Plant Health Management for Backyard Stone Fruit Plantings (Peaches, Cherries, and Plums)

1. Plant Health Management for Backyard Stone Fruit Plantings (Peaches, Cherries, and Plums)

2. Prepared by Mike Ellis Professor and Extension Specialistand Omer Erincik Graduate Research Assistant Department of Plant Pathology The Ohio State University OARDC/OSUE Wooster, OH, 44691

3. Brown rot Symptoms: • Small, circular, light brown spots expand rapidly on ripening fruit, rotting the fruit within a day or two. • Under wet conditions, ash-gray tufts of fungus form on the surface of infected fruit. • Rotted fruit may fall from the tree or remain attached as shriveled mummies. • Blossoms wilt, turn brown, and persist into summer. • Blossom infections can invade the attached shoots or twigs and cause cankers (areas of dead bark). Cankers may enlarge and kill the branch or twig.

4. Brown rot Disease Development: • affects all stone fruit • caused by the fungus Monilinia fructicola. • The fungus overwinters in the previous year's diseased plant parts such as mummies, on the tree or ground and in cankers on the twigs. • In April, May and June, the fungus produces millions of spores. These spores are spread by splashing rain and by wind. • A free film of water on leaves and fruit is required for the spores to germinate and infection to occur. • Wounded fruit are most readily infected. • Fruit rot symptoms become most evident as the fruit start to mature.

5. Peach leaf curl and plum pockets Symptoms: • In spring, developing leaves become severely distorted (thickened and puckered), and have a reddish or purple cast. • Later, as spores form on the leaf surface, the leaves become powdery gray in color. • Shortly after this, the leaves turn yellow or brown and drop. • Diseased twigs become swollen and stunted, and may have a slight golden cast. They usually produce curled leaves at their tips. • Diseased fruit have shiny, reddish, raised, warty spots. They drop shortly after they are infected.

6. Peach leaf curl and plum pockets Disease development: • affects peaches and plums, but not cherry. • caused by the fungus Taphrina deformans. • The fungus survives the winter as spores (conidia) on infected bark and buds. • During cool, wet spring weather the conidia infect new leaves as they emerge from the buds. • Host plant tissues are susceptible for only a short period. As the tissues mature they become resistant. • The disease is not active later in the growing season. • Rain (free water) is necessary for infection.

7. Peach scab Symptoms: • Small, round, olive-green spots generally develop near the stem end or on the side of the fruit exposed to the sun. • Spots may merge to form large, irregular blotches that turn velvety, dark olive-green or black. • Severely infected fruit may become misshapen, or crack open, and drop prematurely. • Small, round, and yellowish-green to yellowish-brown spots develop on the underside of the leaf. • Diseased leaf tissue may dry up and drop out, leaving "shot-holes." If the season is wet, scab-infected leaves usually drop early.

8. Peach scab Disease development: • affects only peaches. • caused by the fungus Cladosporium carpophilum. • The fungus overwinters on bark and in twigs infected the previous year. • During spring and summer, large numbers of microscopic spores (conidia) are formed on twig lesions. • The spores are spread by splashing rain or windblown mist to developing fruit, twigs, and leaves. • Spore germination and fungus growth is most rapid at 65-75 degrees F. • The fruit remain susceptible until harvest; however,the disease is usually not observed until the fruit are well grown.

9. Bacterial spot Symptoms: On leaves: • Small, irregular to angular, deep purple to rusty-brown or black colored spots form on the leaves. • In time, the centers dry and tear away leaving ragged "shot-holes." • When several spots merge, the leaf may appear scorched, blighted, or ragged. • Badly infected leaves may turn yellow and drop early.

10. Bacterial spot Symptoms: On fruit: • Small, round olive-brown to black spots form on the fruit. • They are usually sunken and frequently surrounded by a water-soaked margin. • On some varieties the spots may exude a yellowish gum after rainy periods. • Skin cracking and pitting may occur near the spots during fruit enlargement.

