CO-Horts

CO-Horts

Thursday, July 24, 2014

A Darn Good Year for Fire Blight

Posted by: Alison O'Connor, Larimer County Extension

It seems that the summer of 2014 has been the "best year ever" for fire blight. I've never seen it so much and for awhile, our Extension Office phones were ringing off the hook about people seeing brown branches and crooked twigs from this bacterial disease. Fortunately CSU has a very good Fact Sheet on the subject.

If you haven't seen fire blight, it's characterized by the tip of the branch curling over, resembling a Shepard's crook:
The Shepard's crook of fire blight
If you look further down the branch, most of the leaves will be brown and you'll see a distinct darkening along the stem where the canker has infected tissues:
The bacteria turns the branch/stem a dark brown/black color
So what is fire blight? Well, as I mentioned, it's a bacterial infection caused by Erwinia amylovora that only occurs on plants in the Roseaceae family (apples, crabapples, mountain-ash, hawthorn, etc.). Remember, the Roseaceae family is one of the largest families in our landscapes, so it can affect a number of plants.

Infection can occur in a number of ways...through cracks in the bark or pores in leaves, on insect bodies, by splashing of the spores via rainfall or irrigation and through other natural openings. There seems to be a correlation between fire blight and hail-damaged trees from the previous summer. The bacteria kills cambial tissue (where the xylem and phloem are located) and continues to move down the branch.
Everything brown on this tree is fire blight
It's important to note that the tree will try to ward off the spread of the bacteria. Some species and cultivars are better at doing this than others. While a tree may be labeled as "resistant" to fire blight, it can still get the bacterial infection, but it's better at "sealing" off tissues to stop infection. The bacteria survives winter inside infected tissues and tends to ramp up during warm, wet springs. There is generally bacterial ooze associated with this disease.

So what can you do? Well, the best control is to plant resistant varieties. But that's easier said than done. You can prune out infected tissues during the growing season, but it's crucial that you sanitize your pruning tools between each and every cut. That means you have to spray them with Lysol or Listerine or dip them in a 10% bleach solution. Does this sound like a pain to you? It is. I've done it.

Or you can live with the ugliness of the tree this summer and prune out infected areas during the dormant season. By waiting, you don't have to sanitize. But you have to wait.

Regardless of when you prune, the current recommendation is to cut 8-12" below the edge of visible infection. This is a lot of extra branch you're taking off. And if the infection has moved into the main trunk of the tree, it's best to make a final pruning cut at the base.

For a personal anecdote, I was just at the Gardens on Spring Creek in Fort Collins. One of their apples was absolutely annihilated with fire blight. The director and the city forester were discussing the tree and they came to the conclusion to remove the tree. After making all the pruning cuts to remove the infected branches, the tree would have looked unsightly and wouldn't resemble the proper shape.

There are some pesticides that can be used, both as a dormant control and during flowering. The University of Minnesota Fact Sheet has information on the various types of pesticides that can be used to prevent new infections.

Tuesday, July 22, 2014

Weed of the Moment: Crabgrass and its look-alikes

By: Tony Koski, Turfgrass Specialist

Guess what? You might actually be seeing crabgrass in your lawn this time of year! It was late germinating this spring (we didn't see it in Fort Collins until late May), but now it's large and in charge. This is crabgrass in late May:
Young crabgrass
Now it looks like this (late July):
Small (smooth) crabgrass (Digitaria ischaemum)
Small (smooth) crabgrass--growing in concrete!
(That's a joke)
Small (smooth) crabgrass near sidewalk
Crabgrass seedhead
Many think they have crabgrass, but they don't. Here are some other crabgrass look-alikes that are often called crabgrass, but misidentified...

This is not crabgrass; this is bromegrass (wide, coarse blade; often a "W" watermark on upper tip of leaf):

Bromegrass in a bluegrass lawn
This is not crabgrass; this is annual bluegrass (characteristic apple green color; often with seedheads):
Annual bluegrass in a Kentucky bluegrass lawn
And this is not crabgrass; this is tall fescue (clumps of grass with rough edges on the leaf blade):
Tall fescue in a bluegrass lawn
 This isn't crabgrass either; this is orchardgrass (flat "stems" and tall white ligule):

The ligule is located like a collar on the inside of the leaf

Orchardgrass in the lawn
And no, this isn't crabgrass either; this is yellow foxtail (characteristic red base, yellow-y color):
Yellow foxtail, which can easily be confused with crabgrass.
The great news is that the same products that work on crabgrass
will work on foxtail.
Yellow foxtail--look at that distinctive red color!
Finally, this isn't crabgrass--this is bermudagrass (forms runners, invasive, pointy leaf tip):
Bermudagrass
Crabgrass is characterized by its prostrate growth habit, especially after mowing and a light, apple green leaf color. The seedheads are digitate (finger-like) and will begin forming in earnest in August. Crabgrass is a warm season grass (and a summer annual), so it will die with the first frost.

