consecutive years, 2005 to 2008. Effects of insecticide and fungicide treatments on the incidence of bunch drop. All treatments were performed on five to 15 randomly distributed trees per plots in several ‘Medjool’ orchards on the northern shore of the
Yuval Cohen, Stanley Freeman, Aida Zveibil, Rachel Ben Zvi, Yaakov Nakache, Shimon Biton, and Victoria Soroker
Melike Cirak and James R. Myers
emergence test. The seeds were split into two lots and one lot was treated with Captan fungicide (Bonide Products LLC, Oriskany, NY). Experimental design was a randomized complete block design, with genotype and fungicide treatment as main effects. Depending
Robert E. Call and Michael E. Matheron
Studies were established in 1992 and 1993 in a mature commercial pistachio orchard to determine the effectiveness of several fungicides for control of septoria leaf spot (Septoria pistaciurum). Fungicide treatments used in 1992 were Bravo 720F at 3.0 lbs./A (ai.) and 4.5 lbs./A a.i.; Kocide 101 50W at 8.0 lbs./A a.i. plus Benlate 50W at 1.0 lb./A a.i. Fungicide treatments in 1993 were Bravo 825 WDG at 3.0 and 4.5 lbs./A a.i. and Benlate 50W at 2.0 lbs./A a.i. Treatment replications consisted of two treated trees separated by nontreated trees within the row and nontreated tree rows dividing treated rows. At crop maturity, disease severity was determined by counting the number of leaf spots caused by septoria on ten leaves collected at random from each of the two trees of each replicated plot. All treatments significantly reduced disease severity compared to trees receiving no fungicide treatments. Experimental plots were too small to detect any apparent effect of fungicide treatments on yield. Leaves around nut clusters not receiving fungicide treatments were senescent at crop maturity, while leaves on treated trees showed no sign of senescence.
Whitney J. Garton, Mark Mazzola, Nairanjana Dasgupta, Travis R. Alexander, and Carol A. Miles
. The reported efficacy of applying cauterization (CAU) and/or fungicidal treatments to cankers or excised areas is also quite variable. Studies of pathogens that incite similar canker diseases on fruit trees, such as bacterial canker ( Pseudomonas
A.H. Beany, K. Pernezny, P. J. Stoffella, N. Havranek, and J. Sanchez
Control of downy (Pseudoperonospora cubensis) and powdery mildew [(Podosphoera xanthii (Sphaerotheca fuliginea)] 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 Spring 2004. Seven 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 reduced powdery mildew on adaxial leaf surfaces. Downy mildew appeared unusually late in the crop season and all fungicide treatments significantly reduced it. There were no significant differences among treatments for marketable yield. Although the level of disease occurrence was not sufficient to reduce yields, each foliar spray treatment significantly reduced powdery and downy mildew.
Roy E. McDonald, William R. Miller, and T. G. McCollum
The fungicides thiabendazole (TBZ) or imazalil were applied at 1 g·liter-1 at 24 or 53C to `Marsh' and `Redblush' grapefruit (Citrus paradis i Macf.) to reduce fruit susceptibility to chilling injury (CI) and decay. There was more CI and decay on `Marsh' grapefruit than on `Redblush'. CI was found to be lower in grapefruit that had been dipped at 53C than at 24C. CI was higher after water dips without fungicide. Imazalil was found to be more effective in reducing CI than TBZ. Fungicides reduced decay at both temperatures, and imazalil was better than TBZ. Results of this study confirm the benefits of high-temperature fungicide treatments for maintaining grapefruit quality and indicate some benefits of high-temperature fungicide treatments for reducing CI.
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%.
