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Resources for Plant Diseases

Title Available As Summary Date ID Author
Fusarium Wilt of Mimosa (Albizia julibrissin)
Fusarium wilt is a common and lethal disease of mimosa (Albizia julibrissin)1, also commonly known as silktree. In the United States this disease occurs in the east from New York southward and also in Louisiana, Arkansas and California. Fusarium wilt is caused by the fungus Fusarium oxysporum forma specialis perniciosum. Albizia spp. are the only known host of F. oxysporum'' f.sp. ''perniciosum''. Fusarium oxysporum f. sp. perniciosum colonizes and clogs the tree’s vascular (water-conducting) tissue, and interferes with the movement of plant sap. This results in relatively rapid tree death.
Jan 20, 2015 2811-1020(PPWS-53NP)
Bacterial Leaf Scorch of Landscape Trees
Bacterial leaf scorch is an important and often lethal disease of many landscape trees, particularly in the southern and eastern U.S. In Virginia landscapes it is most often observed on oak, elm, and sycamore; however, many other landscape tree species are susceptible to this disease. The bacterium that causes bacterial leaf scorch colonizes the tree's water-conducting tissue (xylem), disrupting water movement and reducing water availability to the tree. The symptoms of bacterial leaf scorch are very similar to symptoms of other problems that limit water uptake. This is why marginal leaf scorch symptoms caused by other problems, such as drought stress or root disease, are often mistaken for symptoms of bacterial leaf scorch. Laboratory identification of the causal bacterium (Xylella fastidiosa) from affected petiole and leaf tissue is necessary for positive confirmation of the disease.
Feb 2, 2024 3001-1433 (SPES-568NP)
Soybean Rust Incidence and the Response of Soybeans to Fungicides in 2009 Dec 21, 2010 3012-1520
Successful No-Tillage Corn Production Mar 20, 2019 424-030
Successful No-Tillage Corn Production Mar 20, 2019 424-030
Plant Disease Diagnostic Form
Plant Disease Diagnostic Form
Jun 16, 2023 450-097 (SPES-487NP)
Instructions for Completing the Plant Disease Diagnostic Form (#450-097)
The Plant Disease Diagnostic Form was designed to accommodate a wide variety of plants and growing situations; therefore, certain entries on this form may not be appropriate for a particular specimen or situation. Much of the information requested helps reconstruct the "field situation" for the diagnostician. Consider each section of the form carefully; the information provides important clues to the diagnostician that are significant in guiding the diagnostic process and formulating the control recommendation. Your local Extension office staff can assist you in completing the form and include the relevant information requested on the form, so when possible, complete the form with the assistance of your local VCE agent or VCE staff member.
Sep 2, 2023 450-097-A (SPES-512NP)
Problem-free Shrubs for Virginia Landscapes
The most effective form of plant disease control in the landscape is prevention. Disease prevention can be as simple as choosing the right plant for the right place at planting time. This fact sheet was developed as a guide to shrubs that generally experience few problems in Virginia landscapes. Using these species for new plantings should help you avoid troublesome disease and insect problems in your landscape.
Jun 27, 2022 450-236 (PPWS-69P)
Arbustos ideales para los paisajes de Virginia (Problem-free Shrubs for Virginia Landscapes)
La forma más eficaz de controlar las enfermedades de los cultivos en nuestro jardín es la prevención. La prevención de enfermedades puede ser tan sencilla como elegir el cultivo adecuado para el lugar adecuado al momento de cultivar. Esta hoja informativa fue desarrollada como una guía de los arbustos que generalmente experimentan pocos problemas en los paisajes de Virginia. El uso de estas especies para las nuevas plantaciones debería ayudarle a evitar problemas de enfermedades e insectos en su jardín.
Aug 7, 2023 450-236s (SPES-429s)
Problem-free Trees for Virginia Landscapes
Many of the tree species commonly planted in Virginia landscapes suffer from disease problems. Although some diseases can be cured, most must be controlled on a preventative basis. The best option for new plantings is to choose species that have a low risk of developing disease. Listed below, in alphabetical order, are some choices of problem-free trees for Virginia landscapes.
