CO-Horts

CO-Horts

Tuesday, April 28, 2015

Frozen III: The Cold Snap Story Continues….

By Jane Rozum, CSU Extension Horticulture Agent, Douglas County
 
When I last wrote a blog article about last November’s Cold Snap on December 23, 2014 here, I talked about the needle damage on evergreens along Colorado’s Front Range. I related the story of our mild October weather and how temperatures went from the 50° F range to well below zero (-15°F in some areas) in 24 hours or less. Conifers hadn’t acclimated to our cold winter temperatures and many needles froze and turned brown. Some trees had significant needle browning; many young trees were lost. Colorado State Specialist Tamla Blunt authored a bulletin which described the reasons why evergreens received damage.

Since December, Extension professionals in the Front Range and Eastern Plains have been fielding calls from homeowners worried about their evergreens. Some questions have touched upon whether deciduous trees and shrubs were affected by the Cold Snap. Now that spring is here, we are seeing what appears to be Cold Snap damage to these landscape plants.
Thanks to CSU’s PestServe list, green industry and Extension professionals as well as Colorado Master Gardeners and citizens have been chronicling the damage which has been observed on deciduous landscape plants. So far, the list of plants which demonstrate cold damage dieback, sometimes to the ground, is rather lengthy:
 
Trees:
Fruit trees such as Apple, Pear, Cherry
Pyrus calleryana- Callery Pear – less blooms
Prunus cerisifera ‘Newport’
Plums
Salix sp., especially Globe Willow
 
Conifers: Juniper, Arborvitae (in addition to previously observed damage to pines, spruces, etc)

Shrubs:
Burning Bush (Euonymus alatus cultivars)
Cotoneaster species
Rose – cane dieback to ground
Euonymus fortunei cultivars
Boxwood (Buxus sp.), burned or damaged
Privet (Ligustrum)
Spirea
Weigela
Buckthorn (Rhamnus sp.)
Holly
Barberry (Berberis cultivars)
Daphne (Carol Mackie cultivar)
Hibiscus syriacus
Silver Lace Vine Polygonum aubertii  

As more trees and shrubs leaf out, we may continue to see damage from landscape plants that were affected by the November Cold Snap. What have you noticed in your landscape? Please feel free to comment on whether you have seen significant dieback on woody and other landscape plants this year.

39 comments:

  1. I was most mystified about my Silver Lace. I didn't think anything could cause so much die back on that hardy vine. I do see new growth on one of them, but none on the other. Good luck everyone!

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  2. My holly has apparently died. I covered my young cherry and it is doing well. The frost peach is budding out, no flowers yet. No flowers on the pear or apple. The crabapple trees all seem to be fine. Lilacs also are fine. I live in Morrison.

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  4. What remedy to you recommend for damaged trees and shrubs? My Carol Mackie daphnes (established for about five years) are leafing out in only small areas. Should I cut out the "dead" wood? Or, wait a couple of weeks to see if any further leafing out occurs?

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    1. I would check if the buds on damaged trees and shrubs are alive...shriveled dry buds indicate that twig tip is dead. We are seeing the same problem with Carol Mackies in Douglas County. You may want to check to see if the branch buds are dead and wait a bit before pruning to see if it is just late in leafing out.

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  5. Lost about 15% of weigela, all boxwood$ (that character is on purpose); 12 year old pears look awful (very few blooms, stilted leaf development), neighbors arborvitae are pure brown where they weren't fully protected to the south. I am still waiting on the Kentucky Coffeetrees! They don't look very happy... Roses, juniper, crabapple, and burning bush are fine. Euonymus doesn't look good, but is coming back! Central Denver near Botanic Gardens.

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    1. I can be the chemical trail that are killing all the trees.We will be starved to death by the powers that be.Control the food than you control the mass

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  6. Will the shrubs ever come back or should we just replace them?

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    1. It depends on the shrub. In my landscape, I have cut back those shrubs that have died back and waiting to see new growth. If they don't make a decent comeback in my landscape, they will be replaced.

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  7. We live on the eastern plains not far from KS/NE border and we are seeing poor blooms and leafing out on crabapple and ornamental pear. The worst seems to be Euonymus alatus very spotty growth in mature shrubs and little coming at the base. And Euonymus fortunei and Cotoneaster varieties are only showing growth at the base, severe dieback of whole shrub. Other plants showing dieback include spirea, potentilla and can dieback on roses.

