Agriculture & Natural Resources

Hot Topics in Plant Health

This page is used to highlight some of the current HOT TOPIC plant health related issues that are occurring in the state of Delaware.

  1. June 2017 Delaware Cooperative Extension Horticulture Short Courses - June 8, 2017

    Pest and Beneficial Insect Walks, $15  Wednesday, June 14, 4-6 pm, Sussex County Extension Office, 16483 County Seat Highway, Georgetown OR Wednesday, June 21, 4-6 pm, University of Delaware Botanic Gardens, 531 S College Avenue, Newark.  Meet at the e … Continue reading June 2017 Delaware Cooperative Extension Horticulture Short Courses

  2. Clubroot Disease of Brassica species - May 25, 2017

    Chinese broccoli, Brassica oleraceae var alboglabra was diagnosed in the UD Plant Diagnostic Clinic  this week with clubroot, a disease caused by an oomycete fungus- like pathogen. Plasmodiophora can be found persisting in the soil and may be moved alo … Continue reading Clubroot Disease of Brassica species

  3. Red Imported Fire Ants Found in DE - May 22, 2017

    Red imported fire ants have been successfully kept out of Delaware by inspection and eradication efforts of Delaware Department of Agriculture. A recent detection was made in palm trees shipped in from Florida. http://news.delaware.gov/2017/05/22/care- … Continue reading Red Imported Fire Ants Found in DE

  4. Ash Rust - May 17, 2017

    Ash rust, caused by the fungus Puccinia sparganioides, is a disease which affects white and green ash in Delaware. Symptoms on ash appear in mid-May as small yellow to yellow-orange spots on upper leaf surfaces. About ten days later bright orange-yello … Continue reading Ash Rust

  5. National Public Gardens Day May 12 - May 11, 2017

    Friday May 12, 2017 is National Public Gardens Day! Find a garden near you, many have reduced or free admission, and special events. https://publicgardens.org/about-public-gardens/ NFG 5/11/17 orange azalea, Winterthur Gardens, DE    

  6. FUNGICIDES AND BACTERICIDES Available for Home Use 2017 - April 18, 2017

    A 2017 listing of FUNGICIDES AND BACTERICIDES Available for Home Use is posted on the UD Cooperative Extension website: Fungicides Bactericides Available for Home Use-2017    This listing includes commonly found products at local garden center and “big … Continue reading FUNGICIDES AND BACTERICIDES Available for Home Use 2017

  7. New Pest Alert for Allium Leafminer - April 17, 2017

    Allium leaf miner also called onion leaf miner has been detected and confirmed in Lancaster County PA recently. This is a new pest in the U.S.  which affects all onions, chives, shallots, garlic, but the most sensitive is leeks. This pest can also affe … Continue reading New Pest Alert for Allium Leafminer

  8. Invasive Flowering Pear - April 6, 2017

    BRADFORD PEAR trees are blooming now in our Mid-Atlantic landscapes. Also called callery pear, with some cultivars such as Cleveland Select, the flowering pear trees are native to China. Weak in branch structure, these V-shaped trees usually split or l … Continue reading Invasive Flowering Pear

  9. Storm Damage in the UDBG Garden March 2017 - March 16, 2017

    The storm on Tuesday left broken branches and damage due to freezing temperatures. Broken tree branches UD campus    

  10. New Citizen Science Project – A Tree’s Life! - March 16, 2017

    North Carolina State is starting a “citizen science” project to help understand how climate and urbanization affect tree growth and carbon sequestration. You can be a part of this project and follow tree growth over the next few years. A study of red m … Continue reading New Citizen Science Project – A Tree’s Life!

  11. 72nd Meeting of the NJDelMarVaPa Plant Pathologists - March 12, 2017

    Tuesday March 7, 2017 was the 72nd meeting of the NJDelMarVaPa plant pathology group, held at the University of Delaware. We had a good meeting and some lively discussions! Student work was presented, as well as research and disease updates from region … Continue reading 72nd Meeting of the NJDelMarVaPa Plant Pathologists

  12. National Invasive Species Week Feb 27 through Mar 3, 2017 - February 28, 2017

    Invasive species may be insects, plants, fungi, animals, or other invasive types of organisms. Invasive species establish at the expense of our native flora and fauna. Be on the lookout for unusual types of things. Early detection and partnerships for … Continue reading National Invasive Species Week Feb 27 through Mar 3, 2017

  13. Apply Horticultural Oil to Control Scale Insects! - February 6, 2017

    We have a couple of good temperature days in which to apply horticultural oil to control scale insect pests… today and tomorrow. FROM: Stanton Gill, Extension Specialist in IPM and Entomology, University of Maryland, February 6, 2017: If you have tim … Continue reading Apply Horticultural Oil to Control Scale Insects!

