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What to Do about Pot-Bound Plants

By Jeff Gillman, Associate Professor - Department of Horticultural Science

So you've just bought a pot-bound plant and you don't know what to do? Gary Johnson, Chad Giblin and I have been testing various techniques to get trees out of their pot-bound states for the last 8 years or so, and here are some of the things that we've found.

The number one problem with planting a pot-bound tree is that they are usually planted too deeply. Trees in containers often have three inches between their uppermost roots and the soil line -- or even more! When a tree like this is transplanted into a landscape without having its planting height adjusted, the roots circling near the top of the container will eventually press up against the stem of the tree and strangle it to death (photo 1).



Jeff Gillman
Photo 1: Pot bound plant's root system 5 years after planting; tree was planted too deep based on media level in pot


When planting a container grown tree make sure that the first large…

What is the true cost of planting a tree too deep?

Karl Foord, UMN Extension Educator


Karl Foord
Photo 1: Encircling root has significantly stunted this tree.
If you purchased a tree and planted it at the soil line as it was in the pot, it is likely that this tree was planted too deep - with drastic consequences. Research conducted by Gary Johnson, Jeff Gillman, and Chad Giblin has shown that trees planted too deeply tend to generate roots that can strangle the plant. Dr. Jeff Gillman explains more of the science in the following article; however in this article I want to address what I believe is the true cost of making such an error.


Karl Foord
I have two 'Autumn Blaze' maple trees that were planted approximately 10 years ago. Several years ago I checked the planting depth of the trees and discovered that one had been planted too deep (tree 1). Tree 1 had several encircling roots that severely impacted its growth (Photo 1). Tree 2 had a few encircling roots that I caught before much damage was done (Photo 2). What is the…

Bur Oak Blight

Michelle Grabowski, UMN Extension Educator



T. Harrington, ISU
Photo 1: Leaves killed by Bur Oak Blight clinging to the tree after fall leaf drop

A healthy bur oak will drop all of it's leaves in the fall. Leaves that are infected with the fungal pathogen (Tubakia sp.) that causes Bur Oak Blight (BOB) remain attached to the tree into the winter. As a result, now is a good time to examine landscape bur oaks for possible infection with BOB.

Bur Oak Blight causes leaves of bur oak trees to develop brown wedge shaped lesions in July and August. This fungal disease often starts in the lower canopy and progresses up the tree in following years. Some bur oak trees are highly susceptible to BOB. After several years of infection, the entire canopy can appear brown and scorched. These severely infected trees are weakened and often fall prey to secondary pests like two lined chestnut borer and Armillaria root rot. It is possible for bur oaks to be killed by this combination of fungal and inse…

Winter Squash: Easy to Grow and Good for You

Mary H. Meyer, University of Minnesota Professor and Extension Horticulturist



Image Source's Name
Squash and pumpkins can store for several months, if harvested at maturity and properly cured. (Click to enlarge.)


I love winter squash! So with the more than 100 kinds grown at the Arboretum this past summer, it was fun looking at the huge variety and deciding which ones I would try cooking this winter. I settled on 8 'new-to-me' kinds: orange hubbard, fairytale pumpkin, autumn crown, Queensland blue, marina di chioggia, rouge vif d'etampes or cinderella pumpkin, crown, large world of color blend, and 1 'old' favorite: blue hubbard, see photo below. You can still find winter squash at the markets and you can make plans this winter to grow your own squash next summer. Winter squash are easy to grow, have high nutritional value, and some kinds store well for several months. If you can still find open Farmer's Markets, you will likely have a much better selection o…

Understanding the Impact of Pesticides and Choosing Those with the Least Impact

Karl Foord, UMN Extension Educator

I often see recommendations to use the pesticide with the least impact when controlling pests. However, prior to spraying every effort should be made to avoid pest outbreaks by using the best management practices for a particular crop. For example, most fungi need a period of wetness for their spores to germinate. Managing systems to permit maximum airflow reduces drying time on leaves and reduces the opportunities for fungal spores to germinate.

