From January to March 2026

Stress, Spots, and Rots: Key Findings from May–June Diagnostics

Samples from May and June showed a wide range of plant health issues across crops, with both diseases and abiotic factors involved that, in some cases, played a central role in favoring opportunistic fungi. Conifers, in particular, frequently exhibited needle blights related to environmental stresses.

The flow of the diagnostic samples is definitely increasing and weather conditions with strong rains have contributed to the appearance of bacterial diseases.

Sample Volume received by the Clinic from the beginning of the year to mid June.

May Highlights

Diagnostic samples submitted in May were dominated by ornamental and fruit crops, with environmental and abiotic stress identified as a major contributing factor across many cases. Among ornamentals, needle blights (Phyllosticta, Pestalotiopsis, Phomopsis) were commonly observed in combination with stress-related decline on arborvitae and juniper. Boxwood, frequently exhibited Volutella blight and insect damage.

Dieback caused by Volutella on boxwood twigs. The orange masses are the spores of Volutella. This is a combination of symptoms and signs that can be used to recognize Volutella infections.

In fruit crops, tree fruit samples were often associated with abiotic stress and occasional bacterial and fungal diseases. Strawberry diagnostics were dominated by crown and root rot diseases, including black root rot, anthracnose and Neopestalotiopsis (NeoP) disease, along with frost injury. Field crops showed root rot diseases and one wheat sample was diagnosed with Wheat Streak Mosaic Virus, while among vegetable crops, one tomato was diagnosed with Rhizoctonia crown rot.The remaining tomato samples showed abiotic disorders.

One Peony sample had a severe case of coinfection with Tobacco Rattle Virus, Bacterial Leaf Spot and Botrytis blight.

Marbled crown tissue that was confirmed through culturing being caused by anthracnose. The darken discolored tissue is often associated with strawberry black root rot complex .

Peony plant (A) with a co-infection of Botrytis (B), Bacterial spot (C) Tobacco Rattle Virus (D)