If you want to control it now, use any herbicide product containing quinclorac (such as Ortho Weed Be Gon Max Plus Crabgrass Control, Fertilome Weed Out Plus Q or Bayer All-in-One Lawn Weed and Crabgrass Killer). Be aware it may take more than one application to completely kill this persistent weed. It's much easier to control when it's a seedling or use preemergence products in early spring.

The big point to make, with the exception of foxtail and crabgrass, is that quinclorac will not work to selectively remove tall fescue, bermudagrass, bromegrass or annual blugrass from your lawn. So identification of grasses that LOOK like crabgrass is essential before you start spraying herbicides willy-nilly.

Wednesday, July 16, 2014

Here Comes 'da Judge!

Note: While this entry is about entering cookies at the county fair, it could be entering anything, from the dinner-plate dahlia to biggest zucchini to strawberry jam. County Fairs tend to bring out the competitor in all of us in a desire to win the elusive blue ribbon.


Written by: Linda Wilson, CSU Extension Master Gardener in Larimer County

It is 14 days and counting until I come before “The Judge”.  It’s almost Larimer County Fair time, which means it’s time for cookie judging.  You might think winning blue ribbons would be easy for someone who’s been baking for six decades.  Well, it’s not—because my family members are not the judges.

The Fair judges are professionals with consumer science degrees, experience and a list of eight (!) criteria which must be met “…to the letter of the law” (judges’ instructions).  They take their instructions seriously, and even the audience of highly qualified cookie monsters cannot convince them that a medium size cookie is larger than 2 ½ inches!

I start preparing for next year’s fair the very same day as judging.  Why so early you ask?  Well, if you really want to win blue ribbons or champion ribbons, you need to pay attention to the judges’ remarks as to how your current entry did or did not meet the criteria.  Besides, it is always ego-building to hear the judges argue as to why your entry deserves the Champion Ribbon.  It’s not about the $2.00 premium awarded for each blue ribbon, it’s all about the “prestigious honor”—at least that’s what all my taste testers say when I complain about how much I spend on groceries making the winning entry.  (Personally, I think they just enjoy having the treats!)

Here is what I’ve learned about my chocolate chip trial recipes this year:  First, adding almond butter to the basic recipe makes the cookies lighter, but they are dry and are not “characteristic” of a chocolate chip cookie (characteristic is one of the eight criteria).  Secondly, using cake flour instead of all purpose flour yields a 6” cookie which cannot be removed from a hot cookie sheet, because it has the consistency of a wet paper towel.  Finally after using four bags of chocolate chips trying new secret ingredients, my entry will be using last year’s recipe, but making the cookies the correct size.


So, today I’m left wondering, “When the outside temperature is 95 degrees, why am I still heating the oven to perfect recipes?”  Prestigious, competitiveness, or just plain nuts….you be the judge! I know I'm not the only one out there who enters the fair. What do you plan to enter this year?

Tuesday, July 15, 2014

Mystery Plant of the Month: July 2014

Posted by: Linda Langelo, Golden Plains Area Extension

This sample came into my office while working in Wray, Colorado. Any guesses on what this unusual species is? Hint: It's not a Colorado native!



Thursday, July 10, 2014

Plant This Not That: Russian Sage Edition


 
Eric Hammond Adams County
 
Russian sage (Perovskia atriplicifolia)

Let me start by saying that I’m sure there are places for Russian sage in the landscape.   They are tough plants and I’m told they are very unappetizing to deer.  It’s just that I’m sick of seeing their leggy, sprawling and spreading forms in every hell strip, median, shrub border and foundation planting along the Front Range.   Plus, my neighbor has one along our shared fence and it’s continually trying to colonize my yard- oh the indignity. 

 
Russian sage suckering its way under my fence



So I thought I might try and encourage a little diversity by highlighting some similar plants that are a little better behaved and, at least to my eyes, more attractive.   There are actually quite a few smallish shrubs or shrub-like plants that have similar ornamental attributes to Russian Sage.

 
Blue mist spirea (Caryopteris incana and Caryopteris × clandonensis)-

 
Blue Mist Spirea Flower

Blue mist spirea has very similar flower color and timing to Russian Sage.   However, it lacks its sprawling and uneven habit and though it will occasionally come up from seed it does not spread nearly as aggressively.  The remnants of its fruit also add texture to a landscape in the winter months. They are fairly common and easy to find.
Blue Mist Spirea Winter Texture
Mojave sage (Salvia pachyphylla)-




This sage develops showy purple flowers mid-summer.  The foliage is fragrant and semi-evergreen remaining silvery-green late in the fall and early winter.   Once established, plants require little water and in our demonstration garden tend to struggle during wet winters.
Inflorescence of Mojave sage late in the summer

 

Lead Plant (Amorpha canescens and A. fruiticosa)-

 
 Lead plant

There are two species of lead plant commonly grown along the Front Range, A. fruiticosa and A. canescens.  Both are attractive landscape plants which develop purple flowers midsummer and have blue green foliage.  A. fruiticosa is the taller of the two species.  They are low water use once established and are tolerant of infertile soils.  They are native to the plains and in my opinion seem to fit more naturally into western landscapes.    


