CO-Horts Blog

Friday, December 27, 2013

2013 - Out With A Bang!

Alexis Alvey, Horticulture Agent, CSU Denver Extension 

It is the end of the year, that time when the phone is silent, the e-mail box is noticeably empty, and anyone walking into our office is more interested in free Christmas cookies than asking gardening questions.  I am always grateful for this time period when the Horticulture Program can take a much-needed breather before heading full-swing into Master Gardener training in January.  Reflecting on 2013, here are just some of the awesome things that the Denver Master Gardeners and the Denver Horticulture Program have accomplished!

- Nearly 5,000 volunteer hours were donated in 2013 by Master Gardeners to 44 gardening projects throughout Denver!

- Master Gardeners answered nearly 7,000 gardening questions this year!

- 430 pounds of produce were grown in 2013 in our Vegetable Demonstration Garden and donated to the St. Francis Homeless Shelter.

- The most successful Denver Master Gardener Plant Sale ever!  Our two-day sale sold-out!

- A new Native Plant Garden & CO State Children's Home Memorial was installed in front of the Denver Extension office.

- First Native Plant Master class hosted by CSU Denver Extension.

- Master Gardeners taught hands-on gardening sessions at the Colorado Governor's Mansion to young adults who are recovering from substance abuse.  There were five "graduates" of the program and eight total participants.

And also of note: 

- CSU Denver Extension provided help with the Emerald Ash Borer delimitation survey in Boulder.

- 14 new Master Gardeners joined our team of 122 active Master Gardeners here in Denver.

- First statewide webinar partnering with the CSU Alumni Association, and

- New Master Gardener volunteer project at the Haven in Fort Logan which led gardening workshop for women there recovering from substance abuse.

Thanks to all who have helped make this such a wonderful year!  We are looking forward to a fantastic 2014!!  Happy holidays!

Friday, December 20, 2013

Poisonous Poinsettia a Bad Rap!

Kurt M. Jones, Chaffee County Extension Director
I was recently asked about Poinsettia Plants being poisonous.  As a concerned parent of two young children, I decided to do some research about poisonous plants, and learned that the toddler in my life is more harmful to my Poinsettia houseplant than the plant is to him.

This is not true of all plants in our landscape, however.  Some plants that grow in our landscapes or surrounding areas can be dangerous for our children and pets.  One website that I often visit when looking into poisonous plants is  This website is a searchable site written by Dr. Tony Knight, DVM from the CSU Veterinary School.  Dr. Knight is a world-recognized expert on plant toxins for animals, but he cross references many of his plants as affecting humans.
Upon visiting this site and searching for “humans,” a list of 22 plants was returned.  This site has good color pictures of plants, animals affected, and geographic locations of these plants.  Of course, many plants we are not likely to plant in our landscapes like leafy spurge, water hemlock, death camas, or buckeyes, there are some plants that may find their way into our landscapes or potted plants like Oleander, Autumn crocus, Glory lily, Rhododendron, Delphinium and Daffodils.  Easter lilys are especially toxic to house cats.

I also visited the Cornell University website for toxic plants available at and also did a search for poisonous plants for humans.  About 55 plants were returned in this search (including several mushroom species).  Included in this list is the poinsettia, which was surprising.  The Society of American Florists has given a "Clean Bill of Health" to the Poinsettia plant.  It is however wise to keep poinsettias and other plants out of the reach of children and household pets that show a desire to chew or eat plants.  The white latex sap in the leaves and stems is mildly irritating to the mucous membranes of the mouth and in some animals will induce excessive salivation and vomiting if the plant parts are swallowed. The wide variety of hybrid poinsettias available today have very little toxicity compared to the parent species.  Other Euphorbia’s include the various spurges which have been shown to be hazardous to humans when handled or consumed.

I also researched the incidence of plant poisonings for this article and was surprised at some of the findings.  According to the American Association of Poison Control Centers, there were 64,236 (2.7 percent) cases involving plants.  In pediatrics (age 5 or less), the percent is higher (3.7 percent).  Of the plant calls received by poison control centers involved in this report, the poinsettia was number 2 on the list.  For more information, visit their website at  Should you suspect poisoning, call 1-800-222-1222.  If it is an emergency, of course, dial 911.

So what should you do to prevent unwanted poisonings?  First, keep plants out of the reach of children.  Babies and toddlers like to stick new items into their mouths, and plants parts may be a choking hazard even if they are not poisonous.  Learn to identify problematic plants in and around your home.  Do some research on potential plant additions to your home before bringing them home and endangering your children or pets.  Should you have poisonous plants in your landscape or home, consider their removal or take steps to insure they cannot harm your children or pets (exclusion fencing, elevating them in your home).

