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Showing posts from July, 2010

Contents: August 1, 2010

Imidacloprid, Found in Most Homeowner Insecticides, is Translocated to Nectar and Pollen and Kills Good Bugs

Dr. Vera Krischik, Department of Entomology, University of Minnesota

Native plants used in restoration for wildlife and food plants from apples to zucchini require pollinators. Bees and other beneficial insects offer valuable ecosystem services in both natural and managed agriculture ecosystems, so it is essential to protect them. Pollinators and beneficial insects are experiencing serious decline due to insecticide use, lack of nutritionally rich native plants for pollen and nectar, and lack of habitat. Continued loss of pollinators will have an impact on the natural resources and the economy. This issue has been addressed by the Xerces Society, National Research Council Report, the Congressional Research Report, testimony by the National Academy of Sciences to the US Congress, and the media in newspapers and television programs.

Systemic neonicotinyl insecticides used on landscape plants and crops are considered as a major factor in pollinator decline. After the 1998 ban in France o…

Rose Classes and their Performance in Minnesota: Part 2

Kathy Zuzek, UMN Extension Educator

Old Garden Roses

The earliest rose classes fall within a group of roses called the Old Garden Roses. These are the classes that were in existence before 1867 when the first Hybrid Tea was developed. The earliest classes in chronological order are the Gallicas, Damasks, Albas, Centifolias, and Mosses. These five classes were all in existence before 1800 and share some common traits. With few exceptions, they bloom only in spring on previous year's canes. In contrast to the Hybrid Teas, these roses are valued for their mature flowers rather than their buds. Buds are often round or globular and open to produce blooms that are cupped, domed, or are shallow saucers. Oftentimes small inner petals are enclosed within larger outer petals; sometimes petals are produced in a quartered arrangement. Colors among these 5 classes are restricted to pink, white, mauve, maroon, or purple.

Gallicas are the oldest class of Old Garden Roses and are known for …

Home Lawn and Landscape Turfgrass Fertilizer Recommendations Being Revised to be More Environmentally Sensitive

Bob Mugaas, UMN Extension Educator; Dr. Brian Horgan, Associate Professor and Extension Turfgrass Specialist; and Dr. Carl Rosen, Professor and Extension Soil Scientist.

New research results from the University of Minnesota and the University of Wisconsin-Madison necessitate updating our current lawn/turfgrass fertilizer recommendations. For the past 20 to 30 years, one of the more important fertilizer application times was considered to be the end of October and into early November in the Twin Cities and southern Minnesota. Indeed, lawns respond positively with good green color and active growth significantly earlier the following spring when given about 1# of N per 1000 square feet late in the previous growing season. This application came to be known as a late fall or more accurately a late season fertilization. In most years, this typically coincided with about the last mowing of year and with hoses put away or irrigation systems winterized for the year.
Even though this resea…

Canna Yellow Streak Virus

Michelle Grabowski, UMN Extension Educator

Cannas are popular tropical plants that can be easily grown in Minnesota if rhizomes are brought indoors and protected from frost each year. In addition to a variety of flower colors, cannas also differ in leaf color. Leaves that are green to greenish blue, reddish purple, bronze, or variegated with white to yellow stripes can all be found in different varieties of canna. It is important to know what color leaves a particular variety should have however, because a very common virus can cause leaf streaking that many gardeners mistake for variegation.

Canna Yellow Streak Virus (CaYSV) causes yellow to brown streaks along leaf veins of infected plants. Severely infected plants may have poor growth and reduced or no flowers.

