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Thursday, December 1, 2016

Weeds in the Turf Lawn: Invasive Nuisances or Sources of Forage?

By James Wolfin, Graduate Research Assistant

The turf lawn accounts for nearly 2% of the continental United States land cover, and has become engrained in the architecture of many United States neighborhoods and landscapes.  As urban and suburban areas continue to expand, we can expect this number to increase as many yards, store fronts, and commercial buildings are installed to accompany properties.

While the planting of turf lawns alongside most properties is a standard practice, the management practices and personal perceptions of those managing lawns are variable.  Lawns differ in the level of input that is imparted by the landowner.  Input generally refers to the effort that is directed towards maintaining the aesthetics of the lawn, normally in the form of mowing, watering, weeding, and fertilizing.  While each of these practices are generally required to ensure proper turf health, how frequently inputs are applied can vary greatly.  Practicing responsible lawn maintenance practices may be obvious in certain situations.  For example, mowing too frequently can be hazardous due to the fossil fuel emissions let off from a motorized lawn mower and excessive watering or fertilizing can cause harm in the form of runoff, leading to algal blooms in bodies of water.  What may be less obvious are the impacts of weed management practices.  Many land managers differ in the way they perceive weeds, which can have a great impact on the biodiversity that is supported by a lawn.

A weed is generally considered a plant that is undesirable in a lawn for any reason, often due to aesthetics.  Many land managers place a premium on maintaining a uniform, green turf, and believe weeds are a disruption or a nuisance.  What may go unnoticed, however, is the benefit that weedy flowers can have in terms of supporting biodiversity, especially for pollinators.  Weedy flowers often produce nectar and pollen which are collected by pollinators, including honey bees and wild (native) bees.  These floral rewards are essential to the diet of bees, as nectar serves as the main source of carbohydrates in a bee’s diet, while pollen serves as the main source of protein.  While it is impossible to discuss every weedy flower that may exist in a lawn, specific flowers that are popular in lawns or are especially beneficial to pollinators are important to consider.

White CloverWhite Clover
White clover (Trifolium repens) is one of the most common lawn weeds that land managers may encounter.  White clover is often indicative of soils that have low fertility or a situation where lawns are mowed to a very low height.  This plant spreads through a stoloniferous growth habit, where lateral stems grow at or just above the soil surface.   White clover is easily recognizable due to its distinctive leaves, which appear in the form of a three-leaf trifoliate.  Once established in a lawn, white clover will bloom from mid-spring through the fall, generally peaking in May and June.  The blooms of white clover appear in the form of a white flower head that is attractive to a great diversity of bees.   The medium sized blooms provide an adequate landing pad for larger bees, including bumble bees and honey bees, but are also visited by smaller bees.  White clover is a significant source of both nectar and pollen for bees, making it a great addition to a home lawn or garden in terms of supporting biodiversity.  White clover can also benefit overall lawn health due to its ability to fix and add nitrogen to the soil, supporting healthy plant growth.  White clover will bloom at low heights, which will allow a landowner to maintain a normal lawn height (~3.0”) while still supporting bees.

Self-healself-heal
Self-heal (Prunella vulgaris) is a forb from the mint family, Lamiaceae, that receives its name from its history in folk medicine.  A sub-species of this flower, Prunella vulgaris ssp. Lanceolata, is native to Minnesota, making self-heal a useful addition for landowners that want to attract native pollinators.  This flower will grow in home lawns, especially moist areas that receive partial shade.  The central stem of a self-heal flower is distinctive due to its spiked, hairy vegetation that stands upright.  The striking flowers have a violet color and a whorled bloom, giving a tubular shape to the flower.  The tubular shape of self-heal flowers make the nectaries difficult to reach for short-tongued bees.  As a result, self-heal is most frequently visited by long tongued bees, like bumble bees and honey bees (tongue size is strongly correlated with body size).  Self-heal is able to withstand regular mowing, blooming at heights as low as two inches.

Creeping thyme
Creeping thyme (Thymus serpyllum) is another flower from the mint family (Lamiaceae) that is most commonly found in sandy soil areas, but has the ability to establish in a variety of habitats.  Creeping thyme grows by spreading lateral stems in the form of above ground stems (stolons) or below ground stems (rhizomes).  Closely related to the culinary species of thyme, Thymus vulgaris, this species also retains a strong, herbal scent.  The leaves of this plant grow low to the ground in opposite pairs, with flowers that will bloom at heights as low as one inch.  The flowers are pink-purple in color, and form small, open blooms.  The size of these blooms makes the rewards accessible to smaller bees, like mining bees, but may also be visited by honey bees.  In addition to supporting bees, this plant also serves as important habitat for butterflies.  Two species of butterflies, the small blue butterfly and the large blue butterfly, will lay eggs on the vegetation of creeping thyme.  Their larvae will then feed on the leaves before maturing into adult butterflies.  Creeping thyme is also useful as a border plant for gardens, as it acts as a natural deer deterrent.  

