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Leaf spots reduce the surface area available on leaves for photosynthesis and so can result in smaller growth and yield of plants. Weakened plants may produce lesser fruit. Virus caused leaf spots reduces chlorophyll in the leaves, resulting in less photosynthetic activity.
This disease affects strawberry plant foliage causing purple spots 1 ⁄ 8 to 1 ⁄ 4 in (3.2 to 6.4 mm) in diameter across on the upper side of the leaves. [3] At first, the whole spot is purple but as the disease matures the center of the leaf spots on older leaves become tan or gray, then almost white. Lesions on younger leaves remain light ...
Theses leaf spots are an orange-brown rust in color and usually occur entirely on the upper leaf surface, although leaf spots on the undersides of infected leaves have been reported. The spots are fuzzy in texture and approximately 2 cm (0.8 in) in diameter. [2] In some cases, commonly in more susceptible hosts, stem and fruit spots can occur ...
Tobacco mosaic and bacterial leaf spot are two common issues. "The tobacco mosaic virus is transmitted from other plants nearby, mites, nematodes, aphids, and thrips," says Langelo.
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 ...
The pathogen is dispersed and spread via windblown or water-splashed onto lower leaves of the sunflower. [3] Young seedlings are more susceptible, but lower leaves on mature plants frequently are defoliated by Alternaria spp.. [3] Germ tubes are produced by the conidia and grow across the leaf surface before forming an appressorium. [6]
Black leaf, also known as black spot disease can be caused by different types of fungi and bacteria. Most common being Asterina, Asterinella, Diplotheca, Glomerella, Gnomonia, Schizothyrium, Placosphaeria, and Stigmea. Black leaf can affect many different plant species in a wet, damp climate. It may appear as black spots on leaves, stems, and ...
Prevention is the best option for management of gray leaf spot as hyphae on plant debris is the primary source of inoculum. [1] There are various cultivars of St. Augustine grass, perennial ryegrass and tall fescue on the market that have variable resistance to gray leaf spot but none are confirmed as completely resistant.