Extension Plant Pathology Quarterly Highlights June 4, 2004

Extension Plant Pathologist Establishes "Urban Plant Detectives" Program

Urban Plant Detectives is a new program that will be introduced this summer by Texas Cooperative Extension Plant Pathologist Kevin Ong. The aim of this program is to train and equipo master gardener volunteers to enhance their skills in diagnosing plant problems and evaluating potential solutions to plant disease problems. The project will train and utilize Master Gardeners to evaluate and compare biological rational (natural) and chemical fungicides which are commonly used to control powdery mildew on crepe myrtle, or powdery mildew and black spot of roses. These are common plant disease problems that are found in Texas. Participants will be expected to attend all training sessions and to commit approximately two hours per week to the project for the duration of ten to twelve weeks. Information gleaned from this study, with the assistance of the volunteers, will contribute to expand our understanding of these disease control material and will be used in the future recommendations to control these plant diseases.

Master Gardener Training Improved Plant Disease Diagnostic Skills

Texas Cooperative Extension Plant Pathologists contribute extensively to the training of volunteers in the very successful Master Gardener program. Recently, Dr Larry Barnes, Extension Plant Pathologist with Texas Cooperative Extension gave intensive training sessions to 119 Master Gardener students in each of Harris, Galveston, and Jefferson Counties. The training was intended to help develop difficult plant disease diagnostic skills for the students. Pre-test and post-test evaluations were performed on the ability of the students to diagnose correctly various plant diseases. After the training, the average diagnostic proficiency scores were raised to an impressive 80% from a poor pre-instruction score of 17%.

Texas Melon Industry Assisted in Managing Fungicide Resistance Problem

Gummy stem blight is a significant foliar disease in Texas watermelon and cantaloupe production. Previously, fungus that causes gummy stem blight developed resistance to the previously-used fungicide benomyl in the Lower Rio Grande valley and caused a yield loss of $10 million in 1997 alone. Newer strobilurin fungicides were introduced replace benomyl, but recently in 2003, Dr. Tom Isakeit, Extension Plant Pathologist with Texas Cooperative Extension discovered that the fungal pathogen was starting to develop resistance to these new stobilurin fungicides. Dr. Isakeit quickly informed the Texas melon industry through the Texas Vegetable Growers Association and the Texas-Oklahoma Watermelon Association of the situation with recommendation on how to best manage the problem. In February 2004, Dr. Isakeit developed a rapid, three-day laboratory test for determining if a gummy stem blight isolate is resistant to stobilurin fungicides. Previous testing program required about one month for a confirmation. This new technique helps growers make wise, effective fungicide choices, optimize production, and minimize losses due to gummy stem blight. Based on 2003 data, there are about 35,000 acres of watermelons in Texas, with a estimated value of $67.8 million. The 13,000 acres of cantaloupe and honeydew melons grown in the Lower Rio Grande Valley with an estimated value of $56 million are also prone to gummy stem blight damage.

Check out the newest issue of the Plant Pathology Update! This issue discusses Ralstonia solanacearum race3 biovar 2 (Rsr3b2) You can download this file here.