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Showing posts from October, 2009

Field Guides Can Be Fun

Jeff Gillman, Nursery Management Specialist

Different people collect different things. Some like baseball cards, some like shoes, and some like coins. I like books about insects. No, really, I do. Just glancing up from my desk I can count something like 5 field guides, 10 general entomology texts, and a slew of others that fit into categories like insect control, insect taxonomy and insect physiology (I have a lot more at home). If you were to spend some time with these books you would discover rather quickly that, all in all, entomologists are boring writers. No zip, little spark. And that, in a nutshell, is why I like Jeff Hahn's new book Insects of the North Woods so much.

Photo and Cover: Insects of the North Woods, by Jeffrey Hahn. © Kollath-Stensaas Publishing.

Just looking at the cover of Insects of the North Woods you might be convinced that this is just a typical insect field guide. It's got some pretty pictures and, on the back, the obligatory author photo. But when …

What's Up With That?!

Birch Abnormal Growth Syndrome (BAGS) aka. Mouse Ear DisorderCarl Rosen, Extension Soil Scientist and Karl Foord, Extension Educator

The strange leaf symptoms on this river birch tree, taken on August 7 (Photo 1, left) were diagnosed as birch abnormal growth syndrome or BAGS. New leaves are severely stunted and take on a mouse ear appearance. For many years the cause of this disorder was a mystery, but it is now known to be due to a deficiency of nickel.

Photo 1 (left): River Birch 'Summer Cascade' at planting time showing symptoms of nickel deficiency (BAGS). Photo taken August 7, Karl Foord.

Nickel is an element only recently shown to be essential for plant growth and is required in very small amounts. Almost all soils have enough nickel to support plant growth, but under some conditions, nickel deficiency can still occur. The mouse ear symptoms on this river birch were first seen when growing in a peat-based container mix, and were initially misdiagnosed as bud damage fr…

Airborne Aphids

Jeffrey Hahn, Asst. Extension Entomologist

Many people in Minnesota, including the Twin Cities, that spent time outdoors during mid-September encountered large numbers of small dark-colored 'gnats'.  Upon closer examination, these insects turn out to be winged aphids (examples include soybean aphids, basswood aphids,and oat bird cherry aphids).  This has been a favorable summer for aphids and large numbers were produced.

Photo (left): 'Winged and wingless soybean aphids on
buckthorn in spring'.  Christina DiFonzo,
Michigan State University,

While the relatively cool summer had only a minor impact on the development and reproduction of aphids, these conditions had a more significant effect on aphids' natural enemies, such as lady beetles.  The cooler weather slowed down their rate of reproduction which ultimately allowed aphid numbers to thrive.

Aphids have a very unusual and complicated life cycle.  Many typically live on two different host plants.  T…

Lawn Care Tips for October

Bob Mugaas, University of Minnesota Extension Educator

1.Cease lawn mowing when temperatures are cool to cold and the grass shoot growth has essentially stopped. Reducing mowing heights to 2.0 - 2.5 inches for the last two or three lawn mowings of the season will reduce the amount of leaf tissue present over winter and can reduce the amount of snow mold that may occur. It is not necessary to collect clippings as long as they can filter down into the turfgrass canopy at the soil surface. Excessive amounts of grass clippings should not be left on the lawn surface in the fall or at any other time of the year.  Photo 1 (left). Lawn mowing should continue through the fall. Bob Mugaas.

2. A thin layer of leaves can be left on the lawn as long as they are ultimately chopped up as the lawn is mowed through the fall.

3. When confronted with several inches of leaves over the lawn, it is best to rake off the majority of those leaves before mowing and either compost them or use them as mulch ma…

Wealth of Education Found in the Display and Trial Garden

Emily Tepe, Research Fellow, Department of Horticultural Science

If you walk through the St. Paul campus Display and Trial Gardens these days you're bound to see a lot of activity. No, I'm not talking about bees on the flowers (although there were a lot of those with the unusual warm weather in September), I'm talking about students. With the start of the fall semester comes a plethora of courses on plant identification, propagation, diseases and insects. The Display and Trial gardens offer a convenient and valuable living laboratory for these courses. In fact, throughout the year (save for a couple of months in the depths of winter) these gardens offer education to many people in the University community and beyond.

Photo 1 (left): Edible landscape portion of the University of Minnesota Display and Trial gardens. Emily Tepe

An Inspiring Outdoor Classroom
The Display and Trial gardens are comprised of various areas between Alderman Hall (home of the Department of Horticultu…

Put Your Garden to Bed Without Plant Pathogens

Michelle Grabowski, University of Minnesota Extension Educator

As the Minnesota growing season is winding down and first frost is just around the corner, many gardeners are starting to prepare their landscapes for the long winter ahead. Plants are making physiological changes that will allow them to survive Minnesota's cold winter and so are the plant pathogens that have plagued the garden this year. Many plant pathogens overwinter in infected leaves and herbaceous stems that will soon fall to the ground and become part of the leaf litter. Other pathogens survive in live plant tissue like perennial crowns and tree branches. Reducing the number of pathogens that survive from one season to the next is a great way to reduce potential disease problems in the next growing season. Sanitation, the removal of infected plant parts, is an important part of disease prevention. Although sanitation will not prevent all future disease (pathogens can often move in from long distances away), it c…

Components of and Factors Influencing Fall Color

Karl Foord, University of Minnesota Extension Educator

The tree's response to the decreasing day lengths in the fall is to form an abscission layer at the base of each leaf. As this layer forms, it slowly cuts off water and mineral supplies to the leaf and reduces the manufacture of chlorophyll. As chlorophyll supplies decrease, previously masked carotenoid pigments in the leaf become visible. Carotenoid pigments are split into two classes based on oxygen content: xanthophylls and carotenes.   Xanthophylls, which contain oxygen, are yellow. Carotenes, which do not contain oxygen, are orange. Carotenoid pigments absorb light energy like chlorophyll and serve to protect chlorophyll molecules from photo damage. A carotene you may have heard of is β-carotene which is a precursor to vitamin A. In humans, vitamin A is a pigment essential for good vision.

Anthocyanin pigments are another important component of fall color, contributing reds and purples to the fall palate. These pigment…