Cheryl R. Boyer*, Janet C. Cole, and Kenneth E. Conway
Plants of Euonymus fortunei `Emerald Gaiety', `Emerald 'n Gold' and `Canadale Gold' were sprayed to runoff weekly at two sites with one of three fungicide treatments or water (control) to determine fungicide effectiveness in controlling anthracnose caused by Colletotrichum gloeosporioides. Copper sulfate pentahydrate was applied at 0.4 or 0.6 g·L-1 a.i. or mancozeb was applied at 1.8 g·L-1 a.i.. Plants were rated for disease incidence approximately monthly. No interaction occurred between fungicide and cultivar. Differences among fungicide treatments were not apparent until weeks 18 or 20 depending on the site, when plants treated with mancozeb had lower disease ratings than plants receiving any other treatment. Cultivars differed at almost every rating date at both sites. Poison agar experiments were conducted to determine mycelial inhibition by copper sulfate pentahydrate or mancozeb.
Graham Sanders, Elsa Sanchez, and Kathleen Demchak
The increased demand for organic and sustainably grown produce has resulted in a demand for information on organic and biorational fungicides. The efficacy of these fungicides is often not established, yet they are aggressively advertised. In 2005 the efficacy of six organic and biorational fungicides and two controls were evaluated on field-grown red raspberries (Rubus idaeus `Prelude' and `Nova') for gray mold (Botrytis cinerea) management. Phytotoxicity of the fungicide treatments was evaluated on a weekly basis following each fungicide application. Fruit was harvested by hand, sorted into marketable and unmarketable categories and weighed. Subsamples of fruit were evaluated for postharvest disease development. Data analysis showed `Nova' was more susceptible to phytotoxicity than `Prelude'. The application of Phostrol resulted in the highest phytotoxicity rating when compared to all other fungicide treatments. The water spray control, standard fungicide (Captan/Elevate rotation) control, Endorse, and Lime Sulfur treatments resulted in negligible phytotoxity ratings. Applying Milstop, Milstop + Oxidate, and Oxidate + Vigor Cal Phos resulted in similar intermediate phytotoxicity ratings. Differences in marketable yield were nonexistent for the two cultivars and eight fungicide treatments. The predominant diseases observed in the postharvest evaluations were gray mold, blue mold (Penicillium sp.), and rhizopus soft rot (Rhizopus sp.) and/or mucor mold (Mucor sp.). This evaluation will be repeated in 2006.
Richard Marini, John Barden, and Donald Sowers
In 1993 a factorial experiment, involving nine apple cultivars on M.9 root-stock and six fungicide regimes, was established. The cultivars included `Delicious', `Golden Delicious', `York Imperial', `Redfree', `Freedom', `Liberty', NY 74828-12, NY 73334-35, and NY 74840-1. The fungicide treatments included earlyseason sprays of Bayleton or Dodine, separately or combined, and late-season sprays of Captan plus Benomyl alone or combined with early-season sprays of Bayleton plus Dodine. Non-sprayed trees served as a control. In 1995 leaves and fruits were evaluated for disease symptoms. Leaf spot (symptoms caused by black rot or alternaria leaf blotch) was most severe on `Redfree' and NY 73334-35, and least severe on `Delicious', `Golden Delicious', and `York'. By late summer NY 74828-12 had the most leaf abscission, whereas NY 74840-1, `Liberty', and `Delicious' lost the fewest leaves. Early-season fungicide sprays did not reduce early leaf abscission. Sooty blotch and fly speck, but not rots, were nearly eliminated by late-season applications of Captan plus Benomyl. Averaged over all fungicide treatments, more than half of the fruits from `Delicious', `Redfree', and NY 74828-12 were free of disease symptoms. Cultivars with <25% of the fruits without infection included `York', `Liberty', NY 74840-1 and NY 73334-35. `York' and `Redfree' had >25% of the fruits with rots, while all other cultivars had <9% fruits with rots. `Delicious' and NY 73334-35 had the fewest rotten fruits. Rots were not controlled by any fungicide treatment. `Liberty' and NY 73334-35 had the most flyspeck and `Redfree' had the least. `Liberty', NY 74840-1 and NY 73334-35 had the most sooty blotch and `Redfree' and NY 74828-12 had the least.