CO-Horts Blog

Monday, July 27, 2015

Judge or Be Judged!

Photos and Post by Linda Langelo, CSU Program Horticulture Associate
So you have worked hard all season and now the county fair is upon us. You want to show off your very best flowers. Whether you are new or have done this multiple times, it helps to be refreshed by reading these common sense guidelines to make exhibiting fun at fair rather than stressful. Exhibiting starts long before fair. Sometime around January when you are in your recliner looking through all those new seed catalogues you start planning what you want to grow. You see all those wonderful new plants, but you don't have enough room in your yard to plant them. No one is thinking about fair or what to grow to exhibit. But the really experienced exhibitors do, along with the professional exhibitors who might professionally exhibit roses, dahlias, iris or some other flower. It is not a bad idea while still rustling through those catalogues to decide what you might want to exhibit for fair. While you are ordering, add extra to your list of what you are going to grow to exhibit for fair. You order extra because what if one plant gets a disease or something else happens to it. Once you have made your plant list, you might want to stop and plan the appropriate locations for everything in your landscape thinking about sun, water, soil, exposure and fertilizer requirements.

A good grower or gardener will have a great deal of good material to exhibit because of course you plan for hail, drought, wind and flooding, right? So it’s fair time. Once you have a fair book do the following to make fair seamless: 

1) read the rules carefully
2) decide what you want to exhibit, and remember you have already done this in your recliner in January, lastly,
3) follow the rules. If your entry calls for 3 miniature marigolds, do not enter six. This will get you disqualified. Naturally pick extras in case something happens along the way to fair.
4) If possible, prepare the entries the night before or the day of your exhibitions.
5) Pack and carry all the entries you wish to exhibit that preserves the freshness of your flowers.
6) Be on time and have fun.
7) If you are permitted, be present when your entries are being judged. You can learn a lot. Sometimes, the most successful exhibitors are those who have the most experience.

Here are some tips for selecting the best flowers to show:
1) your flower should be free of insects.
2) your flower should be free of disease.
3) your flower should not be malformed.
4) your flower should be free of mechanical damage and soil. The idea is to bring in foliage and flowers in their prime condition. Do not polish any of your specimens. In order to understand what is meant by prime condition you need to familiarize yourself with the flower(s) you wish to exhibit. Know what is typical of the flowers form, maturity and color. Many exhibitors pick coneflowers which are past their prime with slightly faded flower petals that are pointing downward to the ground. When wanting to bring three flowers of a particular specimen, they must be at the same maturity, as close as possible to the same true color of the flower for that specimen and all three the same size or very close. 

It is always best to grow a lot of one specimen so that when fair time comes, you have a lot to cut to fit the requirements. Here is yet another list to keep in mind about how your flower(s) will be judged as you are picking your flower(s):
1) form: uniformity, maturity and shape.
2) stem and foliage: strength and straightness
3) color: intensity and clarity
4) size: typical to variety
5) condition: free from blemishes

You might think this is alot to remember, but I am confident you can do it. If you have any questions, you can always call your local Horticultural Extension Agent. If you are really interested in exhibiting further, there are plant societies for almost every flower on the market. Many are professionally judged such as roses, daylilies and irises. These plant societies have additional guidelines on how those specific specimens are judged.

Thursday, July 23, 2015

Beauty is Only Skin Deep

Posted by Deana Wise, Broomfield County Extension

Beauty Is Only Skin Deep

        In our world, beautiful people are envied. They are viewed as being more successful, happier, and lead more interesting lives. In the insect world, some of the most beautiful are the most threatening to our urban landscapes. We seek to destroy them at all cost.
Fig. 1 Japanese beetle adult.
Photograph courtesy of David Cappaert/University of
Michigan and
          One example is the dreaded Japanese beetle (Popillia japonica). This metallic green pest with brown wing covers, white spots and distinctive antennae (Fig. 1) has been a major problem in the eastern U.S. for close to a century. The adults munch on a wide variety of plants (between 200-300) while the larval form feeds on the roots of grasses. This indiscriminate grazer can rid your garden of flowers, buds and leaves from Roses, Virginia Creeper, and American Linden among others. It has settled in Colorado.
Fig.2 Grub
Photo retrieved from
       The grubs are white with dark heads and the thorax has 3 pairs of well-developed legs (Fig.2). They are usually curved in a C shape and have a distinctive V-shaped rastral pattern (Hairs on the hind end). They feed on the roots of grasses, reducing the plant’s ability to absorb water. Heavily infested turf can be easily pulled up, revealing the grubs beneath.

