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Tag: plant disease

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Healthy Douglas FirChristmas Tree Planting Tips

The lifting, storage, and transport involved in shipments of evergreen planting stock can have long lasting effects. Planting stress affects root quality, and those effects can last beyond planting and can cause plants to not recover completely. Water is probably the most important factor. The system can be thought of as keeping a checkbook. Each stress subtracts from the quality balance remaining for tree health. Some tree nurseries allow for freezer storage of seedlings that may help preserve moisture in the plants and plant roots. Plugs need different care than bare root stock. Proper planting and care to have roots set properly can avoid J root which will cause long term stress on trees.

http://extension.udel.edu/ag/plant-diseases/christmas-trees/

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2014 Meeting of the NJDelMarVaPa Plant Pathologists
2014 Meeting of the NJDelMarVaPa Plant Pathologists

The 69th annual meeting of the NJDelMarVaPa Plant Pathologists was held April 1, 2014, at the University of Delaware.. The informal gathering was hosted this year by Nancy Gregory and Nathan Kleczewski, and serves as a regional update for colleagues and for networking. Attendees included Cooperative Extension personnel, and pathologists from state Departments of Agriculture and from USDA ARS. Information was presented on plant diseases, diagnostics, and field trials.

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MANAGEMENT OF BOXWOOD BLIGHT (caused by the fungal pathogen Cylindrocladium  pseudonaviculatum) will be important in our area over the next few years, after detections in MD, DE, and PA. Be cautious when bringing new boxwood plants into a site with established boxwood. A nursery quarantine or watch area may be a wise thing for landscapers to set up, putting plants on a watch for 4 to 5 weeks before installing in a landscape planting.

Black streaks on twigs of boxwood with boxwood blight
Black streaks on twigs of boxwood with boxwood blight

Dr. Karen Rane, diagnostician with University of MD, spoke with Dr. Jim LaMondia from the Connecticut Ag Experiment Station and Dr. Kelly Ivors from North Carolina State University recently, regarding management in a landscape with mature boxwoods. They emphasized that, if all infected boxwoods are not going to be completely removed and destroyed, then pruning out and destruction on-site of all infected branches is necessary to reduce inoculum.  Just a few fallen leaves will serve as an important inoculum source.  Dr. Ivors said that nurseries in NC use a flamer (used for weed management in organic systems) to destroy fallen leaves on the soil surface after plants have been removed.  Vacuuming hard surfaces using a shopvac can also help to remove fallen leaves.  Drip irrigation system instead of overhead can be important in management.  Wetting of foliage promotes splash dispersal of spores as well as providing the optimum environment for spore germination and infection. Sanitation and fungicide applications will be extremely important for a few years to control boxwood blight. One year of management will not be enough, because microsclerotia in fallen leaves can survive for several years, and serve as a source to cause infections if new growth is not protected.

Dr. LaMondia and Dr. Ivors emphasized the use of protectant and systemic fungicides in combination to help protect new growth from disease and to reduce sporulation.  A spray that includes chlorothalonil should be applied a day or two prior to pruning out diseased material in order to kill spores on the surface of the infected tissue, or soon after pruning.  Both researchers recommended using combination sprays containing both a protectant and a systemic fungicide either as a tank mix of two products with different modes of action or using a pre-mixed product that contains two active ingredients. Both suggested chlorothalonil as the best protectant product.  Fungicides sprays should be alternated every 2 weeks when conditions are favorable for disease, as one or two sprays in a growing season will not control boxwood blight. Dr. LaMondia suggested starting with a tank mix of thiophanate-methyl +chlorothalonil, followed two weeks later with a propiconazole + fludiozinil (Medallion) spray.  Dr. Ivors suggested alternating Palladium (fludioxinil and cyprodinil) and Spectro (thiophanate methyl and chlorothalonil).  The addition of a spreader sticker may be necessary to improve coverage but check individual product labels. Products should be applied by a certified professional with the proper equipment for coverage of large plants, according to the fungicide label. Please see the following web site for some chemical recommendations and rates: http://www.anla.org/docs/government%20relations/boxwood%20blight/7.22.13-BB.pdf