  14. UD Plant Diagnostic Clinic Final Report 2016 - February 1, 2017

    During 2016, the Plant Diagnostic Clinic processed approximately 656 non-survey routine clinic samples. Nursery surveys for Delaware Department of Agriculture resulted in a few samples of boxwood and gardenia.  Other samples were diagnosed in field sit … Continue reading UD Plant Diagnostic Clinic Final Report 2016

  15. Black Walnut Toxicity - January 6, 2017

    Black Walnut Toxicity refers to the inhibition of the growth of plants located near black walnut trees. This is due to a type of allelopathy, where one plant produces a substance that inhibits growth of another plant growing nearby. Black walnut produc … Continue reading Black Walnut Toxicity

  16. Care of Poinsettias 2016 - December 12, 2016

    Take care in transporting poinsettias home from the store. Use a paper bag or plant wrap if available to protect plants from cold and wind. Poinsettias are tropical and prefer temperatures between 60 and 75 degrees F.  Rapid changes in temperature can … Continue reading Care of Poinsettias 2016

  17. Delaware Christmas Trees - December 5, 2016

    This season, many people are shopping for a perfect cut tree or live tree to decorate their homes.

  18. Accurate Mushroom Identification is Important - December 2, 2016

    There have been reports in the news recently regarding the use of mushrooms for health and wellness. Mushrooms and specific fungal strains have long been known to have medicinal or nutraceutical properties. Consumption of fruiting bodies, powders made … Continue reading Accurate Mushroom Identification is Important

  19. Combating Rose Rosette Disease - November 13, 2016

    At The University of Delaware, our faculty member Tom Evans and his graduate student Danielle Novick are part of a large group across the country investigating rose rosette disease, the virus, the mite, and the roses.  Researchers are looking into bree … Continue reading Combating Rose Rosette Disease

  20. It Was An Acorn Year! - November 9, 2016

    Survival of oak trees depends on acorns, and the number of acorns varies from year to year. It seems there is no rhyme or reason to the production of acorns, and that variation may actually help oak trees survive. Drought stress or temperature fluctuat … Continue reading It Was An Acorn Year!

  21. Fruit Rots on Pumpkins - October 21, 2016

    Pumpkins are one of our favorite fall decorations, food sources, and animal feed sources in Delaware.

  22. Boxwood Blight Fact Sheet Updated Sept 2016 - September 20, 2016

    Click for New Updated Fact Sheet on Boxwood Blight DE fact sheet Sept 2016 The fungus Calonectria pseudonaviculata (Cylindrocladium pseudonaviculatum) causes severe defoliation and death of container grown boxwoods, and dieback in older plantings. Most … Continue reading Boxwood Blight Fact Sheet Updated Sept 2016

  23. Bacterial Leaf Scorch Widespread August 30, 2016 - August 30, 2016

    BLS has been very damaging to red oaks in Delaware and the Mid-Atlantic states since the early 1990’s

  24. Fall Fungi - August 21, 2016

    CHICKEN OF THE WOODS or the sulphur shelf fungus (Laetiporus sulphureus) has been seen at the base of trees with large bright yellow and orange overlapping fruiting structures. These fungi are some of the most colorful and identifiable fungi found on l … Continue reading Fall Fungi

  25. Hot and Dry Weather August 2016 - August 14, 2016

    After a cool and rainy start to the season in Delaware, it has turned hot and dry. Rains have come in downpours, most of which runs off. Keep an eye on trees and shrubs, as well as annuals, perennials, and vegetables. Newly planted trees and shrubs may … Continue reading Hot and Dry Weather August 2016

  26. Ornamentals Short Course Pest ID Walks and Workshops 2016 - June 15, 2016

    Pest and Beneficial Insect Walk 2016    Wednesday, June 22, 2016, 4 – 6 PM Credits: 2 Pest., 1 CNP.  UD Botanic Gardens,  University of Delaware Campus, Townsend Hall, 531 S. College Ave, Newark, DE. Learn to identify insect and disease pests, as well … Continue reading Ornamentals Short Course Pest ID Walks and Workshops 2016

