Diseases of plum

A breif description of the diseases of plum

1. Diseases of Plums COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 COURSE TEACHER Dr. PARTHASARATHY S Asst. Professor (Plant Pathology) STUDENT Mr. S. MAHI YASWANTH ID. No. 2015021074

2. DISEASES OF PLUM Brown rot : Monilinia fructicola Black knot : Apiosporina morbosa   (Syn.  Dibotryon morbosum ,  Plowrightia morbosum ) Bacterial canker : Pseudomonas syringae Bacterial spot : Xanthomonas campestris pv . pruni Plum pox : Plum pox virus

3. Brown rot Distribution – world wide History The first published description of a brown rot fungus on decaying fruit was in 1796. Pathogen Monilinia fructicola M. laxa M. fructigena

4. Symptoms The brown rot fungi cause a blight of blossoms and twigs and a soft decay of fruits. Infected blossoms are brown and water-soaked. The fungus grows down the pedicel into the stem which may cause twig dieback. Diseased blossoms and fruit generally become covered with "tufts" of brown fungal material. Fruit infection usually occurs near maturity.

5. Fruit rot Soft decay ©aps.net © aps.net

6. Systematic position Kingdom : Fungi Phylum : Ascomycota Class : Leotiomycetes Order : Helotiales Family : Sclerotiniaceae Genus : Monilinia Species : Monilinia fructicola , M. laxa , M. fructigena

7. Lifecycle ©aps.net

8. Pathogen Conidia are produced on tufts of conidiophores called sporodochia . The conidia are hyaline (colorless), lemon-shaped, and produced in a moniloid manner. Ascospores produced in tubular asci produced on apothecium . Conidia produced in moniloid manner Lemon shaped conidia ©bugwoodcloud.org © media.padil.gov.au

9. Favourable condition Blossom infection occur at 10°C. Wet, warm conditions also increase overwintering inoculum available for blossom infections the following spring. Mode of spread & survival Sources of blossom blight inoculum are mummies, infected peduncles, and cankers. Conidia from these sources are disseminated by splashing or wind-blown rain.

10. IDM Control is by repeated fungicide applications and sanitation.

11. Black knot Distribution North America, Asia, Africa, South America, European union, Canada, the United States and Mexico History Black knot disease is mainly a problem in North America where it is indigenous. A record from 1979 indicated the presence of the fungus on pear. It was first reported as a destructive disease in Massachusetts in 1811. It was first described in 1821 by L. D. Schweinitz from specimens collected in Pennsylvania.

12. Pathogen : Apiosporina morbosa   Syn.  Dibotryon morbosum , Plowrightia morbosum Anamorph : Fusicladium , Authors: Karen L. Snover , Cornell University Phil A. Arneson , Cornell University

13. Symptoms The first symptoms appear as small, light brown swellings of the current or previous season's growth. By the next season the swellings turn olive-green in color with a velvety texture. Over this growing season the knots darken and appear to have a hard, brittle texture. The hard, black knots are the typical symptoms associated with the disease. ©aps.net

14. Knots of varying size on the twigs Infected twigs often appear bent at the tips because of extra cellular growth on one side © aps.net © aps.net

15. Systematic position Kingdom : Fungi Phylum : Ascomycota Subdivision: Pezizomycotina Class : Dothideomycetes Order : Pleosporales Family : Venturiaceae Genus : Apiosporina Species : Apiosporina morbosa

16. Pathogen The fungus produces pseudothecia , fruiting structures that are embedded in the black stroma on the surface of the gall. The mass of pseudothecia is often referred to as the ascostroma . Ascostroma ©aps.net

17. Lifecycle ©ohioline.osu.edu

18. Favourable condition Temperatures between 16°C and 27°C (60-80°F) are ideal for the dissemination, germination, and infection of new plant tissue. Mode of survival and spread Infected plant debris. By ascospores .