Lead plant flower
Newly planted lead plant

Catmint- (Nepeta sp.)-

Catmint

There are a number of different species, hybrids and clones of catmint.  They come in a variety of different heights and several flower colors, but most of those which are common to Front Range landscapes have purple flowers which provide color throughout late spring and summer, especially when deadheaded.   Catmint also attracts a variety of pollinators and butterflies to the garden.
Pollinators are often attracted to catmint



Tuesday, July 8, 2014

Hort - a new trend in camping?

Posted by Irene Shonle, Gilpin County

I just got back from a camping trip  (note to self - avoid I-70 over major holiday weekends!).

As I was walking around one evening, I was amused to notice a mini-trend:  people were bringing plants with them on their trips and decking out their campers:




... or using them as tent canopy weights:
A bit hard to see, but look just above the right-hand blue chair and across
This could possibly save the age-old dilemma of how to deal with your houseplants when you go on vacation -- bring them with you!

Monday, July 7, 2014

Weevil Wisdom


By Jane Rozum, CSU Extension, Douglas County
There’s a new Horticulture Agent in Douglas County, me. There’s so much to learn, from my new environs to the new work routine. Then there are all the garden questions from around the county, What’s this plant? What’s that bug? In the last few weeks, the number of calls to our office is skewed towards insects. In my county, I’m lucky. The Director, Joe Julian, is an entomologist.   When he’s not available to answer questions about insects, however, they fall to me.
Even though I’m a newbie horticulture agent, I’m not new to the question/answer routine in Extension offices. Before going back to school for a Master’s degree, I was a Colorado Master Gardener (CMG) in the northern Front Range for many years. So I have learned what most seasoned CMGs know, there’s always something you don’t know and the challenge is figuring out the problem.
White pine weevil damage on spruce. (Photo courtesy of David Leatherman.) from White Pine Weevil CSU Fact Sheet 5.606
Take for instance, a plant sample that was brought to the CMG in the office a week ago.  This sample was from the terminal end of a Colorado Spruce and was dead. The homeowner stated that it wasn’t just one young spruce in the landscape with this symptom, it was 20. Ugh. My knee jerk reaction was to rattle off reasons for top dieback in spruces, but the sample didn’t fit my usual responses.  The new terminal growth was bent in a shepard’s crook and the inner bark had been stripped leaving just the dead outer bark. There were also sawdust covered oval patches with a larva inside.

White pine weevil chip cocoons. (From Fact Sheet 5.606)
I was stumped. So I did what any new horticulture agent would do: I went into my office and googled, ‘spruce terminal dieback, sawdust cocoon’ on my computer. Eureka! There I found an exact description of the symptoms from CSU Fact Sheet 5.606: White Pine Weevil (Pissodes strobi). Say, what? But the homeowner’s plant is a spruce! With all my experience as a CMG, I had never come across this insect.
As I left my office to talk to the Master Gardener, another CMG had arrived and was explaining to the first: Yes, this is the White Pine Weevil and is a common problem in the Castle Rock area in young spruces. The adults hibernate in leaf litter in the winter, then climb up the tree to the terminal branch to feed a bit and lay eggs just under the bark. When the larvae emerge, they feed under the bark, girdling the terminal tip. As the larvae mature, they make their way down the terminal tip, and at some point decide they’ve had enough and pupate, covering their bodies with sawdust. When adults emerge from the cocoon, they feed a bit on needles and bark, then head down the trunk to hibernate in the leaf litter until next season.
How could an insect that didn’t seem to bother the spruces of urban Northern Colorado Front Range be thought of as ‘common’ just 70 miles south? Thanks to CSU experts, the answer is ‘elevation’. In Ft. Collins, Loveland and other Front Range cities, the elevation is around 5,000 feet. In Castle Rock and Colorado Springs, the elevation is above 6,000 feet. Why would a 1000 feet make a difference for this insect? Only it knows, and it isn’t talking.
As I start my horticulture agent career, the same mantra will prevail as it did when I was a Master Gardener: There is always something you don’t know and the challenge (and fun) is figuring out the problem. Bring it on, Douglas County, I’m ready for more challenges to come my way!
To find out more about White Pine Weevil, check out our CSU Fact Sheet 5.606.