Jun 29, 2022 450-237 (PPWS-70P)
Iris Leaf Spot
Iris leaf spot (also called Heterosporium leaf spot) is the most common disease of iris in Virginia. It is caused by the fungus Cladosporium iridis (syn. Heterosporium iridis). Leaf spotting is most conspicuous on the upper half of the leaf following bloom. Although this pathogen is most common on bulbous iris, it can also cause severe damage to rhizomatous iris, and has also been reported on Gladiolus, Freesia and Narcissus species.
Nov 2, 2021 450-600 (PPWS-90NP)
Juniper Tip Blights Mar 30, 2017 450-601 (PPWS-91 NP)
Anthracnose - A Fungal Disease of Shade Trees
Anthracnose is a generic term for a disease that occurs on many ornamental and forest trees. A number of different fungi cause anthracnose on various hosts. It occurs most commonly and severely on sycamore, white oak, elm, dogwood, and maple. Other host plants that usually show only minor symptoms of anthracnose include linden (basswood), tulip tree, hickory, birch, and walnut. Anthracnose fungi may be host-specific, as in the case of sycamore anthracnose, which infects only sycamore and not other tree species. Anthracnose fungi have similar life cycles, but require slightly different moisture and temperature conditions for infection.
Feb 26, 2024 450-604 (SPES-555P)
Leaf and Flower Gall of Azalea and Camellia
Leaf and flower gall is a disease that is common on azaleas and camellias in the spring. The disease has also been reported on other members of the plant family Ericaceae. It occurs in home landscapes and nurseries, and is often seen on flame azaleas in the forest in the spring. The disease is caused by species of the fungus Exobasidium.
Oct 18, 2016 450-605 (PPWS-92NP)
Black Root Rot of Holly
Black root rot is a fungal root disease that is a serious and extremely common problem on Japanese holly (Ilex crenata), a commonly used evergreen landscape shrub. Inkberry holly (Ilex glabra), blue or Meserve holly (Ilex crenata) are also very susceptible to black root. The disease is not as commonly diagnosed on blue holly and inkberry holly as on Japanese holly in the Virginia Tech Plant Disease Clinic. The black root rot pathogen is soil-borne and can be introduced into a landscape on infected nursery plants. Chinese holly (Ilex cornuta) and English holly (Ilex aquifolium), are resistant to the black root rot pathogen.
Feb 7, 2024 450-606 (SPES-569P)
Verticillium Wilt of Shade Trees
Verticillium wilt is a serious vascular wilt disease affecting many shade tree species and over 80 tree genera, as well as many woody ornamental landscape plants, and herbaceous and vegetable plants. Verticillium wilt most commonly occurs in nursery, orchard and landscape locations. Maple (Acer spp.) are a tree genus commonly associated with the disease, but Verticillium wilt occurs on many other trees and woody ornamentals used in landscapes. Verticillium wilt more commonly occurs in locations with colder climates than Virginia; however, Verticillium wilt does cause disease on trees and woody ornamentals in Virginia.
Feb 29, 2024 450-619 (SPES-571NP)
Rose Rosette Disease
Rose rosette disease (RRD) is a serious disease problem of cultivated roses, and over the past two decades RRD has become the most important rose disease in North America. RRD is caused by Rose rosette virus (RRV). RRD leads to stunting, decline and death of roses, yet there are no easy, economical or particularly effective management tactics for RRD. Currently, the major rose cultivars available to growers are susceptible to RRD.
Dec 20, 2023 450-620 (SPES-556P)
Angular Leaf Spot of Cucumber
Angular leaf spot of cucurbits is caused by the bacterium Pseudomonas syringae pv. lachrymans. The bacterium can attack a wide range of cucurbits including watermelon, melon, squash, cucumber, zucchini, and pumpkin.
Jan 22, 2024 450-700 (SPES-528P)
Anthracnose on Snap Beans
Anthracnose is a major disease of the common snap bean (Phaseolus vulgaris) and can occur on other legumes. It is caused by the fungus Colletotrichum lindemuthianum. When environmental conditions are favorable, crop losses can be as high as 100 percent on susceptible cultivars of snap beans.
Jul 30, 2019 450-719 (SPES-157NP)
Brown Rot on Peach and Other Stone Fruits
Brown rot is one of the most destructive diseases of peach and nectarine in Virginia, and also occurs on other stone fruits such as apricot, cherry, and plum. When environmental conditions favor this disease, crop loss can be devastating.
