Shot hole disease treatment

Information On Shot Hole Disease Treatment

Shot hole disease, which may also be known as Coryneum blight, is a serious issue in many fruit trees. It is most commonly seen in peach, nectarine, apricot, and plum trees but may also affect almond and prune trees. Some flowering ornamental trees can be affected as well. Since little can be done to control shot hole fungus once the trees have been infected, prevention is essential in treating shot hole disease.

Signs of Shot Hole Fungus

Shot hole disease thrives in wet conditions, especially during extended wet periods. The disease is most noticeable in spring, as new growth is most susceptible. Shot hole fungus commonly overwinters inside the infected buds, as well as twig lesions, where the spores may thrive for several months. Therefore, it is important to thoroughly inspect trees after leaf fall for any symptoms.

Most signs of shot hole disease occur in spring, causing spots (or lesions) on new buds and young leaves and shoots. Buds will have a varnished appearance and spots will first look reddish or purplish-brown in color and about ¼ inch in diameter. Eventually, these spots become larger, turning brown and falling out—giving the appearance of gunshot holes in the foliage. As it progresses, the leaves will drop. The stress also affects the tree’s ability to produce, and any fruit that may develop will usually be affected as well with spotting on the upper surface that may even become rough.

Shot Hole Disease Treatment

Infections can occur anytime between fall and spring, but is usually most severe following wet winters. Prolonged spring rains can also encourage this disease, as spores are spread from the splashing rain. Overhead watering may also contribute to the disease.

Good sanitation is key to treating shot hole disease naturally. This is the surest way to keep the disease from coming back. All infected buds, blossoms, fruit, and twigs need to be promptly removed and destroyed. Contaminated leaves around and beneath the tree should be removed as well.

Applying dormant spray — Bordeaux or fixed copper fungicide — in late fall is advisable, following the label instructions carefully. These sprays should not be applied in spring once new growth appears but additional applications may be necessary during wet weather.

Laurel Disease (4)

The Otto Luyken (Prunus laurocerasus “Otto Luyken”) is a dwarf English laurel cultivar that grows well in U.S. Department of Agriculture plant hardiness zones 6 through 8. This compact, broadleaf evergreen shrub only reaches about 3 feet tall with 6-foot spreads and is commonly used as a hedge, as you described in your situation.
Unfortunately, this particular species has been susceptible to multiple diseases and infestations which appear to be infecting your plantings. You appear to have a bacterial infestation and in addition suffer from a pest and/or fungal problem/s. Some of the suggested treatments are life cycle dependent and therefore might not be available until the next growing season.
Bacterial problem One of your pictures suggests that the laurels are affected by a disease caused by bacterial pathogens (Xanthomonas pruni). This disease typically starts in early summer with little, brown sores appearing on the undersides of leaves. The spots grow and develop red borders and yellow halos. The spots eventually fall out of the leaves, leaving behind gaping holes and tattered leaf tissue. Many infected leaves look as though someone peppered them with buckshot.
Because chemical control of shot hole disease is hard to achieve for home gardeners, help prevent this disease from occurring by planting the shrub in a well-draining location. Prune out and destroy any infected plant tissue as soon as you notice it. Rake up fallen plant litter to prevent pathogens from being attracted to the area near your shrub.
Fungal Problem This English laurel cultivar sometimes suffers from root rot and powdery mildew diseases. Root rot pathogens (Phytophthora spp.) enter the roots and disrupt the transfer of water and nutrients. Although the fungi thrive in overly wet soil conditions, affected plants look drought stressed with wilted, discolored, stunted and prematurely dropping foliage. Infected branches and twigs typically suffer dieback while cankers or stains often appear on infected trunks. Various fungus species trigger powdery mildew, a disease that causes a white, powdery growth to form on leaf surfaces. Affected foliage may also appear stunted and misshapen.
Help prevent root rot by planting your Otto Luyken in a site with good drainage. Avoid saturating the soil around the base of your shrub, and water only when the soil feels dry to the touch. Planting your shrub in a full-sun location helps control fungal diseases since most pathogens prefer shady conditions and cooler temperatures. Severe powdery mildew infections may require fungicidal treatment. You could spray your shrub with a 2 percent horticultural oil solution. Following the directions on the product’s label, thoroughly spray the upper and lower sides of the laurel leaves for the best results.
Pest Infestation In addition, shot hole borers (Scolytus rugulosus) still occasionally overrun this shrub. This tiny, dark-colored beetle grows to about the size of a grain of rice and possesses strong jaws for chewing its way into the inner wood of branches and trunks. Adult females lay eggs just underneath the bark, and the larvae emerge to start mining little galleries. Signs of a shot hole borer infestation include little, round holes oozing gummy sap mixed with sawdust. Boring damage typically causes twig dieback.
Chemical control methods don’t work once shot hole borers infest your shrub since the pests live in the protected area just below the bark. Preventative treatment is also difficult because the pesticide products available to home gardeners don’t work effectively. Prune out and destroy all infested plant parts. If the borers attack the trunk, remove the entire shrub.
Or, your cherry laurels may be subject to feeding by the peach tree borer and/or a scale insect.
Peach tree borer – You will have to look around the base of the shrubs. Remove the mulch from around the base of the plant. Look for dieback and the presence of gummosis and/or frass at the root crown. (Cast pupal skins may be visible at exit holes.) Make sure your mulch is no thicker than two inches and keep away from the base of the trunk to prevent boring insects. Here is a link to help you identify the peach tree borer. http://plantdiagnostics.umd.edu/level3.cfm?causeID=166
White prunicola scale – All active stages of the above insect suck plant cell contents from twigs and branches. Heavy infestations usually begin on outer branches. Dieback usually begins on small branches and usually is preceded by leaf yellowing and premature leaf drop. At this point, prune off heavily infested branches showing dieback. Use a soft toothbrush or soft scrubbrush to remove scale covers now.
You can use a dormant oil spray to manage light infestations. Use a dormant oil when deciduous trees drop their foliage usually (Dec-March). Target the spray where the scale is located. Spray on a windless day when the temperature is expected to remain above 40 degrees for 24 hours. Follow all label directions. Check for crawlers in mid-May. You may need to use a hand lens. You can use a summer rate of horticultural oil in June, if need be. Use horticultural oil instead of neem oil.
If you are still in doubt as to your specific diagnosis please contact your local extension office in Montgomery County and share the pictures and any samples with the volunteers at the Master Gardener office at that location. Thank you,