          The adult emerges from the soil in June and feeds for 4-6 weeks. After mating, the female lays 40-60 eggs, 2-3” deep into the soil. The larva remains in the soil for up to 10 months (Fig. 3).   They prefer well maintained, damp turf. The eggs and newly hatched grubs can be damaged or killed by excessive drying of the soil. Older grubs simply move down deeper to survive. They are not affected by overly damp soils.

Fig.3  Japanese beetle lifecycle
Photo retrieved from

          Control of Japanese beetle can be achieved in various ways. One satisfying alternative is to pick the beetles off and deposit them into a container of soapy water or mineral spirits. If you don’t care for hand to hand combat, there are several insecticides labeled for both Japanese beetle stages.

The adults can be killed with various pyrethroid, permethrin, and Carbaryl products.  Neem products or Pyola (pyrethrins in canola oil) are botanical alternatives. As with all chemicals, follow the label and use caution when applying to plants where bees are present.

The grubs can be treated by several methods. Certain parasitic nematodes in the genus Heterorhabditis can be applied to the soil when grubs are present. Another popular biological control is Bacillus popilliae or milky spore. Insecticides include: imidacloprid, chlothianidin, and chlorantraniprole. As with any chemical, it is very important to follow the label.

For more information see fact sheet no. 5.601, Japanese Beetle.

Monday, July 20, 2015

Frozen IV: The Aftermath of November 2014 Cold Snap

Jane Rozum, Horticulture Agent,  CSU Extension – Douglas County
I first want to thank all that responded to the Frozen III, the CO-Hort blog article I wrote on 4/28/15. Your comments on the trees and shrubs affected by last November’s Cold Snap were confirmation of the magnitude of the problem. Willows, boxwoods, fruit trees, elms were mentioned by readers as trees and shrubs that hadn’t yet recovered in your landscapes by the end of April.
Dead hedge July 2015
 Our ‘wait and see’ recommendation about whether plants would recover from the sudden November 2014 temperature plunge was again thwarted by another ill-timed frost. On Mother’s Day 2015, many areas around the Front Range received snow and temperatures below 26 degrees F. This occurred while some trees and shrubs were in a critical stage of leafing out, and much of the new growth froze and turned brown. Ash, Honeylocust, Hackberry and Maple were among trees where new growth froze in Douglas County; other trees and shrubs could have been affected in your locale. While I’m happy to report that many trees re-leafed in my area, there are still trees and shrubs that did not or had areas in the canopy that had poor growth.
Freeze injury (left) and regrowth 2 weeks later (above)                                 
It’s time to evaluate our ‘wait and see’ approach and decide whether landscape plants that were affected by the Cold Snap and Mother’s Day storms will recover. First, I’ve observed that many trees and shrubs along the Front Range have either made full recoveries or have had some dieback but do not have to be removed.
April 2015 (left) same shrub July 2015 (right)


Second, I’d like to preface my comment with a very small botany lesson. Plants need leaves so that photosynthesis can occur: Energy from the sun is converted to energy that the plant needs to grow. So, it stands to reason that without leaves, photosynthesis doesn’t occur and therefore the plant cannot provide the necessary nutrients for survival. If there is no food, plant tissue will die. I’m going to go out on a limb (no pun intended!) and say if your tree doesn’t have leaves now, the landscape plant probably won’t leaf out. Plants don’t have the reserve energy stored in the roots to take a year off from growing; there is no long-term savings account of energy for plants. So, if your plant looks dead now, it most likely will remain that way.
Hibiscus, July 2015 with cold snap damage
One question I’ve received is: There is sucker growth from the base of the trunk, but no growth in the canopy, is my tree O.K? Unfortunately, the sucker growth is the tree’s last ditch effort at survival. Since many landscape trees (especially fruit trees) are grafted onto hardy root stock, suckers from the root stock will not have the same ornamental characteristics as the original tree.   If the canopy did not leaf out, it probably won’t.
Cold damage water sprout growth on Linden
Still not sure whether your tree or shrub is viable? There are people you can contact to check this out. First, call your local Extension office and ask to speak with a Colorado Master Gardener or Horticulture professional. They can examine photos of your landscape plant and offer some advice on your situation. Find your county office information here. Some offices along the Front Range have ‘tree teams’ that will send out trained CMGs for a consultation (for a fee).

