Persimmon tree leaf diseases

Diseases of the Persimmon Tree

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Persimmon trees are excellent, interesting specimen trees, according to Edward F. Gilman, a horticulturist with the University of Florida. The common persimmon (Diospyros virginiana) is native to America and grows well in U.S. Department of Agriculture (USDA) hardiness zones 4 through 8a. The non-native Japanese persimmon (Diospyros kaki) is not as cold-hardy as the common persimmon but has superior fruit, according to David Parker, a horticulturist with Clemson University. Both trees can suffer from a number of diseases.

Leaf Spot

Leaf spot is a fungal disease caused by a several different types of fungi. The disease causes ugly spots to appear on the leaves of the tree. In some cases, the spots fall out, leaving the leaves with a “holey” appearance. In other cases, depending on the particular fungus, the spots may enlarge and spread, become greasy in texture, or develop raised edges. Often, the leaves will curl or shrivel up. Affected leaves may even drop prematurely from the tree. If the fruit is infected, the skin may develop spots or split open.

While leaf spot is unattractive, it is not fatal to the tree. Once a tree is infected, the disease must run its course. To prevent the disease from returning the next year, rake up dropped leaves so the fungus does not overwinter in the soil. Many of the fungi spread on water, so avoid wetting the leaves of the tree during irrigation. Chemical methods such as applying a fungicide are often ineffective, as thorough coverage of trees of this size (up to 60 feet tall) can be difficult.

Vascular Wilt

Vascular wilt is a disease of the water-carrying system of the persimmon tree, including the roots. In persimmon trees, it is caused by fungi of the genre Verticillium. These diseases are not limited to persimmon trees, but can infect vegetables and other plants as well.

As the disease progresses through the tree, the persimmon leaves wilt and begin to turn light green and yellow. Over time, they turn brown and shrivel up. The wood also becomes discolored. Fruit may not develop at all, or it may develop in a disfigured form, or develop partially and then wither and die. Eventually, the tree will die.

The fungi that cause Verticillium wilt live in the soil, and cannot be killed by spraying the tree with a fungicide. Drenching the soil with a fungicide is also usually ineffective, according to J. Louter, a horticulturist with the University of Guelph. The best way to deal with the disease is to prevent it by planting wilt-resistant varieties of persimmon trees in soil that is free of the pathogen.

Twig Blight

Twig blight occurs when the twigs of a persimmon tree begin to die back from the tips inward. This is usually caused by a fungal disease that infects the sapwood of the tree. The fungus enters the tree on the bodies of insects, most commonly, the persimmon borer. As the insect bores into the wood of the tree, the fungus infects the wood.

Twig blight can affect individual branches, causing cankers to develop (dark, sunken, cracked areas of dead wood), or it can affect the entire tree. In the case of the former, the branches can be pruned off in order to stop the spread of the disease. If the tree begins to die from the crown downward, the heartwood is probably infected and the tree will die.

Once a tree is infected, it can only be saved if the diseased limbs are pruned off. The best way to prevent the disease is to control for insects that may carry the fungus. Watch your tree for signs of an insect infestation, and spray the tree with insecticide if necessary.

First Report of Circular Leaf Spot of Persimmon Caused by Mycosphaerella nawae in Spain