For the purposes of this article let's assume that all best efforts were made and a spray as the last resort was required. How would you go about choosing the one with the least impact? The first question might be impact on whom, with the second being how one would measure such impact. At a University of California Davis website a series of pesticides is listed. Each pesticide is rated according to its impact on aquatic live, beneficial insects, honeybees, and humans. The human impact is separated int…

Moth Flies in Homes

Jeffrey Hahn, Assistant Extension Entomologist



Jeff Hahn
Photo 1: Moth fly

Not all small-sized flies that are found in homes are necessarily fruit flies. Another common type are moth flies, also called drain flies. These flies are about 1/8th inch long (or a little less) and are dark-colored with many hairs which gives them a fuzzy, moth-like appearance. They have leaf-shaped wings that are often held roof-like over their bodies (they are sometimes also held flat). If you look closely, you may be able to many parallel longitudinal veins in the wings.

Moth flies can be present anywhere in a home, especially in bathrooms, basements, and kitchens. These flies lay their eggs in moist, organic matter where the larvae, small, slender, legless insects, feed on decaying organic matter, fungi, algae, and similar material. They are commonly found associated with the gelatinous film found in sinks, shower and bathtub drains, and similar places. Moths flies can also be associated with sewa…

Calendar: December 1, 2011

Photo by Scott Bauer, K7244-16


Poinsettias are among the easiest holiday plants to grow. First, you must choose a healthy one, and get it home without suffering any cold damage. It should be wrapped well, then transported in a heated vehicle, not left in the car while you do other shopping. Cut the bottom of the decorative pot covering so excess water drains out, and place the poinsettia in a bright, sunny location. Water thoroughly when the soil surface begins to dry, and then fertilize monthly after four to six weeks. The U of M Extension has a great publication available for more information on the care of poinsettias.

Don't hesitate to buy a fresh Minnesota-grown Christmas tree. They're a renewable crop produced on marginal agricultural land. As trees are harvested, others are planted for future sales. While they grow, conifers reduce soil erosion and provide habitat for wildlife. Once you get the tree home, cut an inch or so off it's base, then set it immediately in …

Disease Resistance of Cold Hardy Grapes

Michelle Grabowski, UMN Extension Educator



Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Photo 1: Anthracnose on grape berries

New research published in Plant Health Progress provides Minnesota grape growers with more information about disease resistance of cold hardy grapes. Canadian researchers tested several cold hardy cultivars of wine grape for resistance to Anthracnose. Anthracnose, a disease caused by the fungus Elsinoe ampelina, can infect leaves, tendrils, shoots, and immature berries of grape vines. Leaves have dark brown to black spots. As leaf spots grow, the center of the spot turns gray to white and eventually falls out. Leaves may appear peppered with small shot holes. Anthracnose lesions on stems and petioles are sunken oval spots that almost look like hail damage, but the edges Anthracnose spots will always be black. Berries infected with anthracnose have brown to black spots with a pale white center. These spots are often described as '…

The Beneficial Challenge

Karl Foord, UMN Extension Educator

Do you actually see things that you do not recognize? I was hunting for agates near Custer, South Dakota and went through a great agate field and picked a number of nice specimens. I then visited a rock shop and was introduced to the prairie agate which I had not seen in any of the rock books. I went back to the agate field and found quite a few prairie agates. I had been in that field earnestly searching for agates before and did not even see these types until pointed out at the rock shop. This begs the question, can you be looking right at something and not see it or rather not recognize it for what it is? It is not that your eyes did not see it but rather your brain was not ready to discern.

