Sweet Cherry Programs


Major Diseases

Bacterial canker or gummosis
Bacterial canker or gummosis (Pseudomonas syringae) is a serious disease of cherry in the Pacific Northwest. It is particularly damaging to young trees and can result in replanting issues if un-managed. Spread of the pathogen is favored by cool, moist weather. Optimum timing for control of bacterial gummosis is in late winter before trees break of dormancy, spring frost, and wet weather occur. In the Fall, apply most materials before autumn rains or after October 1.

Brown rot
Brown rot is a serious disease of stone fruit when wet conditions occur in the orchard. The disease is caused by the fungus Monilinia fructicola although other species (i.e. M. laxa and M. fructigena) have been reported in other regions. There are both floral and fruit phases of the disease. Brown rot is explosive and highly favored by rain events during bloom (blossom infection) and immediately prior to harvest (fruit infection). Many fungicide materials are effective on both brown rot and powdery mildew. Use the products list on the Bloom table for brown rot, as they are effective, and mildew sprays are not recommended at this stage of tree growth. Neither iprodione nor fenbuconazole are first-rate powdery mildew materials. Always follow fungicide resistance management guidelines. Current resistance management guidelines are available at https://www.frac.info

Cherry Powdery Mildew
Powdery mildew, caused by the fungus Podosphaera clandestina, is one of the most serious disease of cherries in the Pacific Northwest. The fungus attacks both foliage and (less commonly) fruit. Most cultivars are susceptible to the disease but it is particularly severe on the cultivar 'Sweetheart'. Management of the foliar phase is important because spores that infect fruit are produced on infected leaves. The fungus survives winter as chasmothecia (the sexual fruiting body); epidemics are initiated in spring when moisture results in ascospore release from the overwintering propagules. Ascospore release requires free moisture at 50F or greater. Ascospores serve as primary inoculum and give rise to powdery mildew colonies that continually produce millions of asexual spores (conidia). Conidia serve to spread and intensify the epidemic on both foliage and fruit. The disease is favored by moderate temperatures and high humidity. Management of powdery mildew in sweet cherries involves intensive and expensive fungicide application programs. Synthetic fungicide groups 3, 7, 11, and 13 are generally effective against the disease. Sulfurs, summer oils, polyoxin salts, and potassium bicarbonate are also effective and good companion products for the synthetic compounds. There is a great potential for the development of synthetic fungicide resistance in the Pacific Northwest due to the large acreage of sweet cherry cultivation, severe disease pressure and pathogen reproductive rate, and intensive fungicide application regimes. Resistance management practices should be practiced at ALL times. Current resistance management guidelines are available at https://www.frac.info

Coryneum blight (shothole)
Coryneum blight or shothole, caused by Wilsonomcyes carpophilus, is a fungal disease of minor importance in the Pacific Northwest. The fungus overwinters in twig cankers. Spores are produced on canker surfaces during early spring rains (or over-the-canopy irrigation) and are splashed to foliage and fruit where they germinate, infect, and cause small lesions. The lesions are small and circular. Necrotic lesion centers may drop giving heavily infected leaves a "shothole" appearance. The disease is managed using fungicide programs early in the growing season.

Major Insects

Leafrollers (Pandemis, Obliquebanded)
Pre-bloom applications of pesticides can be effective and will also conserve natural enemies for leafroller and biological control agents of other pests, such as aphids. If treatments for leafrollers were applied at pink and/or bloom, sampling to determine the density of surviving leafrollers should be completed prior to deciding to apply additional controls at this timing. Most products listed act primarily as stomach poisons versus direct contact to residues, therefore, complete coverage is very important to achieve maximal control. Repeating an application of any product should be based on the leafroller population surviving previous treatments. Use the leafroller models on the WSU Decision Aid System (https://decisionaid.systems) for the optimum timing. Additional Details

Shothole borer
Good sanitation (removing large wood prunings and woodpiles from the orchard) is the best management tactic. Insecticides are only effective against adults. Beetles begin flying in late April and are active through May. The second generation flight begins in late July or early August. Yellow sticky traps placed on orchard borders will detect adult beetle activity. Spraying the border trees (rows) with high water volumes will protect the remainder of the orchard in many situations where external sources are the primary problem. Additional Details

Spotted-wing drosophila
Spotted-wing drosophila (SWD) is one of the newer invasive species from Asia, first detected in the continental US in 2008, and achieving pest status in eastern Washington in 2010. Among the tree fruits, only cherries are considered to be vulnerable to attack preharvest, although like any drosophilid, SWD will use injured or rotting fruit of any type to complete development. SWD can be controlled by several groups of insecticides, and rotation among MOAs is important for resistance management. Monitoring tools are available, and should be used to gain a general idea of pest pressure in a given year. Experience since 2010 indicates that cold winters, especially those with sudden and extreme cold snaps, will decimate overwintering populations, and result in low pressure the following growing season, with little need for spray coverage. Conversely, mild winters and early springs have preceded extremely high pest pressure, necessitating a full season spray program Additional Details