Wednesday, December 18, 2013

Ode to EAB Peeling

By: Alison O’Connor and Tony Koski, CSU Extension

'Twas a cold day in December, and outside the shop,
Were piles of ash branches with emerald ash borer to stop.
The draw knives were lined up on the bench with care,
In hopes that many volunteers soon would be there.

Ash branches from the delimitation survey waiting to be peeled.
The larvae are snuggled down in the logs,
Waiting for spring to emerge and attack like dogs.
The feds and the state will determine their fate,
Hopefully prior to the beetles finding a mate.

EAB was found in an ash in September,
Which Kathleen Alexander quickly came to dismember.
All in the midst of disaster and flood,
Another insect in Boulder--Oh crud.

The City of Boulder was divided into 39 squares,
In each 10 trees were sampled to find EAB lairs.
Two branches per tree of just the right girth,
To find one of the most destructive beetles on earth.

The point of peeling is to remove all the bark,
Because on the outside there is rarely a mark.
A sign under the wood of this terrible green beast,
Are the S-shaped galleries where the larvae feast.
Removing all the bark from an ash branch.
We peel hoping to find the creamy white worms,
When you find one, they tend to wiggle and squirm.
The goal is to remove them completely intact,
The larvae may be sent to Washington D.C., in fact.

Wafer-thin layers are peeled with care,
Straight down to the cambium with nary a tear.
It’s a tedious, yet satisfying kind of work,
Especially with good music and the occasional twerk.
Wafer-thin slices of wood are removed carefully.
 There’s an easy camaraderie among all who peel,
Slowing the movement of EAB is a big deal.
Our hopes are the survey will tell us where it has spread,
To prevent more ash trees from becoming dead.

So that's what we do in the Boulder Forestry shed all day,
We toil away gladly without additional pay.
We feel a little like elves making toys,
Except our end result is preventing EAB joy.
The "bone pile" of peeled branches.

To everyone who lifts a draw knife to volunteer,
We wish you a holiday season full of good cheer!
Happy Holidays from your CSU Horties and the EAB Yule Tree!

Sunday, December 15, 2013

Does Snow Cover Cause Snow Mold in Lawns? Yes....and no...

Posted by Tony Koski, CSU Extension Turf Specialist

Gray snow mold can occur during very snowy winters or on shaded
areas of lawns - whenever snow cover persists for 60 days or longer
Our first long-lasting (for us in the lower elevations anyway ) snow of the year has people thinking of snow mold in their lawns.  When gray snow mold does occur in lawns, it is caused by the fungus Typhula incarnata. Fortunately, that “when” comes pretty infrequently for most Colorado lawns. Unless you live in the mountains or where snow cover persists for more than a couple of months, snow mold is not an important home lawn concern.  The fungus that causes snow mold requires 40-60 days of continuous snow cover before it begins infecting lawn grasses. Even when we do have those rare, extended periods of snow cover, the snow mold that results rarely kills home lawn turf. Kentucky bluegrass and fine fescues are more resistant to this disease, while perennial ryegrass and tall fescue are more susceptible.

The gray, fuzzy mold is easily seen as the snow melts
Prevent snow mold by mulching fallen tree leaves into the lawn with your  mower – or collecting them
if you have deep accumulations of leaves (because leaving a matted layer of tree leaves on the lawn over the winter can mimic snow cover… possibly resulting in snow mold under the leaves). And try to avoid shoveling or plowing snow from sidewalks and drives into long-lasting piles.

Snow mold damage on home lawns is almost always cosmetic,
with only the grass blades being affected.
When snow mold does occur in the home lawn, damage is usually cosmetic and will recover fairly quickly as warm weather occurs in the spring.  Recovery can be hastened by light raking with a leaf rake to lift up any matted grass.  In areas where snow was piled for 3-4 months, turf killed by snow mold can be aerated and overseeded in the spring.  

Raking affected areas with a leaf rake to "fluff up" the moldy,
matted grass will help speed up recovery.
Golf course superintendents apply fungicides to prevent gray snow mold (and another called “pink snow mold”), because both of these diseases can kill the closely mown turf of greens, tees and fairways. However, fungicide applications to prevent snow mold are not recommended for Colorado home lawns since damage to higher cut turf is almost always cosmetic, rarely fatal, and quick to recover in the spring.