Production of persimmon (Diospyros kaki L. f.) has increased significantly during the last decade in Spain as a profitable alternative for fruit growers. In August 2008, after a mild and rainy spring, symptoms of a new disease were observed in commercial persimmon fields located in Valencia Province (eastern-central Spain). Symptoms included circular necrotic spots on the leaves and defoliation. Early fruit maturation and premature abscission were associated with early symptom development in the trees. A fungus was consistently isolated from the margins of leaf lesions. All isolates obtained were hyphal-tipped twice and transferred to potato dextrose agar (PDA). The cultures grew slowly and reached a diameter of 21 to 29 (mean 26) mm within 4 weeks on PDA at 25°C in the dark. Mycelium was initially dark green and ultimately became dark gray to black. Several media and incubation conditions were tested to induce sporulation, but conidia formation was not observed. In April 2009, mature spherical pseudothecia were observed in lesions on fallen leaves that had remained in affected fields during the winter. Ascospores were uniseptate and mostly spindle shaped, 10 to 11.5 (mean 10.3) μm long, and 3 to 3.9 (mean 3.4) μm wide. Fungal colonies obtained from the ascospores were identical to those isolated from the leaf lesions. Morphological characters observed matched those described for the pathogen Mycosphaerella nawae Hiura & Ikata (1). In Korea, the circular leaf spot of persimmon caused by M. nawae was considered an economically important disease in the 1990s, especially in the southern regions (2). Sequences of the internal transcribed spacer (ITS) region of the rDNA were obtained for isolates MY2 and MY3 and deposited in GenBank (Accession Nos. GQ465767 and GQ465768). These sequences were identical to each other and to the sequence obtained from a Korean isolate of M. nawae. Symptoms of the disease were reproduced after inoculation of 2-year-old persimmon trees growing in individual pots. A ground mycelial suspension (5 × 105 CFU ml–1) of strain MY2 was sprayed onto 20 potted trees (200 ml per individual tree) in late May of 2009. Ten trees were sprayed with sterile distilled water as a control. Trees were incubated at 20°C in a growth chamber with a 12-h photoperiod and covered with a semitransparent plastic hood for the first 10 days after inoculation, after which the plastic was punctured for ventilation and trees were incubated at 22°C. The first symptoms (small circular spots on the leaves) appeared on inoculated trees 15 days after inoculation. One month after inoculation, all inoculated trees showed circular leaf spots and severe defoliation, whereas noninoculated trees remained healthy. M. nawae was successfully reisolated from the lesions. To our knowledge, this is the first report of M. nawae causing circular leaf spot of persimmon in Spain.

References: (1) J. H. Kwon et al. Plant Dis. Agric. 1:18, 1995. (2) J. H. Kwon et al. Korean J. Plant Pathol. 14:397, 1998.

Persimmon Tree Diseases: Troubleshooting Diseases In Persimmon Trees

Persimmon trees fit into almost any backyard. Small and low maintenance, they produce delicious fruit in the autumn when few other fruit are ripe. Persimmons have no serious insect or disease problems, so there is no need to spray regularly. That doesn’t mean that your tree won’t occasionally need help, however. Read on for information about diseases in persimmon trees.

Persimmon Fruit Tree Diseases

Although persimmon trees are generally healthy, sometimes they do come down with persimmon tree diseases.

Crown Gall

One to keep your eye out for is crown gall. If your tree suffers from crown gall, you will see galls—rounded growths—on the persimmon’s branches. The roots will have similar galls or tumors and harden.

Crown gall can infect a tree through cuts and wounds in its bark. Persimmon disease control in this case means taking good care of the tree. Avoid crown gall persimmon tree diseases by protecting the tree from open wounds. Be careful with the weed whacker around the tree, and prune when the tree is dormant.

Anthracnose

Diseases in persimmon trees also include anthracnose. This disease is also known as bud blight, twig blight, shoot blight, leaf blight or foliar blight. It is a fungal disease, thriving in wet conditions and often appearing in spring. You’ll recognize anthracnose persimmon tree diseases by the black spots that appear on the leaves. The tree may lose its leaves starting at the bottom branches. You may also see black sunken spots on leaf stalks and lesions on the persimmon bark.

Anthracnose disease is not often lethal in mature trees. These diseases in persimmon trees are caused by leaf spot fungi, and some affect the fruit as well as the leaves. Persimmon disease control when it comes to anthracnose involves keeping a clean garden. The anthracnose spores overwinter in leaf litter. In springtime, the winds and rain spreads the spores to new foliage.

Your best bet is to pick up all leaf litter in the fall after the tree’s leaves have dropped. At the same time, cut out and burn any infected twigs. Many of the leaf spot pathogens appear when the tree is getting a lot of moisture, so water early to allow the foliage to dry quickly.

Usually, fungicide treatment isn’t necessary. If you decide it is in your case, use the fungicide chlorothalonil after the buds begin to open. In bad cases, use it again after leaf drop and once again during the dormant season.

