When fig leaves start looking sad in late summer we get a lot of questions about what can be done. Figs are susceptible to a fungal disease called Fig Rust and it is not uncommon to see symptoms of this fungus on stressed trees. Fig Rust symptoms begin as angular yellow-green flecks on the leaf. The spots become more yellow and eventually turn a yellowish brown. On the underside of the leaf the spots appear as small blisters from [...]
Tomatoes are susceptible to a variety of fungal leaf spot diseases. Proper cultural methods go a long way in preventing them. Septoria leaf spot usually shows up on the lower leaves after the fruit has begun to set. Removal of the lower leaves as the plant grows so that splashing water will not spread the disease is recommended. The fungus overwinters on plant debris or on any plant in the Nightshade family. It can also survive on tomato cages and [...]
I first became aware of this Decline of Post Oaks when visiting a Texas A&M AgriLife Extension booth at an annual trade show several years ago. I had been aware of how the severe drought in 2011 was continuing to plague our trees even more than a decade later, but had not heard of the Post Oak Decline. The incidence of Rapid Decline began in earnest after the severe drought of 2016. Since then I have experienced first hand the devastation this has caused to so many stately old trees. [...]
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 [...]
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 [...]
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 [...]
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 [...]
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. [...]
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 [...]
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 [...]
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 [...]
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 [...]