Shot Hole Fungus On Cherry Laurels

Shot hole fungus, also known as shot hole disease, is a serious fungal disease that creates distinct BB-sized holes in leaves. With the rainy, warm weather we’ve been having this season Shot Hole Fungus is running rampant. Our Arborists report seeing Shot Hole Fungus on lots of Cherry Laurels in this area. Without treatment, this fungus will re-infect your shrubs year after year, not only ruining its aesthetic appeal but also weakening the shrubs health.

Plants Susceptible To Shot Hole Fungus:

Cherry laurel, English Laurel, Cherry Trees

Symptoms:

Most signs of shot hole disease can be seen in spring and early summer.

  • Reddish brown spots on leaves
  • Holes in leaves (can look like insect feeding damage)
  • Defoliation

Most homeowners will see holes in their leaves and immediately think the issue is insects. In the case of Shot Hole Fungus, the original reddish brown damaged spots will dry up and eventually fall out leaving holes in the leaf.

Need Help With Shot Hole Fungus?

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Shot Hole Disease Treatments:

At this time of the year, the damage from shot hole fungus is already done and the disease has already taken hold of the plant. However, our Arborist suggests you sign up for a fungicide treatment plan for next year to ensure your trees/shrubs are protected from Shot Hole Fungus. In the meantime, the best thing you can do is practice proper sanitation and pruning.

Proper Pruning: By using fine hand pruning techniques (not shearing) our plant health care technicians can strategically prune your shrubs/trees to allow better air circulation. This will promote faster leaf drying and lead to less fungal issues overall.

Practice Proper Sanitation: To reduce the spread of Shot Hole Disease and lessen the chance of reinfection/the severity of the infection, proper sanitation is a must. Remove contaminated leaves around and beneath the tree/shrubs.

Proper Watering: Water the soil around the base of the plant. This type of watering will keep the shrubs leaves dry, unlike overhead watering.

Fungicides: For optimal coverage, fungicides need to be used at bud break and continued throughout the year.

Arborist Tip: If your shrubs have Shot Hole Fungus damage and are currently being treated, our Arborists recommend allowing your shrubs to grow out or fine pruning them instead of shearing them. Allowing the shrub to grow out will help hide the holes in the old growth and showcase the healthy new growth not affected by Shot Hole Disease.