 You can also have a Certified Arborist come and evaluate your landscape plants. Many Extension offices have lists of local International Society of Arborists (ISA) that will consult and will also prune/remove trees and shrubs. This is also a fee-based service.

Are the trees and shrubs that survived the storms now safe? Unfortunately, there is no crystal ball that can tell us. These weather events were stressors to the plants and though they survived thus far, it does not mean that they will survive another ill-timed storm. We've had many stressful weather events before the November Cold Snap (drought, etc.), and will continue to have weather-related landscape plant issues.  Colorado’s weather is difficult on trees and shrubs and, for that matter, the people that care for them.

Friday, July 17, 2015

Hort Peeves: Tree Edition

Posted by: Alison O'Connor, Larimer County Extension

I'm starting a new installment called "Hort Peeves"--things that you see in landscapes that simply don't make sense and drive a horticulturist crazy.

There's a lot of construction near my office and dozens of apartment buildings have been built in the last 12 months (mostly student housing for fellow Rams). It's been an experience watching the building process...and more recently...the landscaping process.

But I cannot stay silent about the trees they planted. First of all, they are inferior quality, with crooked trunks, no defined central leader and poor branching.

Second...these are COTTONWOODS (specifically Populus fremontii; the western cottonwood). Like, freakin' enormous, huge cottonwoods. And look where they are planted! Less than 10 feet from the apartments.
A cottonwood for each front yard!
Oh, and what's even better is that the mature size for these trees is 50' wide by 50' tall.
At least they are hardy to Colorado's climate.
Maybe the builders/landscapers don't bank on these trees surviving to maturity? My guess is they probably don't. But that's another peeve--we should plant trees for the tree's life--not to fit into our personal timeline or the maintenance contract. I fear these trees (at least the ones that survive) will have to be removed in a few years, because cottonwoods tend to grow quickly and they are going to outgrow their space soon. This is where the "right plant, right place" rule of thumb becomes so important.

Sigh. Poor trees. "I speak for the trees, for the trees have no tongues." (The Lorax by Dr. Seuss)

Monday, July 13, 2015

Iris Rejuvenation

Jane Rozum, Horticulture Agent, Douglas County
Now that summer is in full swing and the garden has been planted, you can rest easy, right? Well apart from pulling a few weeds, there is a task that you can accomplish in July and early August. Irises are some of our toughest and most durable landscape perennials and are best divided after bloom. July and early August are just fine for refreshing your iris clumps. For best bloom, irises usually need dividing every 3-4 years.

Iris bed in need of dividing
Iris form fleshy, elongated rhizomes which sit at soil level. Large roots extend from the lower portion of each rhizome.  When left undivided for many years, they can form thick mats which can grow on top of each other.  At this point, many rhizomes will not produce flowers.

section of undivided iris
To divide irises, use a digging fork to lift a clump of iris out of the soil. Gently pry the rhizomes apart, shaking off soil to see the individual rhizomes and roots. Break apart large sections of rhizomes into sections which have one or two leaf fans, discarding shrunken or older rhizome areas. For easier replanting, trim the leaves to about 6 inches above the rhizome.
Irises with trimmed leaves
Some gardeners treat the open fleshy area with fungicides to prevent disease, but I don’t bother and haven’t had problems with disease or pests on irises in my garden.

Since iris rhizomes like to sit at soil level, I usually dig “W” shaped planting troughs when replanting.  I place the rhizome mid-W, leaving the roots on either side, in the troughs. Firm the soil around the roots and water. It may be best to plant rhizomes in the same direction, so that as they mature and grow, the rhizomes don’t grow into each other.
'W' shaped planting troughs
rhizomes and roots in planting troughs
A Weld County-Colorado Master Gardener once taught me a neat trick to help remember what color, the standards (upright petals) and falls (downward-growing sepals) of each clump in a mixed iris bed. She writes the colors on the iris leaves with a permanent marker when the plant is blooming. When division time comes a month or so later, she has a record of which color of iris is where. 
iris coloration written on leaf

For more information on irises and division, check out Plantalk Colorado # 1076 and #1071

Thursday, July 9, 2015

I Think That I Shall Never See a Poem as Lovely as....Eriophyid Mite Damage!?

Posted by: Mary Small, Jefferson County Extension

Eriophyid mites are one of the most curious creatures found on landscape plants. Their feeding causes a variety of (and often colorful) plant injury. Deformities, blisters, galls, pockets, velvety patches, silvering and russeting are common descriptors. Damaged tissue may remain green, but I’ve seen white, pink, bronze and/or red colors. 

