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Flooding
Flooding

SATURATED SOIL can lead to problems with roots of trees and shrubs, and ultimately contribute to death or uprooting of trees. When soil becomes saturated through over-watering or heavy rains, plants cannot develop new fine feeder roots that are responsible for uptake of nutrients. A good root system also anchors a plant well into the planting site. Development of a good root system can take time, and over-watering can prevent root growth and establishment. Plants with an under-developed root system are more prone to stress and root disease. Subsequent stress from drought that may occur later in the season can lead to death of plants that do not have a good root system. Trees and shrubs without a good root system are more prone to upheaval and toppling during storms with wind. Proper planting and soil preparation with good drainage may prevent problems in the future.

Saturated soil can also lead to problems in row crops, field crops, vegetables and turf. Good drainage can help  to avoid problems with root rot that may move in following flooding and saturated soil.

Flooding in a corn field
Flooding in a corn field - image courtesy of Daren Mueller

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Steve Hutton - President and CEO of Star Roses and Plants/Conard-Pyle Dr. Michael Dobres - Managing Director of Nova Flora LLC Kathleen Case, Facilitator, Cindy Zook Associates Dr.Thomas Bewick - USDA NIFA, National Program Leader for Horticulture
Steve Hutton - President and CEO of Star Roses and Plants/Conard-Pyle
Dr. Michael Dobres - Managing Director of Nova Flora LLC
Kathleen Case, Facilitator, Cindy Zook Associates
Dr.Thomas Bewick - USDA NIFA, National Program Leader for Horticulture

A two day national Rose Rosette Disease Summit was held in Newark, DE April 15 and 16, with researchers from across the country meeting to discuss the disease, and plans for future research.  Rose rosette disease (RRD) is caused by the rose rosette virus, carried by a tiny eriophyid mite.  The Summit was organized by Dr. Michael Dobres of the Conard-Pyle Company and Dr. Tom Evans of University of Delaware, and sponsored by the All-America Rose Selections and the Garden Rose Council, Inc. The conference included a talk given by Nancy Gregory of UD Cooperative Extension on occurrence and mapping of the disease. RRD has been seen in Mid-Atlantic States since approximately 2001, originally observed on multiflora rose in the landscape. In recent years, RRD has been identified on cultivated roses, including Knockout rose, and has also been identified in public gardens.  University scientists, plant breeders, Cooperative Extension personnel, USDA representatives, private consultants, and rose growers discussed the need for good diagnostic tools, accurate mapping, cultural controls, as well as breeding for resistance. Current control strategies include keeping roses in good vigor, pruning, mite control, and cultural controls such as reducing water on leaves.

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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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Stewart's wilt - image courtesy of J. Pataky, University of Illinois
Stewart's wilt - image courtesy of J. Pataky, University of Illinois

Winter Temperature Index For Predicting Stewarts Wilt 2013

Temperature indexes averaging 106 to 113 combined degrees for December, January, and February, indicate that flea beetle populations could be high. If flea beetles are carrying the bacterium that causes Stewart's wilt in corn, the disease could be a problem this year. Please see the report by clicking the link. Resistant varieties are available, as are controls for flea beetle populations. See the 2013 Delaware Commercial Vegetable Production Recommendations for control Suggestions.

 

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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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  • Advanced symptoms of TCD on black walnut (thinning of crown and bunchy growth toward center of tree)

    August 2012 - THOUSAND CANKERS DISEASE CLOSE TO DELAWARE

Thousand Cankers Disease of Walnut (TCD) is widespread in Virginia in 2012. TCD was confirmed in 2011 in Bucks County, PA, three weeks after a find in Virginia. This disease may already be present in our area, but has not been confirmed. Look for dying walnut trees in  June, July and August showing yellowing and thinning of branches. Samples should be submitted to the UD Plant Diagnostic Clinic. Please see the latest fact sheet:
http://www.colostate.edu/dept/bspm/extension and outreach/TCD Pest Alert Revision for 2012.pdf

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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