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276 BORNE AND FOLIAR PATHOGENS IN PEANUT. H. S. McLean and P. Schmid. Sandoz Crop Protection, 1300 East Touhy Avenue, LY211795 - A Novel Foliar Applied Fungicide for Control of Des Plaines, IL 60018. Powdery Mildew in Cereals and Grapes. W. R. Arnold, M. J. Coghlan, H. R. Hall, E. V. Krumkalns, Lilly Research Cyproconazole, a-(4-chlorophyenyl)-(I cyclopropylethyl 1)-i 1, Laboratories, A Division of Eli Lilly and Company, P. 0. Box 2,4-triazole-lethanol, is a new broad spectrum fungicide with 708, Greenfield, IN. C. Longhurst, Lilly Research Centre Ltd., excellent systemic activity. Cyproconazole systemic activity Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK. is characterized by rapid plant tissue penetration and acropetal translocation. In field trials conducted 1984-1988, cypro- Lilly 211795 is highly effective as a foliar fungicide on wheat conazole has consistently provided control of important foliar and barley powdery mildew (Erysiphe graminis; f. spp. tritici and soil borne diseases in peanut when applied at relatively and hordei, respectively) and grape powdery mildew (Uncinula low rates (0.061-0.098 kg ai/ha) on a 14-21 day spray schedule. necator). The compound penetrates into the plant tissue very Early and Late leafspot (Cercospora arachidicola and Cercosporirapidly and is translocated acropetally. Compound 211795 shows dium personatum) are easily controlled with cyproconazole. excellent protectant activity against mildew resistant to DMI Southern Blight (Sclerotium rolfsii) and Rhizoctonia limb rot chemistry. When used in mixtures with other fungicides, a wide (Rhizoctonia solani) are also controlled by foliar applications range of diseases can be controlled, of cyproconazole within the same rate range as listed for leafspot. Peanuts have excellent tolerance to Cyproconazole and display virtually no plant growth regulation effects. 277 THE EFFECTS OF PENCONAZOLE AND PROPICONAZOLE ON THE 281 ULTRASTRUCTURE OF PYTHIUM ULTIMUM AND PHYMATOTRICHUM OMNIVORUM. J. R. Anciso and S. D. Lyda. Production of hydroxyl radical in photodynamDic biocidal reaction Department of Plant Pathology and Microbiology, Texas Agricultural of methionine riboflavin mixture. 0. 0. Tzeng, and N. H. Lee. Experiment Station, College Station, TX 77843. Department of Plant Pathology, National Chung Hsing University, The accepted mode of action of penconazole (Topasr) and propiconazole (Tiltr) is the inhibition of ergosterol biosynthesis. A time course study Production of hydroxyl radical (-OH) was detected from the on effects of the two chemicals on Pythium ultimum and methionine riboflavin mixture (MR) under continuous illumination Phymatotrichum omnivorum was investigated. The ED 5 0 for P. ultimum by the method developed by Baker and Gebicki. The rate of "OH is 25 ppm with penconazole and 98 ppm with propiconazole, while the production from MR was much greater at pHs 4.0-5.0 than at pHI ED 5 0 for P. omnivorum is 9 ppm with penconazole and .01 ppm with 6,0-8.0, which indicated the possible involvement of iron conpropiconazole. The ED 5 0 (minimum inhibitory concentration) was tamiinant in the reaction. The addition of exogenous iron was chosen as the concentration to observe ultrastructural changes. The primary observation was the loss of normal-appearing endoplasmic stirulatory to the -OH formation of nR. However, the presence reticulum and the abundant appearance of circular endoplasmic of iron chelators like desferal, or phenanthroline, and free reticulum-like material in the treated for both species. P. ultimum radical scavengers like thiourea, all greatly reduced the radiwhich does not synthesize or require sterols has shown "moderate cal forming activity. At pH 4.0, it was also noted that addisensitivity" to penconazole in greenhouse and