11. Bacterial spot Disease development: • affects all stone fruit. • caused by the bacterium Xanthomonas pruni. • The bacteria overwinter in twigs that are infected late in the season about the time leaves are shed. • In the spring, bacteria ooze out from these diseased plant parts onto the plant surface. • The bacteria are then spread by windblown or splashing rain and can result in new infections throughout the growing season. • Bacteria enter the tissues through natural openings (stomata or lenticels) when surface moisture is present. • Warm temperatures (70-85 degrees F) with light rains, heavy dews, and windy weather are most conducive for disease development and spread.

12. Cherry leaf spot Symptoms: • Small circular purple spots appear on the upper surface of the leaf. • Whitish-pink masses of sticky spores (conidia) form within the spots on the undersides of infected leaves during periods of damp weather. • Later, the centers of the spots may dry up and drop out, giving a "shot-hole" appearance. • The most conspicuous symptom, especially on sour cherries, is the golden yellowing of older infected leaves before they drop off. • Spots similar to those on the leaves may also form on leaf petioles and fruit pedicels, causing fruit to ripen unevenly. Spots usually do not form on fruit.

13. Cherry leaf spot Disease development • affects only sweet and tart cherry • caused by the fungus, Blumeriella jaapii . • The fungus overwinters in dead leaves on the ground. • In spring, the fungus produce spores (ascospores) during rainy periods for about six to eight weeks, starting at petal fall. • These spores are spread by wind or splashing rain drops to healthy leaves and serve as primary inoculum for the disease. • The spores penetrate the leaf through stomata (natural openings) on the underside of the leaf. The small purple spots soon appear on the upper surface.

14. Cherry leaf spot Disease development • Masses of secondary or summer spores (conidia) are produced in the spots on the underside of the leaf. • Conidia are spread to other leaves by splashing raindrops and are capable of causing new infections . • Serious leaf spot damage (defoliation) usually occurs in years with numerous rainy periods throughout late spring and summer.

15. Powdery mildew Symptoms: On leaves and shoots: • Spots first appear as circular, white patches on leave surface. • The white spots are growth of the fungus mycelium and its spores. • Lesions spread rapidly, eventually, they may cover the entire leaf. • Diseased leaves often fail to unfold normally, while those of new shoots become narrow, distorted, blighted, and stunted.

16. Powdery mildew Symptoms: On fruit • The disease first appear as white circular spots on young fruit. • The spots enlarge and eventually, may cover much of the fruit. • Later, the skin of the fruit under the spot turns pinkish, and the fungus and its spores disappear. • Eventually the skin becomes leathery or hard, turns brown, and may crack.

17. Powdery mildew Disease development: • affects all stone fruit. • Pathogens: Podospaera clandestina…on cherry Sphaerotheca pannosa…..on peach and other stone fruit. • The former overwinters as in fruiting bodies (cleistothecia) on the barks and latter overwinters as mycelium dormant buds of previously infected twigs.. • In spring, the fungi initiate their growth and produce spores which are carried by wind or rain to leaves, twigs and fruit. • Both leaves and fruit are susceptible to infection when young but they become resistant as they mature. • Most infections occur at moderate temperatures and high humidity. • Free water is not required. • The fungi produce secondary spores later in the growing season cause secondary infections.

18. Management of fruit and leaf diseases • Free water (wet conditions) is required for most fungal pathogens (except Powdery mildew) to infect plants. Any practice that promotes faster drying of fruit and foliage is beneficial for disease control. • Site selection • Select a site with good air movement all-day sun light, and good soil drainage. • Do not plant trees in shaded areas.

19. Management of fruit and leaf diseases • Canopy management • Control timing and amount of nitrogen fertilizer to prevent excessive growth. • Prune out and destroy all dead or diseased shoots and limbs while trees are dormant. • Prune healthy growth to improve air movement and sunlight penetration, to minimize shading and decrease drying time of leaves and fruit during the growing season.

