Tuesday, December 21, 2010

Good Advice on Winter Watering

These articles come from two posts on another blog that I follow, and I thought I would post them here as well.  Along the Front Range, we are in a moderate to severe drought, depending on where you live.  With no appreciable moisture since the end of July, it's a challenge to keep our plants healthy.  Winter watering can help.  Check out these posts on Gardening After Five. 



Thursday, November 18, 2010

Updated MPB Information

I thought a recent post by Dave Leatherman, retired CSFS Entomologist, regarding Mountain Pine Beetle would be beneficial as an update on the behavior of the beetle along the Front Range and questions we are receiving regarding when to spray.  

"If less than a full compliment of beetles hits an urban tree (i.e. an 'unsuccessful' attack from the viewpoint of the beetle), two patterns have been common the last several years:  
  1.  a band of pitch tubes at mid-trunk, with very few on the basal and upper parts of the trunk, or
  2.  a gradation of pitch tubes, heaviest at the base, fizzling out about 10 feet above the ground.

The great, great majority of such trees survive, at least the initial attack.  These sorts of trees, however, do seem prone to re-attack, sometimes later in the same season, sometimes the following summer.  If the trees have high value, rigorous inspection to determine the success of the attack is in order.  IF the tree will not die from the attack in question, preventive spraying is warranted.  The historical spray timetables have become problematic and spraying anytime during the April to early November period might be warranted, depending on the specific circumstances and wishes of the consumer. 

Three things seem clear:  1) the flight season of the beetle is not just late July thru early August anymore (more like April thru early November, with two peaks, one in July-early Aug, and the other mid Oct-early Nov),  2) with the flying beetle population being diluted at any one time over a period of month, successful attacks resulting from a single attack are fairly rare among urban trees, and 3) foliage fading in relation to when observers first see pitch tubes is all out of whack.

For urban areas in CO, NE, and WY and the MPB attacked trees I have seen of late, the following statements apply: 
  • The hosts are overwhelmingly either Scots or Ponderosa pine, the pitch tubes are often large and 'runny' (as would be characteristic of unsuccessful, 'pitch-out' type tubes);
  • IF the attacked trees die, they didn't die of a single attack; most attacked trees display pitch tubes of varying hardness (indicating initial and later attacks);
  • IF the attacks are successful and result in a big emergence of beetles, the trees are usually still green-needled (at least not obviously brown) when this occurs;
  • Emergence is usually in October or November (but sometimes 'on schedule'  in July-August);
  • Relying solely on external evidence is more dangerous than ever because of the above;
  • A hatchet/under-bark-peek is more needed than ever to make a proper diagnosis (and because of the preponderance of strip attacks, looking under the bark on more than one side of the tree is a wise move).
In urban areas, assuming the trees are of suitable diameter (6 inches or more at breast height), I would put pines into three categores:  Likely to be attacked, sometimes attacked, and rarely attacked.  The likely to be attacked pines are Scots, Ponderosa and Lodgepole.  The sometimes attacked would be Limber and Bristlecone.  The rarely attacked pines are Austrian, Mugo, Pinyon, Spruce and other pines."

Thursday, October 14, 2010

Another Tree Problem

Dr. Ned Tisserat, Extension Plant Pathologist, was asked by the city forester in Boulder to come take a look at some Red Oak trees that were declining in one of the parks in the city.  The symptoms are branch dieback with borer holes in the trunks of the trees.   After further investigation, it appears that the branch dieback may be associated with Kermes scale, but the borer holes in the trunk caused by a flat-headed borer were unusual.  Dr. Tisserat isolated Fusarium solani from an area surrounding the borer galleries, but also noticed a gummosis on the branches.  This gummosis was in close proximity to the Kermes scale.  Isolations were done and the gummosis was the result of a bacteria which was identified as Brenneria (Erwinia) quercina.  This bacterium has been previously associated with 'Drippy Nuts Disease' on oaks in California and with an oak decline in Europe.  More investigation is needed to understand if the Kermes scale is contributing to the bacterial infection, where the bacterium is originating from and how the flat-headed borer is involved in the infection process, if at all. 

Tuesday, September 7, 2010

Tomato/Potato Psyllid

This year along the Front Range of Colorado has been devastating for fresh market potato producers and home gardeners alike.  The culprit this year is an insect, the tomato/potato psyllid, which comes to us courtesy of the southern states and Mexico.  They arrive via the southerly air currents that bring us other pathogens like wheat rust.  This insect injects a toxic saliva into the plant that causes the potato to turn yellow with curled leaves.  Potatoes are smaller or non-existent, reducing harvest yields considerably.  Dr, Whitney Cranshaw, CSU Extension Entomologist, was interviewed recently by 9News reporter Adam Chodak.  The video link is attached. 

