JMS Stylet Oil Research Articles

Post-Application Field Persistence and Efficacy of Cordyceps javanica against Bemisia tabaci.

Previously, Cordyceps javanica Wf GA17, a causing agent of whitefly epizootics in southern Georgia, demonstrated superior temperature tolerance and higher virulence against the whitefly Bemisia tabaci than commercial strains in the laboratory. The post-application persistence and efficacy of this fungus against B. tabaci were compared with that of the commercially available C. javanica Apopka97 strain over a two-year field study in cotton and vegetable crops. When blastospores of both strains were applied alone, whitefly populations were not effectively suppressed. Thus, JMS stylet oil was added to fungal treatments for enhancing efficacy and persistence. For 0-day samples, all fungal treatments caused similar but significant levels of immature mortality regardless of fungal strain, propagule form (conidia vs. blastospores), and application method (alone or mixed with JMS). In follow-up samplings, Wf GA17 blastospores + JMS achieved higher control levels than other treatments in some trials, but the efficacy did not last long. The JMS oil alone caused significant mortality and suppressed whiteflies. Over 90% of spores lost viability 24 h after treatment in all fungal treatments. Across evaluation times, there was no difference between the two fungal strains (conidia or blastospores, alone or combined with JMS), but conidia persisted better than blastospores for both strains. Overall, the field persistence and efficacy of C. javanica did not last long; therefore, improved delivery methods and formulations are needed for enhancement.

On-farm trials towards reduced insecticides in main crop potatoes in the Waikato Region of New Zealand

Tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is the vector for “Candidatus Liberibacter solanacearum” (CLso), which causes the serious disease “zebra chip” (ZC) of potatoes. Between 2016 and 2019, a reduced-insecticide approach to control TPP was evaluated. We compared a standard-insecticide weekly spray regime that included Integrated Pest Management (IPM)-compatible insecticides plus JMS Stylet Oil® (JMS) as a wetting agent, with a reduced-insecticide regime where we used the oil on its own on alternate weeks with the insecticide/oil mixtures. Spray programme start dates were determined by: (1) crop scouting; (2) sticky-trap monitoring; and (3) degree-day calculation. Crop scouting combined with a sticky-trap action threshold and degree-day data was an effective method for determining when to start spraying. The most substantial reduction in insecticides was achieved by alternating weekly insecticides with the oil formulation on its own. Sub-samples of TPP from sticky traps situated in the trials tested for CLso confirmed the presence of the bacteria in (commonly known as ‘hot’) TPP throughout the trials. The reduced-treatment approach gave statistically similar levels of ZC to the standard insecticide spray programme.

Powdery mildew epidemics in the nursery: role of chasmothecia in epidemic initiation and fungicide regimes to limit chasmothecia formation

Powdery mildew caused by Podosphaera cerasi is a detrimental fungal disease for the sweet cherry industry. Epidemics in orchards are initialized by ascospores that are released from chasmothecia generated in the fall of the previous year, however, the initiation of epidemics in nurseries has not been explored. The current study aimed to evaluate the origin of disease epidemics in Washington State cherry tree nurseries and to evaluate the efficacy of different fungicide regimes to suppress chasmothecia numbers and ascospore viability. Greenhouse and lab assays in the present study showed that chasmothecia from the nursery are not contributing to powdery mildew epidemics and the disease is originating from an external source such as wind-blown conidia from neighboring orchards. Additionally, intensive synthetic fungicide regimes and late-season JMS Stylet-Oil applications were found to be viable options to inhibit chasmothecia formation. As chasmothecia with a nursery origin are not the initial inoculum, late season fungicide applications to limit chasmothcia formation should only be applied in an orchard setting. Orchard managers can limit epidemics by implementing late-season fungicide applications into their IPM plan that target chasmothecia. Future research should evaluate the dispersal of conidia throughout the cherry tree growing industry of Washington and their role in powdery mildew epidemics in nurseries. Moreover, the physiological and genetic differences between chasmothecia in the nursery and the orchard should be evaluated.

