Compendium of Potato Diseases - (PDF, 101 mb) - USAID

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development decreases with increasing temperatures. Iiigh moisture levels in soils, especially those poorly drained, also tend to increase severity of sclerotial formatior. on new tuber.i. Tuberborne sclerotia range in pathogenicity to stems and stolons from avirulence through moderate to high virulence. The influence of tuberborne sclerotia on the health of the following crop is not consistent and varies from essentially no deleterious effect to a measurable increase in sprout-pruning, stem cankers, and yield reduction. IHigh resistance within potato has not yet been identified. Other Hosts R. solani is a pathogen of numerous crops and weed hosts throughout the world. Its selective pathogenicity depends on the strain present. Control I) Seed treatment isnot effective in heavily infested soils. Use disease-free seed combined with seed treatments such as the systemic fungicides (benoyivl, thiabendazole, or carboxin) or, where acceptable, organic mercury. 2) Soil treatments of benomyl or pentachloronitrobenzene reduce soilborne inoculum, but the returns may not justify the Cost. Selected References 1IEl1N, W.I.. 1969. Evaluation of seed and soil treatments forcontrol of Rhitoctonia scurfand Verticillium wilt of potato. Plant Dis. Rep. 53:425-427. I-RANK.A..and S. K. FRANCI.S. 1970. Ihecllect of a Rhi.:,loia .olani phytotoxin ol potatoes. can. .1.Bot. 54:2536-2540. IlIDI. (i. A., .1.M. III RSI. and 0. .1.STIEI)MAN. 1973. Effects of black scurf (Rhizocionia solani) on potatoes. Ann. App!. 1iol. 74:139- 148. .AMES. W.C.,and A. R. McKENZIE. 1972. The elect of tuber borne sclerotia of Rhi:octonia .olami Kiihn on tile potato crop. A;ii. Potato .J.49:296-31)!. PAR M IT R.J.IR., ed. 1970. Rhioi tonia. odani:Biologyand Pathology. Unik. of Calif. Press, llerkeley. 255 pp. PARNI-EER. 1. R., Jr., R. I. SIEI!RWOOI), and W. I). PI.ATT. 1969. A nast omosis grouping anmong isolates of hanatelphorus c'ucuniri.%. Phytopathology 59:1270-1278. SAN E(1)R I). Ii. I. 1956. Factors influencing formation of sclerotia by Rhi.:otomia.%ortai. lPhytopathology 46:281-284. VAN EMI)IN, .1.If., 1958. Control of Rlhi:octonia ..ohmi Kiihn in potatoes by disinlection ol seed tubersand by chemical treatment of the soil. Eur. Polato .t. 1:52-64. VAN F.MI)I'N..I. I1., R.E. I.ABIJRYERF,and (. M. IICIIEL.AAR. 1966. On thecontrol of Rii:o'tonias.olaniin seed potato cultivation M.puriureum. Fig. 60. Injury at tuber apex, common under certain conditions when Rhizoctonia is present. (Courtesy H. Torres) 54 in the Netherlands. Instituut voor Plantenziektenkundig Onder/oek. Mededeling 412. 42 pp. WENIIAM,. I., If. I.. MacKINTOSII. and If. A. BOIKAN. 1976. Evaluation of fungicides for control offpotato black !eurf diseam, N.Z. J. Exp. Agric. 4:97-101. (Prepared by .1.A. Frank) Violet Root Rot Although infrequent, violet root rot has been reported from most of the major potato-growing areas of the world. Symptoms Aboveground symptoms are not distinctive. The foliage may become chlorotic, and plants may wilt and die suddenly in localized areas in the field. Belowground plant parts are often covered only with a reddish-purple mycelial network on the uninjured skin. Under the mycelial mats, tubers may have dark gray, somewhat sunken spots covered with purplish lack sclerotia. The fungus tends to be limited to the cells near the periderm of the tuber. Wet rot of tubers may develop under mycelial mats. Causal Organism Ih,licobasidiutm purpure'n (Tul.) Pat. (syn. Rhizoctonia 'rocortam(Pers.) iDC) has young hyphae that are light violet, becoming more intensely violet with age. IHyphal branches arise at right angles close to a septum. The mycelium is branched, septate, and distributed evenly over tile host surface. On occasion, strands are clearly visible. l)ark brown to purplish black r funga sclerotia form on the al mats. Sclerotia are essentially round, covered with a thick velvety felt, and vary in diameter from a few millimeters to several centimeters. The basidial stage is present infrequently on the base of potato stems near the soil surface as awhite, superficial growth similar to that of R. solani. The b:tsidium is hyaline, with two to four cells, each bearing a sterigma (0-35 pm in length) that produces a basidiospore (I0-12x 6-7/pm). Disease Cycle The fungus overwinters in the soil as sclerotia. These germinate in the spring and infect the crop. Basidiospores may spread the disease. Other Hosts The fungus parasitizes a wide range of hosts, the most important being carrot, lucerne (alfalfa), asparagus, and sugar beet. Control Rotation may be useful. Avoid rotation with other hosts. Selected References BUDI)IN, W.,and E.M. WAKEFIEI.). 1927. Studies on Rhizovionia ocrgoorionflPers.) D)C. and llelicollavidium,ipuriiurewn (Tul.) Pat. Trans. [r. Mycol. Soc. 12:116-140. DBUDIN, W., and E. M. WAKEFI1:I.I). 1929. Further notes on the connection between Rhizoiontia (rocortom and Ilclicohasidium Trans. Br. Mycol. Soc. 14:97-99. KOTTE, W. 1930. Beobachtungen iber den Parasitismus von Rhizoctoia violacea HlI. auf der Kartoffel. Bar. l)tsch. Bot. Ges. 48:43-51 (Prepared by L. V. Busch) Silver Scurf Silver scurf is probably present in all of the major potato growing areas.