Monday, December 9, 2013

Is there a safe deicing product for sidewalks and plants?

Posted by: Alison O’Connor, horticulture agent, CSU Extension in Larimer County
Deicing salt on a concrete sidewalk.
Welcome to our new normal, as least for the next couple months—constant shivering, chapped lips, static cling from stocking hats and dry hands from the next-to-nothing humidity.  It’s winter!  And while it may not be my favorite season, I grew up in Minnesota, so winter weather is about as normal as mosquitoes.  Since we’ve had a couple of snowfalls here in the Front Range, I thought it might be prudent to write about deicing products.

Just yesterday I was at the Orange Box Store buying a few supplies for a project and saw a gentleman walk out with his 25# bag of deicing salt slung over his shoulder. He was on a mission. His sidewalks should fear him.  More importantly, his plants should take cover.  While applying products to keep our walkways clear of snow and ice, it’s important to remember the green things (though dormant) growing nearby. Everyone knows that deicing products can injure plant material, but is there a safer product to use around desirable vegetation? What about around pets?

Deicing products are primarily comprised of salt. And just like the fancy black sea salt you sprinkle over your baked halibut, all salt is not the same. Salts can cause injury to trees, lawns and shrubs, they can corrode concrete and even do bodily harm to humans if handled improperly. And don’t forget about poor little paws on your four-legged friends.

If you remember your days in chemistry (I don’t), salts are combinations of anions (negatively charged particles) and cations (positively charged particles). Examples are sodium chloride (table salt), potassium chloride (used as a fertilizer) and magnesium chloride (the one you see trucks spraying on our roads). The most problematic element in these salts is chloride…it’s a corrosive ion that damages metal and concrete and is toxic to plants.

Salt damages plants by dehydrating plant tissues (causing burn) or by being toxic in high levels. While most plants have some tolerance to salt injury, repeated applications of deicing products during the winter can result in dieback or even death the following spring. Misapplications of deicers (i.e. dumping piles or using too much) can wash into the storm sewers, causing pollution. Before buying or using any product, read the label carefully and thoroughly and use only as directed.
It's not popcorn, people!
Piles of salt are not effective for snow and ice melt.
Use all deicing products sparingly.
A few of the salt products you might run into while shopping:

Sodium chloride: It’s the most widely available and the cheapest. It doesn’t cause corrosion to concrete, and melts ice best when temperatures are in the 20s. It is the most damaging to plant material. If you use this product, use sparingly and in small amounts.

Potassium chloride: Our salty fertilizer friend. It’s expensive and not as widely used as a deicer because of rising costs of fertilizer. Works best when temperatures are above 15 degrees F. Because it’s most commonly used as a fertilizer, it’s relatively safe to apply near plants.

Magnesium chloride: Good ol’ mag chloride. It’s the most common product used on our roadways before storms (applied as a “brine”), because it lowers the freezing point of soon-to-arrive precipitation. It can melt ice down to -15F, which is a nice benefit. If applied in moderate amounts, it’s relatively safe for plants and pets. Its corrosion potential is low, as is its pollutant possibilities.

Calcium magnesium acetate (CMA): A new kid to the deicing block, it has low corrosion potential, so it’s less damaging to cars, metals, sidewalks and plants. Notice it’s not a chloride product…the “salt” comes from the calcium-magnesium mix and the acetate replaces the chloride.  Plus it’s biodegradable! Its ice-melting properties are equivalent to traditional deicers, but the cost will make you gasp…it may be 20-30 times as expensive as sodium chloride products.  These are often touted as “pet friendly”.

Before using any product, clear away as much snow and ice as possible. Get out your shovel and do your best. If heavy snow is predicted, then try to shovel more frequently. Remember, deicing products are not meant to melt all snow in and ice, but aid you in your removal efforts. If you want to avoid chemistry in your landscape, then consider using sand or kitty litter. While they don’t melt snow, they can provide some much needed traction in slippery spots. Sand and kitty litter are also safe for pets and plants and can be swept up when the snow melts.

If you do use deicing products near vegetative areas, then use caution with potential salt build up—if it’s an especially snowy year, you may consider leaching the areas next spring with clean water. Try not to scoop snow laced with deicing products directly on top of plants, especially if they are sensitive. If you have the opportunity, consider planting more salt-tolerant plants near walkways and driveways. Dr. Curt Swift, former horticulture Extension agent in the Tri-Rivers area, has a great publication on plant tolerance to salts.

So enjoy the snow! And the cold! And the hot beverage waiting for you when you get inside.