New Turf Cures
Previous UF research has shown that silicon amendment results in better yield for sugarcane and rice by increasing growth, mineral nutrition, mechanical strength, and resistance to biotic and abiotic stresses. Now, research has demonstrated that silicon amendment for St. Augustinegrass is comparable to fungicide (chlorothalonil) treatment for control of gray leaf spot fungus (Magnaporthe grisea) under conditions conducive to severe pressure. Silicon deficiency can be a problem especially for sod growers, as sod removal at harvest may remove much of the soluble silicon. When deficient soils (10 to 14 ppm soluble silicon) were amended with calcium silicate slag, St. Augustinegrass gray leaf spot incidence was reduced between 17 and 27 percent. Control was even better (additive) when chlorothalonil was coupled with the amendment (between 56 and 64 percent reduction in whole plant gray leaf spot). Researchers have determined that this “tolerance” is due to the reduction in total number of lesions produced, either by direct effect or by aiding in the resistance to colonization at a new potential lesion site.
Another UF study recently reported was for a potential MSMA replacement. Foramsulfuron, trade name Revolver®, was registered for use in Florida this summer, and it is registered for use on bermudagrass and zoysiagrass. Research in south Florida has demonstrated that this material works as well as, or better, than MSMA on postemergence goosegrass control in bermudagrass. Two applications of the material, seven days apart, effectively controlled all but the largest goosegrass plants in research plots. As an interesting sidebar, this herbicide had no effects in the toxicity testing submitted to the EPA, and was thus exempted from the requirement of obtaining a tolerance when it is used for food crops. (Florida Turf Digest, May/June 2003).
