Thursday, June 21, 2018

Lilac Ash Borer

Lilac Ash Borer- Cassey Anderson CSU Extension Adams County

Most of us are aware of the looming menace posed by Emerald Ash Borer to our ash trees along the Front Range in Colorado. However, we do have another pest of our ash trees, the lilac ash borer. Lilac ash borer can, like their name, impact both lilacs and ash trees. They are more of a concern in ash trees.  Fortunately they are usually not lethal to the tree.  Adult borers emerge from trees in the spring then lay egg on the bark .  The larva which develop then burrow into the tree where they spend most of their time in heartwood.  They then overwinter in the tree and emerge as adults the next year.

Pupal Skin Left Behind by Lilac Ash Borer (from CSU Extension Lilac Ash Borer fact sheet)

Distinctive round/melon shaped holes can often be found on the main trunk of the tree. During the spring and early summer it may even be possible to find the final pupal skins of the lilac ash borer left in the trunk as the mature insect emerges. The pupal skin may resemble a wasp. They are not related to wasps but rather are a type of clearwing moth which has some resemblance. 
Lilac Ash Borer Exit Holes

We had a severe wind event here in Adams County this spring and saw one of the unfortunate side effects of a tree that had been riddled with the insect.  While the damage caused by the larvae rarely kills trees because it does not feed extensively in sapwood it does weaken and makes them more prone to failure.   

This tree snapped a foot or so off the ground exposing the larval galleries both new and old from the feeding of the lilac ash borer. These trees had been planted in a very narrow strip between road and sidewalk, were not getting sufficient irrigation if you looked at past growth and the grass growing around the trees, several of the trees also had visible girdling roots which likely compounded their stress.
Lilac Ash Borer Galleries 

Generally speaking stressed trees are more susceptible to damage from lilac ash borer. Ensuring that existing trees are planted correctly, do not have girdling roots, and are watered appropriately can reduce infestations of lilac ash borer.  Treatment for this insect is not the same as treatment as for emerald ash borer. For treatment options and more information please see our fact sheet on lilac ash borer:

Monday, June 18, 2018

Growing Strawberries. Vertically!

Adapted from “Vertical Gardening with Strawberries” by Al Myers and Andy Hough
By: Andie Wommack, Douglas County Extension

Vertical gardening greatly increases the amount of plants you can grow in a small space. In a research project done at the Hidden Mesa Research & Demonstration Orchard, they were able to plant 1,500 strawberries in 25 vertical tubes. This took up approximately 13.3% or less of the space that would’ve been needed to plant them in the ground. The methods discussed here can be scaled up or down depending on your production goals! 

When growing strawberries, regardless of method, you need to consider which type of strawberry you want. The three types considered for this project were:
·      June Bearing: produces a major crop but only in spring, usually in June
·      Everbearing: produces a major crop in June and another in late summer
·      Day Neutral: produces a large flush of fruit in June, slows production for approximately six weeks and then produces a more consistent harvest throughout the remainder of the growing season
It’s important to know what your goals are for growing any plant. Knowing when you want, and potentially how much fruit you want, can help you choose which type of plant you want to grow. “Day Neutral” varieties were planted for this project because they produce throughout most of the growing season.

Two different methods were tried, and both have pros and cons. PVC tubes held more plants, hold their shape, and require less potting soil than the fabric tubes. However, the initial cost is higher if using PVC. Also, because they hold less potting soil, the plants run out of fertilizer much quicker. Fabric tubes cost less and can be watered through the sides if needed. These tubs need significantly more potting soil and tended to lose their shape as the soil settled toward the bottom.

If you want to grow strawberries in vertical tubes, the number of plants you will be able to plant depends on the diameter and height of the tube. A 6” diameter, 5’ tall PVC pipe was predrilled to hold up to 100 plants. Spacing for holes in the PVC pipe is 2.5” between each vertical row and 4” between holes in a row. The holes drilled in the PVC pipe were 1.5” in diameter. In the fabric tubes, there is 4” between each vertical row and 8” between the holes in the row. A 2” horizontal slit was cut in the fabric for each hole. A 12” diameter, 5’ tall tube held about 72-75 plants.

Signs of insufficient
nutrient levels
You will need to provide support for your tubes regardless of the type of tube you use. The fabric tubes used in this project were reinforced at the top and bottom of the tubes with high-tensile fence wire then secured to an overhead support structure with bailing wire. The PVC pipes were also attached to the overhead support structure in a similar manner. These were all in a greenhouse, so if you have your tubes outside in an unprotected area, support may have to be stronger to hold up to wind.

