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Alfalfa (Medicago sativa L.) is very imported foliage crop in Iraq. During 1981-83, severe mildew infections were observed. The disease appeared in October as white angular colonies of fungal growth limited by the veins on the lower surface of the leaves with corresponding yellowing of the tissues on the upper surface of the leaves. All infected leaves contained numerous cleistothecia, and in November most infected plants were defoliated. The infectivity of the fungus was confirmed by inoculating detached alfalfa leaves with conidia using a brush. Inoculated leaves were placed with their dorsal side up on a filter paper wetted with a solution of 20 p.p.m. of benzimidazole in water in Petri dishes, and incubated at 20° C with a 14 h photoperiod. Inoculated leaves developed characteristic mildew symptoms within 12 days. The conidial stage was reisolated from the inoculated leaves and found to be identical with the original fungus isolated from the infected field plants.                      

Conidia were cylindrical, borne singly, 49-96 x 14-26 (mean 70.4 x 20µm). Cleistothecia were globose, at first yellow, becoming brown at maturity, 172-276 (mean 207) µm diam. The number of asci produced per cleistothecium varied from 16 to 31. Asci were 2-spored, obovate, 64-75 x 24-36 (mean 70 x31) µm. Ascospores were elliptic and hyaline, measuring 27-36 x 14-19 (mean 32 x 17) µm.                        

Based on this information, the fungus was identified as Leveillula leguminosarum Golov. Forma medicaginis (Jacz.) Golov. A new record for Iraq. The only other powdery mildew recorded on alfalfa in Iraq is Erysiphe polygoni DC.                                                                       

Kew Words: Alfalfa, Powdery mildew, Leveillula leguminosarum f.sp. medicaginis