This brings me to the subject of beneficial insects in the garden. Have I not seen them because I did not know what I was looking for? As I look forward to next year's gardening, I want to put the idea of discovering more beneficials at the forefro…

Calendar: November 1, 2011

Dave Hansen, UMN


Last chance! The Arboretum Apple House will remain open until at least November 6. They have the best supply of Honeycrisp in years and have been picking some high quality late season apples this week. Whether you prefer a tart and juicy Haralson, a sweet Fireside or SnowSweet with a balanced flavor, you will find the apples you enjoy the most right now. For updates on the Applehouse inventory, call 952-443-1409. For more information about the Apple program at the U of M, please visit the U of M Apples website.



Dave Hansen, UMN
Chrysanthemums



Potted chrysanthemums in rich, autumn hues are traditional for Thanksgiving. Choose plants with some buds just opening, rather than in full bloom. They'll last three or four weeks when kept in a bright locations. Discard the plants once their flowers fade. It's not worth trying to plant them outdoors. Even though they might survive our winters, most florists mums won't bloom before hard frost, so they aren't use…

The Appeal of Integrated Pest Management (IPM)

Karl Foord, UMN Extension Educator


Green lacewing larvae searching for prey on a yarrow flower.
The goal of IPM is to prevent unacceptable levels of pest damage through the use of pest biology and environmental information. It seeks a solution that poses the least possible risk to people and the environment.

The great appeal of IPM is the understanding of the biological systems at play in the garden and the degree one needs to understand them in order to effectively use IPM strategies. This requires a certain knowledge and skill set. One needs to be able to identify the key insect and disease pests and the types of damage they inflict. One needs to understand the biology of these key pests and how climate influences their behavior. It is also important to understand the natural balances that exist in your garden ecology and to be able to identify beneficial organisms that are a part of that balance. The last item is to understand the use of various chemicals and their effects both di…

Fruit Flies

Jeffrey Hahn, Asst. Extension Entomologist


Jeff Hahn
Photo 1: Fruit fly

Fruit flies are particularly common in homes during fall. These flies, Drosophila spp., are about 1/8th inch long with a tannish body, and a dark-colored abdomen. An easy way to identify fruit flies is by their bright red eyes. However, their eyes do appear darker after they are dead and may not be as distinctive. Be careful, not every small-sized fly you encounter is automatically a fruit fly. Moth flies, phorid flies (also called humpbacked flies), and fungus gnats can also be common in homes. It is important to know which fly you are seeing because control will vary depending on which fly is present. If you have any doubts as to which fly is in your home, have an expert identify it for you.

Fruit flies can potentially be carried into homes in fruits and vegetables or they could fly in from the outside. Once in homes, they are attracted to fermenting and souring smells, e.g. around garbage containers and…

Clean up Fall Leaves and Clean Up Leaf Spot Diseases

Michelle Grabowski, UMN Extension Educator


M.Grabowski, UMN Extension
Photo 1: Fallen Leaves Infected with Apple Scab

As the weather turns cold, disease management in the yard and garden shifts from thinking about protecting plants this year to working to reduce disease problems next year. Many leaf spot diseases of shade trees overwinter in the fallen leaves below the tree. Apple scab on crab apple and tar spot on maple are two examples. When warm wet spring weather returns, these leaf spotting fungi become active again and produce spores that are then blown or splashed onto new emerging leaves. This starts the disease cycle all over again.

Gardeners can help reduce the amount of leaf spot fungi surviving from one season to the next by raking up and removing leaves from underneath trees that experienced a leaf spot problem this year. Leaves should be properly disposed of in a backyard compost or at a municipal or commercial compost facility. The compost needs to heat up in order to k…

Pruning Trees to Avoid "Disasters"

Karl Foord, UMN Extension Educator

USDA Forest Service Figure 1: Crown thinning
Karl Foord, UMN Extension Educator
USDA Forest Service Figure 2: Crown raising
Tree planted in 1997.
Before
After I have Autumn Blaze maple trees that produce great fall color and grow very quickly. In the tree trade they are known as "disasters" because they produce a very dense canopy that is subject to limb breakage in ice storms and uprooting in high winds. To avoid my trees becoming disasters I have pruned them to the point where I was pretty high up in the tree and getting in precarious positions. It was time to get an arborist. I took pictures of the trees before pruning and after pruning to see the difference and then looked on line for verification.

