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Showing posts from July, 2011

Lilies - One of the Queens of the Garden

Karl Foord
Lilium 'Heart's Desire' Asiatic Lily. To see more photos, please view: Lilies Photo Essay.pdf.

Karl Foord, UMN Extension Educator

When entering the world of lilies for the first time, one is dazzled by the large spectacular flowers with variations in color, texture, size, fragrance, petal shape, and flower orientation. This variation is a function of: 1. species groups, such as Asiatic and Oriental designations, 2. single species, such as Lilium longiflorum (the Easter lily), and L. regale (the Trumpet lily), and 3. hybridizations between the above such as Oriental x Trumpet identified as Orienpet or OT hybrids, and Longiflorum x Asiatic identified as LA Hybrids (LA). Although this is still a simplification, it seems like a good place to start.

Cultivars derived from the latter crosses are selected for the best qualities of each species. The result is a hardier more garden persistent heat tolerant plant with sublime beauty. The lily collection at the Minneso…

Watch out for BOB (Bur Oak Blight)

J. Pokorny, MNDNR
Photo 1: Bur Oak Blight

Michelle Grabowski, UMN Extension Educator

In 2010 a new disease of Bur Oaks was identified in Minnesota. Bur Oak Blight, also known as BOB, is caused by a new, and yet unnamed species of the fungus Tubakia sp. It has been identified in Ramsey, Hennepin, Sherburne, Mille Lacs, Washington and Anoka counties in Minnesota. Gardeners should be on the look out for Bur oak trees with browning leaf veins and brown wedge shaped lesions on leaves. Symptoms typically appear in the lower canopy and progress upwards each year. Leaf blight symptoms generally appear in July and August. If you suspect a bur oak is infected with Bur Oak Blight call the Minnesota Department of Agriculture Arrest a Pest Hotline: 651-201-6684 (metro) or 1-800-545-6684 (Greater Minnesota).

More Information about Bur Oak Blight.

Flowers - Beautiful, Nutritious, & Dangerous

Karl Foord
Photo 1: Goldenrod Spider "Flower Spider" "Red-spotted Crab Spider Misumena vatia; Male on top of female who has Spring azure Blue Butterfly Celastrina sp. in grasp

Karl Foord, UMN Extension Educator

While photographing lilies for the article "Lilies - One of the Queens of the Garden," I came upon a blue butterfly (perhaps a Spring Azure Celastrina sp.). I was hoping to photograph it when it had opened its wings. I slowly drew closer only to realize that it was not to open its wings again. It was in the grasp of a flower spider (perhaps a Goldenrod Spider or "Red-spotted Crab Spider" Misumena vatia).

A smaller spider perhaps a male of the species jumped on top of the other spider and then fled. I would expect this was a wise thing to do. This spider was particularly well camouflaged on this Lilium 'Heart's Desire' Asiatic Lily. Flowers are beautiful, nutritious and dangerous, depending on your point of view.

Karl Foord

Calendar: August 1, 2011

Julie Weisenhorn
Big Sky series echinacea 'Sunset'

Constantly pick ripe and oversize produce from your gardens to minimize yellow jacket (wasp) activity and to encourage plants to remain productive as long as possible. Remove fallen fruit as well, before it begins to ferment. Yellow jackets usually aren't aggressive, provided you don't swat at them or disturb them. They're attracted to soda and other drinks, so be very careful when you drink from a can you've set down for a while.

Late August through early September is an ideal time to add flowering perennials to your garden, whether you buy them from the garden center or use divisions from your own or your neighbor's plants, Make sure there are still two or three weeks of decent growing conditions expected after planting. Mulch around the perennials, then cover the area with 4" to 6" of mulch later, when the soil freezes.

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

Contents: July 15, 2011

Julie Weisenhorn
Dahlia 'Japanese Bishop' at the Minnesota Landscape Arboretum.

In this issue of the Yard and Garden News:

New Turfgrass Herbicide Linked to Injury on Some Spruces, Pines and Other Landscape

Snapdragons for Your Cutting Garden
Construction of an Apple Tree
Fishing Spiders
Calendar: July 15, 2011

New Turfgrass Herbicide Linked to Injury on Some Spruces, Pines and Other Landscape Plants

Kathy Zuzek
Photo 1: White spruce symptoms being associated with Imprelis herbicide damage.

Bob Mugaas and Kathy Zuzek, UMN Extension Educators

Reports continue to be received regarding herbicide injury to white spruces, white pines and a variety of other woody and herbaceous landscape plants. The herbicide in question is Dupont's Imprelis, whose active ingredient is aminocyclopyrachlor. It belongs to a new class of broadleaf weed control herbicides which are similar, but not identical, to existing products such as triclopyr or fluroxypyr, both commonly used for control of more difficult lawn weeds such as clover and creeping Charlie.

Kathy Zuzek
Photo 2: White pine symptoms being associated with Imprelis herbicide damage.

Aminocyclopyrachlor is classified as a synthetic auxin or growth regulator type of herbicide. In susceptible plants, the herbicide produces characteristic twisting and curling of the foliage ultimately leading to plant death. Most of us have probably observ…

Snapdragons for Your Cutting Garden

Robin Trott
Photo 1: 'Madame Butterfly.'

Robin Trott, UMN Extension Educator

The hot humid days of summer have arrived, and with them, that childhood favorite, Antirrhinum majus, the ubiquitous snapdragon. Called a "calf's snout" for the flower's snout-like shape, the botanical name Antirrhinum is Greek for "like" and "nose." The specific epithet name majus means large. Hand a child one of these flowers, and the first thing they do is pinch the sides to move the petal "jaw". Not many flowers evoke such whimsical childhood memories like the snapdragon. These prolific annuals come in every color but blue, and start easily from seed.