Twospotted spider mite
Twospotted spider mite (TSM) is the most common spider mite pest of pear, although it has a very broad host range and will also feed on other tree fruits. Unlike apple, some pear cultivars (especially Anjou) have a very low threshold for mite damage, and controls must be applied at lower populations. Like all spider mites, TSM is an induced pest that will be controlled by natural enemies (especially predatory mites) if no disruptive sprays are applied. TSM can also feed on a number of broadleaf weeds, and reservoirs of both pest and predator can build up on the orchard floor. Mowing and herbicide applications beneath the tree may have unintended consequences for population in the tree canopy. Additional Details

Western cherry fruit fly
Western cherry fruit fly is the key direct pest of cherries, and quarantine regulations create a zero tolerance for this pest. Adult flies lay eggs in the fruit, and the larvae feed and develop inside the fruit until they are ready to pupate. A baited yellow sticky trap can be used for monitoring adult emergence of the single generation per year, and a degree-day model is available. Females have a 7-10 day pre-oviposition period, so sprays (either canopy or bait sprays) can start about a week after first fly detection or when the model predicts emergence. Fly emergence continues after harvest, so post-harvest clean up sprays will help prevent future problems, especially if unharvested fruit remains in the orchard. Many of the materials that kill western cherry fruit fly are also effective on spotted-wing drosophila; the neonicotinyls are a notable exception Additional Details

White apple leafhopper
Adults fly from late May until frost. Monitor nymphs on the underside of leaves. Egg parasitoid Anagrus spp. attacks overwintering and summer eggs. Only control this indirect pest when necessary. Carbaryl, if used for apple thinning, is also a very effective leafhopper material but the canopy spray technique may not provide adequate coverage for leafhopper control. Additional Details

Spray Schedule

Dormant

Bacterial canker or gummosis

2 Product Choices

Applications and Notes » 

Delayed dormant

Black cherry aphid

1 Product Choices

Applications and Notes » 

Cutworms

2 Product Choices

Applications and Notes » 

European red mite

3 Product Choices

Applications and Notes » 

San Jose scale & Lecanium scale

2 Product Choices

Applications and Notes » 

Twospotted spider mite

1 Product Choices

Applications and Notes » 

Prebloom

Coryneum blight (shothole)

8 Product Choices

Applications and Notes » 

Black cherry aphid

1 Product Choices

Applications and Notes » 

Cutworms

1 Product Choices

Applications and Notes » 

Leafrollers (Pandemis)

3 Product Choices

Applications and Notes » 

Bloom

Brown rot

8 Product Choices

Applications and Notes » 

Cherry Powdery Mildew

19 Product Choices

Applications and Notes » 

Coryneum blight (shothole)

4 Product Choices

Applications and Notes » 

Petal fall

Brown rot

12 Product Choices

Applications and Notes » 

Cherry Powdery Mildew

17 Product Choices

Applications and Notes » 

Fruittree leafroller

3 Product Choices

Applications and Notes » 

Leafrollers (Pandemis, Obliquebanded)

7 Product Choices

Applications and Notes » 

Shuck fall

Brown rot

13 Product Choices

Applications and Notes » 

Cherry Powdery Mildew

20 Product Choices

Applications and Notes » 

Coryneum blight (shothole)

6 Product Choices

Applications and Notes » 

Black cherry aphid

2 Product Choices

Applications and Notes » 

Leafrollers (Pandemis, Obliquebanded)

7 Product Choices

Applications and Notes » 

White apple leafhopper

1 Product Choices

Applications and Notes » 

Late spring and summer

Brown rot

9 Product Choices

Applications and Notes » 

Cherry Powdery Mildew

22 Product Choices

Applications and Notes » 

Cherry rust mite

1 Product Choices

Applications and Notes » 

Leafrollers (Pandemis, Obliquebanded)

8 Product Choices

Applications and Notes » 

Peachtree Borer

1 Product Choices

Applications and Notes » 

Pear slug

4 Product Choices

Applications and Notes » 

San Jose scale & Lecanium scale

1 Product Choices

Applications and Notes » 

Shothole borer

2 Product Choices

Applications and Notes » 

Spider mites

5 Product Choices

Applications and Notes » 

Spotted-wing drosophila

5 Product Choices

Applications and Notes » 

Western cherry fruit fly

8 Product Choices

Applications and Notes » 

Preharvest and harvest

Brown rot

9 Product Choices

Applications and Notes » 

Cherry Powdery Mildew

19 Product Choices

Applications and Notes » 

Spotted-wing drosophila

5 Product Choices

Applications and Notes » 

Western cherry fruit fly

7 Product Choices

Applications and Notes » 

Fall

Bacterial canker or gummosis

2 Product Choices

Applications and Notes »