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June 19, 2013
Posted by: Tony Koski, Extension Turfgrass Specialist
Wait...lemme guess…you’ve got brown spots in your lawn. Well, the good news is you’re not alone, nor do you need to panic. You’ve probably got Ascochyta (ass-co-kite-a) leaf blight. And it’s caused by drought stress or an inefficient irrigation system. Whoa Nelly! You think we’ve had lots of rain? Unfortunately, that was weeks ago and our soils were so dry that the moisture was used or lost to the atmosphere almost immediately.
But I’m confusing disease versus stress. Let’s go back:
|Classic Ascochyta symptom--withered leaf tip|
|Looks like the mower did it...|
but really, it's because of drought-stressed turf.
|It looks worse than it is. After a little irrigation |
and a little time, the turf will recover nicely.
We live in the mountains. Almost by definition, that means that where we are trying to grow things involves some sort of slope. Some of them are gentle, others are steeper. This particular post will discuss planting on a gentle slope (see the article on the Mountain Gardening website on dealing with steeper slopes and planting retaining walls).
If you are planting on even a gentle slope, it is a good idea to build a shallow shelf or basin to hold water. Otherwise, most of the water goes rushing down the slope and won't penetrate to the roots.
Here's a picture of what I mean:
June 17, 2013
June 16, 2013
I think I have become something of a proselytizer for floating row covers up here in the mountains.
1. You can plant earlier -- floating row covers provide anywhere from 3 to 8 degrees of frost protection, depending on the style (frost "blankets" obviously providing more protection than the thinnest "summer insect covers").
2. They keep off insects. Your arugula will be tender and free of flea-beetle damage if you keep it covered from seed. Same goes for aphids (unless you transplant them into your garden with your seedlings)
3. They keep bunnies, deer, and chipmunks out. No more buffet lunch for these critters! And if you protect your plants with a 1/4" wire mesh beneath the beds to keep out burrowing animals such as pocket gophers and voles, you're in tall cotton. Or tall lettuce. Or whatever. It's nice to see all of my seedlings growing where I planted them, rather than going out to survey the damage each morning. Makes for a much more peaceful existence!
|My new garden with mesh below and floating row cover above -- I'm not battling anything!|
4. You can water right through it. And it keeps moisture in for much longer, reducing watering needs. Heather, who works with me in the office, has been amazed at the difference in the soil moisture in the areas she has covered vs the areas she didn't. She said she had never really used them before, but has now become convinced of their utility. Hurray! Another convert!
5. It protects plants from the nasty drying winds we've had lately. Tender seedlings will quickly be battered to death by the powerful winds that seem to accompany the last days of May and the early part of June.
6. Lettuce and other salad greens are more tender and succulent. Maybe not quite as nice as a greenhouse, but pretty darn good!
7. Plants grow right up under the cover -- it just "floats" over them without squishing. Make sure you have some excess cover at the edges to allow for growth, otherwise as the plants gain height, the row covers will squish the plants (since the cover should be anchored down).
Tips for using floating row covers:
- You can buy floating row covers at garden centers or online (big box stores usually don't carry them)
- Keep the wind from ripping off your cover by using soil anchors, large rocks or lengths of rebar or fence posts. I have come to prefer the latter method the best - it's easier to lift off the posts/rebar, and voles and small chipmunks can scurry under if there are gaps (ask me how I know this!).
- It is harder to water through the row covers when there are hoops holding the cover up -- it tends to just slide off to the edges. For the most part, I don't find hoops to be necessary, and the hoops raise the cover higher into the air where the wind can catch it more easily.
June 15, 2013
|Two Spotted Spider Mite, photo courtesy Clemson.edu|
Spider mites are not insects, but are arachnids which include spiders, ticks and scorpions. They are a common pest problems on many plants, evergreens and trees in yards and gardens in Colorado. The most prevalent is the two-spotted spider mite and they are no bigger than the end of a sentence!
House plants can also be host to the spider mite. One must be persistent with the pest since eliminating them can take months. Unfortunately, you may have plants or evergreens die due to a heavy infestation.
As for biological controls, various insects and predatory mites feed on this mite. One reason the spider mite becomes a problem in yards and gardens is the use of insecticides that destroys their natural enemies. Adequate watering during dry conditions can limit the importance of drought stress on spider mite outbreaks. Periodic hosing of the plant with a forceful jet of water can physically remove and kill many mites. They spread webbing under the leaves and the water may delay egg laying.
Spraying chemicals is not recommended unless the mites are numerous and natural enemies are not present. Chemical control of spider mites generally involves pesticides that are specifically developed for spider mite control. Because most miticides do not affect eggs, a repeat application at a ten to fourteen day interval is needed for control. Horticultural oils and insecticidal soaps can be utilized but oil can suffocate the plant by covering the stoma openings that the leaves use to breathe.