in vitro tests. These tion of ascorbic acid or H 2 0 2 at certain concentrations greatly similar ultrastructural changes found in the nonsterol-synthesizing P. enhanced the generation of the test radical. The rapid increaultimum and the sterol-synthesizing P. omnivorum suggest that another ment of -OH formation via the iron catalyzed Haber-Weiss reacmode of action exists for both of these triazoles. tion was apparently a major factor which contributed to the 278 RESPONSE OF CYST-NEMATODE RESISTANT AND SUSCEPTIBLE SOYBEAN CULTIVARS TO IN-FURROW APPLICATIONS OF 282 photodynamic biocidal activity of MR. ALDICARB. P. M. Phipps, Tidewater Agr. Exp. Sta., VPI&SU, Suffolk, VA 23437-0099. THE EXPRESSION OF RESISTANCE OF USTILAGO AVENAE TO TRIADIMENOL IS AN INDUCED RESPONSE. Wolfram Kdller and Franzine 0. Smith, Department of Plant Pathology, N Y State Soybean cultivars were evaluated with and without applications of aldicarb Agricultural Experiment Station, Geneva, NY, 14456. (Temik 15G) in fields naturally infested with soybean cyst nematode (SCN) in 1987 and 1988. Cultivars were main plots consisting of six 10.7-m rows spaced A strain of U. avenae sensitive to triadimenol (sen) and a 0.9-m apart. Treatments were applied to the seed furrow of two-row subplots menol resistant (2mg/L) laboratory after 15 mutant h of growth (rl) were in treated liquid culture. with triadi- at planting. The experimental design employed 9Initially, four randomized complete Inil rerodcto reproduction of of both in was strains altcme t was almost completel blocks. The effect of cultivars on nematode populations and yield was blocked; however, the inhibitory phase was transient for rl, significant (P=0.05), however, aldicarb only had a significant effect on yield. and full growth resumed after 10 h. This pattern of initial The overall yield of SCN-resistant cultivars (Centennial, Forrest, Pioneer Brand growth inhibition and subsequent recovery was correlated with P9581) averaged 2576 kg/ha (38.3 bu/A) compared to 1917 kg/ha (28.5 bu/A) a decline of sterol precursors, as analyzed by GC-MS. Al- for susccptible cultivars (Essex, York). Aldicarb at 0.56 and 1.12 kg/ha though precursors (pre-dominantly 24-methylenedihydrolanosterol) accumulated during the phase of growth inhibition, improved yield of susceptible cultivars 276 and 390 kg/ha (4.1 and 5.8 uA) and also were still prominent at the onset of renewed growth, and yield of resistant cultivars 363 and 356 kg/ha (5.4 and 5.3 bu/A), they were absent after 24 h of treatment with triadimenol. respectively. Pulse-labeling of sterols at various time intervals after treatment with the inhibitor revealed that the continuous disappearance of precursor sterols is not explained by a dilution of the inhibitor from the target site. 279 EFFECTS OF FUNGICIDE RH3486 ON SCLEROTINIA BLIGHT OF PEANUT IN HIELD AND MICROPLOT TESTS. F. D. Smith, P.M. Phipps 283 and R. J. Stipes, Tidewater Agr. Exp. Sta., VPI & SU, Suffolk, VA 23437. NTRDSESBEGAUE EHOOY .. Lro ~and The fungicide, RH3486, and several other J.M. fungicides Denis. were UCB evaluated Chemicals for control Corp., 5365-A Hood Robin Rd., Norfolk, VA 23513 and UCB Chemical Sector, of Sclerotinia blight of peanut, caused by Sclerotinia minor. Two applications Ave. Louise 326, B-1050 Brussels, Belgium. of RH3486 at 0.56 or 1.12 kg a.i./ha significantly (P=0.05) suppressed disease 69 and 81% and increased yields 2191 and 2243 kg/ha, respectively. Similar UCB is one of the world's leading producers of applications of iprodione (1.12 kg/ha), vinclozolin (0.84 kg/ha), dicloran (3.36 methylamines and their derivatives such as Thiram kg/ha) or PCNB at (5.60 kg/ha) suppressed disease only 42, 47, 21 and 18%, and Ziram fungicides. In efforts to improve worker respectively. Microplots, 76-cm-dia., were infested with S. minor sclerotia from