  27. Weather Woes and Plant Diseases - May 11, 2016

    Hydrangea Frost Damage Photo Credit: Michele Walfred Cloudy, wet, damp, cool and dreary are words that have been heard over and over recently, regarding the weather in Delaware. Cloudy and damp weather is conducive to plant pathogens that infect in the … Continue reading Weather Woes and Plant Diseases

  28. Sanitizing Products for Greenhouse, Nursery, and Landscape Use in Delaware 2016 - April 8, 2016

    A new UD Cooperative Extension fact sheet lists sanitizing products available for use in greenhouse, nursery, and landscape uses. These products can be used to clean and reduce microbial populations on  pots, tools and surfaces.  Products, trade names, … Continue reading Sanitizing Products for Greenhouse, Nursery, and Landscape Use in Delaware 2016

  29. Evaluating Fruit Tree Buds Following Freezing Weather - April 8, 2016

    Penn State University has distributed information from fruit specialist Jim Schupp regarding how to asses fruit tree health following the recent freezing weather:  Peach Bud Survival – Compare the number of live buds to the number a fruiting lateral sh … Continue reading Evaluating Fruit Tree Buds Following Freezing Weather

  30. Bradford Pear – Invasive Plant - March 30, 2016

    Bradford pear trees are blooming now in Mid-Atlantic landscapes. Also called callery pear, with some selected cultivars such as Cleveland Select, the flowering pear trees native to China are weak in branch structure. These V-shaped trees usually split … Continue reading Bradford Pear – Invasive Plant

  31. 71st Meeting of the NJDelMarVaPa Extension Plant Pathologists - March 3, 2016

    The 71st annual meeting of the NJDelMarVaPa Plant Pathologists was held March 1, 2016, at the University of Delaware. It was hosted this year by Nancy Gregory and Nathan Kleczewski, and serves as a regional update for colleagues and for networking, and … Continue reading 71st Meeting of the NJDelMarVaPa Extension Plant Pathologists

  32. UD Plant Diagnostic Clinic Report for 2015 - February 11, 2016

    The final report for the UD Plant Diagnostic Clinic for 2015 has been posted and can be viewed at the following link: Final Delaware Plant Diagnostic Clinic Report 2015 2_10_2016 The Plant Diagnostic Clinic at the University of Delaware is housed in th … Continue reading UD Plant Diagnostic Clinic Report for 2015

  33. Storm Damage and After-care - January 28, 2016

    The recent storm in the mid-Atlantic affected landscapes differently, but here are some tips from the lawn and garden experts in UD Cooperative Extension that you can take to repair your landscape. Leaves – Most of the leaves remaining on trees prior t … Continue reading Storm Damage and After-care

  34. Powdery mildew on turfgrass in December! - December 14, 2015

    An unusual sight on the morning of December 14th in Newark, DE was powdery mildew on turfgrass in a residential lawn. Powdery mildew is favored by cool humid conditions and is usually seen in the spring and fall, in shady areas. Our normal December tem … Continue reading Powdery mildew on turfgrass in December!

  35. Choosing and Caring for Christmas Trees - December 2, 2015

    Many of us choose a fresh cut tree to decorate our homes for the holiday season. Choose a tree with dark green color, good shape, a straight trunk at the base, and no taller than you really need. Check to see if the tree is fresh by bending needles; th … Continue reading Choosing and Caring for Christmas Trees

  36. New Fact Sheet on Bacterial Leaf Scorch of Trees - November 20, 2015

    A new fact sheet from UD Cooperative Extension highlights information on bacterial leaf scorch (BLS) of oak and other trees.  BLS has been problematic in oaks in the red oak group for almost ten years, and has led to the decline and death of many oaks … Continue reading New Fact Sheet on Bacterial Leaf Scorch of Trees

  37. Premature Leaf Drop - September 11, 2015

    Poplar with early leaf drop due to drought PREMATURE LEAF DROP is prevalent in the landscape due to dry weather. Plants are drought damaged by leaf desiccation, slowing of photosynthesis, and slowing of growth. Leaves wilt or roll, turn off-color, and … Continue reading Premature Leaf Drop

  38. NPDN Plant Diagnostic Clinics - July 16, 2015

    Did you know that there is a plant diagnostic clinic associated with every land grant university in the U.S. and beyond?