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Samantha Huff

Samantha Huff is the marketing coordinator at RTEC Treecare. She enjoys learning about the technical aspects of trees and the insects and diseases that prey on them. She hopes that these articles can help homeowners gain control of their tree and shrub maintenance by being aware of the signs and symptoms of unhealthy trees.

Latest posts by Samantha Huff (see all)

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Tags: cherry laurelsfungifungusshot holeshot hole fungus

Did you notice diseased-looking leaves on your peach tree? Late fall is time to repair | The Fresno Bee

Peach leaf curl is a fungal condition that can be managed with fungicide. UC Master Gardeners

Peach leaf curl and shot hole disease of peaches are common problems for the backyard gardener. Both are fungal diseases that are treated with copper-based fungicides in late fall after all the leaves have fallen from infected trees. The same copper product can be used to combat both diseases.

Elinor Teague

Leaf fall dates change every year depending on weather patterns. During the next couple of weeks, monitor your peach and nectarine trees for complete leaf fall and check the weather reports for predictions of rain. Rains and overhead irrigation can wash off the fungicides.

Peach leaf curl

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The most obvious symptom of peach leaf curl occurs in spring during cool, wet weather as the new leaves on peach and nectarine trees turn red instead of green and become thick, curled and distorted. The thicker sections of infected leaves turn yellow and then are covered with a grayish white fuzz of fungal spores. The infected leaves usually fall off and are replaced by a new crop that shows fewer or no symptoms of the disease. Peach and nectarine trees infected with untreated peach leaf curl disease decline in vigor over several years; the fruit is affected, as well.

When choosing trees for your backyard orchard look for resistant varieties. (There aren’t that many resistant varieties available.) If you’ve inherited an unidentified peach tree, plan on spraying for peach leaf curl every fall to minimize chances of infection.

Shot hole disease

Shot hole disease gets its name from the small round holes that are seen in leaves on infected trees. That’s usually the first clue for the home gardener. You’ll also see tan marks or lesions and oozing or gumming on twigs. That’s the second clue. The fungus continues to produce spores through the winter on infected twigs and buds. Those spores are spread by splashing water and rain in spring.

A thorough cleanup of all fallen twigs and leaves helps remove some of the overwintering spores. Pruning out infected twigs before treatment with a fungicide on peach trees infected with shot hole fungus will reduce the number of fungal spores.

Fungicides

Labels on Bordeaux mixtures or liquid copper ammonium complex fungicides list the MCE or metallic copper equivalent. Liquid copper ammonium products are currently the only copper formulations available to home gardeners and they have an 8 percent MCE. Some formulations of copper are approved for use in the organic garden. Bordeaux mixtures are no longer available for sale, but many home gardeners still have the ingredients on their garden shed shelves.

Adding 1 percent horticultural spray oil to the mixture will make it more effective. The oil will also smother some aphids and their eggs, and some scale and mites, as well. Applications of horticultural oils to treat for many species of pest insects are usually made in late spring when the eggs hatch.

Spray the copper mixture to thoroughly drench all surfaces of the tree including bark cracks and crevices. The tree should be dripping wet with fungicide.

Copper levels can build up in the soil eventually making it toxic to microorganisms; copper runoff into gutters or canals can harm some aquatic species. Always read labels carefully, follow instructions for application and disposal of the products and wear protective clothing, goggles and gloves.

Elinor Teague: [email protected]

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Do your chokecherry or plum tree leaves look like they have been blasted with a shotgun? If the leaves are peppered with holes it is probably Shot Hole Disease. Common hosts include trees and shrubs in the plum family such as Russian almond, Mongolian cherry, Nanking cherry, chokecherry, American plum, western sand cherry, Manchurian apricot, Amur chokecherry, pin cherry, peach, nectarine and cherry. There are two possible causes of Shot Hole disease the most common is bacteria but there is also a fungus.

Symptoms

Shot Hole disease bacteria first appears as small, water-soaked, grayish areas on the undersides of leaves. Shot Hole disease fungi appear as small, dark purple spots. Both the bacteria and fungus caused spots become angular and are most numerous at the tip ends and along the midribs of leaves. The infected areas drop out, giving the infected leaves a shot-holed, tattered appearance. On plum, the shot-hole effect is more pronounced than on other stone fruits. Tattered leaves are still functional and normally do not cause significant harm to the tree. Severely infected leaves may eventually turn yellow and drop. Fruit is often reduced in size, sunburned, and cracked. Tree vigor and winter hardiness may also be reduced.