19. IDM A possible biological control agent for black knot may be the fungal parasite,  Trichothecium roseum .

20. Bacterial Canker Distribution – world wide Pathogen Pseudomonas syringae

21. Symptoms Cankers develop at the base of infected buds on trunk and scaffold limbs. Cankers spread more rapidly above the point of infection than below and only slightly to the sides. This results in a long, narrow canker. Cankers develop during the fall and winter but are not visible until late winter and early spring. ©omafra.gov.on.ca

22. Damaged areas are slightly sunken and somewhat darker in color than surrounding bark. As the trees break dormancy in the spring, gum is formed and flows down the outside of the tree. Cankers have a soured smell. The bacterium is a weak pathogen and causes serious damage only when a tree is in a near dormant condition or weakened due to unfavorable growing conditions. ©encrypted-tbn0.gstatic.com

23. Systematic position Kingdom : Bacteria Phylum : Proteobacteria Class : Gammaproteobacteria Order : Pseudomonadales Family : Pseudomonadaceae Genus : Pseudomonas Species : Pseudomonas syringae

24. Pathogen Rod shaped, gram negative bacterium with polar flagella. IDM Avoid using high fertilizer rates in late summer. Succulent, late fall growth is more easily infected. Prune when trees are fully dormant (January and February). Trees showing signs of bacterial canker should be left and pruned after all other trees have been completed.

25. Bacterial spot Distribution North America, Asia, Africa, South America, European union History First described in North America Pathogen Xanthomonas campestris pv . pruni (Smith) Dye Synonyms Xanthomonas arboricola pv . pruni (Smith) Vauterin et al. Xanthomonas pruni (Smith) Dowson

26. Symptoms On Leaf: First small, pale green colour irregular lesions are formed. Angular lesions surrounded by yellow halo are formed. Inner portion of the lesion turn black and drops out giving a “shot hole” or “ragged” appearance and the leaf falls off prematurely. ©intermountainfruit.org

27. On Fruit: Large, sunken black lesions are common on some cultivars, while, on others, only small pit like lesions appear. © omafra.gov.on.ca

28. On Twigs: Cankers are perennial and continue to develop in twigs of 2 to 3 year old Inner bark is penetrated, resulting in deep seated cankers which deforms and kills the twig.

29. Systematic position Kingdom : Bacteria Phylum : Proteobacteria Class : Gammaproteobacteria Order : Xanthomonadales Family : Xanthomonadaceae Genus : Xanthomonas Species : Xanthomonas campestris pv . pruni

30. Pathogen Motile, aerobic, gram negative rod, 0.2 – 0.8 X 0.8-1.7µm with single polar flagellum. Favourable condition Warm, moderate season with temperature of 19-28°c with light, frequent rain accompanied by heavy winds & dews . Mode of survival and spread Has limited capacity for local dispersal by rainsplash . Pruning and insect damage by Cicada spp. transmit the disease.

31. IDM Planting resistant cultivars. No direct control methods are suggested, but bactericides have been evaluated. Bud wood should be obtained from disease free trees, preferably grown in arid region.

32. Plum Pox Distribution – worldwide History Plum pox symptoms were first observed in plums by plum growers in Bulgaria between 1915 and 1918 although some reports indicate symptoms were seen in Macedonia as early as 1910. However the first paper describing the viral nature of the disease did not appear until 1932 when Atanosoff named it " Sarka po slivite " meaning "Pox of Plum“. Classification Group : Group IV(+ ssRNA ) Family : Potyviridae Genus : Potyvirus Species: Plum pox virus Mode of transmission – Aphids (20 species)

33. Symptoms Plum pox virus symptoms appear on leaves, fruits, flowers, and seeds. Leaves and fruit show chlorotic (yellowing) and necrotic (browning) ring patterns, and chlorotic bands or blotches. ©gwoodcloud.org ©gardeningknowhow.com

34. The fruit of plum can be misshapen and deformed. In eastern and central Europe, sensitive plum varieties can exhibit premature fruit drop and bark splitting. ©ucanr.edu

35. IDM Use of resistant varieties. No direct control methods are suggested. Spraying insecticide could control the insect vector.