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Showing posts from September, 2017

Maple tar spot strikes again

M. Grabowski, UMN Extension Educator

For the second summer in a row, tar spot, a fungal leaf spot disease is showing up in large numbers. Tar spot causes large black raised spots on leaves. Black spots are often shinny and look like wet tar. Although the symptoms of tar spot are most dramatic in the fall, the fungus actually infects the leaves early in spring when wet weather coincides with spore release. The fungus can only infect leaves, and will survive Minnesota’s winter in fallen leaves within leaf spots.

Tar spot is not a serious threat to the health of the tree. The leaf spots may cause leaves to drop a bit early but not early enough to do significant harm. Gardeners interested in reducing problems with tar spot in the following year should rake up leaves and place them in a back yard or municipal compost pile.

Prepare for boxelder bugs

Jeffrey Hahn, Extension Entomologist

Boxelder bugs are starting to congregate around the outside of buildings. Take action now if you wish to minimize problems with them later, especially if you have had a problem with them in the past. Although boxelder bugs are just a nuisance, they can potentially enter homes in large numbers. People can see them in their homes not only in the fall, but also during the winter and early spring.

It is not effective to spray the boxelder bugs found in the landscape. Adults have wings and can easily fly onto your property from adjacent areas. It is much more effective to take steps to help prevent boxelder bugs from entering a home to begin with.

There are two basic ways for dealing with boxelder bugs (and other insects, like lady beetles) that try come into your home seeking sheltered areas for the winter: sealing cracks and spaces and timely insecticide sprays. These are steps you can take yourself or hire a professional to do for you.

For m…

Plant hardy bulbs now for early spring pollinators

By Julie Weisenhorn, Extension Educator - Horticulture

Pollinators need pollen and nectar as early as April in some parts of Minnesota. Hardy spring-blooming bulbs such as scilla, allium, daffodil, fritillaria, and crocus provide this much needed early season nutrition. These bulbs require a cold period in order to flower successfully and therefore must be planted in fall (September - October) - in other words: right now!

Bulbs are relatively inexpensive and easy to plant. Bulbs may be purchased locally or ordered from suppliers either through a catalog or online. Most bulbs require warm, sunny locations. Tip: Sun-loving bulbs can be planted underneath deciduous shade trees because they will bloom before the tree leafs out.

Follow planting instructions on the bulb package for depth and site specifications. Make you mark your planting location with a plant label so you remember what you planted next spring. After planting, soak the soil with water. If conditions are dry (little rainf…

Japanese beetles: Aftermath

Jeffrey Hahn, Extension Entomologist

Now that we are safely past the bump in the road called Japanese beetles (JB), it is time to take stock in what happened this year, whether we should be doing anything now, and even what to expect for 2018. Clearly, 2017 was a year of above average numbers of JB. However, this is not the first time we had high numbers of JB in Minnesota and it is unlikely to be the last. So why did we have so many Japanese beetles this year?

Although it might appear that JB occur in cycles (like forest tent caterpillars), in fact their numbers are driven by weather. The most important factor influencing their abundance is a lack of soil moisture. JB eggs and newly emerged grubs are very susceptible to dry soils so during years when we experience drought we typically see relatively fewer JB.

This was true about three to five years ago when we had some very dry summers. However starting in about 2014/2015 we started receiving more normal rainfall and JB numb…

2017 Flowers for Pollinators: Which annuals attract pollinators?

By Julie Weisenhorn, Extension Educator - Horticulture



Planting for pollinator health is on just about every gardener’s mind these days.

While there is a lot of research on how native plants help pollinators, there’s not much on the interaction of pollinators and annual flowers. Many people want to do their part, but may only have space for annual plantings. There are conflicting references to the value of annual flowers as pollinator-friendly plants. Which annual flowers attract pollinators? We want to find out, so we designed this study to address how home gardeners might help reverse pollinator decline. Pollinators are attracted to such plant features as flower form, color, size, and pattern. We've been counting pollinators that visit selected varieties of annual flowers like Salvia, Zinnia, annual Rudbeckia, sunflowers, marigolds, cosmos, snapdragons, hyssop, etc. Read more: Flowers for Pollinators

Wonder how your own yard and garden measure up when it comes to pollina…

From our Turf Blog: Q&A on Fall Lawn Care

Fall is the best time to perform many of our lawn care tasks. Our cool season lawn grasses are
actively growing again after warm summer months, and people want to do want they can now to ensure we have a healthy start to our lawns next spring. Here's a helpful post from turfgrass extension educator Sam Bauer that addresses some current questions about fall lawn care: U of M Turf Blog

Ground beetles are only nuisances

Jeffrey Hahn, Extension Entomologist

Some residents have been finding ground beetles in their homes lately. Ground beetles are a common group of beetles that are usually medium sized and dark-colored. As their name suggests, they are typically found on the ground where they hunt other insects. Because of their predaceous activities, they are considered to be very beneficial.

Occasionally in August and September, ground beetles can be found entering homes. Fortunately they are harmless to people and do no damage to property. Some people mistake them for cockroaches which is an insect that can infest homes so it is important to correctly identify any insects that are found. Ground beetles are short-lived and do not reproduce indoors.

Tolerate ground beetles when found in homes as much as possible. The only necessary control is physical removal, especially when only a few are seen. An option for controlling ground beetles is the use of sticky traps. Set out the traps in are…

Late summer butterfly explosion

Elaine Evans, Extension Educator

If you have been spending time in your flower gardens recently, you may have noticed many brown and orange butterflies visiting plants to drink nectar. Adults of the Painted Lady butterfly, Vanessa cardui, are gathering at flowers in unusually large numbers to prepare themselves for migration down to the southwestern U.S. and northern Mexico. The Painted Lady butterfly is one of the most widely distributed of all butterfly species, but is not frequently seen in Minnesota most years. According to Chip Taylor, director of Monarch Watch at the University of Kansas, this is probably the largest migration he has seen in over 30 years (LJWorld.com September 8, 2017). These larger migrations often follow rainy periods in their wintering grounds.
You can help these butterflies on their journey south by making sure that you have flowers to provide them with the nectar they need to fuel their long journey and keeping these flowers free of pesticides. According to 

Late blight takes out tomatoes

M. Grabowski, UMN Extension Educator

After carefully cultivating tomato plants throughout the summer, many Minnesota gardeners have been shocked to see their plants devastated by blight and fruit rot in a matter of days. The culprit is late blight, a disease of potato and tomato plants. Late blight does not cause significant damage every year in Minnesota but prolonged cool wet weather this year has created ideal conditions for disease.
Late blight is cause by the pathogen Phytophthora infestans, a fungus like organism that thrives in wet conditions. The scientific name of the pathogen translates to ‘plant destroyer’ and the pathogen lives up to its name.  Late blight is the plant disease that ruined the potato crop in the infamous Irish potato famine of the 1840’s and the disease has been responsible for numerous epidemics since then.
How to identify late blight Leaves have large, dark brown blotches with a green gray edge.Stem infections are firm and dark brown.Disease progresses v…