Since potting mix is used in these tubes, they should be treated like a house plant container. This means they should be watered frequently and adequately. A micro-sprinkler was installed above each tube and place on an automatic timer so water percolated down through the tube. Fertilizing is also critical and was done on a weekly basis for the fabric tubes because of the high volume of plants and limited soil quantity. Liquid, foliar, or time-release fertilizers can be used and may alter the fertilizing frequency. You will have plants that die for a variety of reasons, however strawberries produce runners that can be used to replace plants lost. If you are growing your strawberries in a climate-controlled environment you can keep them from year to year if you make sure they are watered throughout the winter and don’t freeze. There are other season-extending methods you can use to try and keep your plants from year to year as well, like a mini hoop house or Agribon row cover cloth to hold in heat and moisture.

Initial costs can be high when purchasing the tubes, plants, and planting media, but once this type of system is set up, it requires a very low amount of maintenance. Weeds will be virtually nonexistent, harvest is easy, and since the strawberries are up off of the ground, there is less cleaning and fungal growth on the fruit which can happen if the fruit gets wet. To reduce costs every season, try to overwinter your plants or collect runners that you can plant and grow during winter to plant again in the spring.

The Hidden Mesa Research & Demonstration Orchard in Franktown, CO planted over 500 varieties of fruits and nuts, along with dozens of types of lavender, herbs, and annual vegetables. Their goal is to explore what food crops can be grown in the Front Range Climate and what cultural methods can be used to overcome the extreme climate challenges here. They also provide options for scalable agriculture, edible landscapes, gardening, and community gardens and orchards.

To learn more about the work being done at Hidden Mesa, please visit:

Wednesday, June 6, 2018

The Buzz on Bees and Wasps

By: Sherie Caffey, Horticulture Agent, CSU Extension-Pueblo County

Western Yellowjacket
Most people know that bees are good. There are, however, those who are still afraid of bees, and of course those who are afraid of wasps. Surprisingly, many don’t know the difference between the two. Bees are typically not aggressive whereas wasps are more likely to sting. We have many species of both here in Colorado, and they differ in many ways.

We have many wasp species that are social and form colonies. These colonies are small in the Spring, and grow throughout the summer. Most wasps feed on live insects, and are important in balancing out pests like caterpillars. Western Yellowjackets, however, are scavengers and feed only on dead insects and garbage.

Yellowjackets are often mistaken for honeybees, but they are not hairy and are more intensely colored. They usually nest underground and their colonies are not usually seen. The Western Yellowjacket is the most concerning stinging insect in Colorado. They become a nuisance around outdoor picnics and garbage. It is estimated that 90% of Coloradans who believe they have been stung by a bee, were actually stung by a Yellowjacket.

European paper wasp
If you have seen a papery, open celled wasp nest under your eaves, in your gutters, or even your grill, it is probably the nest of the European Paper Wasp. They are more slender-bodied than the Yellowjackets, but some have very similar coloration. They feed on live insects, many of which are pests. The fact that they nest in many locations around homes has increased the incidents of stings associated with this wasp.

If you have a wasp nest on your property, and it is not causing an immediate issue, the best course of action is to wait until fall or winter, when the nest will be abandoned, and safely remove it then. You can also take a proactive approach by sealing all openings that allow access to hollow tubes or similar spaces. Active nests that are a nuisance can be sprayed with an insecticide labeled for use on wasp nests. Spray the nest during late evening when the wasps are not flying and most foragers have returned home for the night. Excluding food sources such as open garbage cans or pet food will deter Yellowjackets. They also make traps that will attract Yellowjackets, these are best used in June when colonies are still establishing.

Honeybee, photo by Lisa Mason
           Bees do not feed on insects, only nectar and pollen. One problem we see with honeybees is swarming on sunny afternoons in May and June. Swarming occurs when a colony gets too big and part of it splits off in search of a new home. This is when you will see a mass of bees gathered on a branch or somewhere similar. If you have a swarm, a beekeeper will gladly come remove it for you so they can get a new colony. You can call the Colorado Swarm Hotline toll free at 1-844-SPY-BEES, (1-844-779-2337). It is not advised to kill or spray a swarm with insecticide or water. The hotline is free and you will usually have a beekeeper come to your aide within an hour or two.