safety, strinS- UCB -8-T evaluated (wldtye)or (icaboimderesstnt other methods for ad formulating panedto Thiram and Ziram and concluded that the water- strinS-2(wld-yp) r B83T2 diaroxiid-reisan) ad lanedto dispersible granule (WG) formulation was the most Florigiant peanut. Plots treated three times with RH3486 at 1.12 kg/ha averaged 0 and 1.0 lesions/plot with strain S-2 and B-83-T2, respectively, Untreated plots likewise averaged 27.0 and 31.5 lesions/plot. Three applications of iprodione at 1.12 kg/ha did not significantly suppress disease caused by either strain. Two years of similar field data have shown RH3486 to be an extremely active fungicide against wild-type and dicarboximide-resistant strains of S. minor, apr rit. TeW tchogydvledbUC hs been registered under the trade name "GRANUFLO." The high quality granules readily disperse in water and offer many advantages over traditional formula- tions including being virtually dust-free, easy to package, easy to handle, insensitive to temperature 280 CYPROCONAZOLE: A NEW SYSTEMIC FUNGICIDE FOR CONTROL OF SOIL variations and having improved product efficacy. The Granuflo technology allows opportunities for formulating associations of fungicides which are useful in developing anti-resistance strategies. 1170 PHYTOPATHOLOGY
284 BASELINE-SENSITIVITY OF THREE POPULATIONS OF VENTURIA INAEQUALIS TO FLUSILAZOLE. Franzine D. Smith, Wolfram Khl1er and Diana M. Parker, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. CULTIVARS FOR EXPORT. B. T. Manji, J. M. Ogawa, J. E. Adaskaveg, and J. M. Osorio. Department of Plant Pathology, University of California, Davis, CA 95616. Nectarine fruit in bins were preconditioned to a pit (inner mesocarp) temperature of 21 C and fumigated with methyl bromide, 48 g/m 3 One hundred monoconidial isolates of V. inaequalis were collected from each of two abandoned orchards (orchards 1 and2), where no steroldemethylation inhibitors (DMd ) had been used, and from a research orchard where DM1 fungicides had been used for 12 years (orchard 3). Themean EDso values based on colony diameter were 0.0083 jtg flusilazole/ml, 0.0072 jtg/ml, and 0.0105 jtg/ml for orchards 1, 2, and 3, respectively. ED5o values for individual isolates ranged from 0.002 to 0.0654 jtg/ml, 0.0001 to 0.0469 jtg/ml, and 0.0011 to 0.1108 jig/ml, in orchards 1, 2, and 3, respectively. There was no significant difference between the mean of the log10 transformed ED50 values of any orchard. Our results indicate that the three populations examined had similar mean EDs0 values, and that highly tolerant isolates occurred in natural populations prior to for 2 hr at 21 C. After fumigation, non-treated and fungicide-treated fruit were packed into boxes and stored for 12-14 days at 1 C to simulate transit by ship to oversea markets. In non-fungicide treatments, early-maturing cultivars (May Glo, May Grand, and Spring Red) generally developed less than 5% brown rot (Monilinia fructicola), whereas, later-maturing cultivars (Red Diamond and Firebrite) developed as high as 80% brown rot during the 5 day ripening period at 21 C. Generally, fruit washed with 100 pg/mi chlorine had less brown rot than non-chlorinated fruit. Postharve treatment with iprodione in a water soluble wax further extended the shelf-life of the fruit by 3-5 days. flusilazole exposure. The range and variance of ED 50 values observed in our study also indicates that small sample sizes are unlikely to represent accurately the sensitivity of populations of V. inaequalis to DMI fungicides. 