DandelionDandelion
Dandelion (Taraxacum officinale) is a common perennial lawn weed not only throughout the Unites states, where it is present in every state, but globally.  Dandelion is native to Europe and Asia, but is now present on all continents except Antarctica.  This herbaceous forb is able to establish in a wide variety of conditions and will bloom in full sun, part sun, or full shade.  Dandelion is found frequently in disturbed soils, especially those that are high in potassium content.  The leaves of dandelion vary in size based on the age of the plant, but are easily recognized by their unique, lobed shape.  Dandelion has conspicuous yellow flower heads, containing many individual ray flowers.  This species spreads easily once established in the soil due to dandelion’s prolific seed production and the ability of these seeds to be distributed widely by the wind.  Dandelion does not require pollination and is able to reproduce via apomixes, a form of asexual reproduction in plants.  Despite this, dandelion still produces nutritious pollen that is moderately high in crude protein content.  Although it is often considered a nuisance in residential and recreational lawns, a wide range of insects use dandelion as a source of forage, including many types of bees.  Honey bees, bumble bees, and a variety of solitary bee species will use this plant as a source of both nectar and pollen.  Dandelion can survive and bloom despite mowing at low heights, making it an ideal candidate for a bee-friendly lawn.

Creeping CharlieCreeping Charlie
Creeping Charlie (Glechoma hederacea, aka ground ivy) is an aggressive lawn weed species that is found in every state in the United States, except for certain parts of the Southwest (NV, AZ, NM).  This plant is considered an invasive species in some habitats, and tends to thrive in disturbed sites that are shady and poorly drained.  Once established in a soil, creeping Charlie will spread quickly through aggressive stolons, forming mats that provide dense ground cover.  The flowers of creeping Charlie are easily recognizable, with small, purple, tubular flowers arising from upright, square stems.  Creeping Charlie has been the subject of heavy debate as to whether or not it should be used as a forage source for bees and other pollinators.  While it has many desirable qualities, including ease of establishment and a low-growing nature, recent research suggests that creeping Charlie is not an ideal forage source due to its unique pattern of nectar production.  Creeping Charlie exhibits wide ranges in both the quantity of nectar that it produces, and in the quality of the nectar (sugar concentration).  While some flowers of creeping Charlie will produce great amounts of nectar high in sugar concentration, the average flower from this plant produces less than half the nectar quantity seen in comparable flowers like white clover.  On average, nectar from creeping Charlie is higher in sugar concentration than that of white clover; however the range in sugar concentration is much more extreme.  Because of this, creeping Charlie is considered an inconsistent source of nectar for visiting pollinators, and should be omitted for more reliable alternatives like dandelion and white clover. 

Thursday, November 10, 2016

Preparing your trees for winter

By Gary Wyatt, Extension Educator - Agroforestry and Bioenergy
From http://www.myminnesotawoods.umn.edu


It may not seem like it with the unseasonably warm temperatures we’ve been experiencing this fall,
but winter is on its way. Are your trees and perennials prepared for the changes ahead?
Perennial shrubs and trees, especially conifers, should be watered generously until the soil freezes. Mulching trees will help reduce winter root damage.

Young maples and thin barked trees may benefit from some kind of sunscald protection to prevent the bark from cracking this winter and spring. This protection is usually in the form of a plastic tube or tree wrap which is removed in spring. These practices can also help in reducing winter animal damage. Read more ....



Thursday, October 27, 2016

What to do about fruit flies

Jeffrey Hahn, Extension Entomologist

Fruit flies, Drosophila spp., can be a common insect in homes during fall. Also called vinegar or pomace flies, they are small, about 1/8th inch long with a brownish body and a dark colored abdomen. Fruit flies typically have red eyes which are a good feature to help distinguish them
Fruit flies are about 1/8th inch long and usually have red eyes.
Photo: Jeff Hahn, U of M Extension
between other indoors flies (however this color fades once the flies are dead).

Be careful as there are other small-sized flies, such as fungus gnats, moth flies, and humpbacked flies, that could be confused with fruit flies. There is even a couple of species of fruit flies with dark colored eyes that are a little larger than an average fruit fly. The control varies depending on what the type of fly is found so it is important to verify the insect you are finding in your home.