Friday, June 1, 2018

Fireblight running rampant

Posted by Carol O'Meara, Boulder County Extension

Symptoms of Fireblight include browning/blackened leaves
drooping in a classic 'shepherd's crook'

Pulling into my drive, I noticed the Honeycrisp apple tree we love didn’t look quite right.  From a small distance away, wilt was evident around its branches and a sinking feeling settled in my stomach.  Upon closer inspection, my worst fears were confirmed: this tree has fireblight.

To have an apple tree is to risk infection from this deadly disease, one that includes oozing bacteria, curled, brown leaves, inedible fruit, and spreading cankers.  This year, with several hail storms coming just as the tree was in bloom proved fatal.  Temperatures and moisture played a role in the infestation and my tree is entirely engulfed and without hope for recovery.

My tree isn’t alone.  In the past week, samples and emails have been brought to our office by people in similar situations, conversations sound more like support groups, and the disease is everywhere I look.  My mind cues up the dramatic, Hitchcockesque music each time I see another blighted tree.

It’s a banner season for fireblight, a bacterial disease that is especially destructive to apple, pear, quince and crabapple. It attacks in spring, when temperatures reach 65 degrees F and frequent rain occurs.  Bacteria overwintered in cankers on the tree resume activity, multiplying rapidly.  Hail drives the bacteria around and into woody tissues.

Fireblight bacteria moving back into the twigs, blackening the wood
Our wet early summer weather created good conditions for this damaging disease, and masses of bacteria have been forced up through cracks and bark pores to the bark surface, forming a sweet, gummy exudate called bacterial ooze. Insects are pickingd up the bacteria on their bodies and carrying it to opening blossoms where it infects trees. 
Girdling cankers – areas of disease on the wood - eventually develop from branch or blossom infections.  Leaves wilt, darken and curl to form a shepherd’s crook. This gives the tree a fire-scorched appearance, thus the name "fire blight." 

There is no cure for this disease, so prevention is the best solution. Remove and destroy newly infected young twigs as soon as possible, so that your tree doesn’t become the mother ship for disease in the neighborhood.  Do this when no rain is predicted for at least two weeks.  It may be best to leave pruning until winter when the bacteria are not active. In young twigs, make cuts at least 12 inches below the dark, visible edge of infection to avoid slicing into the bacteria. Remove all blighted twigs and cankered branches. Prune larger limbs about 6 to 12 inches below the edge of visible infection.

After each cut, surface sterilize all tools used in pruning. Spray tools with Lysol or dip tools in 70-percent ethyl alcohol, or a 10-percent bleach solution.  Bleach can rust tools, so if you use this to sterilize your pruners, wash them after you’re done and apply a light tool oil to keep them rust-free.

Be on the lookout for apple scab, a fungus that attacks leaves and fruit, which also favors cool, wet weather.  You’ll seeing the rapid spread of this disease across apples and crabapples.  At first, leaves get yellow or dark olive-colored spots, then turn yellow and fall off.  Fruit develops dark, greasy-looking spots that then become sunken. 

The disease overwinters on fallen leaves, so clean the area during fall.  Avoid overhead watering that can splash spores around. 


Tuesday, May 29, 2018

Crabgrass is Here - Finally!

Tony Koski, Extension Turf Specialist

Seedling crabgrass (May 22) in Fort Collins.
Notice the young plants are coming up in a dead
plant (a weed "cadaver") from last year. This is
why it's important to encourage healthy grass
growth in weedy lawns in the fall - to break the
cycle of seed germination the following year.
The up and down spring – periods of above normal heat and below normal cold spells – has delayed crabgrass seed germination by about 2 weeks. That’s a good thing if you were a little late putting out your crabgrass pre-emergence herbicide (aka crabgrass preventer).

But now that crabgrass HAS germinated, control efforts (if you want to control crabgrass and its warm-season weedy cousins – foxtail and barnyardgrass) should be focused on post-emergence herbicide products. Once you can see these annual grassy weed seedlings, it is too late to use a pre-emergence product.

As with any landscape pest, it is absolutely essential that you accurately identify the pest in question before purchasing and applying the control product. It makes no sense – environmentally, financially, and for your precious time – to apply a product that won’t work because you haven’t correctly identified the pest.