Although many viruses are transmitted from plant to plant by an insect vector, there is no known vector for CaYSV other than humans. Cannas are propagated by splitting the rhizome of one plant, and growing the pieces into ma…

Field Ants in Home Lawns

Jeffrey Hahn, Asst. UMN Extension Entomologist

Some people are finding field ants nesting in their lawns. Field ants are about 1/4 inch long and black (some species are red and black). Their nests are slightly raised and mound-like and can cover a fairly large area in the ground, up to two feet in diameter. It is not uncommon for people to confuse field ants with carpenter ants. Although these two ants are somewhat similar in size and color, carpenter ants do not nest in the soil. The prefer to nest in cavities in rotting wood or in voids found in buildings. Field ants are most active during the day while carpenter ants are most active at dusk, dawn, and during the night. Because of the mounds created by field ants, some people assume these ants are fire ants. Fire ants are about 1/8th inch long or a little larger. They only occur in the southeastern area of the U.S.; the closest fire ants to Minnesota are in southern Tennessee. Minnesota winters are too cold for fire ants t…

Garden Calendar: August 1, 2010

Warm wet weather is favoring the growth of many fungal and bacterial leaf spot diseases in the flower garden. To identify which disease or pest problem you are seeing, visit 'What's wrong with my plant?'

For more information about managing leaf spot diseases, read 'Seeing Spots'in the June 1, 2009 Yard and Garden News.

Yard and Garden News Editor: Karl Foord
Technical Editor: Bridget Barton


Jeffrey Hahn, UMN Extension Entomologist

The rainy weather that much of Minnesota has experienced this year has lead to increased numbers of springtails in and around homes and other buildings. Springtails are very small, between 1/16th - 1/8th inch long. They are usually slender, elongate insects (there is a group of springtails that is round and stout) with moderate length antennae. Most springtails are dark-colored, brown, grey or black although some species are also white, and some are even iridescent and brightly colored
Springtails are wingless and do not fly but they can jump. Unlike grasshoppers, crickets, and other insects that use large back legs for jumping, a springtail uses a forked appendage called a furcula (located underneath the abdomen) to propel itself. When not in use, a furcula is tucked up under the body, set like a mouse trap. When it is released, it extends down rapidly sending the springtail forward. A springtail can jump many times its body length.


Leaf Spots are Sprouting in the Vegetable Garden

Michelle Grabowski, UMN Extension Educator

This summer early warm weather and frequent rain alternating with sunny days have created conditions allowing vegetable gardens to flourish. Many gardeners are amazed at the size of their tomato and corn plants. Recently, however, gardeners have been noticing yellowing and spotting of their prized plants, especially on the lower leaves. This discoloration is caused by several different fungal and bacterial leaf spot pathogens. Unfortunately warm wet weather also favors growth of these pathogens.
Leaf spot fungi and bacteria come into the garden on infected seed or transplants or are blown in on the wind. Many of these pathogens can survive from one season to the next on infected plant debris. Splashing rain carries fungal spores and bacteria from the soil and plant debris onto this year's leaves. Moisture in the plant canopy then allows these pathogens to start new infections. Established leaf spots create a whole new generation of bacte…

Rose Classes and Their Performance in Minnesota: Part 1

Kathy Zuzek, UMN Extension Educator

The number of rose cultivars in the world defies logic. If you open a copy of Modern Roses 12, the most recent edition of the American Rose Society's rose cultivar list, you will find thousands of rose cultivars or varieties listed along with each rose's class, year of release, the breeder who developed the cultivar, parentage, and descriptions of each cultivar's floral and foliage traits, plant habit and thorns.

Before cultivar selection and development, there were only the species or "wild" roses. There are 120 or more rose species in the world and they are found in the temperate and sub-tropical regions of the Northern Hemisphere: the Middle East, Oriental Asia, Europe, and America. The oldest species have single flowers with only 5 or occasionally 4 petals and bloom only once each year in spring. As mutations occurred in some rose species over the course of time, stamens or the pollen producing part of the plant were replac…

Tasty Tomatoes in Containers

Karl Foord, UMN Extension Educator

There is little doubt that one of the best taste treats in a Minnesota Summer is a vine ripe tomato. In this case I am referring to a vine that you grew and a tomato that you picked when you decided it was ripe. In addition the distance it had to travel to your kitchen is measured in feet not thousands of miles. As an aside where did tomatoes come from in the first place?

