scholarly journals Reduction of Phytophthora Blight of Madagascar Periwinkle in Florida by Soil Solarization in Autumn

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 185-191 ◽  
Author(s):  
R. J. McGovern ◽  
R. McSorley ◽  
R. R. Urs

Three field experiments were conducted in southwest and west-central Florida in 1993 through 1995 to evaluate the effectiveness of soil solarization during autumn in reducing Phytophthora blight of Madagascar periwinkle (Catharanthus roseus) caused by Phytophthora nicotianae. Plots (3.6 by 3.6 m) were infested by incorporating winter wheat seed containing P. nicotianae in the upper 15 cm of soil. Solarization was then conducted for 21 to 41 days, primarily during October, using clear, 25- or 50-μm low-density polyethylene mulch. The progress of Phytophthora blight, monitored for 31 to 42 days following planting, was significantly reduced by solarization in all experiments, and final blight incidence was reduced in two of three experiments. Solarization also reduced population densities of P. nicotianae.

Plant Disease ◽  
2002 ◽  
Vol 86 (12) ◽  
pp. 1388-1395 ◽  
Author(s):  
R. J. McGovern ◽  
R. McSorley ◽  
M. L. Bell

Two experiments were conducted during autumn 1997 and 1998 in west-central Florida to evaluate the effectiveness of soil solarization alone and in combination with the biological control agents Streptomyces lydicus (Actinovate) and Pseudomonas chlororaphis (syn. P. aureofasciens, AtEze) and the reduced-risk fungicide fludioxonil (Medallion) in managing soilborne pathogens of impatiens (Impatiens × wallerana, ‘Accent Burgundy’). Naturally infested soil was solarized for 47 or 48 days during September and October using two layers of 25-μm clear, low-density polyethylene mulch, separated by an air space of up to 7.5 cm. Solarization decreased the final incidence and progress of Rhizoctonia crown rot and blight, incidence of Pythium spp. in roots, and root discoloration, and increased shoot biomass in both experiments. The technique also consistently reduced root-knot severity and population densities of Meloidogyne incognita, Dolichodorus heterocephalus, Paratrichodorus minor, and Criconemella spp. The incidence of Rhizoctonia crown rot and blight was reduced by fludioxonil, but not by the biological control agents.


2014 ◽  
Vol 28 (1) ◽  
pp. 200-205 ◽  
Author(s):  
Sanjeev K. Bangarwa ◽  
Jason K. Norsworthy

Nutsedge control is challenging in commercial vegetable production in the absence of methyl bromide, and therefore, an effective alternative is needed. This study investigated allyl isothiocyanate (ITC) as a methyl bromide alternative for purple nutsedge control under polyethylene-mulch. Greenhouse experiments were conducted to compare the retention of allyl ITC in treated soil (3,000 nmol g−1) under low-density polyethylene (LDPE) and virtually impermeable film (VIF) mulches. Field experiments were conducted to evaluate the effectiveness of allyl ITC (6 rates: 0, 15, 75, 150, 750, 1500 kg ai ha−1) under VIF mulch against purple nutsedge. Additionally, a standard treatment of methyl bromide+chloropicrin (67 : 33%) at 390 kg ai ha−1under LDPE mulch was included for comparison. In the greenhouse experiment, the predicted half-life of allyl ITC under LDPE and VIF mulch was 0.15 and 0.59 d, respectively. In the field experiment, it was predicted that allyl ITC at 1,240 and 1,097 kg ha−1under VIF mulch is required to control purple nutsedge shoot and tubers equivalent to methyl bromide + chloropicrin at 4 wk after treatment (WAT). It is concluded that allyl ITC under VIF mulch would need to be applied at 2.8 to 3.2 times the standard treatment of methyl bromide + chloropicrin under LDPE mulch for commercially acceptable purple nutsedge control.


Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 952-960 ◽  
Author(s):  
J. N. Pinkerton ◽  
K. L. Ivors ◽  
M. L. Miller ◽  
L. W. Moore

Field experiments were conducted in silty-clay loam in Corvallis, OR during the summers of 1995 and 1996 to study the effects of green manure cover crops (Sudan grass, rape, and barley), soil solarization, soil fumigation, and combinations of those treatments on population densities of soil pathogens Verticillium dahliae, Phytophthora cinnamomi, Pratylenchus penetrans, and Agrobacterium rhizogenes. Nylon mesh bags containing soil infested with V. dahliae and Phytophthora cinnamomiwere buried 5, 10, 20, and 30 cm deep. Soil solarization was performed over a 54- to 59-day period using a 0.6-mil clear polyethylene film. Maximum soil temperatures recorded at depths of 5, 10, 20, and 30 cm were 53, 48, 39, and 34°C in solarized soil, respectively; these temperatures were 8 to 16°C higher than in corresponding nonsolarized plots. Soil samples were collected before, during, and after solarization to quantify pathogen populations at those four depths. Pot or field studies were conducted subsequent to treatments to determine the effects of treatments on susceptible plants. Soil solarization, cover crops plus solarization, or fumigation with metam sodium resulted in a significant decrease (P< 0.05) in density of P. cinnamomi populations at all four depths and reduced (P< 0.05) V. dahliae at 5 and 10 cm. In greenhouse assays of solarized soils, disease severity was reduced (P< 0.05) for Verticillium spp. on eggplant and Phytophthora spp. on snapdragons. Cover crops alone were not effective in reducing P. cinnamomi and V. dahliae populations. Agrobacterium spp. population densities declined within solarized plots and incidence of crown gall on ‘Mazzard’ cherry rootstock planted in solarized plots was reduced significantly. Population densities of Pratylenchus penetranswere reduced in the upper 30-cm soil profile by solarization.Solarization for an 8-week period during the warmest months of summer could provide an additional management alternative for several important soilborne pathogens in western Oregon.


Plant Disease ◽  
2007 ◽  
Vol 91 (2) ◽  
pp. 142-146 ◽  
Author(s):  
M. Porras ◽  
C. Barrau ◽  
F. T. Arroyo ◽  
B. Santos ◽  
C. Blanco ◽  
...  

Field experiments were conducted in southwest Spain for three consecutive years from 2000 to 2003 to evaluate the effectiveness of solarization and Trichoderma spp., alone and combined, in reducing Phytophthora cactorum soil populations and consequently leather rot on fruit of strawberry plants. Plots (12.5 by 3.3 m), never treated with methyl bromide, were naturally infested by P. cactorum. Solarization was conducted during the summer, using clear 50-µm low-density polyethylene mulch. Trichoderma spp. were applied via drip and dip, adding to the soil 7 days before planting (108 conidia/m2), and strawberry roots were dipped in a suspension of Trichoderma spp. (106 conidia/ml) prior to planting. Solarization reduced the soil P. cactorum population 100% in year 1, 47% in year 2, and 55% in year 3 relative to the untreated control. Trichoderma spp. applications reduced soil populations of P. cactorum and reduced leather rot incidence 76.6% in year 1 and 33.8% in year 2 compared with the untreated control. The combination of solarization and Trichoderma spp. reduced P. cactorum soil population the most each year, 88.9% in January 2001, 97.6% in 2002, and 99.0% in 2003. The very promising effect of Trichoderma spp. and solarization against P. cactorum indicates that there may be future alternatives to traditional chemicals for disease control.