Feb 16, 2024 450-721 (SPES-554P)
Reducing Pesticide Use in the Home Lawn and Garden
Pesticide use affects the quality of human health, the environment, and nontarget organisms in the ecosystem. Therefore, any pesticide application warrants a careful assessment of the expected benefits and risks. Too often, however, homeowners use pesticides inappropriately or without careful consideration of alternatives. This fact sheet outlines general pest control tactics that can easily be implemented for home lawns and gardens, along with other information that home owners can use to make sound pest management decisions. The intent is to ensure that homeowners are aware of alternative control tactics and pesticide characteristics, and that pesticides are used properly and only when necessary
Mar 18, 2024 450-725 (SPES-589P)
Botryosphaeria Canker and Dieback of Trees and Shrubs in the Landscape
Most trees and shrubs are susceptible to dieback and cankers caused by several species of the fungal genus Botryosphaeria. Botryosphaeria fungi are typically opportunistic pathogens. Opportunistic pathogens only cause disease on plants that are stressed. Therefore, avoiding plant stress, which predisposes plant tissue to infection and colonization by this fungal group, is the best strategy to prevent Botryosphaeria disease problems.
Nov 17, 2023 450-726 (SPES-527P)
2024 Pest Management Guide - Field Crops Jan 26, 2024 456-016 (ENTO-566P)
2024 Pest Management Guide - Home Grounds and Animals Jan 19, 2024 456-018 (ENTO-567P)
Virginia Master Naturalist Basic Training Course: Botany Mar 22, 2023 ANR-10NP (CNRE-166NP)
Virginia Master Naturalist Basic Training Course: Botany (Introductory Version) Mar 22, 2023 ANR-12NP (CNRE-165NP)
Commercial Chinese Chestnut Production in Virginia Feb 1, 2023 ANR-279P
Late Blight of Tomato and Potato Jan 19, 2024 ANR-6 (SPES-567P)
Galls and Rust made by Mites Nov 29, 2022 ENTO-532NP
Integrated Pest Management of Hemp in Virginia Mar 2, 2020 ENTO-349NP
Best Management Practices for Boxwood Blight in the Virginia Home Landscape
Boxwood blight is a devastating disease of boxwood that results in defoliation and decline of susceptible boxwood. This best management practices factsheet provides guidelines for home growers of landscape boxwood to avoid introduction of the boxwood blight pathogen into a landscape or, if the disease is already present in a landscape, to manage to disease in the most effective manner and avoid spread of the disease to new locations.
Dec 19, 2023 PPWS-29NP (SPES-557NP)
Virginia Boxwood Blight Task Force
To provide leadership in safeguarding and protecting the ornamental horticulture industry, historical gardens and landscape plantings from boxwood blight.
Jul 1, 2019 PPWS-30
Best Management Practices for Boxwood Blight in Virginia Production Nurseries WITH Boxwood Blight
This Best Management Practice document is a set of guidelines for home growers of landscape boxwood to avoid introduction of the boxwood blight pathogen into a landscape or, if the disease is already present in a landscape, to manage the disease in the most effective manner and avoid spread of the disease to new locations.
Feb 16, 2021 PPWS-32NP (PPWS-87NP)
Best Management Practices for Boxwood Blight in Virginia Production Nurseries WITHOUT Boxwood Blight Version 2, September 2016
This Best Management Practice document is a set of guidelines for home growers of landscape boxwood to avoid introduction of the boxwood blight pathogen into a landscape or, if the disease is already present in a landscape, to manage the disease in the most effective manner and avoid spread of the disease to new locations.
Jan 5, 2021 PPWS-33NP (PPWS-86NP)
Best Management Practices for Boxwood Blight: Best Management Practices for Virginia Retail Nurseries WITH Boxwood Blight
This Best Management Practice document is a set of guidelines for home growers of landscape boxwood to avoid introduction of the boxwood blight pathogen into a landscape or, if the disease is already present in a landscape, to manage the disease in the most effective manner and avoid spread of the disease to new locations.
