Final diagnosis


Brown spot, Alternaria leaf spot (Alternaria alternata)

Small, brown, necrotic spots surrounded by a yellow halo observed on a tobacco leaf. <i>Alternaria alternata</i> (brown spot)
A few wet spots, browning in the center, scattered over the leaf; <b><i>Alternaria alternata</i></b> (<i>Alternaria </i>leaf spot)
First spots of <i><b>Alternaria alternata</b></i> on a Virginia tobacco leaf.
Dark brown spots of different sizes, some with split centres, on Virginia tobacco leaf. <i>Alternaria alternata</i>
These spots are well defined, surrounded by a marked yellow halo, having fine irregular concentric rings. </i></b> <i><b>Alternaria alternata</b></i> (alternaria leaf spot)
Severe early brown spot attack on Burley tobacco; on some leaves significant portions of the lamina are necrotic and tend to tear, break down and disappear. <i><b>Alternaria alternata</b></i> (brown spot)
When climatic conditions are particularly favourable, the spots enlarge and reach more than one centimeter in diameter. <b><i>Alternaria alternata</i></b> ( <i>Alternaria</i> leaf spot)
The spots are often well defined and of irregular shape surrounded by a yellow halo. They may also have darker rings thus giving them the appearance of a target. <b><i><b>Alternaria alternata</b></i></b> (<i>Alternaria</i> leaf spot)
Many brown, necrotic spots have converged on this tobacco leaf; entire lamina areas have become necrotic and dried up. <i><b>Alternaria alternata</b></i>
One can easily observe the concentric patterns of <i><b>Alternaria alternata</b></i> on tobacco leaves.
Several brown, necrotic spots in between the veins of this tobacco leaf. <i><b><b>Alternaria alternata</b></b></i>
On a lower leaf of this particularly susceptible Virginia tobacco, the numerous spots lead to yellowing and premature senescence of the lamina. <b><i>Alternaria alternata</i></b> (brown spot)
Longitudinal, dark brown lesions with lighter centers, can sometimes be observed on the stem of Virginia tobacco. <b><i>Alternaria alternata</i></b> (brown spot)
During the yellowing stage of curing brown interveinal spots may appear quickly on some tobacco leaves. <i>Alternaria alternata</i>
Many dark brown circular spots having concentric rings on the drying leaf. <i><b>Alternaria alternata </b></i>(brown spot)
Some of these spots are more or less covered with a black velvety layer, corresponding to the number of conidiophores topped with brown multicellular conidia. <b><i>Alternaria alternata</i></b> (<i>Alternaria</i> leaf spot)
<i><b>Alternaria alternata</b></i> (brown spot) produces a multitude of multicellular conidia, arranged in chains on relatively short conidiophores.