  39. Cucurbit Downy Mildew July 2015 - July 2, 2015

    Cucurbit downy mildew was confirmed on watermelon leaves in Delaware on July 1, 2015. Contact your specialist for management recommendations.   nfg 7/2/2015

  40. Emerald Ash Borer and Ash Tree Health - June 23, 2015

    Adult emerald ash borer EMERALD ASH BORER has been found in several surrounding states, but has NOT been found in Delaware to date. An article appeared in the 6/20/15 Wilmington News Journal regarding trapping efforts and preparedness for the detection … Continue reading Emerald Ash Borer and Ash Tree Health

  41. 2015 Fungicides and Bactericides Available for Homeowner Use in Delaware - June 15, 2015

    2015 Fungicides and Bactericides Available for Home Use An updated listing of fungicides, biorational products, and bactericides for home use in Delaware has been published. The listing is a compilation of products found at retail stores in the Newark, … Continue reading 2015 Fungicides and Bactericides Available for Homeowner Use in Delaware

  42. University of Delaware Students Develop App for Christmas Tree Diagnostics - May 18, 2015

    UD App Development Team Conifer diagnostic app is the first of the UD Pocket Farmer App series for UD Cooperative Extension. A group of students began development of the app in January, with availability expected in the Apple Store in mid-summer. See t … Continue reading University of Delaware Students Develop App for Christmas Tree Diagnostics

  43. UD Students Develop App for Christmas Tree Diagnostics - May 18, 2015

    An interdisciplinary team of students at the University of Delaware has developed a new app called PocketFarmer designed to help Christmas tree farmers in the region diagnose, identify and mark potentially diseased plants.

  44. Ag Day at UD April 25, 2015 - April 30, 2015

    Nancy Gregory talking to new Newark residents Ag Day was cool weatherwise, but a warm atmosphere for the crowds who came out to learn about and purchase plant, and see the other exhibits. It was a great day. I enjoyed being side-by-side with the Master … Continue reading Ag Day at UD April 25, 2015

  45. Bee Removal Assistance - April 22, 2015

    Check the link below for individuals in each county in Delaware who will remove swarms of honey bees. 2015 Swarm Removal List Delaware

  46. Home Orchard Production – Apple, Pear, and Stone Fruit Disease Management - February 26, 2015

    New Fact Sheet 2/25/2015 – Home Orchard Production – Apple, Pear, and Stone Fruit Disease Management – Nancy F. Gregory Growing fruit in a backyard or home orchard can be rewarding or can be very frustrating, depending on disease and insect pests that … Continue reading Home Orchard Production – Apple, Pear, and Stone Fruit Disease Management

  47. Poinsettia Sick? - December 12, 2014

    Your poinsettia isn’t looking too sporty?? First, water once a week until soil is moist. Next, keep it out of drafty areas and heat vents. If after watering, your poinsettia doesn’t perk up, it could be suffering from a root rot. Carefully knock the pl … Continue reading Poinsettia Sick?

  48. New Invasive Insect Pest – Spotted Lanternfly - November 4, 2014

    Spotted Lanternfly Adult The spotted lanternfly, a poor flying but strong jumping moth-like pest that attacks grapes, apples, tree of heaven (Ailanthus), and other hosts has been found in Berks County Pennsylvania. The inch long insect is a potentially … Continue reading New Invasive Insect Pest – Spotted Lanternfly

  49. Fringe Tree Possible Host for Emerald Ash Borer - October 23, 2014

    Fringe tree, Chionanthus virginicus, Image L V Gregory On October 14, 2014, the USDA Systematic Entomology Laboratory (SEL) at the Smithsonian confirmed partial adult and larval specimens recovered from a white fringetree (Chionanthus virginicus) as em … Continue reading Fringe Tree Possible Host for Emerald Ash Borer

  50. Phytophthora Resistant Plants for the Landscape - October 15, 2014

    Phytophthora Resistant Plants Phytophthora root rot, a soil borne disease caused by a fungus-like organism, is a widespread problem which can affect many woody and herbaceous landscape plants. Azalea, holly, rhododendron, and juniper are the most frequ … Continue reading Phytophthora Resistant Plants for the Landscape

  51. Healthy Christmas Trees Before and After - September 25, 2014

    Christmas 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 n … Continue reading Healthy Christmas Trees Before and After

  52. Ash Rust is Here! - May 28, 2014

    Symptoms of ash rust on the lower surface of leaves. Note orange sporulation of the fungus. We see ash rust almost every year, but this year there seems to be quite a bit of it. The fungal rust disease is very dependent on the spores produced by the al … Continue reading Ash Rust is Here!

