Plant Industry Services
Beech leaf Disease (BLD) is caused by the foliar nematode, Litylenchus crenatae mccannii. The nematode infests the buds and leaves of beech trees, causing decline and mortality. Infected leaves show dark interveinal banding and become distorted and leathery. The nematode was first observed in Ohio in 2012 and has since spread to 12 northeastern states. How the nematode spreads long distances in presently unknown. In 2021, BLD was confirmed in Prince William County, Virginia, and in 2022 the nematode was confirmed in Fairfax and Stafford Counties. VDACS, in collaboration with the VA Department of Forestry continue to survey and monitor for BLD on nursery stock and in the forest.
Currently not established in Virginia, Chrysanthemum white rust (CWR) is a USDA quarantined plant pathogen that poses a potential trade barrier to growers if introduced. The disease also poses a risk of increasing management costs if introduced into the Commonwealth, as control of this pathogen requires weekly fungicide applications. For these reasons, VDACS plans to continue monitoring and eradication efforts to keep this pathogen out of the Commonwealth.
Laurel wilt (Raffaelea lauricola) is a serious disease of plants in Lauraceae, which includes redbay, sassafras, and avocado. The fungus disrupts the vascular tissue within the plant, causing rapid wilt and death. The fungus is vectored by the redbay ambrosia beetle (Xyleborus glabratus), which is native to Asia. However, long distance spread of the disease in the U.S. is mostly attributed to the movement of infested wood. The beetle and fungus were first detected in Georgia and South Carolina in 2004 and have since spread to 12 southeastern states. In 2021, the disease was confirmed in Scotts County, Virginia. VDACS, in collaboration with the VA Department of Forestry and Virginia Tech, deploy traps in southwestern and eastern Virginia to detect for the presence of redbay ambrosia beetle.
Phytophthora ramorum was first identified in North America in 2000 as a lethal stem canker disease of oak and tan oak along the coastal range of California. Imported nursery stock including Rhododendron, Pieris, Kalmia, Camellia and Viburnum can harbor the pathogen and could impact the movement of nursery and forest products if introduced into Virginia. VDACS conducts extensive statewide surveys for this pathogen every year in nurseries and the natural environment. Each year, VDACS tests between 200 to 350 plant and water samples from 30-40 municipalities across the state, aided by advanced notifications provided by USDA. VDACS also samples water from natural waterways to detect P. ramorum and other Phytophthora spp. from forested environments. .
Plum pox is a viral disease caused by the plum pox virus (PPV), which infects tree species in the genus Prunus, including plums, peaches, cherries, almonds, and apricots. PPV does not kill trees, but it reduces the yield and marketability of fruit. The virus is considered the most devastating disease of stone fruit in Europe.
The disease was first described in Bulgaria in the early 1900’s and has since spread throughout Europe. In the United States, PPV was first detected in Pennsylvania in 1999 and in Michigan and New York in 2006. In 2019, after substantial eradication efforts, the USDA declared the U.S. free from PPV. VDACS continues to apply for federal grant funding to survey for the disease, which has not been detected in Virginia.
To date, Ralstonia solanacearum Race 3 Biovar 2 has not been detected in Virginia and is not known to be established in the United States. However, if introduced, it has the potential to be a serious bacterial disease of solanaceous crops and Geranium. VDACS continues to intercept any introductions from imported stock from outside the country. In 2023, VDACS collaborated with USDA APHIS PPQ to eradicate a shipment of potentially infected geraniums from Mexico.
Thousand Cankers Disease (TCD) is a disease complex of walnut, caused by the fungus Geosmithia morbida and vectored by the walnut twig beetle, Pityophthorus juglandis. The beetle bores into branches and introduces the fungus, which then causes small cankers. If beetle populations are high enough, the number of cankers increases until they coalesce and girdle branches, restricting the movement of nutrients and eventually killing the tree. Trees may be infested for many years before showing symptoms. A survey from 2021 to 2022 could not detect the disease in many locations that were confirmed in 2011, and no walnut twig beetles were recovered from trapping in the greater Richmond area. In 2022, TCD was confirmed from four symptomatic trees in Fairfax, Prince William, and Chesterfield Counties.
Tomato Brown Rugose Fruit Virus (ToBRFV) was first identified from Israel in 2014 and since has spread rapidly across the globe. The virus infects tomato and peppers, causing distortion, stunting, and mosaic or necrotic lesions on the leaves and fruit. It is dispersed long distances through infected seed and spreads mechanically from plant to plant. In 2021, ToBRFV was confirmed in Virginia. It has been recently detected in several other eastern states and is a concern for tomato growers in Virginia.
In 2022, VDACS confirmed the emerging fungus Ceratobasidium theobromae (synonym: Rhizoctonia theobromae), the putative causal agent of Vascular Streak Dieback (VSD), on woody ornamentals that are grown in Virginia. Symptoms of VSD vary among plant species, but generally include leaf chlorosis, scorched leaf margins, stunting and/or wilting of current year’s growth and streaking or discoloration within the vascular tissue. Currently, VDACS is working with other states to identify plants displaying symptoms of VSD. VDACS is participating in a multi-state survey to help determine the spread and distribution of C. theobromae in the southern region of the United States. Research is extremely limited, however VDACS in collaboration with Virginia Tech have developed a publication which outlines the current situation, symptoms, host plants, and best management practices to monitor and control VSD in nurseries. VDACS strongly recommends that all growers follow the best management practices listed in the publication to prevent or manage the disease.
State Plant Pathologist
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