Persimmon anthrax
Persimmon anthracnose is one of the most devastating diseases affecting persimmon trees, especially in recent years. Many growers have suffered significant losses due to this disease, with some experiencing total crop failure. The disease can cause severe defoliation, premature fruit drop, dieback of new shoots, and even the death of entire plants.
**Symptoms**
The disease primarily affects shoots and fruits, although leaves can also be infected. On the fruit, small dark brown to black spots first appear on the surface. These lesions gradually expand into round or oval shapes, becoming slightly sunken. The outer layer turns yellow-brown, with a diameter ranging from 5 to 25 micrometers. The center of the lesion becomes dense, gray to black, and under wet conditions, it exudes pinkish, viscous material. As the infection progresses, the lesions penetrate deeper into the fruit, forming black masses. Usually, each affected fruit has one or two lesions, but many may fall off prematurely.
On the leaves, infections typically start at the petioles and veins, appearing as yellowish-brown spots that later turn dark brown or black. The lesions are elongated or irregular in shape.
New infections usually begin in late May to early June. Initially, small black circular spots form on the surface, which then turn dark brown. The lesions grow larger, becoming oblong with a slightly sunken center. The bark splits longitudinally, and black dots—spore-producing structures—appear. When humidity is high, red spore masses develop on these black spots. Lesions can be up to 10–20 mm long. The xylem beneath the lesions decays easily, and the tissue breaks apart. If the lesions on branches are large, the parts of the branch above them often die.
Fruit infections typically occur from late June to early July and can continue until harvest.
**Pathogen**
The causal agent is *Gloeosporium kaki* Hori, also known as *Colletotrichum gloeosporioides*. It belongs to the fungal subphylum Ascomycota and produces conidia (asexual spores) in characteristic structures.
**Transmission and Disease Conditions**
The pathogen overwinters in infected branches, fallen fruits, leaf scars, and winter buds. Spores are produced in late summer and spread through wind, rain, insects, and direct contact through wounds. The incubation period varies: 3–6 days for mycelium invasion and 6–10 days for direct infection. High temperature and humidity significantly favor disease development, particularly after heavy rains or during the summer rainy season. Some persimmon varieties, such as 'Rich' and 'Yokono', are more susceptible.
**Prevention Methods**
1. Improve cultivation practices, especially proper fertilization and irrigation to avoid excessive vegetative growth.
2. Remove initial infection sources by pruning diseased branches and fruits during winter, and burning or burying fallen fruits.
3. Use disease-free seedlings. Inspect all incoming seedlings carefully and treat them with a 1:3:80 Bordeaux mixture or 20% lime milk for 10 minutes before planting.
4. Apply protective sprays throughout the growing season. Before flowering, spray with 5 times lime sulfur or 45% crystal lime sulfur diluted to 30 times. In June, mid-June, mid-July, and mid-August, use 1:5:400 Bordeaux mixture. Later, apply 1:3:300 Bordeaux mixture or 70% mancozeb wettable powder diluted to 400–500 times, 50% benomyl wettable powder at 1500 times, or 70% thiophanate-methyl wettable powder at 1000 times. You can also use disinfectants like 100 grams per liter for additional protection.
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