Texas Plant Disease Diagnostic Lab

The Texas Plant Disease and Diagnostic Lab at Texas A&M University will test samples of diseased leaves from trees/shrubs and samples from lawns showing possible signs of disease. Please read the directions for payment and collection of samples. NOTE: They do not want DEAD LEAVES! Living tissue is best for diagnostic purposes. For a lawn sample, a 4"-6" divot with about 1" of soil/roots taken from the area NEXT TO the affected area (transition zone) is preferred to sending a sample of dead grass. Tree/shrub leaves that are just beginning [...]

By |2023-02-28T08:25:50-06:00November 30th, 2022|Disease|
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Galls

Plant galls are fascinating to me. They are all around us, yet we seldom notice them unless they appear in a favorite landscape tree. Plant galls are produced by a variety of organisms which include mites, wasps, midges, thrips, fruit flies, moths, psyllids, and aphids, as well as bacteria and fungi. Most plant galls are not harmful to the host plant, with the exception of some formed by bacteria and fungi. Many plant galls are produced by the host plant in response to the egg laying activity of the insects [...]

By |2023-02-28T08:27:30-06:00October 2nd, 2022|Disease, Insects, Trees|
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Seiridium Canker of Leyland, Arizona and Italian Cypress

With the increased use of these three evergreen members of the Cupressaceae family in Central Texas, it is inevitable that we have begun seeing increased incidences of this common canker disease. Although Italian Cypress seems to be the most common species to be affected due to its prevalence in the landscape, this disease can also infect juniper and arborvitae. Leyland Cypress is now showing more symptoms in Central Texas, most likely because it is planted in soil that is not as well-drained or as high in organic content that the [...]

By |2023-02-28T08:31:43-06:00February 4th, 2022|Disease|
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Ganoderma Butt Rot

The presence of a “fruiting body”, or conk, at the base of a tree or palm is a sign that the tree may be infected by a species of fungus called Ganoderma. There are several species of this fungus that affect different hosts. This one is Ganoderma sessile, and it affects oaks, maples, honeylocusts and other hardwoods. The conks appear annually in summer and fall at the base of the tree or on a lateral root close to the trunk. The fungus enters through wounds in the trunk commonly made [...]

By |2023-02-28T08:32:25-06:00January 4th, 2022|Disease, Trees|
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Root Knot Nematodes

Root Knot Nematodes (Meloidogyne spp.) are parasitic microscopic worm-like animals that infest plant roots and interfere with the uptake of water and nutrients. Infected plants will appear stunted, they may wilt on hot days even though soil is moist, they may have chlorotic or light green leaves and usually have reduced yields.       The roots will have "knots" on them where the nematode has entered the plant, and the "knots" do not come off easily, as can be seen on this nematode infested potato.         [...]

By |2023-02-28T08:33:07-06:00July 21st, 2021|Disease, Fruit & Nuts, Insects, Plants, Vegetable Gardening|
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Gray Leaf Spot on St. Augustine Lawns

Gray Leaf Spot (Piricularia grisea) usually shows up on St. Augustine Lawns during late spring to early summer, especially if there is abundant moisture available. Spring rains and nighttime watering schedules contribute to disease incidence. Many times cultural practices contribute to the lawn’s susceptibility to disease. Avoid high nitrogen fertilizers, weed and feed fertilizers and frequent, shallow watering. Do not water in the late evening or overnight. Catching the clippings while the disease is active will slow the spread of the disease, as will cleaning mower blades with alcohol before [...]

By |2022-01-15T12:08:01-06:00July 21st, 2021|Disease, Lawn Care|
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Gummosis in Fruit Trees

Gummosis is a term that refers to the presence of  amber-colored sap oozing from the trunk or branches of a tree. It is important to understand that the term “gummosis” is a symptom, not a cause of a tree ailment. Anything that stresses the tree can be a causal factor. It is necessary to determine the cause of the stress in order to mitigate future damage to the tree. Gummosis has a variety of causes: Environmental stress: Compacted soils, poorly drained soils, light sandy soils, use of weed and feed [...]

By |2022-01-15T12:09:08-06:00July 7th, 2021|Disease, Fruit & Nuts, Insects, Plants, Trees|
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Early Blight of Tomato

What is Early Blight? Early Blight is a common fungal disease of tomatoes caused by the fungal organism Alternaria solani. As with most diseases, stressed plants or plants in poor health are more susceptible. This disease can also affect potatoes. The Early Blight fungus generally starts at the bottom of the plant, affecting leaves, stems, and fruits. Dark spots with concentric rings develop on the leaves, and if the fruit is affected spots begin at the stem end, forming a dark sunken area with concentric rings. How do we prevent [...]

By |2023-05-02T09:23:19-05:00June 29th, 2021|Vegetable Gardening, Disease|
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Bacterial Leaf Spot on Peppers

This devastating disease can infect peppers and tomatoes. Prevention is the key, as once the disease has taken hold treatment is not effective. Bacterial leaf spot causes lesions that look like they are soaked with water. The spots usually appear on the lower leaves first, and as the disease progresses the spots are purple brown with a light brown center. When the spots appear on the peppers, they cause spotting and raised cracks, which open the fruit up to infection by other disease organisms. There are no resistant varieties and [...]

By |2022-01-15T12:28:04-06:00May 12th, 2021|Vegetable Gardening, Disease|
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Tomato Leaf Curl

Most gardeners have experienced leaf curl on tomatoes at one time or another. It is important to understand the cause so that you can make the decision on whether it is necessary to remove the plant from the garden or not. Some causes are environmental and may be attributed to physiological conditions. When this is the case, removal of the plant is unnecessary. Leaf Roll, aka Physiological Leaf Curl, is often seen during excessively moist, cool conditions. The leaf rolls “upward” and becomes leathery in texture. Curling leaves may also [...]

By |2022-01-15T12:28:56-06:00May 12th, 2021|Vegetable Gardening, Disease|
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Pepper Leaf Spot

I know that I am not the only one who has had this disease on their peppers. It appears in the late spring to summer when we have had frequent rainfall. Of course, if you are overhead watering, you would see it as well. Bacterial leaf spot on peppers can be a devastating disease if not caught and treated early. This is why I always preach that your garden needs to be in sight of your house so that you can check it often. This disease is often fatal once [...]

By |2022-01-15T12:29:54-06:00May 5th, 2021|Vegetable Gardening, Disease|
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Sick Tree Care

The vast majority of diagnostic questions I receive each year are related to trees with health issues. Many of these issues could be avoided by proper (and consistent) care of the tree from the day it is planted. Sometimes things do go wrong, and knowing what to do can be instrumental in reviving the health of a tree. Trees have the amazing ability to “compartmentalize” diseased and damaged tissue, and to produce healthy tissue around it. If a tree has been stressed by environmental issues such as compaction in the [...]

By |2022-02-23T13:45:36-06:00January 6th, 2021|Disease, Insects, Plants, Trees|
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