Cherry Tree Pests and Diseases
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Show more translationsShow less translationsCherry trees are a valuable crop worldwide, but unfortunately, they are susceptible to various pests and diseases that can significantly impact their fruit yield and quality. Effective management and control strategies are crucial for maintaining healthy orchards and ensuring good production. Growers should plan an environmentally friendly approach to tackle them. Seeking advice from local professionals is highly recommended. Some of the most common and economically important pests and diseases of cherry trees are mentioned below.
Common Pests of Cherry Trees
- Western and European Cherry Fruit Fly (Rhagoletis cingulata and R. cerasi)
They are considered two of the cherry tree’s most destructive and common pests, particularly in Europe and North America. The adults can easily be distinguished by the characteristic banding pattern on the wings. Adult flies lay their eggs just under the skin of ripening cherries. The hatched white larvae (maggots) feed on the fruit’s flesh, causing it to rot and drop prematurely. No damage from the pest on the fruits is commercially acceptable, and growers must take all possible preventive measures to avoid any yield loss.
Management Strategies
Farmers can use yellow sticky traps with a pheromone attractant to monitor and reduce adult fly populations. Additionally, removing infested fruit from the orchard floor can help reduce future populations by eliminating breeding sites. In orchards with a known pest history and large populations, spraying with insecticides may be needed to target adult flies before they lay eggs. Following label instructions and using products approved for cherries is crucial to minimize environmental impact and product rejection in the market.
- Black Cherry Aphid (Myzus cerasi)
The black cherry aphid is a common pest of cherry trees, especially in temperate regions. These small, black insects suck sap from leaves and shoots, causing curled and distorted foliage. Severe infestations can stunt tree growth (reduce photosynthetic capacity) and reduce fruit quality.
Management Strategies
Encouraging natural predators (e.g., ladybugs and lacewings) can help keep aphid populations under control. Pruning and removing infested shoots can help reduce aphid populations and prevent the spread of the infestation. Always disinfect the pruning tools when moving from one tree to the next. Chemical control (systemic insecticides) should be the last resort since aphids can easily develop resistance to pesticides. Insecticidal soaps and oils can be effective, particularly when applied early in the infestation. Farmers are strongly advised to avoid spraying during the day, especially during flowering, to protect the bees.
- Oriental Fruit Moth (Grapholita molesta)
The oriental fruit moth is a major pest of stone fruits, including cherries. The larvae bore into shoots and fruit, causing wilting and premature fruit drop. Infested fruit is unmarketable, and heavy infestations can cause significant yield losses.
Management Strategies
Pheromone traps can be used to monitor adult moth populations and determine the timing of insecticide applications. Insecticides targeting larvae can be applied during vulnerable stages of the moth’s life cycle. Rotating different classes of insecticides can help prevent resistance development and ensure the best and longest-lasting efficiency of chemical control. Finally, regular pruning to remove damaged shoots and infested fruit can help reduce moth populations and prevent further damage in the orchard.
- Spotted Wing Drosophila (Drosophila suzukii)
Drosophila suzukii, commonly known as the spotted wing drosophila, is a relatively new and highly destructive pest of cherry trees. It has become the major pest problem in traditional cherry-producing regions in north Greece and other countries, with the farmers having difficulty controlling it efficiently and losing a significant part of their production. Wet weather and high humidity during fruit ripening are especially beneficial for the pest to infest and reproduce. Unlike other fruit flies, this pest can lay eggs in unripe fruit due to its serrated ovipositor, leading to significant crop losses. The larvae feed on the fruit, causing softening, discoloration, and eventual collapse. The damage renders the fruit unmarketable, and secondary infections by fungi and bacteria often occur in damaged fruit. If the pest exists within the fruit and it is harvested, it can continue to damage the fruit even in the storage unit and move on to the next, causing significant post-harvest losses. For this reason, buyers are very careful when purchasing fruits and may reject a whole batch of cherries if they find D. suzukii, even in a few fruits.
Management Strategies
Regular monitoring with bait traps helps detect the presence of adult flies early. This information is critical for timing control measures effectively. Removing and destroying infested fruit can help reduce the pest population. However, this is rarely possible, especially in larger cherry orchards. Most cherry producers choose to harvest the fruits as soon as they ripe to avoid losses. Similarly, removing all fruits from the trees and the orchard floor is essential to decrease the population and the risk of infestations the following season. Since no damage/infestation is commercially acceptable and the fruits may lose their commercial value, farmers usually choose to apply chemical control. While insecticide sprays can be effective, their application must be carefully timed and rotated to avoid resistance. Spinosad and pyrethroid-based insecticides are commonly used against D. suzukii. The applications usually start when the cherry fruit starts changing color from greenish to pink-red. Some farmers say they may need to apply up to 5 sprays in areas where the pest exists in large populations. You must always consult your local licensed agronomist before applying any chemical product.
- Other cherry “enemies”:
Birds and Rodents (e.g., Pocket Gophers): Birds can be a major problem, especially in sweet cherry orchards since they feed on the fruits. On the other hand, pocket gophers or moles can injure or even kill cherry trees by feeding on the crown and roots of the tree.
Other pests of interest for cherry trees are the: leaf miners, Spider Mites (red mites), Pacific Flatheaded Borer, Shothole Borer (Scolytus rugulosus), Nematodes, Cherry Thrips, and Cherry Slugs.