Tuesday, August 3, 2010

Update on Thousand Cankers Disease

The following is an excerpt from an email sent to several listservs by Whitney Cranshaw regarding a new confirmation of Thousand Cankers Disease in Tennessee.
"Thousand cankers disease of walnut has been confirmed from Tennessee.  This was first identified about 10 days ago with a sample we received from Knoxville, but a formal announcement has been pending per the Tennessee Department of Agriculture's wish to delay announcement for further confirmations.  As this has been done, and I see an AP report on the internet, I think that we can now let it be generally known. 

The known infestation is in and around Knoxville.  As this is a fairly recent find, the extent of the infestation has not been delimited.  But the extent of the infestation suggests that this disease (i.e., the walnut twig beetle and its associated fungus, Geosmithia morbida) has been there for a decade or more.

This is a disaster of tremendous proportion.  It had been my deepest hope - clearly a naive hope - that this problem would stay bottled up in the western states where black walnut, Juglans nigra, is planted but not native.  I had long ago given up that black walnut would survive in the West and that is a sad situation, but not tragic.  Now that it is irrevocably established in the center of the native distribution of Juglans nigra, there are no geographic/ecological barriers to prevent its ultimate spread throughout the US.  Furthermore, the fact that the disease appears to be progressing as a lethal tree killer in Tennessee as it has been doing for 10-20 years in the Rocky Mountain States answers the question as to whether this is a regional problem.

It also suggests that there may well be many other infestations in the Midwest that have gone undetected.  This is a very difficult disease to detect in early stages.  Apparently in Tennessee, as in our area, what attracted attention were plantings that showed symptoms of apparent drought stress.  But it is not drought stress nor related to drought.  For some help with this situation we have a web site:  http://www.colostate.edu/Depts/bspm/extension%20and%20outreach/thousand%20cankers.html.  There are sheets on diagnosis, Q & A, and a fact sheet (that needs a bit of updating).  Also available are links to pictures and powerpoint talks, including the version of "Nightmare on Walnut Street" that I presented at the ISA meeting last week in Chicago.

I am assuming that there will now be a scramble to have state quarantines become a reality.  As I understand it, following Missouri's lead, that Nebraska, Kansas, Michigan and Indiana have or are in the process of enacting state quarantines that restrict movement of certain Juglans material that originates from TCD-affected states.  And this disease is a deal breaker.  It is relatively slow to develop, at least compared to DED or EAB, but its progress will be inexorable.  My guesstimate from watching it in urban settings is that about 30 years after this is introduced into a city, all the black walnuts will be dead.  That is based on the disease taking 10-20 years to show symptoms after the initial point infestation and 10-15 years for it to progress across a city once the first symptomatic tree is detected.  How this disease will progress where there are native stands affecting the epidemiology will undoubtably change things in ways we will all have the unfortunate chance to see in the upcoming years. 

However, containment/slow the spread is still something we need to throw ourselves into.  The longer you can delay the introduction of the disease (by movement of fungus contaminated walnut twig beetles), the longer your black walnuts can survive.  Perhaps with dedicated effort we can push back the ultimate effects of this disaster for a generation or two in many areas, giving us valuable time to develop means of managing it and finding resistant cultivars."

Posted by Whitney Cranshaw, 8.2.2010

Wheat Virus Survey Results

Since wheat harvest is now finished and we are headed into corn season, I thought I would share the general results of the wheat virus survey.  In this survey we test for five known wheat-infecting viruses, Cereal Yellow Dwarf Virus (CYDV, formerly known as BYDV-rpv), Barley Yellow Dwarf Virus (BYDV-pav), High Plains Virus (HPV), Wheat Streak Mosaic Virus (WSMV), and Triticum Mosaic Virus (TriMV). A total of 368 ELISA's (enzyme-linked immunosorbent assay) were performed in the diagnostic clinic. Of all the ELISA's run, 252 of these were for the wheat breeding program.  There were a total of 116 wheat samples sent in to the clinic from growers, extension agents and crop consultants.  The results of those 116 samples were 79 virus positive and 37 virus negative.  The results reported here are the compilation of the 79 virus positive wheat samples from growers and do not include the results of the wheat breeding program.

