ABSTRACT
There are several abiotic maladies of creeping bentgrass that are weather related. Stresses can induce physiological changes in plants that may manifest themselves in the form of color changes in creeping bentgrass and annual bluegrass foliage. Frost may induce a purpling and high-temperature stress a leaf chlorosis (i.e., yellowing). Both of these color changes can be confused with diseases. Mechanical stresses causing bentgrass to decline similarly can be confused with disease. Laboratory diagnosticians help to sort out many of these issues for golf course managers. Turfgrass pathologists can be baf›ed by the presence of fungi and bacteria that are found in association with chlorosis and decline, but there often is no consistent relationship among symptoms and organisms. Many of these organisms are saprophytes (living or senescent, dying or dead tissues or senectophytes), but their dominance in samples can be good indicators of other stress factors. Then there are symptoms such as etiolated, yellow-green leaves or white, chlorophyll-deœcient leaves that mimic disease, but no causal agent can be found. Some examples of the latter include etiolated tiller syndrome and white leaf disease. There also are diseases that are new and little is known about them. Acidovorax bacterial disease œts this category and is considered in this section. Finally, when environmental and mechanical stresses combine with poor growing environments, pathogens, and saprophytes there can be foliar color changes, decline in density, and some or all can contribute to the summer bentgrass decline complex.