This is not crabgrass! Crabgrass and other seedling
grassy weeds are still very small now. This is a
clump of tall fescue - which will not be killed by
crabgrass control products containing quinclorac.
For example, crabgrass and the other just-germinating warm season grassy weeds are still very tiny now. If you have large, fast-growing, “ugly” (coarse, clumpy, wide-bladed) grass growing in your lawn NOW it is NOT crabgrass – which means that none of the herbicides labeled for control of crabgrass will eliminate these unsightly, undesirable grasses. We have blogged previously about grasses that people mistakenly refer to as “crabgrass”. These unattractive, perennial grasses can’t be controlled with either the pre- or post-emergence crabgrass control products.

What to use NOW for young/seedling crabgrass, foxtail, and barnyardgrass? The following products are available in the garden product aisle at big-box and hardware stores, and at better nurseries and garden centers. What they all have in common is the ingredient “quinclorac” (and all contain herbicides for broadleaf weed control as well, like 2,4-D, dicamba, MCPP, etc.). Quinclorac provides excellent control of the most common summer annual grassy weeds: crabgrass, foxtail, and barnyardgrass in bluegrass, ryegrass, and fescue lawns.

Bayer Advanced Lawn Weed & Crabgrass Killer (quinclorac, 2,4-D, dicamba)
Ferti-Lome Weed Out with Crabgrass Killer (quinclorac, 2,4-D, dicamba)
Monterey Crab-E-Rad Plus (quinclorac, 2,4-D, dicamba)
Ortho Weed B Gon Max plus Crabgrass Control (quinclorac, 2,4-D, dicamba)
Roundup for Lawns - Northern Lawns (make sure it’s the Roundup FOR LAWNS!; quinclorac, dicamba, MCPA, sulfentrazone)
Spectracide Weed Stop For Lawns Plus Crabgrass Killer (
quinclorac, dicamba, 2,4-D, sulfentrazone)

Crabgrass and its cousins are much easier to
control now - when they are small plants- than
in a couple of months when they have grown to a
plant of this size. Large crabgrass plants are very
difficult to kill.
It’s much easier to control crabgrass and its cousins this time of the year, when they are small. These grasses grow larger very quickly as we get sustained warm/hot temperatures. Large crabgrass plants are much more difficult to kill.

Make sure that you are spraying the right product for the weed in question! If you need help with the identification of weedy grasses – or any weed – in your lawn, you can bring a sample to your county Extension office. Or email me a high resolution photo of the grass ( 

We've blogged about crabgrass and other weedy grasses before...go here and here to see more photos of crabgrass and other weedy grasses, with hints on how to identify and control them.

And, as always, read the label for any pesticide you use and follow all instructions to ensure effective weed control and to avoid injury to your lawn or other non-target plants in your landscape.

Thursday, May 24, 2018

Springtime means mowing...and mowing again

Posted by: Alison O'Connor, Larimer County Extension

When it comes to the lawn, I'm a total Lawn Geek. I love my lawn. I'm pretty sure it stems from my days mowing lawns when I was a kid. My brother, Jeffrey, had a business called the "Lawn Ranger" and he gave me a few select clients (read: clients he felt weren't as lucrative to him). I love the smell of fresh cut grass and my sneakers stained green from all that chlorophyll. Maple the beagle also enjoys her green feet.
Maple pretending to be disinterested...but she's really proud of her green paws!
But this time of year, it's tough to keep up with the lawn and how quickly it's growing. Cool season grasses, like Kentucky bluegrass and tall fescue, seem to grow inches overnight and mowing the lawn to keep it tidy can seem like a chore. Plus, you're trying to time mowing between rain showers. Recently, it seems I've rushed home from work to mow, only to find that the lawn is too wet from a shower that blew through. Drat.