2008 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Mrittunjai Srivastava ◽  
Lara Bosco ◽  
Joe Funderburk ◽  
Anthony Weiss

Feeding by the western flower thrips, Frankliniella occidentalis, causes damage to the fruits of pepper, and the species is the key vector of Tomato spotted wilt virus. Effective management integrates conservation of populations of the natural predator, Orius insidiosus, with the use of reduced-risk insecticides, namely spinosad. We conducted field experiments in northern Florida in 2005 and 2006 and in central Florida in 2006 to evaluate the new reduced-risk insecticide spinetoram for control of thrips and to determine the impact on natural populations of O. insidiosus. Spinetoram at 61 g ai/ha was as effective as spinosad at 140 g ai/ha against the western flower thrips and the other common thrips in Florida, Frankliniella tritici and Frankliniella bispinosa. The mean numbers of the predator were very high in all treatments in each experiment, and their numbers relative to the numbers of thrips indicated that predation was sufficient to suppress thrips populations in all treatments. Broad-spectrum insecticides when included in the experiments provided little or no control; sometimes, they flared thrips numbers compared to untreated pepper. Accepted for publication 25 October 2007. Published 18 January 2008.


1996 ◽  
Vol 21 (1) ◽  
pp. 186-187 ◽  
Author(s):  
David J. Schuster

Abstract Transplants were set 10 Mar, 18 inches apart on 8-inch-high beds of EauGallie fine sand covered with white polyethylene mulch. Each plot consisted of a single 15 ft row with rows on 5 ft centers. Treatments were replicated 4 times in a RCB design and were applied with a 2.5 gal, hand-held CO2-powered sprayer on 3, 10, 17, 24 Apr, 1, 8, 15, 22, 31 May, 6 and 12 June. The sprayer was operated at 60 psi and delivered 60 gpa for the first two applications, 90 gpa the next two applications, and 120 gpa for the remaining applications using a single nozzle fitted with a D-5 disk and #25 core. On 10 May and 19 June, the numbers of tomato pinworm leaf rolls were counted by two persons in a 2 min. whole plot search. On 10 May, the numbers of Liriomyza spp. leafmines were counted by two trained observers in a 1 minute whole plot search. Pinworm and leafminer damage counts of both persons were totalled. Fruit were harvested on 10 May, 1, and 15 June. The number and weight of undamaged fruit and the number and weight of fruit damaged by armyworm larvae and flower thrips (fruit with five or more oviposition dimples on the blossom end) were determined.


Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 481-488 ◽  
Author(s):  
F. J. Louws ◽  
M. Wilson ◽  
H. L. Campbell ◽  
D. A. Cuppels ◽  
J. B. Jones ◽  
...  

Acibenzolar-S-methyl (CGA 245704 or Actigard 50WG) is a plant activator that induces systemic acquired resistance (SAR) in many different crops to a number of pathogens. Acibenzolar-S-methyl was evaluated for management of bacterial spot (Xanthomonas axonopodis pv. vesicatoria) and bacterial speck (Pseudomonas syringae pv. tomato) of tomato in 15 and 7 field experiments, respectively. Experiments were conducted over a 4-year period in Florida, Alabama, North Carolina, Ohio, and Ontario using local production systems. Applied at 35 g a.i. ha-1, acibenzolar-S-methyl reduced foliar disease severity in 14 of the 15 bacterial spot and all 7 bacterial speck experiments. Disease control was similar or superior to that obtained using a standard copper bactericide program. Acibenzolar-S-methyl also reduced bacterial fruit spot and speck incidence. Tomato yield was not affected by using the plant activator in the field when complemented with fungicides to manage foliar fungal diseases, but tomato transplant dry weight was negatively impacted. X. axonopodis pv. vesicatoria population densities on greenhouse-grown tomato transplants were reduced by acibenzolar-S-methyl treatment. Bacterial speck and spot population densities on leaves of field-grown plants were not dramatically affected. Acibenzolar-S-methyl can be integrated as a viable alternative to copper-based bactericides for field management of bacterial spot and speck, particularly where copper-resistant populations predominate.


1936 ◽  
Vol 14c (12) ◽  
pp. 438-444 ◽  
Author(s):  
J. E. Machacek ◽  
F. J. Greaney

The results of field experiments made in 1932, 1933, and 1934, to determine the effect of mechanical seed injury on the incidence of root rot caused by Fusarium culmorum and on yield in wheat are presented.Successful positive attacks of Fusarium root rot were experimentally induced in field plots. The tests showed that reduced emergence, increased root rot, and reduced yield uniformly followed the planting of injured wheat seed; and that the amount of disease increased and the yield decreased with an increase in the degree of seed injury. In these experiments Mindum and Marquis wheat seemed equally affected by seed injury.The investigation suggests that the large annual losses in yield caused by root-rot diseases of cereals in Western Canada may be substantially reduced by sowing clean, vigorous, sound seed.


