St. Augustine Needs Attention Now

Phone calls have started again this year about spots or lesions on St. Augustine leaf blades. This is Gray Leaf Spot (Pyricularia Grisea). Symptoms include oval or circular tan lesions that are bordered by purple to brown margins.

Gray leaf spot develops in warm, wet weather. Lawns with irrigation systems are especially predisposed if irrigation is running more than necessary or at the wrong time of day. Leaves wither and die if many lesions develop, giving the turf a brownish color.

To manage Gray leaf spot avoid excessive fertilization with nitrogen when warm, humid weather is expected. Avoid late afternoon and evening watering. Prune trees and undergrowth to improve air movement and light intensity.

As for insects, Chinch Bugs, is primarily a problem on thick mats of turf in sunny, open areas. It is most commonly reported as a pest on St. Augustinegrass, but also infests centipedegrass, zoysiagrass, and occasionally Bermudagrass.

The southern chinch bug adults are oblong, oval, and black with shiny white wings. They are 1/6-1/5 inch long. Each wing bears a distinctive, triangular black mark. First and second instars are bright orange. Third and fourth instars are darker red, and the last instar resembles the adult.

Chinch bug populations are concentrated near the surface of the soil. On St. Augustinegrass, feeding is primarily restricted to the tender basal area of grass blades and nodes of runners. Yellowish spots first appear and soon

Date Created: 10/22/2004.