As for many evergreen cultivars, the soaps and oils can remove the silvery blue-gray color from the needles. The color will return in the next year's growth in most cases. Don't use sulfur spray unless it has been shown to be safe for that plant in your locality. Sulfur is a skin irritant as well as an eye and respiratory hazard, so always wear appropriate protective clothing.
June 14, 2013
If you live in the mountains, you surely practice what I call the "hardening off" dance.
You have houseplants like geraniums that want to spend the summer outside.
You have seeds that you started inside.
All of these plants need to be slowly acclimated from their nice pampered existence indoors to the harsh realities of the mountain climate.
|Houseplants and seedlings hardening off in the shade|
I recommend first putting them outside on a cloudy day or in the shade, in order to expose them to wind.
Then expose them to gradually increasing amounts of sunshine - dappled first (if you can find it), then full sun, then longer periods of full sun.
Of course, at this time of year, there's always the threat of frost, so even after the plants toughen up a bit, I watch the forecast, and bring them in if it threatens to drop below freezing. Hence "the dance".
Okay, confession time. Despite knowing better, I had been harboring a common juniper less than ten feet from my house (in defensible space zone 1, the most important area to mitigate that is closest to your house --see this publication for more details: http://csfs.colostate.edu/pdfs/FIRE2012_1_DspaceQuickGuide.pdf ).
Junipers are extremely flammable due to their high resin content, and should be removed from zone 1. I knew this, but I liked the way it looked in its bed, and I just couldn't bring myself to remove it.
|Garden bed after the Juniper was removed. I forgot to take a before picture.|
Nothing like teaching a class on fire preparedness followed by firewise landscaping to make you practice what you preach! I finally ripped it a couple days ago when the snow all melted. I'll have to review the bed once the remaining plants come in to see what I want to do with it. On the bright side, I guess it gives me a new opportunity to buy plants -- I didn't have many open spaces left in my garden.
For more information on firewise landscaping, please see this fact sheet: http://www.ext.colostate.edu/pubs/natres/06305.html
I meant to get this post out earlier, but I just didn't have time!
Many winter annual weeds have already come up: cheatgrass, alyssum, field pennycress, and more. The key to controlling winter annual (and summer annual weeds a little bit later) is to control them before they go to seed. The trick is to get all of the seeds that germinate, and to not let any go to seed. New crops may come up from the seeds that are in the soil; get them while they're little, too. A few years of persistence, and you will find dramatically fewer weeds. But persistence is the key!
In a perfect world, you'd just hoe them all under when they look like this:
|Field pennycress (Thlaspi arvense) just germinating -- so easy to hoe at this stage|
|Cheatgrass (Bromus tectorum) before flowering. Just hoe - no need to bag.|
This is the ideal stage to control these annuals, because there are no flowers and thus no seeds, so no need to pull and bag seed heads -- a tiresome and land-fill intensive process. Also, the root system is small and fragile. It is very satisfying to go out and destroy thousands of weeds with a few whacks of the hoe. Sort of like the fairy tale of "the Valiant Little Tailor" who kills seven with one blow. This is also a good time to use an herbicide, if that's what you prefer.
Depending on where you live and the weed, it may or may not have gone to seed already (sorry I didn't get this posted sooner!).
|Cheatgrass gone to seed|
As I was working in our demonstration garden a couple of afternoons ago, I admired the lacy blue-green foliage and abundant yellow flowers of the golden smoke, or Corydalis aurea that had seeded its way around the garden. It is a native pioneer plant, readily colonizing disturbed, open soils. Given how the pocket gophers routinely take out parts of the garden every year, I am grateful for its willingness to fill in and cover that bare ground. It is pretty short lived, and can start to look ratty in the garden later in the season, but while it is at its prime, like it is right now, I let bloom merrily away.
|Golden smoke or Corydalis aurea|
This is all probably familiar to many people who grow in the mountains. What's the discovery, you say? It has an unusual, sweet smell! Somehow, I had never realized it until the other day when I was weeding. I kept smelling something sweet on the air that I couldn't recognize. I kept looking around at all the plants, but most weren't blooming yet, and most of them weren't fragrant, anyway. It finally dawned on me that it was the golden smoke, and I confirmed it by getting down on my knees and putting my nose in the plant. Who knew?
Another fun factoid about this plant with which I was already familiar is that the seeds are ant-dispersed. The seeds have a tiny little nutrient-rich appendage on it (an aril or elaiosome). Ants gather the seeds, bring them into their nests and feed the elaiosome to their larvae. The seeds are left intact (and safe from predation) to germinate later. Cool little mutualism, there.
June 13, 2013
Posted by: Micaela Truslove, Broomfield County Extension
|Zinnias attract pollinators, so are a great |
companion plant for the garden. (Photo:
Yarrow (Achillea millefolium) is a great example of a flower with
shallow nectaries and small flowers which can be used in the garden
to attract beneficial insects (courtesy of Carol O'Meara, Boulder County
|Lady beetles, especially in the larval stage, are|
predators of many insect pests. (Photo: Micaela
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Last updated: June 20, 2013 04:00 AM