  • 39 samples had single virus infections; the sample was positive for only one of the five viruses tested.
    • CYDV (3 positives)
    • BYDV-pav (13 positives)
    • HPV (6 positives)
    • WSMV (14 positives)
    • TriMV (3 positives)
  • 40 samples had co-infections; meaning the sample was positive for two or more of the viruses tested.
    • 32 samples were co-infected with 2 viruses
    • 7 samples were co-infected with 3 viruses
    • one sample was co-infected with 4 viruses
    • there were no samples that tested positive for all five viruses
  • Of the 32 samples that were positive for two viruses, 17 of those samples were positive for WSMV and TriMV.
Overall, WSMV is still the number one wheat virus in our state, either singly or co-infected with other viruses.

Thursday, May 27, 2010

Summer Reminder--Don't Move Firewood

Yesterday a news release was sent out from the Colorado Department of Agriculture reminding folks who are planning to go camping not to take firewood with them, but instead to 'Buy It Where You Burn It'.  The concern is that insects and diseases can be transported by moving wood from different parts of the country and even within the state. 

The complete article can be found at http://www.colorado.gov/cs/Satellite?blobcol=urldata&blobheader=text%2Fhtml&blobkey=id&blobtable=MungoBlobs&blobwhere=1251632560946&ssbinary=true

Wednesday, May 26, 2010

More Stripe Rust News

This morning we received information that stripe rust has been confirmed in the southern panhandle of Nebraska.  It was found in two fields south of Chappell, NE located in Deuel County.  One field was irrigated and the other field was dryland.  The irrigated wheat was in the boot stage and the dryland wheat had the flag leaf emerging.  This information was provided by Drew Lyon at the Panhandle Research and Extension Center in Scottsbluff, NE. 

So what does this mean for Colorado growers?  If we have another round of cool, wet weather, the impact of stripe rust could be severe.  We are already receiving spotty reports from the Northeast area of CO as well as western Kansas and with this new information, chances are it is in the NE part of the state.  If the temperatures warm up and we start drying out, we may not see much stripe rust, but Mother Nature never was very good about letting us know her intentions.  As far as we know, the stripe rust resistance in varieties such as Bill Brown, Hatcher, Hawken, Infinity CL, Snowmass, TAM 111, Thunder CL, Winterhawk, Yuma/Yumar is still holding.  There is mounting evidence that the resistance in Jagger, Jagalene and derivatives of these varieties may have been broken. 

Friday, May 21, 2010

Stripe Rust is in Colorado!

Posted by Ned Tisserat and Scott Haley on the Cereal Rust Survey listserv:  Multiple observations of stripe rust on wheat have now been made in Eastern Colorado.  We just received three samples in the Diagnostic Clinic yesterday that confirms these observations.  Infections thus far are most prevalent in the southeast part of the state but it appears to be moving north as would be expected.  Infections at this point appear to be at low levels, but good moisture and continued moderate temperatures may promote its continued development.  Wheat in SE Colorado is mostly a few days either way of the heading growth stage.  If you are out scouting fields and find rust, we would like to have samples sent to the Diagnostic Clinic so we can forward them to WSU for race typing. 

Some Insect-Issue Thoughts and Predictions

Whitney Cranshaw, CSU Entomologist/Extension Specialist is providing his thoughts on insect issues that we may or may not see this summer: 

"This part of the state has had quite a spell of unusual weather.  Last fall we had a severe cold snap on October 13 and a very cool winter, often with some snow cover.  It has been above average with moisture, continuing the trend of last summer, and this spring has been very cool, with everything delayed.  Based on those conditions and some other things, I am going to guess on a couple of insect related events."

YellowjacketsDown.  The cold, wet spring is going to have the colonies get off to a slow start.  Furthermore last year wasn't great for them and the winter may have knocked out some queens.

Honey BeesVery rough start.  Late summer/early fall conditions were poor for setting up winter stores that allow colonies to survive winter.  Then this spring was late with bloom.  We now have abundant blooming, but weather is usually too cool for foraging.  Altogether this has to be very stressful for colonies and I suspect many starved out.

European mantids (aka 'praying mantid').  Down.  At least around here this is a marginally adapted insect.  It tends to be abundant in seasons when the previous winter was mild.  Last winter was not and I suspect that many of the eggs were killed.

Tobacco budwormDown.  Another marginally adapted insect that will freeze out if the overwintering pupae freeze.  Last winter there was a lot of deep soil freezing, which should have dinged the populations.