May summary table for the sample received and Diagnosed

Crop	County	Diagnosis
Soybean	Highland	Fusarium root rot
Soybean	Highland	Rhizoctonia crown rot
Wheat	Henry	Wheat streak mosaic
Apple	Ashland	Slime flux suspected
Apple	Columbiana	Fire blight
Apple	Lorain	Abiotic stress
Apple	Lorain	Abiotic stress
Apple	Lorain	Abiotic stress
Apricot	Wayne	Bacterial spot
Muskmelon	Wayne	Abiotic suspected
Peach	—	Peach leaf curl
Pear	Lucas	Pseudomonas blossom blast
Raspberry	Wayne	Anthracnose; frost damage
Raspberry	Cuyahoga	Phytophthora root rot
Strawberry	Pike	Frost damage
Strawberry	Pike	Black root rot; Neopestalotiopsis
Strawberry	Wayne	Black root rot; Neopestalotiopsis
Strawberry	Summit	Neopestalotiopsis; black root rot
Strawberry	Wayne	Black root rot
Strawberry	Wayne	Neopestalotiopsis
Strawberry	Wayne	Angular leaf spot
Strawberry	Wayne	Black root rot
Strawberry	Pike	Frost damage
Arborvitae	—	Environmental stress
Arborvitae	Richland	Environmental stress
Arborvitae	Montgomery	Phyllosticta tip blight
Arborvitae	Stark	Phyllosticta needle blight
Arborvitae	Franklin	No root rot pathogen
Arborvitae	Montgomery	Environmental; Pestalotiopsis
Arborvitae	Logan	Phyllosticta Needle Blight; environmental
Arborvitae	Montgomery	Pestalotiopsis; environmental
Arborvitae	Montgomery	Root rot (Phytopythium); stress
Arborvitae	Montgomery	Pestalotiopsis; transplant stress
Arborvitae	Franklin	Environmental stress
Boxwood	Cuyahoga	Leafminer damage
Boxwood	—	Leafminer; cold damage; Volutella blight
Boxwood	Franklin	Macrophoma; mite; frost damage
Boxwood	Franklin	Volutella blight; mite; psyllid
Boxwood	Franklin	Volutella blight
Cedar	Franklin	Pestalotiopsis needle blight
Cedar	Franklin	Sirococcus needle blight
Cherry	Greene	Botryosphaeria canker; stress
Cypress	Highland	Botryosphaeria canker
Dogwood	—	No disease detected
Dogwood	Putnam	No pathogens observed
Dogwood	Franklin	Colletotrichum leaf spot
Elm	Hamilton	Leafminer
Juniper	Franklin	Pestalotiopsis tip blight; scale; environmental
Juniper	Montgomery	Pestalotiopsis tip blight
Juniper	Montgomery	Phomopsis needle blight
Lilac	Wayne	Salt damage
Maple	Montgomery	Verticillium wilt not detected
Maple	Montgomery	Abiotic stress
Mixed ornamentals	Montgomery	Herbicide drift
Oak (red)	Franklin	Biscogniauxia (formerly Hypoxylon) canker
Oak (red)	Montgomery	Biscogniauxia (formerly Hypoxylon canker
Oak (red)	Montgomery	Leafminers; Tubakia
Pachysandra	Stark	Volutella blight; scale
Pachysandra	Franklin	No pest or pathogen
Peony	Wayne	Tobacco Rattle Virus; Botrytis blight; Bacterial leaf spot
Petunia	Licking	Botrytis blight; temperature stress
Pine	Montgomery	Brown spot needle blight
Rhododendron	Franklin	Colletotrichum leaf dieback
Smoke bush	—	Verticillium wilt
Snowball bush	Stark	Leaf beetle larvae
Spruce	Richland	Abiotic stress
Spruce	Richland	Abiotic stress
Spruce	Franklin	Environmental stress
Spruce	Summit	Abiotic stress
Spruce/Arborvitae	Montgomery	Spider mite; stress
Spruce (blue)	Montgomery	Sudden needle drop
Taxus	Franklin	Abiotic stress
Walnut	Franklin	Not processed
Golf turf	Delaware	Leaf spot
Golf turf	—	Leaf spot; mower damage
Home lawn	Shelby	No disease
Kohlrabi	Wayne	Black rot
Onion	Wayne	Bacterial streak rot
Potato	Lake	Fusarium dry rot; soft rot
Pumpkin	Washington	Bacterial spot
Squash	Washington	Bacterial spot
Tomato	Wayne	Rhizoctonia crown rot
Tomato	Stark	Aphids; Ethylene damage
Tomato	Holmes	Abiotic stress
Tomato	Wayne	Spray injury
Tomato	Washington	Herbicide injury

June Highlights

Diagnostic trends in June closely mirrored those observed in May, with environmental stress continuing to play a key role in plant health issues. Ornamental plants, particularly conifers, showed continued problems with needle blights, root and crown rot diseases (Phytopythium and Phytophthora), and general stress-related decline. Broadleaf ornamentals exhibited leaf spots (anthracnose), cankers, and insect damage.

In fruit crops, strawberry diseases remained prominent, including black root rot, NeoP, and anthracnose, along with several fruits affected by frost injury. Verticillium wilt was diagnosed on tomato, and angular leaf spot was diagnosed on zucchini squash. Fire blight was diagnosed on apple and crabapples.

One wheat sample was diagnosed with Barley Yellow Dwarf Virus.

The heads were bleached and nearly empty, with little to no kernel development. Although BYDV infection is reported to cause reduced yield, it is unclear whether the poor kernel formation observed in this sample was caused solely by the viral infection or if additional abiotic stress factors also contributed to symptom development.