289 EFFICACY OF COPPER RESINATE AND TRI-BASIC COPPER SULFATE IN PEANUT DISEASE CONTROL. W.W. Osborne and J. D. Taylor. IAI, 285 Inc., South Boston, VA 24592; and J Skippers, VA 23879. & S Consultants, Inc., SULFUR DIOXIDE RESIDUES IN TABLE GRAPES AFTER S0 2 FUMIGATION. J. L. Smilanick, J. M. Harvey, P. L. Hartsell, D. J. Henson, C. M. Harris, D. C. Fouse, and M. Assemi. USDA, ARS, HCRL, 2021 South Peach Avenue, Fresno, CA 93727 Grapes were fumigated to evaluate factors that influence sulfur dioxide (SO2 ) residues. Residues with SO2 decreased rapidly after fumigation; the S02 half-life was 24-48 hr. Grapes fumigated at warmer temperatures accumulated higher but less persistent residues than those fumigated at low temperatures. Immature grapes accumulated more S02 than mature grapes. S02 residues were located on or near the berry surface. Grapes infected with Botrytis cinerea or injured by cuts accumulated more S02 than sound grapes. Sulfur dust applied before harvest left no S02 residues. The decay suppression with low (312-1250 ppm) SO2 doses was only slightly inferior to that obtained by standard doses (2500 ppm). S02 residues after low doses did not exceed 10 ppm. High residues can be avoided by low-dose fumigations, good temperature management, and use of grapes free from rot or injuries for storage, 286 EVALUATION OF FUNGICIDES FOR CONTROL OF LEAF RUST AND SEPTORIA BLOTCH OF WHEAT. R. T. Gudauskas, A. K. Hagan, E. L. Carden, and N. R. McDaniel, Dept. of Plant Pathology and Gulf Coast Substation, Auburn University, AL 36849 During 1983-1988, 24 fungicide treatments were evaluated for control of leaf rust and Septoria blotch on highly susceptible cultivars 'Blueboy' and 'McNair 1003' and a less susceptible cultivar 'Fla. 301'. One or two applications of each fungicide were made between growth stages 8 and 10.2. Most of the fungicides tested reduced the severity of both diseases as compared to the unsprayed control. Yield increases associated with fungicide treatments in the highly susceptible cultivars ranged from 268 to 2016 kg/ha; yield increases in 'Fla. 301' ranged from 0 to 806 kg/ha. Fungicides giving the highest levels of disease control and yield increases included diniconazole, propiconazole, mancozeb, terbutrazole, and triadimefon. 287 USES OF FUNGICIDE COMBINATIONS CONTAINING TETRAMETHYLTHIURAM DISULPHIDE OR THIRAM ON APPLES, PEARS AND STRAWBERRIES. J.M. Denis and P. Creemers. UCB Chemical Sector, Ave. Louise 326, 8-1050 Laboratory and field studies conducted during the past four years with copper resinate and tri-basic copper sulfate show an inverse relationship between chemical rates and control of major peanut diseases. Copper resinate was the most economical and effective treatment when compared with tri- basic copper sulfate and other fungicides currently being used for the control of major peanut diseases. 290 EVALUATION OF AGRI-CHEMICALS ON SPORES AND MYCELIUM OF STIGMINA CARPOPHILA AND MONILINIA FRUCTICOLA. A.J. Feliciano, J.E. Adaskaveg, and J.M. Ogawa. Univ. of California, Davis, 95616. Spores of S. carpophila (Sc) and M. fructicola (Mf) were exposed to (chemical/concentrations-pg/mi al.): NaOC1/400; Hg/D2; Cu/1800; ziram /1800, captan/50, 500, 1200; iprodione/1200; and captafol/10, 100,500, using the cellophane-transfer technique. Spores were exposed for 2 or 24 hr, rinsed for 0, 24, 48, 72 or 96 hr, and plated on PDA. Colony formation (cf) was determined after incubation for 10 da at 25C. Inhibition of cf for each fungus at chemical concentrations tested was: Sc - Hg, NaOCi, or captafol/2 hr (chemicals/exposure); captan/24 hr; Mf - Hg or NaOCI/2 hr; and captan or captafol/24 hr. Ziram, Cu, or iprodione did not inhibit cf of either fungus at both exposures. Rinsing increased the rate of growth but not % cf. Increasing concentrations of captan decreased the time of exposure that inhibited cf: Mf - 16 hr exposure/50 pg/ml, 12/500, 8/1200; and Sc - 4/10, 4/100, and 2/500. In a 24-hr, direct exposure study using mycelium growing on cellophane, 1200 pg/ml of captan or 500 pg/ml of captafol did not inhibit mycelial growth of either fungus. Current concepts of defining chemicals as fungicides may need re-evaluation based on fungal tissue, chemical concentration, exposure time, and duration of incubation on a medium. 