Plant Disease Management Handbook

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Cherry (Prunus spp.) - Prunus Necrotic Ringspot

Cause This problem is apparently related to low levels of boron in early spring. A virus was implicated but never found.

Symptoms Poor growth and off-color generally show in time when affected trees or branches have smaller unopened green buds on shorter stems. Eventually, blossom buds open but soon abscise at the pedicel base, leaving a ring of persistent green bud scales.

Plant growth is restricted and compact as seen in this pictue.

Photo by Iain MacSwann, 1972.

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Apple (Malus spp.) - Replant Disease

The 2018 cherry pre-harvest tour looking at cover crops (right side) used to prevent replant disease after a cherry orchard has been removed.

Jay W. Pscheidt, 2018.

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Apple (Malus spp.) - Flat Apple Disease

Cherry (Prunus spp.) - Nematode, Dagger

Note the numerous enations on the underside of the leaf.

Photo by Jay W. Pscheidt, 1990.

Cause Prunus necrotic ringspot virus (PNRSV), which has many strains that have produced variously named diseases over the years including necrotic ringspot, tatter leaf peach ringspot, recurrent ringspot, cherry rugose mosaic, rose mosaic, and almond calico. PNRSV is responsible for yield losses of up to 15% in sweet cherry and up to 100% in peach.

Corum sweet cherry with shothole symptoms and positive for PNRSV.

Jay W. Pscheidt, 2016.

This tree was positive for Prunus necrotic ringspot virus.

Jay W. Pscheidt, 2016.

Image related to Cherry (Prunus spp.)-Prunus Necrotic Ringspot

Note the extensive shotholing.

Photo by Jay W. Pscheidt, 1990.

Note the necrotic ring spots on this Kwanzan flowering cherry.

Photo by Melodie Putnam, 1997.

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Cherry (Prunus spp.) - Sour Cherry Yellows

Lapin cherry leaf with ringspots and line patterns due to the Prune Dwarf Virus.

Jay W. Pscheidt, 2016.

Note the healthy tree on the right, and diseased tree on the left.

OSU Extension Plant Pathology Slide Collection, circa 1950's.

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Cherry Cultivar Susceptibility

Image related to Cherry (Prunus spp.)-Powdery Mildew

Severe powdery mildew infection of these cherries.

Jay W. Pscheidt, 2000.

Each of these cherries has a small powdery mildew colony near the stem end of the fruit.

Bob Spotts, 2009.

A few colonies on the underside of the cherry leaf.

Photo by Jay W. Pscheidt, 1989.

Note the small black specks (cleistothecia) within the white area.

Photo by Jay W. Pscheidt, 1997.

Chains of spores are formed on conidiophones.

Jay W. Pscheidt, 2019.

A few colonies on the underside of the cherry leaf.

Jay W. Pscheidt, 2016.

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Pear (Pyrus spp.) - Storage Rots

Image related to Cherry (Prunus spp.)-Postharvest Rots

Rainier cherry with several rots at once including Botrytis, Alternaria and Cladosporium.

OSU Plant Clinic Image, 2013.

Post harvest rots of sweet cherry with Botrytis sp. on the left (center of fruit), Monilinia sp. (brown rot) in the middle and Penicillium sp. on the right. (Also Monilinia sp. around the Botrytis mycelia as well.)

Jay W. Pscheidt, 2020.

Cause There are many reasons that cherries may develop surface depressions or "pits" on the outside of the fruit. The most common cause is physical damage during harvest or postharvest handling. As a response to this damage pits may appear after a few days in cold storage. Some cultivars, such as Van, Lapins, and Sweetheart are more sensitive than others. The following cultivar list is from resistant to pitting to susceptible: Regina, Chelan, Bing, Skeena, Sweetheart, Lapin and Rainer.

Image related to Cherry (Prunus spp.)-Pitting

Pitting may be subtle as on the left cherry or obvious such as on the cherry to the right.

Yan Wang, 2015.

Depending on conditions or the year, cherry pitting can be severe.

Yan Wang, 2015.

Cause Many Phytophthora species, fungus-like microorganisms, cause a root rot of stone fruits. P. cactorum is the only species reported from the Pacific Northwest and then only on apricot and peach in Washington. OSU Plant Clinic records indicate P. cactorum on cherry in the Willamette Valley of Oregon.

Image related to Cherry (Prunus spp.)-Phytophthora Root Rot

Close up of the root crown where a cut has been made with a pocket knife to expose the transition between healthy (white) and diseased (dark brown) vascular cambium.

OSU Plant Clinic collection, 2012.

In cross section you can see how the both xylem and phloem have turned necrotic on the right side of this stem.

OSU Plant Clinic Image, 2016.

Rotted roots.

OSU Plant Clinic collection, 2012.

The vascular cambium has been exposed at the base of this tree to show discoloration coming from below ground.

Jay W. Pscheidt, 2016.

Small orchard with many trees dead from root rot.

Jay W. Pscheidt, 2016.