Category Archives: Diseases

Diagnosing Lawn Problems

There are many things that can cause a lawn to decline and die. Drought, soil compaction, excessive shade, chemical injury, pests and diseases are among the many possible contributing factors. If you are watering and fertilizing properly, and if the turf is receiving adequate sunlight, the problem may be due to pests or diseases. The AgriLife Extension Office in Harris County can assist you with diagnosing your lawn problems. In order to properly diagnose your lawn problem we need to see a sample. Here is how to take… Read More →

Landscape Pest & Disease Workshop

If you work in the green industry and deal with pests and diseases in the landscape, or work at a garden center and answer questions from customers on plant diseases and pests; then don’t miss out on the Landscape Pest & Disease Workshop on January 29, 2016. We have an excellent group of presenters that will cover the following  program topics. Pollinator Protection Pesticide Laws & Regulations Landscape Disease Management Landscape Ornamental Pests (Common Culprits & New Invasives) Turfgrass Disease Diagnosis & Management Continuing Education Credits available  TDA Pesticide… Read More →

Plant Health Workshop

The Plant Health Workshop is an annual cooperative program between Texas A&M AgriLife Extension and the Organic Horticulture Benefits Alliance that focuses on managing plant pests with less pesticides. This year’s event features speakers on Transitioning to Sustainable Landscape Practices, Laws and Regulations Update, Pollinator Protection, New Landscape Pests, and Rose Rosette. AgriLife Horticulture agents will also conduct a tour of the ongoing research and demonstration plantings at the Harris County Extension Office. Click here to register!

Crown Gall

We received an email last week from our friend Gaye Hammond a Master Rosarian with the Houston Rose Society regarding a sighting of crown gall on roses. Besides roses, crown gall affects many woody ornamental plants, fruit trees and brambles. Crown gall is caused by a soil-borne bacterium Agrobacterium tumefaciens. Once in the soil, the crown gall bacterium can survive for several years in decomposing galls from infected plants. The bacterium gets into the plant through wounds that occur during planting, grafting, pruning or by chewing insects feeding… Read More →

Seeing Canna Rust?

Cannas are a popular herbaceous perennial that can be grown in containers, as a boarder background or as a specimen in gardens and landscapes throughout Harris County. It did not take long after the wet spring for fungal problems to start rearing their ugly head. We have recently received several emails and calls regarding orange pustules on Canna leaves. Yes, your plant has Canna Rust (Puccinia thaliae). The Puccinia fungus requires long periods of humid weather, poor air circulation and waterlogged soil to grow and flourish. That sounds just… Read More →

Oak Leaf Blister

We are getting many calls and emails about oak leaves that are malformed and brown. The cause is Oak Leaf Blister (Taphrina caerulescens). This fungus attacks the leaves as they are emerging in early spring causing them to grow in a malformed way, with bulges, depressions, cupping and twisting. The affected areas turn from a light green to brown color. Leaves with severe infections will drop from the tree. Oak leaf blister affects many species of oaks including water oak, willow oak and live oak. The fungus attacks… Read More →

Crape Myrtle Powdery Mildew

Powdery mildew attacks many different species of plants including crape myrtle, phlox, roses, rock rose, honeysuckle, snapdragons and zinnias to name a few. It causes a white powdery covering to form on leaves and stems and can cause severe distortion of new growth and stunting of plants when conditions are favorable for its development. Powdery mildew is most prevalent in mild weather conditions, and high humidity. Crowding of plants minimizes air movement and can increase problems with this disease. The best management strategy is to avoid it with… Read More →

The Case of the Missing Squash, Cucumber, and Melon…

We’ve received questions at the Extension Office about squash and cucumber plants that are blooming but not setting fruit. Sometimes there are “tiny fruit that don’t grow, but just shrivel up and die.” Have you noticed this in your garden? The most likely cause of such fruit problems on squash, muskmelons (cantaloupe), cucumbers, watermelons and other cucurbit vegetables is a lack of pollination. These plants have separate male flowers (bloom attached by a small, thin stalk) and female flowers (small fruit at base of bloom). Pollen must be… Read More →