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Puccinia thaliae is the causal agent of canna rust, a fungal disease of Canna. Symptoms include yellow to tan spots on the plant's leaves and stems. Initial disease symptoms will result in scattered sori (clustered sporangia), eventually covering the entirety of the leaf with coalescing postulates. Both leaf surfaces, although more predominant ...
Peach tree leaves displaying various stages of the shot hole disease: brown spots on the leaf with conidium holders in the middle (center) that eventually fall off, leaving BB-sized holes behind (left) Shot hole disease of apricot leaves. The fungal pathogen Wilsonomyces carpophilus affects members of the Prunus genera. Almond, apricot ...
On leaves, lesions begin as chlorotic (yellow) spots that expand to become deep brown and necrotic on the upper leaf surface. [3] These spots often have a discolored, light center where sporulation can occur, and many have a yellow "halo" around the margins. This halo is caused by the toxin cercosporin, produced by Cercospora species. [1]
Purple spots may also appear on the leaf undersides. Plant growth, root development, and seed and fruit development are usually reduced in potassium-deficient plants. Often, potassium deficiency symptoms first appear on older (lower) leaves because potassium is a mobile nutrient, meaning that a plant can allocate potassium to younger leaves ...
Septoria cannabis is a species of plant pathogen from the genus Septoria that causes the disease commonly known as Septoria leaf spot. Early symptoms of infection are concentric white lesions on the vegetative leaves of cannabis plants, followed by chlorosis and necrosis of the leaf until it is ultimately overcome by disease and all living cells are then killed.
Spots first appear on the upper surface of lower leaves as faint brown to black pinpoint dots. As the dots enlarge to become brown to dark-brown circular spots, a yellow "halo" generally develops as a border around each spot. This disease is frequently seen as early as June 1 in both North Carolina and Virginia.
Once on the leaves, the spores germinate and penetrate through the stoma. [2] The subsequent infection causes chlorosis of the leaves in localized yellow spots. As the season continues into summer, apothecia begin to form, giving rise to brown-black leaf lesions that resemble spots of tar. [2] Leaves retain their yellow border from the initial ...
At initial stages, small yellow spots are formed on the surface of the leaf. These spots may be better observed using assistance of a light source. As the disease progresses, lesions start to form on the leaves, stems, pod, and petioles. Lesions are initially small, turning from gray to tan or brown as they increase in size and the disease gets ...