NFG 9/3/13

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Phytophthora root rot, a soil borne disease caused by a fungus-like organism, is a widespread problem which can affect many of our woody and herbaceous landscape plants. Azaleas, hollies, and rhododendron are probably the most frequently affected plant group in the landscape, especially in wet soils. Submit a sample including roots to the Plant Diagnostic Clinic and we can confirm what the problem is. Don't continue replanting with susceptible hosts. Increase drainage and plant a more resistant shrub or tree.  The best control for Phytophthora is to avoid getting it started in the first place. Phytophthora is favored by planting susceptible species and cultivars in poorly drained soils, or by overwatering even in sites with adequate drainage. Once a Phytophthora problem is established in a landscape site, the best option is probably to remove the affected plants and replace with resistant species. Some possibilities include Ilex glabra (inkberry holly), Clethra alnifolia (summersweet), Itea sp (sweetspire), Physocarpus opufoliius (Eastern ninebark), and Leucothoe fontanesiana.  Examples suggested by extension agents in North Carolina include nandina, Chinese holly (cultivars including 'Rotunda', 'Dwarf Burford' and 'Carissa'), liriope, Indian hawthorn, and Camellia sasanqua cultivars (Camellia japonica is susceptible). The rhododendron hybrids: Caroline, Martha Isaacson, Professor Hugo de Vries and Red Head are considered resistant.  In addition, the azalea cultivars 'Formosa', 'Fred Cochran', 'Fakir' and 'Corrine Murrah' are considered highly resistant.  Other resistant azalea cultivars include Rhododendron poukhanese, Formosa, Fakir and Corrine Murrah, 'Merlin', 'Hampton Beauty', 'Higasa', 'Pink Gumpo' and 'Delaware Valley'.  Susceptible cultivars include 'White Gumpo', 'Hinodegiri', 'Hershey Red', 'Coral Bells', 'Pink Pearl' and 'Hino Crimson'.  Susceptible cultivars are also among the most widely planted. Camellia sasanqua is resistant to root rot while C. japonica is highly susceptible. Keep in mind that resistant hybrids are not immune. Chemical control is generally not practical for the homeowner, and involves a drench or injection by a certified applicator.

NFG 7/1/2013

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Boxwood blight caused by the fungus Cylindrocladium pseudonaviculatum was confirmed in a retail nursery in Delaware on June 19, 2013.

Leaf spot on boxwood infected with the boxwood blight pathogen
Leaf spot on boxwood infected with the boxwood blight pathogen

 

Black streaks on twigs of boxwood with boxwood blight
Black streaks on twigs of boxwood with boxwood blight

Boxwood blight was first identified in the U.K. in 1994 and then in the U.S. in October of 2011. The disease has been identified in nurseries and landscapes on boxwood and pachysandra. It has been confirmed in NC, CT, VA, RI, MD, MA, OR, NY, PA, OH, and Delaware. It was identified in the UD Plant Diagnostic Clinic in 2012, but came from plants in Maryland. In June of 2013, boxwood blight was identified in a retail nursery in Delaware.

See the new fact sheet from University of Delaware Cooperative Extension at: http://extension.udel.edu/factsheet/boxwood-blight-caused-by-the-fungus-cylindrocladium-pseudonaviculatum/

See the links below from American Nursery and Landscape Association and Connecticut Agricultural Expt Station:

www.BoxwoodBlight.org

http://www.ct.gov/caes/cwp/view.asp?a=3756&q=500388

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Attendees at the 2013 NJDelMarVaPa Plant Pathology Meeting at UD in March
Attendees at the 2013 NJDelMarVaPa Plant Pathology Meeting at UD in March

The 68th annual meeting of the NJDelMarVaPa Extension Plant Pathologists was held in at the University of Delaware in Newark, DE on March 21, 2013. The one day meeting has been held at the University of Delaware for all of its 68 years, and was hosted this year by Nancy Gregory.  The meeting has traditionally been a day to share field trial results, interesting plant disease reports, and to allow graduate students to present research to a small group.  It has always been a chance for regional Extension professionals to network and interact on a day filled with scientific presentations and good conversation.

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Results of the short survey we passed out at the recent DNLA Landscape and Turf Conference.
79 surveys were completed, out of approximately 120 persons in attendance (66%):
65% were aware of the UD Plant Diagnostic Clinic
48% were aware of the services offered by the UDPDC
20% utilized the services by submitting a sample
50 % of submitters (10% of overall surveys) submitted more than one sample.

Many lawn and landscape professionals do not know about the Clinic. If they do, they often contact the county offices to submit a sample (which is absolutely fine). Many submitters are repeat submitters!

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Swiss needlecast is an increasing problem on Douglas fir trees. This fungal disease results in yellow to brown tips of second and third year needles on lower branches. Needles will drop in late summer.  Look for fungal fruiting bodies along the stomates on the underside of the needles. Fungicide sprays must be used to control this disease when spores are released in the early spring during wet weather.  Spray when new shoots are 1/2 to 1 inch long and spray again two weeks later.  Please contact your local Cooperative Extension office for recommendations on specific fungicides to use.

Fruiting Bodies of the Swiss Needle Cast Fungus on Needles