At each mowing, obey the 1/3 Rule. This means you don't remove more than 1/3 of the total leaf tissue. This helps keep the lawn neat and prevents hay piles. What this also means is you may have to mow two or three times each week in the spring since the grass is growing so fast. (For someone like me, it's great! For others, this is where mowing becomes a pain.)  NOTE: Those who do mowing for a living - commercial mowing and landscape firms, parks, etc. - mow on a schedule and sometimes can't stick to the 1/3 Rule. This is real life. Fortunately, the grass survives!
A comparison of mowing heights. The photo on the left is how tall the lawn was prior to mowing. The middle picture is ignoring the 1/3 Rule and cutting it too short. The photo on the right is mowed at the proper height for the height of the lawn.
Hay piles are ugly, often clump together and can discolor the grass. Worse, hay piles means you've removed too much plant tissue, which can stress your turf. Stressed turf is more susceptible to drought, weed pressure and disease.
(Not my yard!) Hay piles. We've all done it, but try to avoid this by obeying the 1/3 Rule.
Worse than hay piles are scalping the turf. This means you're essentially removing ALL of the leaf tissue. Doing this in the spring, even once, can result in the turf struggling all season. Don't scalp. Raise your mowing height!
I couldn't bring myself to fully scalp the lawn, but you get the idea. This is just a bit too short and the lawn will get stressed.
Over the weekend, I cut the lawn with the mower set at its highest height. The lawnmower was still sputtering and choking (so was I, for that matter). Once you get the lawn height under control, mow regularly to keep it at that height (still obeying the 1/3 Rule). Once the spring growth rush has passed, set your mower at one height all year and keep the grass at 2.5 to 3.5" tall, depending on what you prefer.
Ahhhh....fresh cut grass!
Mulch your grass clippings back into the turf. Mulching keeps fertilizer (and pesticides) in the lawn system and provides free nutrients! Grass clippings are mostly water and do not add to thatch problems. I only bag my clippings a couple times of year--when the grass gets too tall and mowing nearly kills the engine and also when I want to use clippings in the garden (or feed them to the chickens).
The garlic is lovin' the grass clippings!
Lizzy is a Lawn Geek too!
So there you have it. Maple was a good citizen and helped me mow the lawn and kept track of the height. I mowed once on Sunday and again on Monday, just to reduce the height and get the lawn a bit more tidy. You can see my progression below.
It's good to use a beagle as your measuring device for your lawn. At least the lawn isn't up to her knees anymore!

Wednesday, May 23, 2018

2018 CSU Cool Season Trial Results

Posted by James E. Klett, Professor, CSU Department of Horticulture and L.A.

The 2017-18 Cool Season Trial evaluated 121 varieties planted in mid-October 2017 through April 2018. Numerous varieties were selected as top performers by Flower Trial Garden Committee on April 25, 2018.

During the trial, all plants were monitored and observed weekly. They were watered and liquid feed until sprinklers were winterized in early November, then hand watered when soil was dry and temperature above 40ºF. There was some snow cover for about 6 to 8 weeks during the trial period. The top seven are described below. These cool season plants should be considered when planning your fall/spring color displays. They will brighten up your fall into winter displays and winter into spring displays. For more information visit our website, and click on cool season trials.

·         Best of Show Pansy- ‘FreefallXL Purple Face’ from Floranova

Plants were vigorous and sturdy as well as being covered by blooms. White centers really made the dark purple stands out. Vibrant flowers covered the plant all over including not just the top but also sides of plant. This entry also won the Best Trialing Pansy category.

·         Best Light Blue Pansy- Pansy Inspire® Plus Exp. Marina Improved from Benary 

Plants were very uniform and blooms covered the top as well as on the sides. The light blue color was around the outer edge of the flower followed by a band of white and a dark purple/blue center created a great combination of colors. A dainty appearance is created by the unique flower color combined with slightly ruffled petal edge.

·         Best White Pansy- Cats™ White from Benary 

Plants were noted for impressive flower power and a nice uniform growth habit. Attractive purple whiskers added interest to the slightly primrose colored flowers with a splash of yellow in the center. The color of this pansy would brighten up any landscape border or container planting.

·         Best Yellow Pansy- Spring Matrix™ Yellow Improved from Pan American Seed 

The bright yellow flowers were very abundant and eye catching as they were well above the foliage for maximum flower power. Clear yellow flowers had no markings so color really popped.  The abundant blooms were also noted for being weather resistant and maintained their shape.

·         Best of Show Viola- Viola Endurio® Blue Yellow with Purple Wing from Syngenta 

Plants were highly rated for great vigor and uniformity. Vibrant flowers were a combination of three different colors. Varying shades of dark purple, violet and yellow created a lot of interest and although flower color was variable the overall result was very captivating. A spreading habit makes it best massed in beds or dripping out of a container. This entry also won the Best Novelty Viola category.

·         Best Light Blue Viola- Bel Viso Marina Improved from Floranova   

Plants had a very nice mounding growth habit. The flowers were very abundant on uniform plants. The light blue flower with white centers had a smaller dark blotch for a unique eye. Its tidy and uniform growth habit makes it great for tight spaces, narrow boarders and window boxes or tucked into a rock garden. 

·          Best Yellow Viola- Bel Viso Yellow from Floranova
The vibrant blooms were a unique shade of yellow and had small dark whiskers. Flowers seemed to be slightly larger than others in this category.  The vigorous plants looked like a bouquet of prolific yellow flowers.