The arborist pursued two strategies, crown thinning (Figure 1) and crown raising (Figure 2) both taken from the USDA Forest Service publication, "How to Prune Trees".
The before and after pictures show that some lower limbs were r…

Calendar: October 1

Julie Weisenhorn
Acer saccharum (Sugar Maple)
Leave a couple inches of stem attached when you pick pumpkins. Since they have almost no frost tolerance, they must be harvested or protected if frost is forecast. Pumpkins ripen best on the vine, but may turn orange in storage if not completely ripe when picked. Wipe them clean with a damp, slightly soapy cloth, then put them in a warm sunny spot for a week or two to cure them. Store in a cool dark place.

Continue to mow the lawn as needed, and rake fallen leaves so grass doesn't mat down and encourage snow mold development. Or, if the leaves aren't too deep, run a power mower over them several times. This chips them into little pieces that filter harmlessly through the grass into the soil, recycling a small amount of nutrients as they break down. Otherwise, use the leaves to protect bulbs and flowering perennials, or compost them.

As the gardening season winds down, so does the Yard and Garden News. Beginning this month, we will …

Fall Webworm

Jeffrey Hahn, Asst. Extension Entomologist


Jeff Hahn
Photo 1: Fall webworm feeding on black walnut
Fall webworm, Hyphantria cunea, is a web building moth that is common from mid to late summer.  It is yellowish or greenish with long, fine white hairs with two rows of black spots down its back, growing to about one inch long when fully grown.  However, an easier way to identify fall webworm is from the silken webbing that covers the ends of branches where the caterpillars feed in nonsocial groups.  These caterpillars feed on the leaves of over 100 different species of deciduous trees and shrubs, including black walnut, birch, ash, crab apple, elm, and maple.  

Fortunately, fall webworm normally has little impact on the health of large, vigorously growing, well-established trees (it is possible that small trees or shrubs can be completely defoliated in one season and could be injured).  Fall webworms are usually no worse than an eyesore because of the webs they construct, making management …

The "Cursed" Thistle - Canada thistle Cirsium arvense (L.) Scop.

Karl Foord, UMN Extension Educator



Photo 1: Canada thistle rosette in lawn.

Whenever I weed my gardens I always manage to find a number of Canada thistle plants, Cirsium arvense (L.) Scop. These are not the rosette seedlings that I see in my lawn which are fairly easily dealt with (photo 1). These are aerial shoots coming from established roots (photo 2). A mixed planting garden bed presents its own set of problems in dealing with this weed. Why is Canada thistle so persistent?


Missouri State University
Photo 2: Canada thistle underground root structure and aerial shoots.
Canada thistle is persistent for three reasons. Seed production, deep roots giving rise to stems, and root pieces that can regenerate plants.

Seed production per plant averages 1,500 seeds per plant but vigorous plants have been known to produce more than 5,000 seeds with viabilities greater than 20 years. So it will take persistence to reduce the seed load in the soil. Lesson 1: never let thistle go to seed. This wi…

Preserving the Harvest: Growing Everlastings in your Cutting Garden

Robin Trott, UMN Extension Educator, Douglas County


Robin Trott
Helichrysum (strawflower).
My house has been full of beautiful floral arrangements all summer, and the fall arrangements are outstanding, however, we will soon enter the cold months, and I can't envision a house without the color from my garden. To avoid this, I have made sure to include some everlasting plants in my cutting garden: Limonium sinuata (Statice), Helichrysum (Strawflower), Gomphrena, Achillea (Yarrow), Celosia (Cockscomb), and ornamental Grasses are all good candidates for air-drying. Once dried, I use these everlastings in bouquets, sachets, wreaths and holiday crafts.


