37:
227:
321:
332:
The development and severity of the disease is dependent on a number of environmental factors. Studies have found that hours of relative humidity >80%, degree-hours of wetness, and mean night temperature are paramount in predicting model plants' susceptibility to infection. The pathogen favors
288:
Downy mildew on hops has a polycyclic disease cycle. The pathogen overwinters as mycelium in hop crowns. The pathogen infects crown buds, resulting in the emergence of infected shoots and primary basal spikes in the spring under correct conditions. This initiates the disease cycle. Infected crowns
279:
Primary and secondary spikes result in stunting shoots and brittle leaves. Primary spikes also cause shortened internodes. Aerial spikes adversely affect the development of the plant, resulting in bines (the long, flexible stem the plant uses to climb) falling away from the string on which hops is
266:
The most characteristic symptom of hop downy mildew are the “basal spikes” that form on the plant. These structures result from systemically infected shoots and are “stunted and have brittle, downward-curled leaves from which masses of purple to black sporangiophores and sporangia are produced.”
333:
extended periods of wetness, high humidity, and mildly warm temperatures ranging from 15.5–21 °C (59.9–69.8 °F). Leaf infection can occur at temperatures as low as 5 °C if wetness persists for 24 hours or longer, indicating the primary role of moisture level in infection.
293:
to infect leaves, cones, and shoots. This secondary cycle or sporulation and infection persists throughout the season. Mycelia grow systemically throughout the plant, leading to the infection of the crown and buds in which the pathogen will overwinter.
280:
allowed to climb. Infected leaves and cones show symptoms as well. Infected leaves will change color, ranging from purple-gray to black downy growth. Infected cones become hard and brown and display disrupted development.
289:
may also produce uninfected shoots. The cycle becomes polycyclic as sporangiophores with sporangia emerge on the underside of infected leaves. Mature sporangia are dispersed via wind and release
305:
to produce a recombinant oospore. While oospores are classically thought to be the chief survival structure of oomycetes, their role in primary infection in downy mildew of hops is uncertain.
475:
650:
573:
612:
457:
Johnson, D.A., et al. 2009. Downy mildew. Pages 18 to 22 in: Compendium of Hop
Diseases and Arthropod Pests. American Phytopathological Society, St. Paul, MN.
317:
are consistent with other oomycetes and fungal-like pathogens. High levels of moisture and warmer temperatures facilitate the germination of many pathogens.
560:
670:
468:
36:
599:
431:
617:
675:
665:
660:
502:
655:
150:
627:
552:
251:
is an obligate biotrophic pathogen, meaning that it can only live and grow in living host tissue.
172:
31:
578:
405:
127:
395:
117:
547:
212:
107:
74:
61:
644:
216:
87:
604:
355:
255:
like most downy mildews, is highly host-specific and thus will only infect hop (
525:
400:
383:
534:
226:
48:
409:
276:
3) “Aerial spikes”, which occur on lateral branches or trained vines
586:
519:
302:
290:
97:
320:
565:
273:
2) “Secondary spikes”, which arise from infected apical meristems
591:
496:
539:
220:
500:
270:
1) “Primary spikes”, which arise from infected hop crowns
384:"Predicting Infection Risk of Hop by Pseudoperonspora humuli"
444:
Coley-Smith, J. R. 1962. Overwintering of hop downy mildew
432:"Managing hop downy mildew early in the season is critical"
328:. The dark coloration is consistent with sporulation.
356:"Hop Downy Mildew | NC State Extension Publications"
509:
448:(Miy. and Tak.) Wilson. Ann. App. Biol. 50:235-243.
234:. The brown coloration is a characteristic symptom.
469:"Diagnostic manual for plant diseases in Vietnam"
267:These spikes can exist as three distinct types:
243:Downy mildew on hops is caused by the pathogen
8:
382:Gent, David; Ocamb, Cynthia (10 June 2009).
497:
20:
467:Burgess, Lester; Knight, Timothy (2008).
399:
324:The underside of a hops leaf infected by
166:(Miyabe & Takah.) G.W. Wilson, (1914)
651:Water mould plant pathogens and diseases
319:
313:The environmental conditions favored by
301:, in which an antheridium fertilizes an
225:
342:
230:Cones of the hops plant infected with
191:(Miyabe & Takah.) SkalickĂ˝, (1966)
7:
628:cc5f6284-7e69-43e7-bb01-75d09a7eeee0
425:
423:
421:
419:
377:
375:
350:
348:
346:
198:(Miyabe & Takah.) Sacc., (1912)
14:
16:Species of single-celled organism
35:
481:from the original on 2012-03-21
430:Lizotte, Erin (15 April 2015).
297:A sexual stage also exists for
1:
184:Miyabe & Takah., (1905)
692:
671:Protists described in 1914
259:) and also Japanese hop (
178:
171:
156:
149:
32:Scientific classification
30:
23:
511:Pseudoperonospora humuli
446:Pseudoperonospora humuli
401:10.1094/PHYTO-99-10-1190
326:Pseudoperonospora humuli
245:Pseudoperonospora humuli
232:Pseudoperonospora humuli
208:Pseudoperonospora humuli
160:Pseudoperonospora humuli
25:Pseudoperonospora humuli
247:, an oomycete protist.