Squash bugs, Striped cucumber beetlesDown.  At least around here these also are marginally adapted insects.  They tend to be abundant in seasons when the previous winter was mild.  Last winter was not and I suspect that the overwintering adult stages of both of these had above average mortality.

Mites on lawnsWay down.  Good winter moisture in many places made clover mites a minor issue this year.

Miller mothsDown.  Low numbers were present last year and few eggs likely were laid in fall.  There have been no reports of cutworms active in crops yet, further suggesting that the insect numbers are low.  Plus, with all the moisture there will be abundant flowering of native plants which will provide an abundance of nectar sources for the moths; they will not aggregate around landscape plantings as occurs in drought years.  Flights will be later than normal, below normal in total number of  moths, and will be dispersed so people will not notice them as serious nuisance pests.

Aphids on trees and shrubsUp.  Cool, wet springs usually signal prolonged, heavier activity of many aphids at least until the end of June when natural enemies (e.g. lady beetles) come roaring back.

SlugsUp.  Last season was a building year.  They should be in great shape heading into the 2010 season.

Wednesday, May 12, 2010

Isn't Spring in Colorado Wonderful?

Wow!  It's May 12th and in a normal environment we would be admiring bedding plants placed around the patio and watching our vegetable transplants slowly acclimate to their new surroundings in your garden.  But we live in Colorado where spring snowstorms seem to come out of nowhere and all of a sudden our gardens and landscapes are turned into 'plantsicles' under the weight of the snow.  Driving into the CSU campus this morning I noticed that the damage on the west side of Fort Collins appears to be worse than the central or east side of town, although there is still plenty of damage to see.

I did make a few observations this morning on the damage that has occured:
  • The trees that are damaged most heavily appear to be trees that are in full flower (crabapples especially seemed hard hit) or fully leafed out. 
  • Trees with a spreading habit rather than upright also seem to be harder hit.
  • Trees that have not fully leafed out, such as Lindens, appear to have very little to no limb breakage.
  • Trees with a pyramidal shape (some of the ornamental pears, etc.) also appear to have very little to no limb breakage.

The recommendation would be to get out and inspect your landscape as soon as feasible for any signs of breakage or damage.  http://www.ext.colostate.edu/mg/gardennotes/616-MatureTrees.html will provide information on when and how to prune trees, if needed, as well as providing information on when or if there is a need to hire a certified professional arborist.  Here on campus this morning, the tree crews were already out pruning trees and cleaning up fallen branches. The road around the Oval was closed to traffic to allow crews to get the job done.  The elms around campus have really taken a beating this season with the early fall snowstorm and now the late spring snowstorm.  Hopefully all the damaged trees will survive in good shape.  As always, if you have any questions, you can contact the Plant Diagnostic Clinic at CSU or contact your local County Extension Office for more information.

Thursday, March 25, 2010

Official CSU Protocol on Medical Marijuana

There has been much discussion between Extension Agents, Specialists and Diagnosticians regarding diagnosis of disease or insect problems related to medical marijuana. The following protocol has been vetted by CSU Legal Counsel and Extension Administration:

The General Counsel's staff at Colorado State University has informed CSU Extension of the following in regards to medical marijuana. These restrictions apply to all CSU Extension staff members to include Master Gardener Volunteers.

1. While the use of medical marijuana is legal in the state of Colorado, marijuana remains a schedule 1 illegal drug under Federal law and as such, Colorado State University Extension cannot be involved with this item.

a. Assistance with medical marijuana plant health questions will not be provided.
b. Individuals requesting such information will not be provided referral information.

2. Our offices are considered drug free workplaces as CSU is a Federal contractor.

a. Marijuana plants and/or plant parts are not permitted in CSU Extension offices.
b. Marijuana plants or plant parts delivered to or left at CSU Extension offices will be turned over to legal authorities for destruction.

3. If CSU Extension employees or volunteers (including Master Gardeners) assist medical marijuana growers, they will be acting outside the scope of their employee/volunteer role and assume personal liability for any legal action that may be taken against them.

Based on this information from General Counsel, the Plant Diagnostic Clinic will not accept marijuana plants for diagnosis, nor can we offer assistant via phone or email.

CSFS Talking Points on ODC

Here in the clinic, we've received several phone calls regarding the effectiveness of a product on the market called Organic Disease Control or ODC. The product is a colloidal chitosan which states that it will increase resin production in trees to help reduce attacks by Mountain Pine Beetle. Sky Stephens, Colorado State Forest Service Entomologist, has provided talking points regarding this product. To date, no testing has been done to determine the impacts of Agrihouse ODC on mountain pine beetle in lodgepole or ponderosa pine. One point from the information provided is that until specific testing is done to determine the impacts of ODC on mountain pine beetle, CSFS encourages landowners to use well-tested products with a proven track record to protect important pine trees on their land.

