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Claude E. Thomas and E.L. Jourdain

Field evaluations for resistance against downy mildew, incited by Pseudoperonospora cubensis [(Berk. and Cart.) Rostow], were conducted on 942 U.S. Plant Introductions (PI) of Cucumis melo L. (melon). A disease index (DI) was calculated for each entry. Based on DI, PI 124112 was highly resistant (DI = 3.7), and PIs 124111, 122847, 124210, 145594, and 165525 were resistant (DI = 3.0, 2.8, 2.6, 2.7, and 2.5, respectively). PIs 124111 and 124112 had one or more plants that exhibited a highly resistant reaction type (RT 4). Resistant (RT 3) plants were identified in 31 accessions, and 49 accessions bad moderately resistant (RT 2) plants.

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C.E. Thomas

Field evaluations for resistance against downy mildew, incited by Pseudoperonospora cubensis (Berk. & M.A. Curtis) Rostovzev were conducted on 1076 U.S. Plant Introductions (PI) of Cucumis melo L. (melon). A disease index (DI) was calculated for each entry that had one or more resistant plants. Based on DI, PIs 271329 and 401644 were the most resistant overall (DI = 2.6 and 2.8, respectively). However, resistant plants exhibiting reaction type (RT) 3 were identified in 68 accessions, and 110 accessions had moderately resistant (RT 2) plants.

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Anthony P. Keinath and Virginia B. DuBose

Twenty-six cultivars and two numbered selections of Cucurbita pepo L. pumpkin and four cultivars of C. maxima Duchesne pumpkin were evaluated in field experiments in 1996 and 1997 in Charleston, S.C. The four C. maxima cultivars (`Mammoth Gold', `Big Max', `Rouge Vif d'Etamps', and `Lumina') and three C. pepo cultigens (HMX 6686, HMX 6688, and Magic Lantern) had lower powdery mildew [Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci] severities than did the other C. pepo cultivars. Overall, C. maxima cultivars also had less foliage showing virus symptoms and less downy mildew [Pseudoperonospora cubensis (Berk.& M.A. Curtis) Rostovzev] than did C. pepo cultigens. Mid- and long-season cultigens of both species (≥100 days to maturity) produced a greater number of marketable-quality fruit than did short-season cultigens. Cucurbita maxima and C. pepo produced similar numbers of marketable fruit; however, more potential marketable yield was possible in C. maxima since most fruit were affected by virus. The C. pepo cultigens Spookie, HMX 6686, and Spooktacular produced the greatest numbers of marketable fruit. In general, no cultigens were well-adapted to the growing conditions of the humid coastal plain of the southeastern United States.

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Kyle M. VandenLangenberg and Todd C. Wehner

.D. Wehner, T.C. Klosinska, U. Kozik, E.U. 2012 Screening cucumber for resistance to downy mildew caused by Pseudoperonospora cubensis (Berk. and Curt.) Rostov Crop Sci. 52 577 592 Chen, X.M. 2005 Epidemiology and control of stripe rust [ Puccinia

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William L. Holdsworth, Carly F. Summers, Michael Glos, Christine D. Smart, and Michael Mazourek

disease is caused by the oomycete pathogen Pseudoperonospora cubensis (Berk. & Curt.) Rostov., which has a host range consisting of more than 60 species belonging to 20 genera in the Cucurbitaceae family, and includes important crops such as cucumber

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Adam D. Call, Todd C. Wehner, Gerald J. Holmes, and Peter S. Ojiambo

Cucurbit downy mildew caused by the oomycete Pseudoperonospora cubensis is economically the most important disease of cucumber ( Cucumis sativus L.) ( Palti and Cohen, 1980 ). Studies on the host range of P. cubensis indicate that ≈20 genera

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Adam D. Call, Adam D. Criswell, Todd C. Wehner, Kaori Ando, and Rebecca Grumet

Downy mildew, caused by the oomycete pathogen Pseudoperonospora cubensis (Berk. & cucumber ( Cucumis sativus L.) ( Palti and Cohen, 1980 ). Other economically important hosts of P. cubensis are melon ( Cucumis melo L.), watermelon [ Citrullus

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Jason Cavatorta, George Moriarty, Mark Henning, Michael Glos, Mary Kreitinger, Henry M. Munger, and Molly Jahn

( Cladosporium cucumerinum ), downy mildew ( Pseudoperonospora cubensis ), and powdery mildew ( Sphaerotheca fuliginea ). The development of ‘Marketmore 97’ resulted from the addition of resistance to the following diseases: alternaria leaf spot ( Alternaria

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C.E. Thomas and E.J. Caniglia

Seventeen U.S. honeydew-type cultivars of melon (Cucumis melo L.) and three control cultigens were evaluated in replicated, artificial inoculations under controlled conditions for resistance against downy mildew and Alternaria leaf blight. All cultivars tested were susceptible to downy mildew. However, all of the tested cultivars were significantly more resistant to Alternaria leaf blight than the susceptible control. Twelve of these cultivars were not significantly more susceptible to Alternaria leaf blight than the two resistant controls. These cultivars may provide useful sources of Alternaria leaf blight resistance for incorporation into other commercial melon types.

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A.H. Beany, K. Pernezny, P. J. Stoffella, N. Havranek, and J. Sanchez

Control of downy (Pseudoperonospora cubensis) and powdery [(Podosphoera xanthii (Sphaerotheca fuliginea)] mildew on `Sweet Dumpling' winter squash (Cucurbita maxima) was evaluated at the University of Florida, IFAS, Indian River Research and Education Center (IRREC), in Fort Pierce, Florida during the Spring of 2005. Three foliar spray fungicide treatments were evaluated against an untreated control. Powdery and downy mildew ratings (estimated percentage of foliage damage) and marketable yields (mt/ha) were measured. Plants in the untreated plots had significantly higher powdery and downy mildew ratings. All fungicide treatments significantly reduced both mildews. There were no significant differences among treatments for marketable yield. Although the level of disease occurrence was not sufficient to reduce yields, Gavel alternated with Nova, Bravo Ultrex weekly, and Cabrio + Forum alternated with Bravo Ultrex + Manzate 75WG reduced downy mildew by ≥50%.