1. Giant-hill plants, taller than normal plants. 2. Mahogany browning in low temperature storage. 5. Wind injury. 3. Low temperature leaf injury from 4. Hail injury. temperatures above those freezing tissue. 6. Photochemical oxidant air pollution injury. COLOR PLATES '
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, ,. ,o . ; , . o , . r. , -' .L ,
Page 3 and 4:
Compendium of Potato Diseases W. J.
Page 5 and 6:
In memory ofimy respected colleague
Page 7 and 8:
Acknowledgments Planning Committee
Page 9 and 10:
Introduction 1 Potato Disease 1 The
Page 11 and 12:
A potato disease is an interaction
Page 13 and 14: Fig. 1.A, Lower portion of young po
Page 15 and 16: +q I B Fig 4. Natural openings in a
Page 17 and 18: Part I. Disease in the Absence of I
Page 19 and 20: more heavily in the vascular region
Page 21 and 22: the air temperature when tubers are
Page 23 and 24: iiO A B 'D C Fiq. 14 Second growth:
Page 25 and 26: identifying tissue bruised by black
Page 27 and 28: Internal Sprouting multiple sprouts
Page 29 and 30: conditions permits normal leaf deve
Page 31 and 32: Epidemiology Oxidant injury is pres
Page 33 and 34: sevritof stnting, chiorosis. loss o
Page 35 and 36: Selected Reference brown to bronze
Page 37 and 38: Part II. Disease in the Presence of
Page 39 and 40: should be planted on land with at l
Page 41 and 42: Control I) Use disease-free tubers
Page 43 and 44: FOI-SO M. D, and I. A. FRIEDMAN. )9
Page 45 and 46: Fungi Powdery Scab liberating powde
Page 47 and 48: Histopathology Sort of sporangia de
Page 49 and 50: any time but generally occurs late
Page 51 and 52: '40 ff .. . '1 f . ."L', . '1 .,. "
Page 53 and 54: A \, 2) Powdery mildew is rarely a
Page 55 and 56: R., Inst.. Kew. Surrey. ngland. 609
Page 57 and 58: TORRES, H.. E. R. FRENCH, and I.. W
Page 59 and 60: d AC D A 0 Fig 53 Gray mold. A, Bot
Page 61 and 62: strands of pigmented hyphae. Sclero
Page 63: tuber malformation. Roots are also
Page 67 and 68: 13. Bacterial soft rot. Erwinia car
Page 69 and 70: 24. Wart. Synchytrium endobioticum
Page 71 and 72: 34. Pleospora herbarum (Stemphylium
Page 73 and 74: 44. Charcoal rot. Macrophomina phas
Page 75 and 76: 55. Leafroll virus. Current season
Page 77 and 78: 67. Mop-top virus. Primary tuber 68
Page 79 and 80: 77. Aster yellows mycoplasma sympto
Page 81 and 82: Symptoms Small, localized, light br
Page 83 and 84: obovoid, and 14-30 X 5-10 pm. Pycni
Page 85 and 86: invaders through the IFusarium lesi
Page 87 and 88: necrosis extending into the tuber t
Page 89 and 90: do not survive drying. Both species
Page 91 and 92: cauisal. Tesis Magister Scientiae e
Page 93 and 94: penetration, and subsequent disease
Page 95 and 96: have been demonstrated, including t
Page 97 and 98: In P..floridana,strains of PVY" and
Page 99 and 100: infects certain comnie,-cial stocks
Page 101 and 102: cytoplasm of infected potato cells
Page 103 and 104: WETTER, C. 1971. Potato virus S. No
Page 105 and 106: 3) Resistance has not been identifi
Page 107 and 108: nm), which do code for coat protein
Page 109 and 110: Symptoms AMV may induce Other predo
Page 111 and 112: Disease Cycle I)escriptions of Plan
Page 113 and 114: Selected References KASSANIS, B. 19
Page 115 and 116:
Control 1)Avoid locations in wkhich
Page 117 and 118:
The "yellows" types of disease, cha
Page 119 and 120:
modifying cultural practices and by
Page 121 and 122:
immature females in the white or ye
Page 123 and 124:
l.aboratory, Control. and Quarantin
Page 125 and 126:
They attack many major crops in the
Page 127 and 128:
infested areas of North America sev
Page 129 and 130:
antennal tb l tuberce u antenna eye
Page 131 and 132:
carbon tetrachloride, applied at th
Page 133 and 134:
Diagnostic Microbial Structures Scl
Page 135 and 136:
Surface and or interior Shades of g
Page 137 and 138:
Equivalent Names of Potato Diseases
Page 139 and 140:
Common Name Causal Factor Other Nam
Page 141 and 142:
Common Name Causal Factor Other Nam
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coalesce-union of similar structure
Page 145 and 146:
many days following removal of the
Page 147 and 148:
Index Abrasions, tuber surfaces. 14
Page 149:
Irost tolerance in. 9 aniligena. 68
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