Photo 1: Tumbler. Karl Foord.Tomatoes were first domesticated by early Indian civilizations of Mexico. Cultivars were taken to Europe in the mid 1500's and then back to North America by colonists in the early 1700's. Tomatoes were slow to catch on because of their similarity to the poisonous belladonna of the nightshade family. The appeal for tomatoes took hold in the middle of the 19th century. In 1863 there were 23 known cultivars whereas in 1883 there were several hundred cultivars. Presently there are around 7,500 cultivars with a great variety of fruit sizes shap…

Garden Calendar: July 16, 2010

Photo 1: Apple Maggot Traps Karl Foord.
Apple maggot flies are out there! See what I caught in my traps. Note the small plastic bag containing a pheromone to attract the flies.

Correction from July 1 edition of Y&G News. Past editor and Rose expert David Zlesak noted an error in last editions rose pictures. The Frau D.H. rose that is labeled at the Arboretum in the main garden is incorrect. There was one there, but a sucker from a neighboring rose snuck in and people pruned the true Frau out accidentally. See attached picture for correct flower.

Time to renovate strawberries!

We are still in the picking season for summer raspberries.

Wondering what those spots are on your rose? Black spot is common this time of year but so are several other leaf spot diseases. Check out "What's Wrong with my Plant?"

Photo 2: Frau DagmarKarl Foord.

Yard and Garden News Editor: Karl Foord
Technical Editor: Bridget Barton

The Japanese Beetles Are Coming

Jeffrey Hahn, UMN Extension Entomologist
Actually they are already here as their presence was reported on June 21 (in the Twin Cities area). Japanese beetles are typically first active in the Twin Cities the first week of July but the early spring allowed them to emerge sooner than normal. These beetles are broadly oval and about 3/8th inch long with a bright emerald green head and prothorax (the area directly behind the head) and shiny bronze colored wing covers. An important distinguishing feature are the five small white tufts of hair along each side of the abdomen and two larger white tufts on the tip of the abdomen.
Japanese beetle adults feed on over 300 different plants, commonly eating the foliage of rose, grape, linden, birch, crab apple, cherry, birch, Norway maple, mountain ash, and willow. They skeletonize the foliage, eating the leaf tissue between the veins. They particularly like to feed on plants in sunny areas and typically will start eating leaves at the top of plant…

The Top 14 Best Roses for Minnesota

Karl Foord and Kathy Zuzek, UMN Extension Educators

I photographed the rose collection at the Arboretum last week and tried to make sense of the many rose classifications and the varieties within each classification. Twenty three classes are evaluated in the publication Roses for the North(1). The British Association of Rose Breeders (BARB) has identified 30 rose classes, and the American Rose Society has identified 56. Regardless of which system you choose, the situation is complicated. Being faced with this situation, I consulted our rose expert Kathy Zuzek, who is the lead author of the Roses for the North publication. We decided to address the issue with two articles. The first would suggest the best rose cultivars for Minnesota based on Kathy's twenty plus years of experience. The second would be an historical article describing why there are so many categories, what each looks like, and how that category performs in Minnesota. The second article will appear in the Jul…

Bacterial Blight Blacken Lilac Shoots

Michelle Grabowski, UMN Extension Educator

Photo 1: Bacterial leaf spot of lilac Photo by M.Grabowski UMN Extension. Recent wet weather has favored the growth of a bacterial pathogen of lilac called, Pseudomonas syringae pv. syringae. This bacterial pathogen can infect shoots, young twigs, leaves and occasionally flowers. Dark brown to black spots can be seen on infected leaves. The spots are often surrounded by a pale yellow halo. With age, the center of the leaf spot often falls out, resulting in a shot hole appearance to the leaves. Often several spots grow together into large irregular black blotches on the leaves. Even more dramatic is infection of shoots and young stems. Sunken black lesions can be seen on green stems. If the infection encircles the stem, all of the leaves beyond the infection, turn black and wither. This often results in 6-8 inches of blackened withered leaves.

Photo 2: Bacterial shoot blight of lilac Photo by M.Grabowski UMN Extension.
Although most gardeners…