(A) Pine affected by Phytophthora root rot and (B) young fir trees with Phytopythium and root stress caused by overfertilization

Summary table for the sample received during the first two weeks of June

Crop	County	Diagnosis
Winter wheat	Putnam	Barley yellow dwarf virus
Raspberry	Pike	Cane blight
Strawberry	Wayne	Anthracnose
Strawberry	Ashtabula	Not specified
Strawberry	Ashtabula	Black root rot and Anthracnose
Strawberry	Wayne	Anthracnose
Arborvitae	Franklin	Spider mites; Phyllosticta needle blight
Arborvitae	Montgomery	Phyllosticta needle blight; environmental stress
Boxwood	Cuyahoga	Mite; Volutella blight
Boxwood	Hamilton	Volutella blight
Boxwood	Butler	Volutella blight; leafminer
Boxwood	Franklin	Volutella blight
Boxwood	Franklin	Winter damage
Cedar	Franklin	Spider mite; Environmental stress
Cherry ornamental	Franklin	Not specified
Conifer mix	Butler	Phyllosticta needle blight; stress
Dahlia	Franklin	No Cyclamen mites observed
Elm	Montgomery	Vascular pathogens not detected
Elm	Montgomery	Leafminer; weevil
Fir	Morrow	Phytopythium root rot; root stress overfertilization
Juniper	Montgomery	Phomopsis blight
Maple	Franklin	Armillaria not confirmed
Oak (red)	Montgomery	Tubakia; nutritional
Pine	Medina	Phytophthora root rot
Pieris	Hamilton	Cold damage
Smoke bush	Summit	Colletotrichum anthracnose
Viburnum	Wayne	Phytophthora root rot
Tomato	Pike	Verticillium wilt
Zucchini	Wayne	Angular leaf spot

April in review

During April at the C. Wayne Ellett Plant and Pest Diagnostic Clinic (https://ppdc.osu.edu/home), the most frequently recorded problems observed in conifer trees were needle blights and needle casts. Phyllosticta needle blight on arborvitae was a recurring diagnosis and is commonly associated with underlying environmental stress rather than acting as a primary, aggressive pathogen. Phyllosticta species affecting arborvitae, most commonly Phyllosticta thujae, are widely described as opportunistic or secondary pathogens that become established after events that weaken host defenses. Reported predisposing stress factors include winter injury, drought stress, soil moisture extremes, transplant shock, excessive or improper pruning, crowding, and poor air circulation within dense or sheared canopies. As a result, management recommendations focus on alleviating stress factors such as improving watering practices, correcting soil moisture issues, reducing canopy density to improve airflow, and avoiding pruning during wet conditions.Rhizosphaera needle cast was diagnosed on Norway spruce, Stigmina needle cast on Norway spruce and Colorado. A pine sample showed a coinfection of Dothistroma needle blight and Diplodia tip blight.

Fungal fruiting bodies spores

Phyllosticta fruiting bodies and Phyllosticta spores under the microscope

The pests most frequently identified as causing damage on boxwood are leafminers, psyllids, and mites. As a side note, the boxwood samples submitted were generally small in size. For accurate diagnosis, it is important to submit at least 5–10 twigs or material that is representative of the symptoms observed. Always place the material in a zip-sealed bag before shipping it to the Clinic.

plant with symptoms of insect damage

The circular lesions are old leafminer damage, while the white stippling is caused by boxwood mites

In the fruit category, strawberry samples were diagnosed with anthracnose. We also received an apple sample exhibiting powdery mildew along with spray injury, and a pear sample affected by Pseudomonas blossom blast. Rainy conditions and low temperatures, particularly frost events during bloom, can increase the incidence of blossom infections.

Bacterial disease on pear

Characteristic symptoms of Pseudomonas Blossom blast, a bacterial infection favored by rain and low temperatures

In the vegetable category, Pythium spp. was diagnosed in several hydroponic leafy green samples, Pantoea bacterial blight was diagnosed on garlic, and Fusarium wilt was diagnosed on tomato.

oomyctes infections

Lettuce plants with roots showing brown discoloration caused by Pythium spp. infection

For cut flowers we observed cyclamen mites on snapdragon and ranunculus. The ranunculus plants were also affected by bacterial blight (Xanthomonas spp.)