Snapdragons are most productive in full sun (6-8 hours a day), but can tolerate some light shade. Plant in well drained soil, and amend sandy or heavy soils with organic material: compost or peat moss. The root system is shallow and fine, and can be easily damaged by cultivation. Surround plants with…

Construction of an Apple Tree

Karl Foord, UMN Extension Educator

Most apples trees today consist of an upper part, the scion, and a lower part, the rootstock, to which the scion has been grafted (Exhibit # 1). The scion produces the apples with which you are familiar such as Honeycrisp or Haralson. The rootstock confers a number of important traits on this 'compound' plant such as precocious flowering and size reduction. A tree on its own rootstock would produce a full sized 25' high tree and could take 6 to 7 years to flower. A dwarfing rootstock can reduce the size by 50% or more and reduce the time to flowering to 2 or 3 years. Size reduction makes more efficient use of space and facilitates numerous operations such as picking, pruning, and spraying. Rootstocks confer other traits on the plant such as disease resistance, stress tolerance, and ability to tolerate low


Thus apple breeding and improvement efforts must not only create and test scions for fruit quality and disease resista…

Fishing Spiders

Jeff Hahn
Photo 1: Typical fishing spider. Note its size.

Jeffrey Hahn, Assistant Extension Entomologist

Spiders have been very common in and around homes lately. One type that has been particularly conspicuous is fishing spiders. Fishing spiders belong to the family Pisauridae (which also includes nursery web spiders). They are the largest spiders in Minnesota with a body length up to one inch long. Including the legs, they can be as large as several inches across. They are sometimes confused with wolf spiders to which they are very similar in appearance.

Fishing spiders are generally brownish and can have stripes on the body and chevron markings on the abdomen. However, color is not a good method to identify fishing spiders. You can partly do it by size. Another way is to look at the eyes. Like other spiders, fishing spiders have eight eyes which are arranged in two rows of four. As you look straight at the face of a spider, the bottom row (called anterior eyes) is straight or…

Calendar: July 15, 2011

University of Minnesota Extension

What's wrong with my plant?" tool on UMN Extension Website

This time of year, a multitude of plant problems become very visible in gardens across Minnesota. Insects, diseases, wildlife, environmental and cultural problems can all cause garden plants to look less than their best. In order to determine the best management practices to bring plants back to healthy vigorous growth, gardeners need to know what's causing the problem in the first place.

The University of Minnesota Extension Horticulture team has developed a user friendly online diagnostic tool called 'What's wrong with my plant?' located on the Extension Garden page. Following simple steps, gardeners are able to narrow down the possible problems based on the symptoms they are seeing. Once the pest is identified, a link is provided to a publication describing the pest and management options.

Planning a trip to the Minnesota Landscape Arboretum? Check out the calendar …

Cool Wet Weather Results in Rotten Strawberries

Michelle Grabowski, UMN Extension Educator

M.Grabowski, UMN Extension Photo 1: Rotten strawberry with characteristic dusty gray spores of gray mold
As the new crop of strawberries is being harvested, many gardeners may be dismayed to see that their long awaited berries have spots of soft brown rot, often covered in dusty gray spores. The source of the problem is a common fungal pathogen known as Botrytis cinerea, or gray mold.

Gray mold is prevalent this year because of the cool wet weather in Minnesota during the days that the strawberry plants were flowering and growing green fruit. The gray mold fungus thrives in high humidity and temperatures between 59 - 71F. The longer the leaves of the plant stay wet, the more likely the fruit are to rot.

The gray mold fungus survives from year to year in old plant debris. Fungal spores form on old dead leaves and are blown onto the strawberry blossoms.

Gray mold reduces the strawberry crop in two ways. Often one or more flowers within a clust…

Asian Long-horned Beetle Found in Ohio

Jeffrey Hahn, Asst. Extension Entomologist

Kenneth R. Law, USDA APHIS PPQ
Asian long-horned beetle adult.

The Asian longhorned beetle (ALB), Anoplophora glabripennis, was recently found for the first time in Ohio, 30 miles southeast of Cincinnati. This exotic borer, originally from Asia from southern China, Korea, and Japan, was first found in North America in 1996 in New York. Two years later it was found in Chicago (but was eradicated there). Since then, it has also been discovered in New Jersey (2002), Toronto (2003), and Massachusetts (2008) before being found in Ohio.

This is a good reminder to be watching for ALB in Minnesota. Although it has not been discovered here yet, we have a lot of trees this borer loves to attack, including maple, American elm, and willow. It is important for people to be familiar with ALB so suspicious insects can be reported. In Ohio, a private citizen found insects in three maples that she thought could be ALB and reported it to entomologist at …

What's in a Cone?

Karl Foord
Photo 1: Korean Fir Abies koreana 'Horstmann's Silberlocke.' To view all photos, please open PDF.

Karl Foord, UMN Extension Educator

Cones are a big part of the ornamental appeal of evergreens. The cones provide spectacular colors, such as the iridescent cones of the Korean fir (Photo 1), and striking geometric patterns formed by the interlacing scales of red tamarack cones and light pink Acrocona spruce cones (Photos 2 and 3).

To view all photos in this article, please click here: Gymnosperms 7-1-11.pdf

Most but not all gymnosperms have male and female cones on the same tree (Photo 4). The male cones are short lived but the female cones persist for several years. The persistent female cones are the seed bearing structures of gymnosperm plants of which conifers are the most abundant. The word "gymnosperm" comes from the Greek meaning naked seed as opposed to other flowering plants termed angiosperms whose seeds are enclosed during pollination. Conifer …