291 MITOCHONDRIAL PLASMIDS IN ENDOTHIA PARASITICA. N. Mahanti and D.W. Fulbright. Dept. Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824. Hypovirulent strains of Endothia parasitica found in Europe and North America are associated with dsRNA. One strain of E. parasitica (CL25) from Michigan has all the characteris- -tics of dsRNA-associated transmissible hypovirulence but harbors no detectable dsRNA. Studies with CL25 show plasmids are present in mitochondria. These plasmids are in low titer and have been difficult to isolate consistently. The plasmid DNA was isolated by electrophoresing total mitochondrial DNA in an Brussels, Belgium and Opzoekingsstation van Gorsem, agarose gel, cutting the plasmid band from this gel, followed Brede Akker 3, 8-3000 Sint-Truiden, Belgium. by electroelution. The restriction enzyme Saulll-A was used Field trials with Thiram alone or in combination with to clone the plasmid into vector PRL 498. Southern hybridizaother fungicides were conducted at the Fruit Research tion studies show that this plasmid is present in some virulent Station of Gorsem. The use of the compound Thiram in and other hypovirulent strains even though the plasmid bands fungicide combinations showed an increase of are not visible in gels after ethidium bromide staining. Therefore these plasmids may not have a direct effect on hypovirupreventive activity, a broadening of the spectrum of lence but may be affecting the mitochondrial genome. activity, and a decrease of the selection pressure of the fungicide with which it was combined. It is concluded that Thiram is an effective fungicide partner when used on apples (scab), pears (scab) and strawberries (grey mould). 288 VARIABILITY OF DISEASE DEVELOPMENT IN NECTARINE Voj. 79, No. 10, 1989 1171
Page 1 and 2: Abstracts of Presentations at the 1
Page 3 and 4: Twenty Fusarium solani (Mart.) Sacc
Page 5 and 6: means used to derive them were not
Page 7 and 8: 46 A COMPARISON OF THE EPIPRE AND K
Page 9 and 10: 62 THE INCIDENCE AND IMPACT OF SPHA
Page 11 and 12: 79 83 82 SELECTION AND USE OF OXALA
Page 13 and 14: nificantly among plots but there wa
Page 15 and 16: Chrysanthemum morifolium (florists'
Page 17 and 18: anine ammonia lyase (PAL) and hydro
Page 19 and 20: studies. YST plants were uniformly
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Page 25 and 26: shown to be double-stranded circula
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Page 29 and 30: Spatial patterns of disease were st
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Page 33 and 34: y suppression of Mn oxidizers in th
Page 35: Colbaugh. Texas Agricultural Experi
Page 39 and 40: Department of Agronomy, University
Page 41 and 42: 316 SEROLOGICAL NONIDENTITY OF IRIS
Page 43 and 44: amended with 25 g/L of KC1O Prelimi
Page 45 and 46: lacZ gene fusions have been used to
Page 47 and 48: Department of Plant Pathology, Univ
Page 49 and 50: causative agent of greening, howeve
Page 51 and 52: and chitosan heptamer will be discu
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Page 55 and 56: M. Laakso and J. W. Moyer, Dept. of
Page 57 and 58: 443 The stability of antigenic dete
Page 59 and 60: seed decay by 10%. Phomopsis seed d
Page 61 and 62: LARYAFD, QMKAA, FGLDG and TERH, in
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Page 65 and 66: The primary cell walls of grasses c
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Page 79 and 80: agar diffusion tests and spore germ
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682 PHYTOPHTHORA CINNAMOMI. Univers
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698 SCREENING OF VESICULAR-ARBUSCUL
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