Distorted snapdragon leaves infested with cyclamen mites

April Summary Table

Crop	County	Diagnosis
Ranunculus	Franklin	Cyclamen Mites and Bacterial Blight
Snapdragon	Franklin	Cyclamen Mites
Zinnias	Franklin	No Pests Found
Apple	Wayne	Powdery Mildew Spray Damage
Apples	Logan	Botryosphaeria canker
Pear	Medina	Pseudomonas Blossom Blast
Strawberry	Franklin	Anthracnose
Strawberry	Franklin	Anthracnose
Strawberry	Franklin	Anthracnose
Strawberry	Franklin	Anthracnose
Strawberry	Franklin	Anthracnose
Arborvitae	Montgomery	Phyllosticta Needle Blight and Environmental
Arborvitae	Montgomery	Pyllosticta Needle Blight and Environmental
Arborvitae	Montgomery	Pyllosticta Needle Blight and Environmental
Arborvitae	Montgomery	Phyllosticta Needle Blight and Environmental
Arborvitae	Montgomery	Pestalotiopsis Needle Blight and Environmental
Arborvitae	Montgomery	Phyllosticta Needle Blight and Environmental
Arborvitae	Hamilton	Botryosphaeria Canker
Arborvitae	Montgomery	Spider Mite Damage (Suspected)
Arborvitae	Montgomery	Phyllosticta Needle Blight and Environmental
Arborvitae	Wayne	Phyllosticta Needle Blight and Environmental
Arborvitae	Summit	Phyllosticta Needle Blight and Environmental
Arborvitae	Montgomery	Phyllosticta Needle Blight and Environmental
Beech	Summit	Leaf Beech Disease Not Detected
Boxwood	Wayne	Volutella Blight, Psyllid, Mites
Boxwood	Franklin	Box Tree Moth Not Observed
Boxwood	Montgomery	Old Leafminer and Mite Damage
Boxwood	Franklin	Boxwood Leafminer, Psyllid and Mites, Possible Root Damage
Boxwood	Franklin	Salt Damage Cold Damage
Boxwood	Butler	Volutella, Leafminer and Mites
Boxwood	Franklin	Cold Damage (Small Sample Size)
Canaan Fir	Miami	Sirococcus Spores, No Root Rot Pathogens
Conifer	Monroe	Stigmina Needle Cast
Fir Frasier	Logan	Phytopythium Root Crown Rot
Hawthorne	Cuyahoga	No Pathogen Found (Root Sample)
Holly	Franklin	Environmental, Phyllosticta leaf spot
Impatiens	Richland	Thrip Damage INSV Negative TSWV Negative
Lavendula	Delaware	Phytophthora Oomycetes not detected, Botrytis Growth
Oak	Butler	No Pest or Pathogens Observed
Oak	Wayne
Pentas	Licking	Nutrient Imbalance Low EC, Viral Panel Negative
Pine		No Pest or Pathogen Found
Pine	Montgomery	Dothistroma Beedle Blight and Diplodia Tip Blight
Rose		Crown Gall Negative (Culturing and PCR)
Spruce	Franklin	Sudden Needle Drop Suspected
Spruce And Arborvitae	Licking	Dothistroma (spruce) and environmental Stresses
Spruce Colorado	Monroes	Stigmina Needle Cast
Taxus	Montgomery	Environmental Suspected
Garlic	Wayne	Patoea Bacterial Blight
Tomato	Wayne	Negative For Viruses (Nutritional Possible)
Tomato	Highland	Fusarium Wilt

As the diagnostic season begins to ramp up, we are seeing a steady increase in sample submissions and a growing diversity of plant health issues. The following is a brief summary of diagnostic activity from January through March, highlighting key trends in crops, disorders, and pathogens observed during this early part of the year.

January
In January, samples were received across a range of categories including ornamental plants, vegetables, and fruit crops. Ornamental submissions were largely affected by abiotic and environmental issues, such as mechanical damage and cold damage. Ethylene was observed in tomatoes grown in greenhouse settings. Powdery mildew was diagnosed in several perennial plants grown in greenhouse. Neopestalotiopsis disease and anthracnose was diagnosed in two strawberry plants.

February
February submissions were dominated by vegetable and ornamental samples, with a strong prevalence of root and crown diseases. Multiple lettuce samples were diagnosed with Phytophthora root rot. Fusarium root rot was diagnosed on pepper. Ornamental Bonsai (juniper) samples showed Phomopsis spores. Diaporthe associated with possible environmental stresses was observed on Canaan fir. Environmental stresses were reported in several cases, including cold damage on strawberry.