CSFS Talking Points Regarding ODC (pdf)

Monday, February 15, 2010

Pine Wilt Nematode and Mountain Pine Beetle Along the Front Range: Is There a Connection?

We've received several samples in the Diagnostic Clinic this month of Scots pine that have been hit with Mountain Pine Beetle (MPB) from areas along the front range and one of those samples also had Pine Wilt Nematode (PWN) (Bursaphelenchus spp.). So we are asking ourselves, which came first, MPB or PWN? And, is one exacerbating the other? To see if we can answer this question, we are collecting samples of MPB hit Scots pine that are being cut down in counties along the Front Range to process for PWN to see if there is any correlation. The specific counties we would like samples from are Larimer, Weld, Boulder, Adams, Jefferson, Denver, Arapahoe and Douglas. The samples should be from trees no higher than 6000 ft elevation. The samples should be collected from branch areas closest to the trunk and should be no more than 3 inches in diameter and about 6-8 inches in length. Samples will be processed at no charge to the submitter. Samples should also be sent within 1-2 days of the tree being cut down. Samples can be sent to the Plant Diagnostic Clinic, E215 Plant Sciences Bldg, Colorado State University, Fort Collins, CO 80523-1177. If you have any questions, feel free to call us at 970-491-6950.

Tuesday, February 9, 2010

Dr. Tisserat's Turf Presentation at ProGreen

Dr. Tisserat's ProGreen presentation on common turfgrass diseases and their control. If you weren't able to make it to ProGreen or just want an extra copy, the presentation is in PDF format and the link is below.

ProGreen Turfgrass 2010 Presentation

Friday, January 29, 2010

Answering Questions About Spraying for MPB and Other Bark Beetles

I've fielded several phone calls this week regarding Mountain Pine Beetle/Ips Beetle and whether homeowner trees in the urban areas should be sprayed for prevention of MPB/Ips attacks. I asked Fort Collins Assistant City Forester Ralph Zentz, and his reply is as follows:

"In the Front Range urban areas, the main host is still Scotch/Scots Pine (about 80% or more). Austrian pines are rarely hit and I have not seen or heard of any othe them being killed by MPB in any of the communities. Ponderosa is the second most hit species of pine in our cities, but lodgepole, pinyon, bristlecone, eastern white pine and others have been hit as well. Mortality in scotch pine runs about 10% when they are hit; the same is true for Ponderosa.

In the foothills and mountains of the Front Range, the MPB population is building in the native Ponderosa according to Dave Leatherman, Entomologist, formerly with CSFS.

Spraying should occur prior to May, however there may be a few earlier flights, but (in my opinion) not enough to warrant earlier spraying. It is critical that people realize that just because a tree is hit, it does not mean it will be killed from the pest. 10% or less mortality is reported from all the communities from Colorado Springs north to Fort Collins."

In a previous blog posting, there is a link to 'Mountain Pine Beetle Information' from October 30, 2009 that provides the most recent information compiled by the Colorado State Forest Service and Colorado State Extension. Scroll down to the date and the link is at the end of the posting.

The links to fact sheets from CSU Extension on MPB and Ips/Engraver Beetles are posted here. These sheet should also provide information for concerned homeowners.

As always you can call the Plant Diagnostic Clinic with your questions, or contact your local County Extension office for the latest information.

Monday, January 4, 2010

New Colorado Dept. of Agriculture Regulations on Japanese Beetle

Colorado Department of Agriculture is instituting new regulations for the importation of plant material into Colorado that will protect Colorado by reducing the introduction of Japanese Beetle into the state. These regulations will take effect on January 1, 2010. Links to the regulations, a presentation to Extension Horticulture Agents and Best Management Strategies for Control of Japanese Beetle are at the end of this post. These new regulations have no effect on what growers can ship out of Colorado. These regulations only affect plant material (which includes, among other items, soil, compost, manure, and grass sod) imported into Colorado from states east of Colorado. Any questions regarding these new regulations can be directed to Laura Pottorff, Colorado Department of Agriculture, Nursery Program Manager, 303-239-4153.

Best Management Strategies (PDF)
Presentation to Extension Horticulture Agents (PDF)
CDA Regulations effective 1.1.2010 (PDF)