The experiments were repeated at least twice. Leaves and leaf fragments of 1.0 g of freshly harvested plant material was thoroughly ground with a mortar and pestle in 40 mL methanol. The methanolic solution was decanted and passed through four layers of cheesecloth to remove plant particles. The solution was taken to dryness by flash evaporation EX 527 in vivo at 37 °C and the residue was stored at −20 °C. A number of creosote plants were selected and transplanted to the Montana State University greenhouse

facility. Inoculation of leaves was accomplished by making two to three pin pricks through each of many leaf blades and then flooding the surface with a suspension of 107 spores mL−1. Uninoculated leaves were treated in the same manner, but without the introduction of the spore suspension. The leaves were held at 23 °C in 100% relative humidity for 5–7 days and then evaluated for symptom production. Re-isolation of the putative pathogen was accomplised in the same manner as described above for fungal isolation and recovered fungi were evaluated based on cultural and morphological characters. Over the course of a number of years several sites in the southern deserts of Utah were sampled in May and June for endophytic microorganisms associated

with L. tridentata, but with no success. In midwinter, the roots, stems and leaves of a number of bushes were sampled in an area south of St. George, UT, and only one fungal endophyte, and no other this website microorganism, appeared in the root specimens of the symptomless plants that had been sampled. In early spring, close examination of the leaves of many creosote bushes in this area revealed that

they were showing disease symptoms, i.e. small necrotic spots having one or more black pustule-like fruiting stuctures (pycnidia) associated with each lesion. From these diseased areas of the leaves it was possible to isolate the same fungus that had been isolated from the symptomless roots old of this plant species. Interestingly, cultures of this fungus were odoriferous but not in the same manner as that of the host plant. The fungus in each case possessed the following cultural and morphological characteristics. Colonies on PDA are 50–55 mm after 8 days at 23 °C, olivaceous to greenish olivaceous, forming concentric rings, later turning completely black due to formation of pycnidia; aerial mycelium is almost absent, margin is regular and reverse concolorous. Conidiomata are pycnidial, solitary (sub-)globose to broadly ellipsoidal, glabrous or with some hyphal outgrows, on the agar surface and immersed, later forming concentric rings, 120–200 × 113–145 μm. Ostioles (one to three) are nonpapillate sometimes slightly papillate, circular to oval and 20–25 μm in diameter. The pycnidial wall is pseudoparenchymatous, composed of angular cells and comprises two to four layers.