Glomerella Gummosis of Citrus Species in Puerto Rico

Abstract

This article deals with the results of research on a serious gummosis disease found in the Isabela region, especially attacking citron, grapefruit, sour orange, and orange. Further studies indicated a rapid spread of the disease in the vicinities of Isabela, Adjuntas, and Jayuya, seen now "in scions and grafting stocks in nurseries and groves" of citrus. Inoculations of the fungus on these citrus fruits proved the pathogenicity of this organism. Then accurate control methods were adopted by inoculating spore suspensions into the injured tissues and keeping these seedlings at a temperature range of 24° to 26° C. and a relative humidity of 60 to 80 percent. Control seedlings with stem injuries, but no fungus spores inoculated into them were also held under these scientific conditions until they healed well, thus developing healthy callus around the inactivated diseased areas. However, the "Glomerella gummosis", as it is called, is not necessarily a foot rot. It attacks through stem wounds and even causes leaf infections that then invade the petioles and enter stems where it causes pitchy lesions, and "teardrops" ooze from cankers.