  53. 2014 Regional Meeting of Plant Pathologists - April 2, 2014

    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 Kleczewsk … Continue reading 2014 Regional Meeting of Plant Pathologists

  54. New! UD Plant Diagnostic Clinic Report and other Reports Posted - March 12, 2014

    Please see the following link for the 2013 Plant Pathology Clinic, Survey, and Research Reports Bulletin: http://extension.udel.edu/ag/plant-diseases/delaware-plant-pathology-results-and-reports-bulletins/ Click on the downloadable pdf for all of the r … Continue reading New! UD Plant Diagnostic Clinic Report and other Reports Posted

  55. Watch for Tobacco Mosaic Virus in Petunia - February 12, 2014

    This message is an alert for growers and retail bedding plant sellers that some petunia seedlings have been detected in the U. S. that are infected with tobacco mosaic virus (TMV). TMV is very common and has a wide host range, but infection in flats of … Continue reading Watch for Tobacco Mosaic Virus in Petunia

  56. Winter Injury and Frost Cracking - January 31, 2014

    Frost Cracking Maple. Image courtesy of B. Johnson The Clinic recently received an inquiry via our Ask an Expert feature, about the bark splitting on a red maple tree. A key piece of information was the south west exposure of the tree. The maple is suf … Continue reading Winter Injury and Frost Cracking

  57. Mulberry Weed: a New Invasive Plant in Delaware - December 4, 2013

    Mulberry Weed (Fatoua villosa) Description and Geographic Distribution Mulberry Weed or hairy crabweed (Fatoua villosa) (Thunberg) Nakai is an invasive exotic Asian species from the Mulberry family (Moraceae).  First reported in Louisiana in 1964 by J. … Continue reading Mulberry Weed: a New Invasive Plant in Delaware

  58. Management of Boxwood Blight in the Landscape - September 15, 2013

    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 est … Continue reading Management of Boxwood Blight in the Landscape

  59. Fungus-like Things That Grow in Mulch and on Lawns - July 12, 2013

    FUNGI AND SLIME MOLDS grow in mulch composed of organic debris and wood chips. Fungi and fungus-like organisms such as slime molds are decomposers, and they do it very well to the benefit of our ecosystem. Without fungi, we would be deep in organic deb … Continue reading Fungus-like Things That Grow in Mulch and on Lawns

  60. Phytophthora Root Rot in Flooded Soils - July 2, 2013

    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 … Continue reading Phytophthora Root Rot in Flooded Soils

  61. Boxwood Blight Confirmed in Delaware - June 24, 2013

    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   Black streaks on twigs of boxwood with boxwood b … Continue reading Boxwood Blight Confirmed in Delaware

  62. Storm Damage - June 11, 2013

    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 ar … Continue reading Storm Damage

  63. Rose Rosette Disease Summit in Newark, DE April 15-16 - April 19, 2013

    Steve Hutton – President and CEO of Star Roses and Plants/Conard-PyleDr. Michael Dobres – Managing Director of Nova Flora LLCKathleen Case, Facilitator, Cindy Zook AssociatesDr.Thomas Bewick – USDA NIFA, National Program Leader for Horticulture A two d … Continue reading Rose Rosette Disease Summit in Newark, DE April 15-16

  64. 68th Meeting of the NJDelMarVaPa Plant Pathologists - April 19, 2013

    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 h … Continue reading 68th Meeting of the NJDelMarVaPa Plant Pathologists

  65. Winter Temperature Index For Predicting Stewart’s Wilt in Delaware Sweet Corn, 2013 - March 13, 2013

      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 bee … Continue reading Winter Temperature Index For Predicting Stewart’s Wilt in Delaware Sweet Corn, 2013

  66. Users of the UD Plant Diagnostic Clinic - December 3, 2012

    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 Clinic48% were aware of the services of … Continue reading Users of the UD Plant Diagnostic Clinic

  67. Nematode Control Recommendations Updated - November 15, 2012

    The Control Recommendations for nematode problems in soybean, corn, and vegetables have been updated in 2012 and may be viewed or downloaded from the Nematology section of the website.

  68. Thousand Cankers Disease of Walnut - September 30, 2012

    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 … Continue reading Thousand Cankers Disease of Walnut

  69. Swiss Needlecast on Douglas Fir - April 27, 2012

    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 stomate … Continue reading Swiss Needlecast on Douglas Fir