Plant Disease Identification and Control

Information on plant disease identification and control, including rot, freeze damage, rust, blight, mold, scales, bacteria, viruses, fungus, wilt, mildew, gall, mites, moths and cankers. Tips on integrated pest management and herbicide summaries.

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Gumming is frequent in the spring and fall, when the disease is most active. Photo by K. Peter.
Cherry Disease - Bacterial Canker - Articles Articles

Cherry Disease - Bacterial Canker

Kari A. Peter, Ph.D.

While bacterial canker, Pseudomonas syringae, can occur on all stone fruit trees and on apple and pear blossoms, it is only important in the Northeast on sweet and ornamental cherry trees. More
Source: H.J. Larsen, Bugwood.org
Apple Disease - Apple Union Necrosis and Decline - Articles Articles
Apple union necrosis, caused by tomato ringspot virus, affects the graft union of apple trees, resulting in gradual tree decline. More
Typical fruit lesions are distinct, almost circular, rough-surfaced, olive-green spots up to ¾ inch in diameter. Heavily infected fruits are usually misshapen and may crack and drop prematurely. Photo by K. Peter.
Apple Disease - Apple Scab - Articles Articles

Apple Disease - Apple Scab

Kari A. Peter, Ph.D.

Apple scab, Ventura inaequalis, is Pennsylvania's most important apple disease, attacking wild and cultivated apple and crabapple. More
Source: University of Georgia Plant Pathology, University of Georgia, Bugwood.org
Peach Disease - Anthracnose - Articles Articles

Peach Disease - Anthracnose

Kari A. Peter, Ph.D.

Most years, anthracnose, caused by two Colletotrichum species, is considered a minor disease of peach. If left unchecked, this disease that attacks peach fruit can cause serious fruit rot infection. More
Photo by Kathy Demchak.
Strawberry Disease - Anthracnose - Articles Articles
Anthracnose, caused by species in the genus Colletotrichum, can manifest as a fruit rot, crown rot, and/or leaf spots, as well as lesions on petioles and runner stolons. More
Photo by Kathy Demchak.
Raspberry Disease - Anthracnose - Articles Articles
Anthracnose, commonly called "cane spot" or "gray bark," occurs in several species of Rubus. More
Photo by Kathy Demchak.
Strawberry Disease - Angular Leaf Spot - Articles Articles
Angular leaf spot, caused by the bacterium Xanthomonas fragariae, is frequently problematic in strawberry plantings. More
Angular leaf spot close up. (Photo by K. Demchak)
Strawberry Disease - Angular Leaf Spot Favors Cold, Wet Conditions - Articles Articles
Angular leaf spot, caused by the bacterium Xanthomonas fragariae, is most prevalent in cold, wet conditions. More
Dull, olive green areas visible on the undersides of leaves are the first evidence of apple scab.
Tree Fruit Disease - An Apple Scab Review - Articles Articles
Early season apple disease management is primarily directed at controlling scab. More
Photo by K. Peter.
Tree Fruit Disease - Alternaria Rot - Articles Articles

Tree Fruit Disease - Alternaria Rot

Kari A. Peter, Ph.D.

Alternaria rot, Alternaria alternata, is a common fungus found on stone and pome fruit. The disease can occur during preharvest and postharvest. More
Source: Dalphy O.C. Harteveld; Apple and Pear Australia Ltd. Used under Creative Commons 2.0 license: creativecommons.org/licenses/by/2.0/legalcode
Apple Disease - Alternaria Leaf Blotch - Articles Articles
Alternaria leaf blotch, caused by Alternaria mali, is a disease that affects apple leaves. More
If ripe fruit are not kept cold, Rhizopus rot can take over very quickly. (Photo: K. Peter)
Peach Disease - Rhizopus Rot - Articles Articles

Peach Disease - Rhizopus Rot

Kari A. Peter, Ph.D.

Management strategies are discussed for mitigating the postharvest disease Rhizopus rot on peaches and nectarines. More
Tree Fruit Diseases - Postharvest
Tree Fruit Diseases - Postharvest - Articles Articles

Tree Fruit Diseases - Postharvest

Kari A. Peter, Ph.D.

There is a need to figure out novel disease management strategies necessary for staying one step ahead of postharvest decay pathogens. More
Explorando e Identificando Enfermedades en Tomates
Explorando e Identificando Enfermedades en Tomates - Videos Videos

Explorando e Identificando Enfermedades en Tomates

Marley E Skinner, Montserrat Fonseca Estrada, Tianna DuPont, Mike Basedow

8:37

Este video revisa los fundamentos de la exploración adecuada y la identificación de enfermedades comunes y sus síntomas. More
Downy mildew on pumpkin. Photo: Beth K. Gugino, Penn State
Vegetable Disease Updates: August 30, 2017 - Articles Articles
Within the past week, there have been three separate reports of downy mildew on jack-o-lantern pumpkin in eastern Virginia. More
Plant Health Diagnosis: Assessing Plant Diseases, Pests and Problems
Plant Health Diagnosis: Assessing Plant Diseases, Pests and Problems - Online Courses Online Courses
$59.00
Learn a process for diagnosing plant health problems, including signs and symptoms of diseases, pests and insects, and environment or management issues. More
Map of cucurbit downy mildew currently reported along the east coast as of 26 July 2017 (cdm.ipmpipe.org).
Vegetable Disease Updates for July 26, 2017 - News News
The rainy weather is not letting up and neither is downy mildew pressure. More
Postharvest fungicide sprays are necessary to prevent defoliation from cherry leaf spot. Photo: K. Peter, Penn State
Getting the Upper Hand on Tree Fruit Diseases in July - News News
Conditions may be optimal for several fungal and bacterial pome and stone fruit diseases in July. More
Scouting and Identifying Tomato Diseases
Scouting and Identifying Tomato Diseases - Videos Videos

Scouting and Identifying Tomato Diseases

Marley E Skinner, Mike Basedow

8:21

Tomatoes are an important and profitable crop for many vegetable growers. This video reviews the basics of proper scouting and identification of common diseases and their symptoms. More
Map of cucurbit downy mildew currently reported along the east coast as of 30 June 2017 (cdm.ipmpipe.org).
Vegetable Disease Updates for June 30, 2017 - News News
Be on the lookout for diseases, as well as timber rot in high tunnel tomatoes, that spread in some of the recent rain events that moved across the Pennsylvania. More
Watch out for brown rot on sweet cherries. Photo: K. Peter, Penn State
Protecting Cherries From Brown Rot - News News
As the sweet cherry harvest commences, there are concerns about brown rot. Management options are discussed. More
Photo: P. Landschoot, Penn State
SDHI Fungicides for Turfgrass Diseases - Articles Articles

SDHI Fungicides for Turfgrass Diseases

Peter Landschoot, Ph.D.

As summer approaches, plans are being finalized for disease prevention and control programs. More
Upper surface of affected shrub rose showing round leaf spots with an orange center on yellowing leaves. Image: R. Benner, Penn State
Rose Rust in the Landscape - Articles Articles
Rose Rust is uncommon on ornamental roses in Pennsylvania but it does occur, especially in mild, wet spring conditions. More
Be vigilant and scout for apple scab! Photo: K. Peter, Penn State
June Diseases for the Grower Radar - News News
Diseases for the fruit grower radar and their management strategies are discussed as we wrap up May and begin June. More
Too late to manage peach leaf curl when symptoms are present. Photo: K. Peter, Penn State
Disease of the Month: Peach Leaf Curl - News News
Peach leaf curl has caught many folks off guard this year. Tips for preventing the disease next season are discussed. More