20. Management of fruit and leaf diseases • Sanitation • Remove all infected fruit and mummies as well as blighted twigs from the tree. • Rake out and dispose of fruit mummies and leaves (cherry leaf spot) that have fallen to the ground. • These sanitation measures will reduce the number of spores that can initiate these diseases. • Fungicides • On susceptible varieties, fungicides may be required to obtain an acceptable level of disease control.

21. Management of fruit and leaf diseases Disease Resistance • For most disease, resistance is not available. • For bacterial spot and powdery mildew, susceptible varieties should be avoided.

22. Susceptibility of common peach cultivars to Bacterial spot Resistant: Candor, Cresthaven, Earliglo, Encore, Harbelle, Harbinger, Harbrite, Harken, Jerseydawn, Norman, Pekin, Ranger, Redkist, Redskin Tolerant: Biscoe, Earlirio, Garnet Beauty, Glohaven, Jerseyqueen, Loring, Rio-Oso-Gem, Sentinel, Springold, Summerglo, Sunqueen, Sunshine, Surecrop, Topaz Susceptible: Autumnglo, Blake, Harmony, Jerseyland, Redcrest, Redhaven, Sweet Sue, Suncrest, Sunhigh, Triogem, Tyler, Velvet, Washington

23. Peach canker Symptoms: • In early spring, gummy drops of sap first appear around wounded bark • The inner bark begins to break down, causing the cankered surface. • During wet periods spores ooze out of these cankered surfaces in tiny orange or amber colored, curled strands. • During the summer, healthy bark grows over the edges of the narrow, oval shaped cankers. • Over a period of years, a series of dead callus ridges form as the canker gets larger. • Eventually, the canker may completely surround a branch. The portion of the branch above the canker then dies.

24. Peach canker Disease development • affects all stone fruit, but most severe on peach. • caused by the fungi, Cytospora leucostoma and Cytospora cincta. • These fungi are weak pathogens and generally do not attack healthy, vigorous peach bark. Winter injury, insect damage, and mechanical injury are common types of wounds serving as entry points. • The fungi survive the winter in cankers or in dead wood. • During spring and summer, spores produced in the cankers are spread by wind and rain to wounds on the same or nearby trees. • Infection and canker development depend on temperature and the species of fungus involved. Cytospora cincta is favored by lower temperatures than Cytospora leucostoma.

25. Management of peach canker Site selection: • Trees should be planted in sites with well drained soil and good air circulation. This promotes faster drying. • Do not plant trees in shaded areas. • Do not plant new peach trees near established trees with canker. Pruning: • Prune young trees carefully to avoid weak, narrow-angled crotches. Narrow-angled crotches are frequent sites of breakage and winter injury. • Delay pruning until early spring. This promotes quick healing and avoiding winter injury. Sanitation: • Remove and destroy cankered limbs, branches and dead wood while pruning. These limbs or branches serve as a reservoir for the disease causing fungi.

26. Management of peach canker Promote vigorous, healthy peach trees: • Do not over-fertilize late in the season. Winter injury is more common on these trees because winter hardening is delayed. • Trickleirrigation during dry period help to increase resistance to the disease Avoid mechanical and insect injury • Maintain a good control program for other diseases and insect pests, especially borers Protect trees from winter injury • White latex paint applied to the southwest side of trunks and lower scaffold branches may help avoid cold injury during winter.

27. Black knot Symptoms: • The fungus mainly affects twigs, branches, and fruit spurs. • On infected plant parts, abnormal growth of bark and wood tissues produce small, light-brown swellings. • In late spring, the rapidly growing young knots have a soft (pulpy) texture and become covered with a velvety, olive-green growth of the fungus. • In summer, the young knots turn darker and elongate. • In fall, they become hard, brittle, rough and black. • During the following growing season, the knots enlarge and gradually encircle the twig or branch. • Smaller twigs usually die within a year after being infected. Larger branches may live for several years before being girdled and killed by the fungus.

28. Black knot Disease development • affects only plum and cherry. • caused by the fungus, Apiosporina morbosa. • The fungus overwinters in knots on twigs and branches or in the infected wood. • In spring, the fungus produces spores on the surface of the knots. • These spores are ejected into the air during rainy periods and are blown for moderate distances by wind currents.

