share the same species parents, but differ in the direction of the cross (which species served as the female and which as the male). Just as the cross is reversed to produce each cultivar, so is their cultivar name - ‘Aglo’ is Olga’s name spelled backwards.
Smooth crabgrass. Strand Memorial Herbarium
In Minnesota, both large and smooth crabgrass are the two crabgrass species that invade our lawns. Both species are annuals and grow most vigorously following germination in the late spring through mid summer. Since they are annuals they germinate and grow from seed each year. They produce many flowering stems from a single plant and consequently produce many seeds from each of those stems. The plants have no frost tolerance and are easily killed when the first fall frost arrives. Prior to being destroyed they will have produced thousands of seeds from each plant, which serves as a seed source for next year’s crabgrass crop.
Controlling crabgrass is usually best achieved with the use of a preemergence herbicide applied just prior to the crabgrass seeds germinating. In Minnesota, that usually means getting the product down early in May for the southern part of the state and late May in the north. With the cooler than normal conditions this spring, those timing dates should be still be O.K. It’s important to remember that preemergence products do not kill the weed seeds but rather the seedling plant as it germinates and emerges from the seed but before it has a chance to emerge from the soil and become visible. Always follow label directions on the products that you purchase for crabgrass control. Most often they will require you to apply about Ľ inch of water following application to ensure that you get the product down to the soil where it binds to soil particles and is ready to do its job. Also, applying these materials too early (e.g. early to mid April) often results in poor control as the herbicide’s effectiveness diminishes over time and may not be strong enough to kill those seedlings germinating later in June or early July.
Large crabgrass. Strand Memorial Herbarium
Sometimes it’s hard to get the time or opportunity to apply a preemergent herbicide before crabgrass seeds begin to germinate and start to emerge from the soil. Crabgrass seedlings are usually lighter green in color and have a rather wide, short first leaf. Thus, these seedlings can be fairly easy to spot as they emerge from the soil. At that point, while the crabgrass plants are very young, you can apply a postemergence weed killer and get very good results. The smaller the plant the more effective you will usually be. These materials are available at garden supply stores. Again, always follow label directions for their use. Once plants are fairly large and it’s late in the season, it is usually best to forego control at that time and wait until the following spring when a preemergent material can be applied.
If you would rather not use herbicides to control crabgrass, maintaining a vigorous, dense lawn minimizes any space in which crabgrass seeds can germinate and get established. Also, mowing at 2.5 to 3.0 inches will further restrict sunlight to the soil surface and that will also minimize germination of crabgrass seeds as they require light to germinate.
European pine sawfly. Jeff Hahn
A common sawfly on pines, especially mugo, is the European pine sawfly. It grows to about 3/4 inch long, has a dark head and a dark green body with grayish green stripes. European pine sawflies overwinter as eggs on needles that were laid the previous summer. In a normal year, they hatch from mid to late May, depending on where you live in Minnesota. Once they hatch, European pine sawflies feed gregariously, i.e. in non-social groups, on the old growth. They blend in well with the needles and are difficult to see.
Despite the presence of the sawflies, usually the first evidence you see is missing or partially eaten needles. Defoliation can vary from minor to severe (in severe cases essentially all of the needles can be consumed except the new growth). Pines usually survive feeding from European pine sawflies, especially if the damage is minor. However, when a large percentage of needles are chewed, it can impact the appearance of trees or shrubs (needles on stripped portions of the stem do not come back).
If you have pines, especially if you have had a history of European pine sawfly problems, check your trees or shrubs regularly starting in early to mid-May to detect them soon after they hatch and before they can cause too much damage. The biggest challenge is find these insects before they chew many needles. Remember that they feed gregariously so they can all be on just a single branch.
You have several options to deal with European pine sawflies once you find them. You can physically remove (most people use a rubber glove to do this). If you would like to use a low impact insecticide, try insecticidal soap. The spray must directly contact the insects and you may need to repeat the treatment because there isn’t any residual activity. Such sprays fortunately have little or no impact on other insects or animals. Another effective low impact product is spinosad. If you wish to use a product that has residual activity, there are many insecticides available including esfenvalerate, bifentrhin, and permethrin.
Indianmeal moth. Jeff Hahn
Many people have finding small moths flying in their homes lately, especially in their kitchens. These insects are Indianmeal moths and are pests in a wide variety of dried food products, including all types of processed cereal products (such as flour, cake mix, cereals, pastas, etc.), spices, chocolate, dry beans, popcorn, raisins and other dried fruit, nuts, and powdered milk. They can also be found in non-human food items, such as bird seed, dry pet food, grass seed, dry plant displays, and rodent baits.
Indianmeal moths are usually two colors- coppery brown on one half of the wings and a light gray color on the other half (closest to the head), making them easy to recognize. However, one has to be careful in identification since the scales can easily be rubbed off and make an Indianmeal moth look uniformly buff or cream color. The adult does not feed in the before mentioned foods, but rather the larva stage. Indianmeal moth caterpillars grow to about 1/2 inch long and are generally cream-colored. It is common for these caterpillars to web infested areas.
When you have an Indianmeal infestation, it is necessary to find the source(s) of the infestation. Check through your cupboards, closets, basements, and other places where you store susceptible products (don’t forget about bird seed and dry pet food). Not only look inside packages but check for any spills of foods. This can be challenging, but be persistent in your inspections.
Throw away the infested materials you find. You can save food (e.g. bird seed or dry pet food) by placing infested items into the freezer at 0°F for at least four days. Be sure to clean up any spills find you find. Stored uninfested dry food in heavy plastic or glass containers with tight lids to prevent insects from attacking it.
