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The leaves begin to turn brown at the margins and necrosis progresses towards the base of the leaf. [2] Cankers, which may or may not have black spots, may appear in the epidermal cortical tissue and on the stems of infected plants. Black spots, if visible, are pycnidia and/or perithecia. Black rot is a common symptom on the fruit of gummy stem ...
The species can be a major agricultural pest insect in North America. Spotted cucumber beetles cause damage to crops in the larval and adult stages of their life cycle. Larvae feed on the roots of the emerging plants, which causes the most damage since the young plants are more vulnerable. [1]
Small water-soaked lesions, maturing into sunken and brown spots with or without a yellow halo. May show concentric rings with purple margins. Necrotic tissue may fall out to appear shot-holed. Leaf spot on many plants and crops. Septoria: Small brown spots, that turns light tan to white in the centre. Leaf spot on many crops Bipolaris
Didymella bryoniae, syn. Mycosphaerella melonis, is an ascomycete fungal plant pathogen that causes gummy stem blight on the family Cucurbitaceae (the family of gourds and melons), which includes cantaloupe, cucumber, muskmelon and watermelon plants.
The younger larvae are thin white caterpillars with numerous small black spots. As the larvae mature they become plump and darker in color and they lose their spots. The larvae tuck themselves into crumpled dead leaves to pupate for 8 to 10 days. The life cycle varies by environmental conditions ranging from 22 to 55 days.
Cercospora is a genus of ascomycete fungi. Most species have no known sexual stage, and when the sexual stage is identified, it is in the genus Mycosphaerella. [2] Most species of this genus cause plant diseases, and form leaf spots.
A. a. f. sp. lycopersici (AAL) infects only certain cultivars of tomato plants and is often referred to as Alternaria stem canker of tomato. [3] AAL ' s main symptom is cankers in the stem. It resides in seeds and seedlings, and is often spread by spores as they become airborne and land on plants. It can also spread throughout other plants. [4]
The black spots can become about 5 millimeters in diameter. [1] As the season continues, the tissue around the original spot may become necrotic. [4] In severe cases of the disease there is premature shedding of leaves, blight of young leaves and shoots, and complete defoliation early in the fall. [1] Fruits that are infected become crumpled. [1]