Jan 6, 2021 PPWS-34NP (PPWS-89NP)
Best Management Practices for Boxwood Blight: Best management Practices for Virginia Retail Nurseries WITHOUT Boxwood Blight
This Best Management Practice document is a set of guidelines for home growers of landscape boxwood to avoid introduction of the boxwood blight pathogen into a landscape or, if the disease is already present in a landscape, to manage the disease in the most effective manner and avoid spread of the disease to new locations.
Jan 6, 2021 PPWS-35NP (PPWS-88NP)
Best Management Practices for Boxwood Blight for Greenery Producers
Best management practices for boxwood blight (also called “box blight”) for greenery producers are practices recommended to avoid the introduction and spread of boxwood blight, caused by the fungus Calonectria pseudonaviculata (syn. Cylindrocladium pseudonaviculatum). The recommendations in this document are designed to avoid spread of boxwood blight within a planting or to new locations when pruned tips are collected, sold and/or used for holiday greenery1. These recommendations are relevant to anyone involved in the greenery (“tipping”) industry, including small and large-scale greenery producers, home growers who sell boxwood tips, and people who tip-prune boxwood on other people’s property. Care must be taken at all levels of greenery production to prevent the spread of the boxwood blight pathogen and avoid economic losses associated with this disease.
Jan 6, 2021 PPWS-39NP (PPWS-95NP)
Best Management Practices for Boxwood Blight for Professionally Managed Landscapes and Public and Historic Gardens in Virginia
Boxwood blight is caused by the fungal pathogen Calonectria pseudonaviculata (syn. Cylindrocladium buxicola). Boxwood blight was first described in the United Kingdom in the mid-1990’s and by 2002 was found in several other European countries and New Zealand. In September 2011 boxwood blight was discovered in North America. Symptoms of the disease include leaf spotting (Fig. 1), elongate, dark cankers on stems (Fig. 2), defoliation, and dieback (Fig. 3). The primary means by which the disease spreads is the inadvertent introduction of infected boxwood to existing plantings. The pathogen can also spread by spores, which readily adhere to equipment and work clothes, and by microsclerotia, which survive in infested soil and plant debris. This document outlines best management practices for landscapers and property managers to reduce the risk of spreading boxwood blight to landscapes and public and historic gardens, and to manage the disease if it is introduced.
Feb 1, 2024 PPWS-49NP (SPES-552NP)
Nematode Management in Field Crops
This is a guide for understanding the biology of plant nematodes, how they affect different crops, how to sample for them, how to interpret nematode sample results and management strategies.
Feb 23, 2024 SPES-15NP (SPES-531NP)
Mortality of Great Rhododendron (Rhododendron maximum) in Virginia
Since 2015, Extension specialists from Virginia Tech (VT) have visited and collected plant and soil samples from several large areas of dying great rhododendron (Rhododendron maximum) in Virginia’s mountainous regions. In 2016 VT specialists met with Virginia Department of Forestry, US Forest Service personnel, and other experts to revisit some of these sites. No consistent cause of this mortality has yet been identified. It is possible that a variety of factors are stressing the rhododendrons in these areas to a point where opportunistic pathogens or insects can successfully attack and kill them. The following information summarizes our observations and diagnostic results from four separate great rhododendron mortality sites in Virginia. This information is not equivalent to a research study, which would also include samples taken from healthy great rhododendron for comparison; however, we are confident that we have ruled out two diseases that are frequently mentioned both online and anecdotally as a cause of this mortality, specifically Phytophthora root rot and Botryosphaeria dieback.
Aug 21, 2019 SPES-151P
Instructions for Sampling and Submitting Crop Nematode Samples Dec 12, 2023 SPES-16NP (SPES-530NP)
Fusarium Wilt of Mimosa (Albizia julibrissin) Aug 13, 2020 SPES-230NP
Vascular Streak Dieback: An Emerging Problem on Woody Ornamentals in the U.S. Feb 28, 2024 SPES-483P (SPES-587P)
Apple Blotch Disease
In this publication, we describe apple blotch disease, also known as Marssonina leaf blotch, an emerging apple disease in the Eastern United States. This disease leads to severe apple tree crown defoliation that indirectly affects the apple fruit size, color, yield and twig development. The causal gent of this disease is a fungus Diplocarpon coronariae (also known as Marssonina coronaria).
Jun 14, 2023 SPES-509NP
Aerial imagery to improve disease diagnosis and management in field crops Aug 11, 2023 SPES-515NP