March
March saw the highest volume and diversity of submissions, largely from ornamental crops. Diagnoses included a wide range of fungal diseases such as needle casts (Swiss, Stigmina), root rots (Pythium, Rhizoctonia, Phytophthora, Globisporangium), and needle and leaf blights (Phyllosticta, Cryptocline). Several samples showed abiotic stress related to herbicide exposure, ethylene exposure, transplant shock, or cold injury. Oystershell scales were identified on a chestnut sample.

Table 1. Sample received and diagnosed by the Clinic from March to January
Host	County	Month	Final Diagnosis
Insect ID	Unknown	Jan	Drosophila
Oak Red	Cuyahoga	Jan	Mechanical Damage
Spatiphyllium (?)	Franklin	Jan	Abiotic Watering Related Issue
Cannon Ball Tree	Franklin	Jan	Eutypella Dieback (Suspected)
Insect ID	Unknown	Jan	Leaf-Footed Bug
Strawberry	KY	Jan	Neopestalotiopsis and Anthracnose
Insect Id	Montgomery	Jan	Jumping Spider No Other Pests
Tomato		Jan	Abiotic Ethylene Heat Damage
Veronica	Delaware	Jan	Powdery Mildew
Bonsai	Cuyahoga	Feb	Phomopsis Spores
Bonsai	Cuyahoga	Feb	Phomopsis Spores
Lettuce	Franklin	Feb	Phytophthora Root Rot
Lettuce	Franklin	Feb	Phytophthora Root Rot
Lettuce	Franklin	Feb	Phytophthora Root Rot
Lettuce	Franklin	Feb	Phytophthora Root Rot
Pepper	Franklin	Feb	Fusarium Root Rot
Canaan Fir	Geauga	Feb	Diaporthe (secondary) Environmental Stress
Elm	Delaware	Feb	Phytoplasma Negative (Nested PCR testing)
Arborvitae		Feb	No Pest or Pathogen found, Environmental Suspected
Strawberry	Wayne	Feb	Cold Damage
Insect Id	Butler	Feb	No Insect Found
Begonia	Licking	Mar	Rhizoctonia Root Rot and Environmental stress
Tomato		Mar	Environmental Abiotic (Ethylene damage)
Rhododendron	Wayne	Mar	Cladosporium Leaf Spot (Asked Larger Samples)
Garlic	Wayne	Mar	Garlic Bloat
Spruce	Wayne	Mar	Needle Cast
Spruce Blue	Marion	Mar	Swiss Needle Cast
Taxus	Cuyahoga	Mar	Globisporangium Root Rot
Fir	Marion	Mar	Suspected Herbicide
Fir	Marion	Mar	Suspected Herbicide
Spruce Black Hill	Marion	Mar	Suspected Herbicide
Arborvitae	Lorian	Mar	Transplant Shock Suspected
Chestnut	Ashland	Mar	Oystershell Scale
Cypress False	Lorian	Mar	Phyllosticta Needle Blight
Ranunculus	Clinton	Mar	Pythium Crown Rot
Taxus	Lorian	Mar	Cryptocline Needle Blight
Fir Douglas	Cuhyaoga	Mar	Pine Needle Scale (?)
Hemlock	Wayne	Mar	No significant number of pests found
Lobelia		Mar	Ethylene Exposure Or Herbicide suspected
Marigold		Mar	Ethylene Exposure Or Herbicide suspected
Spruce	Franklin	Mar	Spider Mite Damage
Tomato		Mar	Ethylene Exposure Or Herbicide
Arborvitae	Franklin	Mar	Phyllosticta Blight
Spruce	Franklin	Mar	Stigmina Needle Cast
Arborvitae (Roots)	Franklin	Mar	Phytophthora Root Rot (Immunoassay)
Lettuce	Lake	Mar	Pythium root rot and Botrytis
Spinach	Lake	Mar	Pythium root rot Botrytis
Spruce	Franklin	Mar	Possible herbicide damage