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  8. So far all our large cottonwoods and silver poplars have only leafed out on the very ends. Sent out catkins, but no leaves on the interior of the trees. Crabapples are struggling with only a few leaves; two cherries have no leaves, buds are dry, but the twigs do not snap - so we will wait and see. Three apples are marginally ok, one is iffy. Waverly area. Replies?

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  9. May 5, 2015 Loveland Colorado near foothills . Crab apples didnt bloom. Leaves came out from the top down. Fruit trees. We're weeping. Apricot grown from seed (15 yr old) are leafing out from the top down as are some of the apples. Cherries look dead but still have pliable branches . Not one fruit tree blossomed. Cotoneasters and 90% of lilacs all survived. Will be interesting to follow.

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  10. My Jonathan flowered and is leafing out. The Granny Smith just 20 feet north of it has not a single leaf. Is the tree a goner?

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  11. Fort Collins: I have five privet bushes that still haven't leafed out and think the frost may have caused massive twig dieback. Should I trim them down the ground in the hope they'll eventually send up new growth in the next season?

    Does the extension office have any recommendations for a hardy replacement that will tolerate moderate shade? I'm thinking Siberian Peashrub or perhaps a Viburnum.

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    1. If your privets have not yet leafed out, you may want to cut them back to where there is growth. No growth at this point (mid-June) may mean they need to be replaced. CSU Extension recommends many shrubs that do well in our climate. Go to www.ext.colostate.edu, and use the search feature to look for a Fact Sheet on Shrub varieties.

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  12. Two cherries, one old and one young, no leaves. With the warm days of Feb their buds were getting bigger then the rain and freeze. The buds dried up and fell off to your touch. Branches and tips don't snap but remain flexible. Will they put any leaves on this year? We are usually picking cherries by end of June. The raccoons have even come back and appear quite disappointed. Our burning bushes are finally putting on leaves from the base so I'll trim off the dead cane. Not a good year for my 150+ variety of irises since the warm/rain/freeze. They goose necked as bud stalks inner cells collapsed but it's amazing what the sun coming out can do. Straightened up their stalks. Those buds had freeze damage. Snow wouldn't have been a problem, it was all the rain, saturating them, followed by the freeze. In Feb it appeared we were 2 weeks ahead of schedule now we are a month behind. Good luck everyone! South Suburban Golf Course area, south western part of Centennial.

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  13. Lost 6 of 10 fruit trees, 3 cherry, 1 apple and 2 peaches, no sign of coming out but branches are pliable. Greeley Area

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  14. Lost 3 Crabs apples. No sign of leaves, or buds but the branches are a bit pliable in spots still. Lost 4 elms - two of which are quite large. Two I grew from Seeds. Pretty heartbroke about them. I know they are just elms but nothing grows out here where it's hot and there are no other trees. My Boxwood 1/2 of it died. Is there any chance any of them will come back? 3 of the 10 Crabs have leaves on ONE branch or just the trunk in spots. Do I cut them down? What about my big elm tree??

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    1. At this point (mid-June) you should see growth on your boxwoods. You can check to see if the twigs are alive by scraping your nail on the twig. If the tissue underneath is white or green, it's alive, if it's brown and brittle, it's dead and should be removed. You may want to consult a certified arborist about your Elm trees to see if they need to be removed.

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  15. N of Longmont - 4 of my 5 20-year-old globe willows have leaves on only 1 or 2 branches; the other put out a couple of leaves that have shriveled up. A robust weeping willow put out leaves in April but is now losing them all. Anyone have experience with these willows after cold damage? I'm hoping that CSU Extension is continuing to monitor these comments, because many of us have been patiently observing our trees since the April 30 replies.

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    1. Willow also seem to be hard hit by the Cold Snap. The leaf shriveling could be from another frost (many Metro Denver areas were hit by a Mother's Day frost ) or the tree may not have enough reserves to maintain leaves on the tree. Our wet May also may have water-logged the soils and killed roots. You may want to consult with your Extension office about your tree.

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  16. My plum tree, as well as two of my neighbors' trees and a friend's tree 3 miles away seem to all be dead, little to no leaf growth. I am assuming this i due to the cold snap/snow in May. Question: are they dead, all the plum trees in Denver or are the damaged but will come back?