181:Peronoplasmopara humuli
329:
235:
323:
229:
360:content.ces.ncsu.edu
330:
239:Hosts and symptoms
236:
188:Peronospora humuli
638:
637:
503:Taxon identifiers
394:(10): 1190–1198.
261:Humulus japonicas
204:
203:
199:
195:Plasmopara humuli
192:
185:
129:Pseudoperonospora
683:
676:Oomycete species
631:
630:
621:
620:
608:
607:
605:NHMSYS0001495246
595:
594:
582:
581:
569:
568:
556:
555:
543:
542:
530:
529:
528:
498:
491:
490:
488:
486:
480:
473:
464:
458:
455:
449:
442:
436:
435:
427:
414:
413:
403:
379:
370:
369:
367:
366:
352:
197:
190:
183:
162:
40:
39:
21:
691:
690:
686:
685:
684:
682:
681:
680:
641:
640:
639:
634:
626:
624:
616:
611:
603:
598:
590:
585:
577:
572:
564:
559:
551:
546:
538:
533:
524:
523:
518:
505:
495:
494:
484:
482:
478:
471:
466:
465:
461:
456:
452:
443:
439:
429:
428:
417:
381:
380:
373:
364:
362:
354:
353:
344:
339:
311:
286:
257:Humulus lupulus
241:
193:
186:
167:
164:
158:
145:
118:Peronosporaceae
34:
17:
12:
11:
5:
689:
687:
679:
678:
673:
668:
666:Peronosporales
663:
658:
653:
643:
642:
636:
635:
633:
632:
622:
609:
596:
583:
570:
557:
544:
531:
515:
513:
507:
506:
501:
493:
492:
459:
450:
437:
415:
388:Phytopathology
371:
341:
340:
338:
335:
310:
307:
285:
282:
240:
237:
213:plant pathogen
202:
201:
176:
175:
169:
168:
165:
154:
153:
147:
146:
142:P. humuli
139:
137:
133:
132:
125:
121:
120:
115:
111:
110:
108:Peronosporales
105:
101:
100:
95:
91:
90:
85:
78:
77:
72:
65:
64:
62:Diaphoretickes
59:
52:
51:
46:
42:
41:
28:
27:
15:
13:
10:
9:
6:
4:
3:
2:
688:
677:
674:
672:
669:
667:
664:
662:
661:Hemp diseases
659:
657:
654:
652:
649:
648:
646:
629:
623:
619:
614:
610:
606:
601:
597:
593:
588:
584:
580:
575:
571:
567:
562:
558:
554:
549:
545:
541:
536:
532:
527:
521:
517:
516:
514:
512:
508:
504:
499:
477:
470:
463:
460:
454:
451:
447:
441:
438:
433:
426:
424:
422:
420:
416:
411:
407:
402:
397:
393:
389:
385:
378:
376:
372:
361:
357:
351:
349:
347:
343:
336:
334:
327:
322:
318:
316:
308:
306:
304:
300:
295:
292:
284:Disease cycle
283:
281:
277:
274:
271:
268:
264:
262:
258:
254:
250:
246:
238:
233:
228:
224:
222:
218:
214:
210:
209:
200:
196:
189:
182:
177:
174:
170:
163:
161:
155:
152:
151:Binomial name
148:
144:
143:
138:
135:
134:
131:
130:
126:
123:
122:
119:
116:
113:
112:
109:
106:
103:
102:
99:
96:
93:
92:
89:
88:Stramenopiles
86:
83:
80:
79:
76:
73:
70:
67:
66:
63:
60:
57:
54:
53:
50:
47:
44:
43:
38:
33:
29:
26:
22:
19:
656:Hop diseases
510:
483:. Retrieved
462:
453:
445:
440:
391:
387:
363:. Retrieved
359:
331:
325:
314:
312:
298:
296:
287:
278:
275:
272:
269:
265:
260:
256:
252:
248:
244:
242:
231:
217:downy mildew
215:that causes
207:
206:
205:
194:
187:
180:
179:
159:
157:
141:
140:
128:
81:
68:
55:
24:
18:
309:Environment
645:Categories
365:2017-10-24
337:References
253:P. humuli,
315:P. humuli
299:P. humuli
291:zoospores
249:P. humuli
136:Species:
49:Eukaryota
587:MycoBank
579:11116678
548:Fungorum
526:Q7255252
520:Wikidata
485:14 March
476:Archived
410:19740033
303:oogonium
173:Synonyms
114:Family:
98:Oomycota
94:Phylum:
45:Domain:
566:3204008
124:Genus:
104:Order:
625:NZOR:
618:162120
592:119090
553:119090
540:PSPEHU
408:
574:IRMNG
479:(PDF)
472:(PDF)
211:is a
82:Clade
69:Clade
56:Clade
613:NCBI
561:GBIF
535:EPPO
487:2018
406:PMID
221:hops
600:NBN
396:doi
263:).
219:on
75:SAR
647::
615::
602::
589::
576::
563::
550::
537::
522::
474:.
418:^
404:.
392:99
390:.
386:.
374:^
358:.
345:^
223:.
84::
71::
58::
489:.
434:.
412:.
398::
368:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