Robin Trott
Echinacea (purple coneflower).
Harvest your everlastings when the flowers are not fully open and in good condition. Don't wait too long, because flowers too far along will not dry satisfactorily. Select flowers or seed pods that are as close to perfect looking as possible because flaws, such as insect damage, become more…

Swarming Ants During Late Summer

Jeffrey Hahn, Asst. Extension Entomologist


Jeff Hahn
Photo 1: Field ant swarmers

There have been numerous sightings of winged ants during August and September throughout Minnesota. These winged ants are reproductives, i.e. new females (soon to be queens) and males. The fly out of their nests at the same time, usually in large numbers for the purpose of mating. After mating, the queens fly off in search of favorable sites to build their own nests and the males die shortly afterwards.

Although nearly all ants swarm, different species do so at different times of the year. Right now cornfield ants and field ants are the primary swarmers that are active. Both of these ants nest in the soil in exposed sites and can be commonly found in lawns and other turf areas. Cornfield ant queens are about 1/4 inch long while field ants are a little larger.

Because of their size, field ants are sometimes mistaken for carpenter ants. However, carpenter ants do not nest in the soil and swarm just d…

Black Leaves on Black Eyed Susan

Michelle Grabowksi, UMN Extension Educator


J. Beckerman
Photo 1: Septoria Leaf Spot on Rudbeckia

This time of year the beautiful display of yellow flowers put on by Black Eyed Susan plants (Rudbeckia sp.) is often ruined by the plant's leaves turning partly or completely black. The leaf discoloration is caused by the fungal pathogen Septoria rudbeckiae. This pathogen causes dark brown to black leaf spots much earlier in the season. The disease often begins on the lower leaves of the plant and may go unnoticed. As the season progresses, so does the disease.

By September, plants may not have a single green leaf remaining. Septoria rudbeckiae will survive in plant debris, so it is best to remove infected stems and leaves at the end of the season. These should be discarded in a backyard compost that gets hot or at a municipal composting site. Next year, thin plants and remove volunteer seedlings to provide good air movement around plants. Water with drip irrigation or early in the day…

Q&A: What is the Implication of the Freeze Warning on Apple Crops?

Julie Weisenhorn
Emily Hoover, professor and department head, UMN Department of Horticultural Science

Question: What is the implication of the freeze warning on the apple crop?

Answer: It depends on how cold it gets. The temperature within an orchard is not consistent. The "rule of thumb" is about 10% of the fruit on the tree will freeze if the temperature drops to 28 degrees Fahrenheit and remains so a few hours. Ninety percent of the apples will freeze if the temperature drops to 25 degrees Fahrenheit and remains so for a few hours.

However, the level of sugar in an apple also changes the severity of the event. The higher the amount of sugar, the lower the temperature has to be before freezing will occur because sugar lowers the freezing point of a solution. (Think Chemistry 101). Note that if the fruit freezes on the tree, but is not touched until it thaws, the fruit is fine to harvest.

Emily Hoover is a professor and department head in the UMN Department of Horticultural…

Calendar: September 15, 2011

Bridget Barton
Three-Mile Drive at the Minnesota Landscape Arboretum, October 2010.
According to the Minneapolis Star Tribune, the Minnesota DNR is predicting the best fall color in ten years, thanks to abundant rain during the growing season, as well as a hot, humid summer. The DNR fall color reports are now available, to help find the most vibrant color in the state. The University of Minnesota Climatology Working Group, a division of the DNR, has more interesting information about the cause of the spectacular color show we enjoy each fall.