Common Diseases of Cherry Trees
- Brown Rot (Monilinia spp.)
Brown rot is a highly damaging fungal disease that affects blossoms, shoots, and fruit of cherry trees. It is caused by several species of Monilinia, with M. fructicola being the most common. Infected blossoms wilt and die, while infected fruit develops brown, sunken lesions covered with gray-brown spores. in severe cases, M. fructicola can cause yield losses of up to 80% or more in cherry orchards.
Management Strategies
Planting disease-resistant cherry varieties can help reduce the risk of brown rot infections. However, this measure is usually insufficient, and farmers must adopt an integrated approach. Fungicides can be applied during bloom and pre-harvest periods to protect against infection. Timing is critical, as applications must be made before symptoms appear. It is essential to use bee-friendly products and spray only very early in the morning or during the night (after sunset) so that bees are not active in the orchard. Bees are essential for pollinating cherry trees, especially in orchards where no self-fertile varieties are cultivated. Finally, pruning can be applied to improve air circulation, remove infected plant material, and reduce infections. Additionally, removing mummified fruit and fallen debris from the orchard floor can limit the spread of the fungus and its overwintering.
- Cherry Leaf Spot (Blumeriella jaapii)
Cherry leaf spot is a fungal disease that primarily affects leaves but can also infect fruit and stems. Symptoms include small, purple spots on leaves that eventually turn brown and drop out, leaving a shot-hole appearance. Severe infections can lead to premature leaf drop, reducing the tree’s vigor and fruit production.
Management Strategies
Fungicides can be applied at regular intervals, starting from petal fall, to protect against infection. Rotating fungicides with different modes of action is important to prevent resistance.
Raking and removing fallen leaves from the orchard floor can help reduce overwintering inoculum. Finally, growers can further decrease the severity and risk of the disease by planting resistant cherry varieties and applying proper pruning to improve air circulation.
- Bacterial Canker (Pseudomonas syringae)
Bacterial canker is an important and destructive disease of cherry trees caused by the bacterium Pseudomonas syringae. It primarily affects young trees and can cause significant damage to buds, blossoms, leaves, and fruit. Symptoms include sunken cankers on branches and stems, gummosis, and dieback of shoots.
Management Strategies
Pruning should be performed only during dry weather. Moreover, removing infected plant material can help reduce bacterial populations and prevent the spread or overwintering. To reduce the risk of transmission of the bacteria from one tree to another, growers should always disinfect pruning tools. Copper-based bactericides can be applied during dormant and bloom periods to help reduce bacterial populations and protect against infection. Finally, there are some cherry varieties resistant to the bacterial canker that can help reduce the impact of the disease and, in combination with the measures mentioned above, decrease losses.
- Crown gall (Agrobacterium tumefaciens)
Crown gall is a significant bacterial disease affecting cherry trees. This soil-borne bacterium enters cherry trees through wounds on the roots or trunk, often resulting from mechanical injury, grafting, or insect damage. Once inside, the bacterium integrates a portion of its DNA into the host plant’s cells, leading to the formation of tumor-like structures known as galls. These galls disrupt the plant’s vascular system, impeding the flow of water and nutrients from the roots to the canopy. Consequently, affected trees exhibit stunted growth, reduced vigor, smaller leaves, and poor productivity. Young trees, especially those in new plantations or nurseries, are more susceptible to the disease and can suffer significant damage or even death if the infection is severe.
Management Strategies
Management of crown gall primarily involves preventive measures, as there are no effective chemical treatments for the disease. Preventing injury to trees, using disease-free planting material, and avoiding planting susceptible rootstocks in contaminated soils are essential strategies. Biological control methods, such as using non-pathogenic strains of Agrobacterium (e.g., Agrobacterium radiobacter strain K84) to outcompete the pathogen, have shown promise in reducing the incidence of crown gall. Additionally, maintaining proper sanitation and promptly removing and destroying infected plants can help limit the spread of this destructive disease.
Integrated Pest and Disease Management
Effective management of pests and diseases in cherry orchards requires an integrated approach that combines multiple strategies to minimize damage and maximize yields. The farmer should regularly monitor and scout the cherry orchards to detect pest and disease problems early. Implementing cultural practices that promote tree health and reduce pest and disease pressure is also crucial. Farmers are advised to protect and boost the population of crop pests’ natural enemies and use chemical control (pesticides and fungicides) only when it is absolutely necessary and after consulting a licensed agronomist (to define the appropriate product, amount, and time of application).
References:
- https://anrcatalog.ucanr.edu/pdf/2951e.pdf
- https://www2.ipm.ucanr.edu/agriculture/cherry/Crown-gall/
- https://extension.usu.edu/pests/research/backyard-cherry-pests
- https://u.osu.edu/cfaescapstone/tree-fruits/cherries/pests/
- https://www.pubs.ext.vt.edu/422/422-018/422-018.html
- https://www.bartlett.com/resources/monilia-laxa.pdf
- https://www.canr.msu.edu/news/horticultural-practices-to-combat-american-brown-rot-in-sweet-cherry-orchard-systems
- https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0011/1489700/Blossom-blight-and-brown-rot.pdf
- https://fruitsandnuts.ucdavis.edu/cherry-diseases-disorders
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