Insecticides are not effective. They have no effect on insects protected in food packaging. As long as a food is present, treating countertops, cupboards, or other places you might find the moths provides little benefit.
A select group of weed and feed type products produced by The Scott’s Miracle-Gro Company are being recalled due to invalid registration with the Environmental Protection Agency (EPA). Registration numbers were not granted on these products. These products have been pulled from retailers and the EPA has directed consumers to stop using them. The EPA and the Ohio Department of Agriculture are conducting laboratory tests on these unregistered products to determine what risks may be associated with them.
How will I know if I have a recalled Scott’s Miracle-Gro product?
On the product label, typically in small print, you will find the EPA Registration number. You will know if you have a recalled product if one of the following numbers are listed:
62355-4, 538-301, 538-299, or 538-304
These registration numbers can be found on such products as “Garden Weed Preventer + Plant Food”, “Miracle Grow Shake ‘n’ Feed All Purpose Plant Food Plus Weed Preventer”, and other Scott’s garden weed control and plant food products.
The Scott's Miracle-Gro Company is cooperating with the EPA and other state and federal regulatory agencies to resolve this issue. Company representatives have publically apologized for this incident and desire that consumers maintain trust in their company. They have announced that they have identified the employee responsible for the violation of federal pesticide registration and are taking action. If you have one of the recalled products they ask that you do not take it back to the retailer that you purchased it from. Instead, they ask that you call them at 888-295-0671 or visit their website at www.scotts.com to arrange for a special, prepaid box through UPS to be sent to you for the product to be returned to them. You will have your purchase price refunded and also be given coupons for Scott's Miracle-Gro products.
For the latest information regarding this recall, please consult the EPA website at: http://www.epa.gov/reg5rcra/ptb/news/.
What is an EPA registration number anyway?
Pesticides are registered with the EPA and the registration process is important to protect human health and the environment. Products meeting EPA standards are given an EPA registration number. This number is broken down into two or three parts to designate the company, particular product, and sometimes also the distributor of the product.
Even with a valid EPA registration number, the product must ALSO be registered for sale, distribution, and use in Minnesota for it to be used in Minnesota. Minnesota pesticide registration is handled by the Minnesota Department of Agriculture (MDA). Pesticides sold by Minnesota retailers are routinely checked to make sure that what is sold is registered for use in Minnesota. If there is a question about a particular product’s status in Minnesota, especially if you purchased it out of state (i.e. you facilitate distribution of the product into Minnesota and become a distributor), please check if the product is registered for use in Minnesota. This can be done by going to the Minnesota Department of Agriculture website- Registered Product Search page and entering the EPA registration number (http://www2.mda.state.mn.us/webapp/lis/productsdefault.jsp). The EPA registration number is also a valuable tool to look up more information about a product, especially in the case of a human health or other emergency.
At some point in caring for yards and landscape plantings, there usually comes a time when there is a need for weed control. While plucking a few weeds by hand is sometimes all that is needed, there are other times when the aid of a weed killer (herbicide) may be more practical and effective. However, going to a local retail outlet for those weed killers often confronts one with a staggering array of herbicide choices. Not only are there a lot of choices, the extremely fine print on most labels can make it very difficult to determine whether or not this is the right product for your weeds. Following is some practical information to help navigate the herbicide options.
The label on a herbicide container by law must provide the active ingredients and their concentrations (among other information). The active ingredients are usually listed by the chemical name derived from their chemical structure, (e.g., (±)-2-(4-chloro-2-methylphenoxy) propanoic acid). For most of us, the chemical name is of little help in knowing what is actually in the product. The common chemical name (e.g., dithiopyr) or an abbreviation (e.g., MCPP) is often listed below the active ingredient list, following the chemical name, or by itself. The common chemical name can be more helpful in knowing what’s in the product. The active ingredient is very important as we search for products that meet our needs. No matter what herbicide brands are being carried at our local garden center, if we know for instance that 2, 4-D is very effective at controlling dandelions in lawns, we can find products that contain it and are labeled for that weed and be confident we are getting what we need regardless of the brand name. Nonetheless, most of the time, people pay little attention to the active ingredients and depend on the label to tell them whether or not the weed in question is something the product will control AND how to use it in a manner that will kill the pest and avoid injury to other desirable plants, ourselves and the environment.
The remainder of this article will briefly discuss some of the old standby products as well as some of the newer items for weed control in home lawns and landscapes. Common chemical names (e.g., dithiopyr, balan, MCPA) will be used throughout the article. This article does not specifically include lawn fertilizer products that also contain an herbicide, often known as ‘weed-and-feed’ products. Nonetheless, the herbicides mentioned in the article are common to many of the weed-and-feed products. Check the ‘weed-and-feed’ product label to find out what herbicide(s) it contains. In addition, herbicides used for complete vegetation control with long residuals to keep areas clean of all vegetation during the year are not included. Materials not available for homeowner use but accessible to the commercial lawn care industry are also not included.
Following this article is list of the more commonly available lawn and landscape weed control products in the Twin Cities area. Not all of the materials would necessarily be offered at one retail outlet. Rather these are the more commonly available materials offered for sale by various garden centers and stores in the Twin Cities area. It is not intended to be a complete list of all products available by a particular manufacturer or that may be carried by any particular retail outlet.
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Back issues Yard & Garden Line News for the past nine years are online.
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Happy gardening!David C. Zlesak, Ph.D.
Editor
Extension Educator