Bacterial Applications for Annual Bluegrass Control
Annual bluegrass (Poa annua) is a weed on golf courses and other highly managed turfgrass, where it competes ggressively with the desired grasses and produces seed prolifically. The bacterium Xanthomonas campestris pv. poae infects and suppresses the growth of annual bluegrass without affecting desirable turfgrass species. It infects Poa plants through wounds in the stem and leaf tissues and multiplies in the vascular system, causing wilting and death of the plants. This bacterium is available for experimental use on golf courses under an Experimental Use Permit (EUP) from the EPA (usually the last step before registration). When is the best time to apply the bacterium for maximum annual bluegrass control?
Applications of X. campestris pv. poae to control annual bluegrass were made in consecutive months in a study in Japan. In pot treatments, applications in October and February through April produced acceptable reductions in annual bluegrass by the following spring. Fall or very early spring (February) treatments resulted in more than 75% reduction in seedhead production. The best control was obtained when maximum bacterial numbers were reached within 1 month of treatment. In field studies on Kohrai (Zoysia matrella) turf and in Kentucky bluegrass (Poa pratensis) turf, both spring and fall treatments were highly successful. However, in bentgrass (Agrostis palustris) turf, control of annual bluegrass was slower. October and/or March treatments effectively inhibited seedhead production, but an April treatment was too late to prevent seed scattering.
Taking into account late-emerging annual bluegrass, the optimum strategy for timing of treatments is:
Imaizumi, S., A. Tateno, K. Morita and T. Fujimori. 1999. Seasonal factors affecting the control of annual bluegrass (Poa annua L.) with Xanthomonas campestris pv. poae (JT-P482). Biol. Control 16(1):18-26.
Releasing Lacewings for Longtailed Mealybug Control
Periodic releases of a green lacewing reduced populations of the longtailed mealybug (Pseudococcus longispinus), in an interior plantscape in Texas. Approximately 150 lacewing eggs were placed on each six-inch pot of pothos ivy. Each such release of lacewing eggs kept longtailed mealybug populations below aesthetic injury levels for four weeks. Aesthetic qualities require the plant to retain its lower leaves and have no obvious evidence of mealybug infestation, such as yellow leaves or honeydew.
Goolsby, J. A., M. Rose, R. K. Morrison and J. B. Woolley. 2000. Augmentative biological control of longtailed mealybug by Chrysoperla rufilabris (Burmeister) in the interior plantscape. Southwestern Entomologist 25(1):15-19.
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