Fruit flies are associated with fermenting, moist, relatively undisturbed organic material. This is often due to overripe and decaying fruits and vegetables but can also be in a variety of other sources, such as soft drink, wine, and beer residue in unclean containers (and have been sitting around for a while) and trash containers with wet garbage that are not cleaned regularly.

These flies can also be found in unusual, unexpected sites. In one case they were found infesting an osage orange that had been set out to control spiders (which by the way does not work) and forgotten about. As it became soft and started to decay, it attracted fruit flies which infested it.

The best control of these flies is to find the source of the infestation and remove it. While this is straight forward, it can be easier said than done. You often have to be a detective to locate the problem as it may not be immediately obvious what they are infesting. Particularly examine areas where fruit flies are found but keep in mind that the infestation source may not always be near where fruit flies are found; it could even be in a different room. Keep inspecting after you find the breeding site as there may be more than one infestation source.

It may be tempting to kill the adults by spraying, swatting or trapping them but this rarely eliminates them. As long as a food sources remains, fruit flies can reproduce faster than you kill the adults. It is very difficult, if not impossible, to get ahead of the problem and eliminate all of the flies by directing control at the adults.

Friday, October 14, 2016

2017 Minnesota Gardening Calendar available

2017 Minnesota Gardening Calendar
30 pages of tips, photos, guidelines for MN gardeners
The 2017 Minnesota Gardening Calendar is a great resource for the gardeners in your life! It is a terrific holiday gift, housewarming gift (especially new homeowners who have never owned a yard), host gift, or just a thanks-for-watching-my-plants gift. Whatever your reason, this is the time to get your copies. Buy online or in person from selected University of Minnesota bookstores and the Minnesota Landscape Arboretum giftshop. Written by Extension Horticulturists. the 2017 Minnesota Gardening Calendar features monthly lawn care and gardening. Featured writer and turf extension Educator Sam Bauer contributes an informative article called Water Saving Strategies for Home Lawns and provides guidance on reducing our water use without sacrificing a great looking lawn. And then there are the photos! Each month features a timely photo that reminds us Minnesota landscapes are beautiful at any time of the year!
Timely photos each month
Timely gardening tips each month

Articles by Extension experts
Important guides for successful gardens


There's still time for dormant seeding - a good option for good lawn next spring

“I know I missed the best time for seeding my lawn which is mid-August to mid-September. Can I still seed even though it’s October and temperatures have been mild?” According to turfgrass Extension educator, Sam Bauer, “Just wait, dormant seeding in November will be your best option." True temperatures are warm during the month of October, and a homeowner could get some seed germination before winter snows, but this is touch-and-go. Bauer recommends saving your time and money and wait dormant seed in mid- to end-November. Read more.

Thursday, September 29, 2016

Temperature Control in a Bumble Bee Nest

Karl Foord - Extension Educator, Horticulture

The previous post linked to a video showing a new born bumble bee. The following video is of the same nest but involves a different observation.

To view and photograph the nest I had to pull away the straw covering the nest. This exposed the nest to the direct sun and evidently increased the temperature of the nest beyond the acceptable range of the worker bees. In this video a worker bumble bee uses her wings to fan and cool the nest. The wings are moving so fast that they practically disappear, a little like airplane propellers.

To give a sense of perspective, the engine on a propeller driven airplane rotates some 43 times in one second. I timed the wing speed of bumble bees in one of my videos to 172 beats per second. No wonder the wings are impossible to see when filmed at regular speed. In the second half of the video I have slowed the speed of the action by a factor of 4 and it is still difficult to see the wings moving. You can see the wings just when they begin to move and when they stop moving. Enjoy the blur as another one of the fascinating things one can find in the garden.

Observe a Newborn Bumble Bee

Karl Foord Extension Educator, Horticulture

Some of the folks maintaining the Display Garden located on the St. Paul Campus discovered a Two Spotted Bumble Bee nest (Bombus bimaculatus). On June 5th I found the nest with the help of Julie Weisenhorn and took some video.

This is a young nest and relatively early in the season, so the worker bumble bees are significantly smaller than the Queen. This bee is identified in the video.

In addition a new born bumble bee appears from under the top end of the nest. This individual can be recognized by the white hair covering its body. Later the hair in some places will turn golden and in other places black. Other evidence that this is a new born come from the shape of its wings. Notice that the wings on this bee are flat and curve around the base of the abdomen. The bee will proceed to pump hemolymph (the fluid of their circulatory system) into the veins of the wings. This will will expand and straighten the wings after which they will dry and become hardened. Only after this will the wings become functional and enable the bee to fly.
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