Pest & Disease Control for Persimmon Trees

Every fruit tree has the future potential for disease and insect damage. Factors such as location and weather will play a part in which issues your tree encounters. If available, disease-resistant trees are the best option for easy care; and for all trees, proper maintenance (such as watering, fertilizing, pruning, spraying, weeding, and fall cleanup) can help keep most insects and diseases at bay.

NOTE: This is part 5 in a series of 9 articles. For a complete background on how to grow persimmon trees, we recommend starting from the beginning.

Trees appear stunted and slow growing. Leaves may be reduced in size. Little or no fruit. If plant is dead, inspect roots for hard, woody tumors. Note: many things can cause stunted trees.

Control

  • Consult County Extension Agent

Appear as small brown or purple spots on leaves. Leaves may turn yellow and fall. Weakens the tree.

Natural Control

  • Serenade® Garden Disease Control

Scale

Tan to gray, 1/16” hard, scaly shell covers developing young. Usually on the bark of young twigs and branches, may also be on fruit. Sap feeding weakens the tree. Control during the dormant season and at 1/2” green in needed.

Natural Control

  • Rub off with burlap

Other Control Options

  • Consult County Extension Agent

Appears as black spots on leaves, may fall from bottom upwards. Other symptoms may include black sunken spots on leaf stalks and lesions on bark.

Natural Control

  • Serenade® Garden Disease Control
  • Rake and burn leaves each fall

Fruit Drop

Caused by excessive vegetative growth. Too much fertilizer can produce excess growth, as can too much pruning.

Natural Control

  • Decrease Nitrogen and reduce pruning

Other Control Options

  • Consult County Extension Agent

Sunscald

Susceptible in winter.

Natural Control

  • Paint trunk with white, water-based paint, or use a tree guard

Other Control Options

  • Consult County Extension Agent

Persimmon Phylloxera

Small insect appear that feeds on leaves. Causes little damage except for deformed leaves.

Control

  • Consult County Extension Agent

Persimmon Trunk Borer

Insects tunnel into the trunk of young trees near soil line.

Natural Control

  • Dig out with thin wire or cut out with sharp knife.

Other Control Options

  • Consult County Extension Agent

Mealybug

Adults are ¼“ long, flat, oval shaped with a white waxy covering. Yellow to orange eggs are laid within an egg sac. Crawlers are yellow to brown in color. Over winters as an egg or very immature young in or near a white, cottony egg sac, under loose bark or in branch crotches, mostly found on north side. Damage is by contamination of fruit clusters with egg sacs, larvae, adults and honeydew, which promotes growth of black sooty mold.

Control

  • Consult County Extension Agent

Whitefly

Adults are tiny, white winged insects found mainly on the underside of leaves. Nymph emerge as white, flat, oval shapes. Larvae are the size of a pinhead. Suck plant juices from leaves causing them to turn yellow, appear to dry or fall off plants.

Natural Control

  • Traps

Other Control Options

  • Consult County Extension Agent

Thrips

Tiny, slender, fringed wing insects ranging from 1/25 to 1/8” long. Nymphs are pale yellow and highly active and adults are usually black or yellow-brown, but may have red, black or white markings. Feed on large variety of plants by puncturing them and sucking up the contents.

Natural Control

  • Traps

Other Control Options

  • Consult County Extension Agent

Mites

Pinpoint size, many different colors. Found on undersides of leaves. Sap feeding causes bronzing of leaves. Severe infestations have some silken webbing.

Control

  • Consult County Extension Agent

Root Rot

It causes weak plant growth and the development of small yellow leaves. Terminal growth may be stunted or die back. Plants often collapse and die during hot weather.

Control

  • Consult County Extension Agent

In This Series

  • Introduction

Getting Started

  • Acclimate
  • Planting

Care & Maintenance

  • Fertilizing
  • Pest & Disease Control
  • Pruning
  • Spraying
  • Watering

Other Topics

  • Harvesting

Persimmon tree – leaves turning black

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