Erineum mite on viburnum
Eriophyid mite injury does not usually affect plant health. Exceptions include mites that transmit viruses, such as rose rosette or situations where plants are heavily infested and/or already stressed from something else.  

Plant damage may appear shortly after bud break, when the mites emerge from their overwintering sites on or near the host plant and begin feeding on new growth. Depending on the mite, more generations can appear throughout the growing season. 

Russet mites on tomato leaf

Most plant owners or managers find the damage from these miniature “walking carrots” a bit disconcerting because of the odd shapes, appearance and colors.  It almost looks like some alien invasion has taken place. What I find disconcerting is the mites can be hard to find because of their size (1/100”) and well, yes, the age of my eyes. 

Eriophyid mite damage to spruce
On top of that, some of the injury looks pretty similar to that from herbicide or freezes. Telling the difference between mite damage and these environmental problems can be pretty tricky. Finally, I want to know where the heck the mites go when the plant tissues start to dry out.  I save the damaged samples to show our volunteer clinicians. But if the infested plant has started to dry, the critters disappear into thin air (well, that’s how it seems!) I have always supposed they found greener pastures in the carpet or on someone’s desk.

Eriophyid mites on maple leaves
When management is needed, (and it’s often too late for that), there are several options. Sometimes the plant obliges the homeowner and drops the offending part (like ash flower galls). If the tissue remains on the plant, it can be pruned out. Herbaceous plants with heavy infestations (such as a tomato) can be pulled. Soaps, oils, kaolin clay, neem oil and sulfur are some of the “softer” chemical options. But they need to be applied while mites are still moving about. Once gall-makers have finished their creations, it’s too late to treat.  Time for us to sit back and admire their handiwork!

Monday, July 6, 2015

Who dunnit? Voles or Pocket Gophers?

By Irene Shonle, CSU Extension in Gilpin County

There are many burrowing animals in Colorado that can cause damage to lawns, gardens, and pastures. The first step to resolving the problem is to figure out which animal (or animals) caused the damage.
The main four types of burrowing animals are voles (8 species), pocket gophers (4 species), prairie dogs, and Wyoming ground squirrel.   Moles are rarely found in Colorado, and only in the very eastern plains.  If you are outside that area, the species causing damage is one of the other four.
  In this post, I'll just be discussing the difference between voles and pocket gophers, since these are the critters I most often deal with in the mountains.

This year has been a very bad year for voles.
Voles cause several types of damage.  They gnaw on bark of trees and shrubs, sometimes girdling it entirely and causing the death of trees. Most damage occurs in the winter when voles move through their grass runways under the protection of snow. The greatest damage seems to coincide with years of heavy snowfall.
Vole damage to trees and shrubs is characterized by girdling and patches of irregular patterns of gnaw marks about 1/16 to 1/8-inch wide. Gnawed stems may have a pointed tip.
Other signs of damage by voles include: 1- to 2-inch-wide runways through matted grass with open 1-2 inch holes and spongy soil from burrowing activity. 
It is common to see voles, as they are active all year round, and are frequently above ground.

Vole damage on lilac. Notice small, irregular tooth marks, all under what was the snow line.


Vole trails in lawn after snow melted in spring
Add caption

Vole hole and trail in clay soil

Vole hole and trail in snow.  Note the oval-shaped OPEN hole

Examples of vole holes.  
They will often burrow near a rock, but not always.

Pocket gophers
Pocket gophers rarely appear above ground, spending most of their lives in burrows.  Prairie dogs and Wyoming ground squirrels, on the other hand, are frequently seen above ground.
The mounds that pocket gophers create are fan-shaped to round and usually have closed entrances, unlike prairie dogs and Wyoming ground squirrels. 
The main signs of damage from pocket gophers include mounds of soil (with no apparent hole), eskers (solid tubes of soil) above ground when the snow melts in the spring, and suddenly wilting plants (due to root damage).   If you walk across an area inhabited by pocket gophers, your foot will frequently break through into their tunnels.  The tunnels are usually 2.5-3.5” in diameter, and are usually found in the top 4-18” of soil.

An example of an esker - these solid soil tubes are only seen as the snow melts, and are a result of burrowing activity in the snow.

Fan-shaped mound with closed hole is typical of pocket gophers in the summer

 Now that you have a good idea of who dunnit, please refer to the following fact sheets for help with dealing with them:  6.507 Managing Voles in Colorado, 6.515 Managing Pocket Gophers.