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    1. Not all plum trees died in the Cold Snap or the Mother's Day freeze. It is hard to know why some where affected and others were ok. You can check to see if the twig is alive (see other reply above) or consult a certified arborist or call your local Extension office to talk about specific problems with your tree.

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  17. I live in downtown Brighton. I have a weeping cherry, a sour cherry, a Bing Cherry, an Italian plum and a Granny Smith apple with no leaves. Some branches are pliable. Are they dead? Should I remove them or wait and see what happens next year.

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    1. If the tissue beneath the bark on the twigs is pliable and is white or green, your trees may still be alive...but no leaves this late in Spring is worrisome. You may want to consult with your local Extension office via phone or email (send photos) about your trees.

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  18. Large 16 yr old Weeping Willow and a smaller curly willow in Thornton have one to two branches with very few leaves. Talked to a tree service who told me they both had to come down as there aren't enough leaves to sustain them. Felt silly but was actually crying while receiving the news. IS THERE ANY HOPE? I have to decide soon if I am going to have them chopped down.

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  19. So sorry to hear about your trees. Willows were hit hard by the Cold Snap and many did not survive up and down the Front Range. You may want to consult your Extension Office (send photos if you can). You may also want to see if your county office has a Certified Arborist list so you can get a second opinion about your trees.

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  20. We live in the Masonville area. Our 8 foot Rose of Sharon did not leaf out at all but the branches seem pliable but no buds. Our Elberta Peach tree is the same. Out of four Apple trees, three have only leafed about 50 % of their size. Should we wait and see and keep water and fertilizer on them and hope for the best? Also Dutch Elm has hit our area hard. Are they gone or might come back?

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    1. Again, Fruit trees were hit hard by the November storm, many did not leaf out this spring. If they haven't already leafed out, I would check again to see if the twigs are still alive. At this point in the year, trees need leaves so they can send energy to the roots; if they haven't leafed out yet, they may not survive. I'm not sure I understand your question about Dutch Elm disease, but the fungal pathogen is still around and can infect American Elm trees. There are new cultivars that are resistant to Dutch Elm disease

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  21. I have a weeping willow that has grown a ton each of the last 4 years. It was leafing out in May until we got 6" snow on Mothers day. All the leaves died and it hasn't leafed out again like my maple trees. The branches seem pliable still and a bunch of shoots keep trying to sprout out of the trunk at the base. Is it dead or will it leaf out next year? I'm in Castle Rock.

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    1. Water sprouts at the base of the tree and no growth at the branches is not a good sign. If you don't see growth from the branches this year, it means the top growth may have died. If you are uncertain, you may want to consult with a certified arborist.

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  22. So my plum tree still has not leafed out and it is now late July. We have fed it with fertilizer made for fruit trees and sprayed the tree and surrounding area with kelp fertilizer. We have plenty of suckers pushing up, which we have been removing to conserve the tree's energy. It did have a few leaf clusters in mid June and a single flower but those have all withered and died. Is there hope for this tree or should we remove it now and replace it with a new tree in the fall?

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    1. It is difficult to recommend removal without seeing the tree; it is your call on whether you need to replace the tree or not. If the tree does not have leaves at this point, it won't have the energy to push new growth next year.

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  23. My 2 apple trees have lots of leaves on their branches, but no apples (they're on 2 different properties here in the Denver area). Do you think the cold snap affected them? Will they produce fruit next year?

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    1. The mid-May freeze most likely killed the flower buds, so no fruit this year. We can be hopeful that next year we won't have an ill-timed frost.

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  24. My Barberry did not leaf out this spring in Syracuse, NY. There was a hard freeze in the lat winter -25 degree F, after what was a warm December. There is new growth at the bottom. Barberry are 3 feet in diameter. When I break a a twig it is light green in the on the perimeter. Should I cut it all the way back to the new growth? Or should I wait until next Spring before cutting it back hard to the new growth?

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  25. We have a ornamental crab apple tree in our front yard. a couple of years ago a section of the tree showed damage. Fewer, smaller leaves and much lighter color than the rest of the tree. This year the bark is pealing on the east side of the tree only. ( the troubled section is supported by the bark that died.) I noticed the problem first after applying Black munch that was quite wet and it rained a lot shortly there after. The section has leaves this year but not as thick as in past years. If a neighbor applied round-up to a rock area next to the tree would this cause a problem with the roots on that side of tree? ( rock area on east side of tree )

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