The Minnesota Landscape Arboretum and the Minnesota Grape Growers Association are teaming up for the upcoming collaborative, 4X4 Culinary Series at the Arboretum. For the series, U of M Enologist Katie Cook will lead participants through four food and wine pairings over a series of four dinners prepared by leading Twin Cities chefs. Participants can sign up for any or all of the dinners to experience a full array of local wines and meals this fa…

Emerald Ash Borer Found in Two New Sites

Jeffrey Hahn, Asst. Extension Entomologist


Jeff Hahn
Photo 1: EAB on purple trap
Emerald ash borer (EAB) has been confirmed in two new locations by the Minnesota Dept. of Agriculture (MDA) on Friday August 26. One find was detected in the city of La Crescent in Houston county while the second was found in the Great River Bluffs State Park in Winona county, just eight miles apart. This is the first time EAB has been found in Winona county. Both discoveries were made when an EAB adult was found on sticky purple panel traps that were deployed by the MDA. No infested trees have been found to date, although surveys in those areas are ongoing.

For more information see the MDA news release. Late Breaking News:  On Wednesday August 31, MDA reported that EAB was found on another purple trap about 7 miles northwest of the positive trap location at Great River Bluffs State Park and about 7 miles east of Winona. 


September Ushers in Prime Time for Home Lawn Care Activities

Bob Mugaas, UMN Extension Educator



Bob Mugaas
Late summer lawn and landscape.



The arrival of the Minnesota State Fair and its wrap-up on Labor Day weekend, mark the beginning of one of the best times of the year for initiating and renewing home lawn care activities. When it comes to repairing and rejuvenating your lawn after it has endured the stresses of another summer, avoid the temptation to also be winding down your lawn care efforts once Labor Day has passed. The main reason is that our grass plants are entering a very active period of growth triggered by a shortening of the days, cooler temperatures and usually a return to more frequent rainfall. Following are a number of brief lawn care tips that can help restore any lawn's health and vigor.

1. The middle of August through the middle of September is one of the best times of the year for lawn renovation and reseeding. Practices such as dethatching and aerifying are all best done at this time of year. Again, the primar…

Giant Swallowtails

Jeffrey Hahn, Asst. Extension Entomologist



Wendy Pritchard
Photo 1: It's a treat to see a giant swallowtail

There have been several reports of people seeing giant swallowtails, Papilio cresphontes, in the Twin Cities areas recently (they undoubtedly have been seen in other areas of Minnesota as well). This is noteworthy as these spectacular butterflies are not native to Minnesota but can occasionally be found during the summer as migrants from the south.

You can recognize a giant swallowtail because of its size, its wingspan ranges from 4" - 5 ½", and its black wings with yellow spots; the yellow spots on the forewings form an 'x'. Don't confuse it with a black swallowtail which also has black wings but is smaller, its wingspan is as large as 3 ½" and the yellow spots on its forewings are parallel and do not cross. Giant swallowtails can not reproduce in Minnesota as they need citrus trees and related plants for food for the larvae.

Verticillium Wilt in Shrubs and Shade Trees

Michelle Grabowski, UMN Extension Educator



M.Grabowski, UMN Extension
Photo 1: foliar symptoms of verticillium wilt on smoke bush


Several shrubs and shade trees exhibiting symptoms of verticillium wilt have been recently observed in Minnesota. Verticillium wilt is caused by the fungus Verticillium dahliae. This pathogen infects through roots and moves into the vascular system of the plant. Infected trees and shrubs may have small pale leaves or leaves with scorched edges in chronic infections. In severe infections, leaves may be completely discolored yellow to red, curl, wilt and die. Often symptoms of verticillium wilt appear on one to a few branches in the canopy. If you suspect Verticillium wilt may be a problem in a shade tree or shrub, peel back the bark on an infected branch and look for grayish streaking in the sapwood. To learn more about Verticillium Wilt visit the UMN Extension web publication Verticillium Wilt of Trees and Shrubs.

Be Aware of Wasps

Jeffrey Hahn, Asst. Extension Entomologist




Jeff Hahn
Photo 1: Aerial yellowjacket nest

This is a common time of the year for wasp (primarily yellowjacket) nests to become conspicuous and more noticeable by homeowners. These nests have been present all summer but were small enough that they were not noticed then. Although this year would be considered to be no more than an average year for wasps primarily due to the late spring we experienced, if you have a wasp nest present on your property they are still a potential problem. What you decide to do with a nest can depend on a number of factors, such as how close to human traffic the nest is, is the nest is exposed or not, and how close to a hard frost we are.