29. Black knot Disease development • Only succulent green twigs of the current season's growth are susceptible to infection. • Only a few hours of rain are apparently required for infection at temperatures above 55 degrees F. • Knots may become visible by the late summer of the year of infection but often are not noticed until the following spring. • The fungus continues to grow in infected wood during spring and fall, causing the knots to elongate several inches each year and eventually girdle affected twigs and branches.

30. Management of Black knot • Site selection: • Trees should be planted in sites with well drained soil and good air circulation. This promotes faster drying. • Do not plant trees in shaded areas. • Avoid planting trees next to or downwind from an orchard with a black knot problem. • Sanitation: • infected twigs should be pruned out by making cuts 6 inches below the knot before bud break and destroyed by burning or burying . • This sanitation measure will reduce the number of spores that can initiate the disease. • Fungicides • On susceptible varieties, fungicides may be required to obtain an acceptable level of disease control

31. Management of Black knot • Use disease resistant plum varieties • Most commercially grown plum varieties, including Stanley and Damson, are highly susceptible to black knot. • Early Italian, Brodshaw, Fallenburg, Methley and Milton are moderately susceptible. • Shiro, Santa Rose, and Formosa are slightly susceptible • President is apparently resistant to black knot. • Japanese varieties of plums are generally less susceptible than most American varieties.

32. Phytophthora root rot Symptoms: Above ground • Affected trees exhibit poor terminal growth, sparse and cholorotic foliage, and progressive decline. • Some trees exhibit early reddish discoloration of leaves in late August or early September. • Eventually, infected trees usually die. Below ground • A diagnostic reddish-brown discoloration of the inner bark and wood can be observed on the crown or main roots of infected plants. • A sharp line separates the reddish-brown (diseased) and white (healthy) portion of the crown.

33. Phytophthora root rot Disease development: • caused by several species of the fungus Phytophthora. • The fungus overwinters and persists in soil for many years. • The fungus requires extremely wet or saturated soils in order to infect and cause significant damage; thus good soil drainage is important for control. • When soils are saturated, the fungus produces spores, called zoospores. Zoospores use flagella to swim to susceptible plant tissue where they cause infection. • The longer the period or periods of soil saturation, the greater the risk of infection. • Some species may also be introduced to the orchard on contaminated planting stock or through movement of contaminated soil.

34. Management of Phytophthora root rot • Proper site selection • Plant in well-drained soil. • Plant on raised planting beds if soil does not have excellent drainage. • Select a site that does not have a previous history of problems with the Phytophthora root rot. • Use disease resistant rootstocks • Mazzard cherry rootstocks are more resistant than Mahaleb cherry rootstocks to some species of Phytophthora. • the effectiveness of resistant rootstocks is limited since resistant rootstocks control some species of Phytophthora but not others. • On peach most currently available rootstocks are susceptible.

35. Using Fungicides For Stone Fruit Disease Control • Fungicides are very important for disease control in commercial stone fruit production, and may be required in backyard stone fruit plantings if highly susceptible varieties are grown; however, the emphasis for disease control in backyard plantings should be placed on the use of disease resistance and the various cultural practices previously mentioned.

36. For backyard growers that do require fungicides in the disease management program, fungicide recommendations are available for stone fruit in Bulletin 780 “Controlling Disease and insects In Home Fruit Planting”.

37. Selected literature for backyard fruit production and plant health management: • Bulletin 591. “Growing and Using Fruit at Home” • Bulletin 780. “Controlling Diseases and Insects in Home Fruit Planting” • “Midwest Tree Fruit Pest Management Handbook” These can be obtained through your county extension agent or the Extension Publications Office, The Ohio State University, 385 Kottman Hall, 2021 Coffey Road, Columbus, Ohio, 43210-1044

38. To get more information about plant diseases visit the websites below. http://www.ag.ohio- state.edu/~plantdoc/extension.php http://www.ohioline.ag.ohio-state.edu