Texas Plant Disease Diagnostic Lab-
WHAT Wednesday Videos
Category Archives: Fungi
Perfect conditions for Cercospora
Be on the lookout for Cercospora leaf spot in your landscape plants! Recent weather conditions around the state like cool temperatures and high humidity seem to trigger an increase in Cercospora activity. Check your colorful fall annual bedding plants, including zinnias, hydrangeas, snapdragons and azaleas, for necrotic or purplish, angular leaf spots. A: Cercospora symptoms on a recent Pansy sample B: Conidiophores on leaf edge C: Cluster of Cercospora conidiophores
Seen around College Station (Central TX).
Some patches in lawns caught my eye this week. It was interesting to note that there were several lawns in my neighborhood had patch symptoms. Most appear to be due to rhizoctonia blight (common name of disease = brown patch, yellow patch or large patch). I just call it brown patch. The “smoky” halo at the edge of the damage area of the turf was evident in many of them. I have also been getting some reports from the Dallas-Fort Worth area that this disease (caused by the… Read More →
Root rot galore
A quick wrap of things seen in the last couple of weeks as temperature begin to get cooler. At the Plant Clinic, we have some samples with root rot damage. These are root rots of all kinds, occurring on woody ornamental and turf grasses. Why is there a pickup in the incoming samples? There is not an easy answer. It may be that since weather is getting cooler, more people are out in their yards -resulting in greater observations of the damage in the landscape. Another explanation could… Read More →
Algal leaf spots on Magnolia (Training at the Plant Clinic part 4)
Blog article #4 by Marissa McCarthy (for partial fulfillment of BESC 484 requirement) Algal leaf spot is caused by the subcuticular leaf parasite from the genus Cephaleuros. This specific algal leaf spot is C. virescens and was sent into the lab on a magnolia from a private residence. Cephaleuros thrives in environments that are warm with high humidity, or poorly aerated soils. Characteristically this algae is harmless, causing only minor leaf spots on the upper surface of leafs that are raised, textured, orange to brown in color, with… Read More →
Tar spots on oaks (Training at the Plant Clinic part3)
Blog article #3 by Marissa McCarthy (for partial fulfillment of BESC 484 requirement) Trabutia quercina is an ascomycete fungus that specifically targets species of oak trees, creating a disease commonly known as Tar spot on the leaves. The Tar spot was found on a live oak sample that was sent into the lab from a private residence. This fungus is characterized by the formation of black, blotchy lesions on the upper side of oak leaves, especially along the veins of the leaves. The lesions gradually expand and… Read More →