For more information, see the following article on wasps (yellowjackets),


Late Leaf Rust on Raspberry

Michelle Grabowski, UMN Extension Educator



M.Grabowski, UMN Extension
Photo 1: Late Leaf Rust on Red Raspberry
Bright orange powdery spots on red or purple raspberry leaves are symptoms of late leaf rust, a fungal disease caused by Pucciniastrum americanum. This pathogen can also infect individual druplets in the fruit, turning them into small bright orange powdery masses on an otherwise delicious looking fruit. Late leaf rust needs to alternate between raspberry and white spruce trees. It does not survive on raspberry plants from year to year. Removing nearby white spruce trees is not an effective way to control this disease, however, as spore can travel long distances on the wind. High humidity in Minnesota this summer has favored infection with late leaf rust.

Calendar: September 1, 2011

Dave Hansen, UMN Extension


It's that time of year again! The Apple House at the Arboretum is officially open for business. Purchase apples from a changing inventory of 50 varieties throughout the season - from long-time favorites to recent University of Minnesota introductions, including Minnesota's new State Fruit, the Honeycrisp! Select from a variety of specialty food items and merchandise in the AppleHouse Gift Shop. All proceeds benefit the University of Minnesota's apple research program. See the Arboretum website for more information.

Bonus: the Apple House was featured this morning on WCCO!

Now is the time to start prepping your amaryllis plant to bloom in time for the holidays. Cease watering around Labor Day, and store the plant in a cool, dark room for 8-12 weeks. Bring the plant back out mid-November, and remove dead foliage. Set the bulb in bright light and water the soil thoroughly. Usually one or more flower stalks appear first, but occasionally they are prece…

Bacterial Spot Shows up on Tomatoes

Michelle Grabowski, UMN Extension Educator


M.Grabowski, UMN Extension
Photo 1: Bacterial spot on an heirloom tomato


Bacterial Spot, caused by the bacteria Xanthomonas campestris pv. vesicatoria, has been found in several areas of Minnesota. This bacterial pathogen causes dark brown to black leaf spots with a pale yellow halo around them. Often the leaf spots dry up and crack, resulting in tiny holes at the center of the spot. Probably the most noticeable symptom of bacterial leaf spot of tomato, are the raised brown or black corky spots on fruit. These spots range in size from the diameter of a pencil tip to the diameter of a pencil eraser. Fruit spots can be seen on both green and ripe tomatoes. The spots are superficial and do not rot the fruit. Therefore the tomatoes can still be eaten, although they may be difficult to peel if you plan to use them in your next batch of spaghetti sauce. To learn more about managing bacterial spot of tomato read 'What are those spots on my tomat…

Peppers - Sweet and Heat!

Karl Foord
Photo 1: Sweet peppers



Karl Foord, UMN Extension Educator


I traveled to Bagley, Minnesota to Ter-Lee Gardens, the home and farm of Terry and Loralee Nennich. Ter-Lee Gardens offers Pick-Your-Own strawberries at the farm and almost every vegetable that you can think of, most of which is marketed at the Bemidji Area Farmers' Market. I had heard that Loralee was growing more than 50 varieties of peppers and was intrigued. Terry is a colleague of mine and he persuaded Loralee to give me a tour of the two high tunnels where she was growing her peppers. You can see the peppers she showed me on photos 1 and 2.



Karl Foord
Photo 2: Hot peppers



Most pepper cultivars come from the species Capsicum annuum, whose center of origin is Mexico. The Habanero and Tabasco peppers come from C. chinense and C. frutescens, respectively. The center of origin for these species is the Amazon River basin in northern South America. The amount of variation in size shape and color is impressiv…