Several calls have been coming in over the past few weeks regarding unusual leaf symptoms on almonds. For the most part, the symptoms have appeared across varieties, but with one variety being more heavily affected within a single orchard. Symptoms also have appeared in waves, starting about mid-April, again in May, and then again in June. Orchards all over the San Joaquin Valley have been calling in with reports, varying in ages, varieties, nutritional status, and orchard spray practices. The symptoms appear to start off as small, yellow pin-head sized lesions on the leaf (Figure 1). Following a few days of heat, the lesions enlarge, and become necrotic, often abscissing from the leaf (Figure 2). The margins of the leaf appear to be the most severely affected, with some damage evident throughout the leaf blade. Figure 1: Initial damage observed of foliar problem commonly experienced in the 2010 crop year. Photo provided by Allan James, Mid Valley Ag. Figure 2: Damage to almond leaves experienced in the spring of the 2010 growing season. These symptoms appeared later than the symptoms observed in Figure 1, usually after a hot spell. I initially thought that the problem was due to foliar nutrient sprays – either due to contaminated products or cation activation (iron, zinc, manganese, magnesium, etc.) by a rain event. This didnt seem to fit the symptoms in every orchard due to some orchard owners not spraying foliar nutrients. Symptoms also appeared similar to potassium deficiency, but the widespread occurrence throughout the valley does not support a nutrient deficiency. The possibility of corky spot was brought up, especially since the leaf symptoms look similar to the pictures of this disease. Corky spot is an unknown disorder that tends to be associated with nonpareil planted on seedling almond type rootstock (i.e. bitter almond). Due to the widespread occurrence of this symptom across differing orchard ages, nursery