In severe cases, the bacteria will penetrate into branches, causing cankers. Cankers are often found along the trunk and major branch crotches. Cankers typically are dark brown and sunken in the branch; the inner tissues will turn orange-red. These pockets of bacteria will release a pus-like ooze and can plug the flow of water and nutrients, causing leaves to wilt and branch tips to die.

Disease cycle

Shot Hole disease bacteria overwinter in the twigs, buds, and other plant tissue. In the spring the bacteria are spread by rain to leaves, shoots, and fruit. Spring infections can occur after the leaves begin to unfold. Temperatures above 65°F and warm rains are needed for the bacteria to multiply, become exposed, and be spread. After these first infections, which are rarely noticed but do initiate the disease each year, the severity of the secondary infections depends on the weather. A moderately warm season with light, frequent rains accompanied by heavy winds or recent injury to the leaves or fruit, such as wind-blown soil particles and hail, may result in severe outbreaks.

Secondary spread of Shot Hole disease can occur from oozing summer cankers and leaf and fruit lesions during warm, wet weather. The systemic movement of the bacteria from leaves and shoots contributes to the formation of cankers. These cankers can be spread during budding to healthy nursery trees.

Control

No sprays are available to control Shot Hole disease bacteria. Rake leaves and twigs from under the tree to remove the bacteria from the area. Trim out cankers going at least 6 inches into healthy wood. Remove the infected branches and burn them. Fungicide sprays are usually not needed, especially for established trees. For young trees, a spray with products containing chlorothalonil can be used to prevent the spread of the Shot Hole disease fungus. This fungicide will not control bacteria.

Planting resistant varieties is the most effective control measure. There a quite a few varieties of peaches highly tolerant of Shot Hole disease. Resistance in plums, nectarines, and apricots is not as common. Nurserymen are well aware of the degree of susceptibility of the varieties they sell and they can provide good information for specific areas. Since trees in poor vigor are more susceptible, orchard management programs should be designed to maintain good vigor.

My sources for this news release were North Dakota State University and Penn State University Extension. If you would like more information about “Shot Hole Disease of Trees & Shrubs in the Plum Family,” contact Bob Drown at 605-244-5222 Extension 109 or by e-mail at [email protected]

What caused tiny holes in bark of plum tree? | The Sacramento Bee

Garden Detective: This fruitless plum tree appears half dead. Its demise appears to have been hastened by shothole borers. Judy Schulz

Experts tackle readers’ garden questions.

Q: Can you please let me know what you think might be wrong with our fruitless plum tree. When you enlarge photos, you can see tiny holes and splitting bark. Also, less than half the tree bloomed this year. Normally we spray to prevent getting plums but we didn’t spray this tree. I’m not sure if we need to have tree dug up and removed. Please advise.

Judy Schulz, Citrus Heights

Sacramento’s “Bug Man” Baldo Villegas: I think that the tree should be replaced. It looks like the shothole beetles have gotten into the dead part of the tree. I can’t make out if the tree is partly alive as I see some blooms in the back of the tree.

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It is hard to figure out what killed the tree. It could be over-watering or the use of a “weed and feed” product on the lawn near the tree.

To diagnose the cause of death, one would have to do a site inspection and ask lots of questions – especially if weed and feed products were used on the lawn near the tree. It could also be due to too much water on one side of the tree. I am open to other guesses.

Regardless of what caused the tree’s decline, the shothole borers – little red-black beetles about 1/10th of an inch long – appear to have infested the trunk and branches. According to University of California integrated pest management notes, shothole borers (Scolytus rugulosus) attack stone fruits (such as plum trees) as well as pears, apples and almonds.

Shaped like little black bullets, these beetles tunnel into fruit tree bark and wood, weakening and damaging trunks and branches. These borers most often attack very young trees or trees weakened by disease or other factors (such as exposure to herbicides or prolonged drought).

Insecticides are not recommended. Infected wood should be removed and destroyed immediately. As what appears to be the case of your tree, severely infested trees should be removed.

Baldo Villegas is a retired state entomologist and master consulting rosarian. The Bee’s Debbie Arrington contributed to this report.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h&[email protected] Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

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