Plant Diseases

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Close up of a green sycamore tree leaf with irregular brown spots.
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Defoliated Sycamore Trees?

September 7th, 2023
By Belinda Messenger-Sikes
Have you been seeing a lot of defoliated sycamore trees recently? Sparse foliage and early leaf drop on sycamore trees might be due to anthracnose. The cool, wet spring in many parts of California provided the perfect conditions for this disease.
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Credit: Steve Garner, Flikr.
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Wet Weather Dos and Don'ts

January 11th, 2023
By Lauren Fordyce
An immense amount of rain has fallen across California in recent weeks. While rain is incredibly beneficial, in excess it can cause serious problems. The continued wet conditions opens the door for many pests, so see the list of dos and don'ts below for common wet weather pest prevention tips.
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Sunburned bell pepper with a necrotic spot
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What are Abiotic Plant Disorders?

October 3rd, 2022
By Lauren Fordyce, Belinda Messenger-Sikes
Abiotic plant disorders are generally caused by environmental conditions, rather than microorganisms. They are sometimes called noninfectious diseases. Abiotic disorders can develop if a plant's needs are not being met.
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A drought-tolerant garden bed of California poppies, Ceanothus, and Watsonia. Photo by Tina Saravia, UC ANR.
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Drought or Disease?

September 26th, 2022
By Karey Windbiel, Belinda Messenger-Sikes
With ongoing drought and local water restrictions in place in many areas of California, you may start to see landscape plants suffering from stress caused by a lack of water, calledwater stress. Water-stressed plants can have symptoms that resemble diseases caused by plant pathogens.
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Thinning canopy is an early sign of Bot canker. [Credit: J. Downer]
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Bot Canker: Have You Heard of It?

July 28th, 2022
By Karey Windbiel
Ever heard of Bot canker? "Bot" stands for Botryosphaeria which is a plant disease that results in cankers of trees and other woody plants. This fungal disease can be worse under drought conditions when trees are stressed.
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Horn/nose development on tomato fruit (Credit: N Volesky)
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Abiotic Problems of Tomato

July 11th, 2021
Originally published in the Summer 2021 issue of Utah Pest News. Many problems that gardeners experience with tomato plants are not related to insect pests or diseases. Rather, they are associated with adverse growing conditions due to the environment or production practices.
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A yellow green sweet pea leaf with brown spots from a fungal disease.
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Does my plant have a disease?

March 9th, 2021
By Belinda Messenger-Sikes
Figuring out what's wrong with your plant takes a little detective work. Plants can look unhealthy for a number of reasons, including diseases, pest insects, or even environmental conditions like sunburn, too much water, not enough water, wind damage, and other issues.
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Downed tree with exposed roots in front of residence.
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Storm Damage in Landscapes

January 27th, 2021
Strong winds from the latest winter storm have downed trees and branches throughout Northern California and may have also damaged plants in your garden and landscape. Further damage from wind or hail can be reduced with proper cultural care.
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Close up photo of blackish sooty mold covers a branch of green pomegranate leaves and some pomegranate fruit.
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Finding Soot Afoot? It Could be Sooty Mold

October 6th, 2020
By Belinda Messenger-Sikes, Karey Windbiel
Sooty mold is a black fungal growth that looks like a layer of soot covering the leaves of a plant or a sidewalk. The aptly named disease is common in gardens and landscapes, appearing wherever a large infestation of plant-sucking insects are found.
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Figure 1. A healthy backyard lawn. (Credit: C Reynolds)
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Lawn Problems: Diseases Are Not Always To Blame

July 16th, 2020
By Janet S Hartin
Your customers want their lawns to be beautiful and functional (Figure 1) but dead patches or other problems sometimes occur. Figuring out the cause of turfgrass damage can be a challenge since many plant pathogens affect grasses as well as numerous abiotic (non-living) disorders.
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