1997 ◽  
Vol 87 (3) ◽  
pp. 250-258 ◽  
Author(s):  
D. O. Chellemi ◽  
S. M. Olson ◽  
D. J. Mitchell ◽  
I. Secker ◽  
R. McSorley

Soil solarization was shown to be cost effective, compatible with other pest management tactics, readily integrated into standard production systems, and a valid alternative to preplant fumigation with methyl bromide under the tested conditions. Solarization using clear, photoselective, or gas-impermeable plastic was evaluated in combination with metham sodium, 1,3-dichloropropene + chloropicrin, methyl bromide + chloropicrin, pebulate, or cabbage residue. Strip solarization, applied to 20-cm-high, 0.9-m-wide beds, was conducted to achieve compatibility with standard production practices and resulted in soil temperatures 2 to 4°C above those temperatures resulting when using conventional flatbed solarization. Soil temperatures were 1 to 2°C higher at the edges of the raised beds, eliminating any border effects associated with solarization. Following a 40- to 55-day solarization period, the plastic was painted white and used as a production mulch for a subsequent tomato crop. The incidence of Southern blight and the density of Paratrichodorus minor and Criconemella spp. were lower (P < 0.05) in solarized plots. No differences (P < 0.05) in the incidence of Fusarium wilt and the density of nutsedge and Helicotylenchus spp. were observed between plots receiving solarization and plots fumigated with a mixture of methyl bromide + chloropicrin. The severity of root galling was lower (P < 0.05) when soil solarization was combined with 1,3-dichloropropene + chloropicrin (16.2 + 3.4 g/m2) and a gas-impermeable film. The incidence of bacterial wilt was not affected by soil treatments. Marketable yields in plots using various combinations of soil solarization and other tactics were similar (P < 0.05) to yields obtained in plots fumigated with methyl bromide + chloropicrin. The results were validated in several large scale field experiments conducted by commercial growers.


Weed Science ◽  
2005 ◽  
Vol 53 (5) ◽  
pp. 683-689 ◽  
Author(s):  
Leopoldo E. Estorninos ◽  
David R. Gealy ◽  
Edward E. Gbur ◽  
Ronald E. Talbert ◽  
Marilyn R. McClelland

Red rice, which grows taller and produces more tillers than domestic rice and shatters most of its seeds early, is a major weed in many rice-growing areas of the world. Field experiments were conducted at Stuttgart, AR in 1997 and 1998 to evaluate the growth response of the Kaybonnet (KBNT) rice cultivar to various population densities of three red rice ecotypes. The ecotypes tested were Louisiana3 (LA3), Stuttgart strawhull (Stgstraw), and Katy red rice (KatyRR). Compared with KBNT alone, LA3, the tallest of the three red rice ecotypes, reduced tiller density of KBNT 51%, aboveground biomass at 91 d after emergence (DAE) 35%, and yield 80%. Stgstraw, a medium-height red rice, reduced KBNT tiller density 49%, aboveground biomass 26%, and yield 61%. KatyRR, the shortest red rice, reduced KBNT tiller density 30%, aboveground biomass 16%, and yield 21%. Tiller density of rice was reduced by 20 to 48% when red rice density increased from 25 to 51 plants m−2. Rice biomass at 91 DAE was reduced by 9 and 44% when red rice densities were 16 and 51 plants m−2. Rice yield was reduced by 60 and 70% at red rice densities of 25 and 51 plants m−2, respectively. These results demonstrate that low populations of red rice can greatly reduce rice growth and yield and that short-statured red rice types may affect rice growth less than taller ecotypes.


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