Apple Disease Control and Bloom-Thinning Effects by Lime Sulfur, Regalia, and JMS Stylet-Oil

Apple (Malus × domestica Borkh.) growers require management practices that will produce high-quality fruit while minimizing the number of chemicals used for adequate disease control and horticultural practices. Certain chemicals applied for bloom thinning also have fungicidal properties and could provide protection against early season diseases in addition to crop reduction. Over 5 years, treatments of lime sulfur (LS), Regalia (an organically approved biofungicide), and JMS Stylet-Oil (JSO) were evaluated for protection against apple scab (Venturia inaequalis [Cooke.] G. Wint.), powdery mildew (Podosphaera leucotricha [Ellis & Everh.] E. S. Salmon), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein.), and quince rust (Gymnosporangium clavipes [Cooke & Peck] Cooke & Peck in Peck), as well as crop load reduction and fruit finish. Both LS and Regalia reduced apple scab and cedar apple rust in four out of five test years. Treatments of Regalia applied with JSO provided disease protection and crop load reduction similar to LS applied with JSO. We provide evidence that LS and Regalia, applied as bloom thinners, can reduce chemical applications used during bloom by combining two chemical spray functions: one for disease protection and one for crop load management.

Interruption and Reduction of Erysiphe necator Chasmothecia Development Utilizing Fungicidal Oil

Grape powdery mildew epidemics, caused by Erysiphe necator, are initiated by the release and subsequent germination of ascospores from mature chasmothecia. Interrupting the development of chasmothecia prior to overwintering may reduce or prevent the overwintering of E. necator in vineyards, thereby reducing initial disease incidence observed the following growing season. At the end of the grape growing season in 2014 and 2015, one application of Organic JMS Stylet Oil (Vero Beach, FL) at a rate of 10 ml/liter was applied on four treatment dates using an air-assisted backpack sprayer onto Chardonnay grapevines within a vineyard. Leaves were collected weekly and chasmothecia enumerated from the first observation of chasmothecia primordia development until the onset of rains (approximately 5 weeks). In 2014, all stylet oil treatment plots developed significantly fewer chasmothecia than nontreated control plots in 2014 (P = 0.04), and there were no differences in treatment date observed. No treatment differences were observed in 2015. Because chasmothecia were still produced despite stylet oil treatment, a single post-véraison stylet oil application to interrupt chasmothecia development would not be an economical management option for reduction of grape powdery mildew.

Mineral oil foliar applications in combination with insecticides affect tomato potato psyllid (Bactericera cockerelli) and beneficial insects in potato crops

ABSTRACTTomato potato psyllid (TPP), Bactericera cockerelli (Sülc) (Hemiptera: Triozidae), is a vector for Candidatus Liberibacter solanacearum (Lso), a phloem-limited bacterium that causes severe production problems within the New Zealand potato industry. Field trials were conducted over three consecutive growing seasons between 2013 and 2016 at Pukekohe, New Zealand to determine the efficacy of an isoparaffinic petroleum distilled oil (JMS Stylet Oil®), applied as a foliar treatment within an insecticide programme, to control TPP. The effects of treatments on potato yield, tuber dry matter content and the incidence of zebra chip (ZC) in fried potato crisps were also assessed. This research demonstrated that JMS Stylet Oil, when used in combination with insecticides, achieved fewer insecticide applications, leading to reduced numbers of TPP nymphs and eggs on potato foliage, and lower incidence of ZC in deep-fried tuber crisps than weekly insecticide sprays, without adversely affecting plant growth and crop yields.

Managing Apple Crop Load and Diseases with Bloom Thinning Applications in an Organically Managed ‘Honeycrisp’/‘MM.111’ Orchard

Although demand for organic produce continues to increase in the mid-Atlantic, few apple (Malus ×domestica Borkh.) growers in the region have adopted organic management practices due to the considerable disease, insect, and weed pressure, as well as the lack of effective crop load management tools. In this study, lime sulfur (LS) and Regalia® (R) were applied in different sequences (i.e., LS/LS, LS/R, R/R, and R/LS), each in a mixture with JMS Stylet-Oil, to chemically thin apple flowers in an organically managed ‘Honeycrisp’/‘MM.111’ orchard. There was also a nontreated control, a “grower standard” control (LS at 11 mm fruitlet diameter), and a hand-thinned control. The treatments were evaluated for their ability to reduce crop load, as well as to control powdery mildew [Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon], cedar apple rust (Gymnosporangium juniperi-virginiana Schwein.), and quince rust (Gymnosporangium clavipes Cooke & Peck). All treatments reduced crop load compared with the nontreated control, and after the first application of LS or R, the number of fertilized king blooms was reduced and fertilization was prevented in all side blooms. All bloom thinning treatments had more fruit peel russet than the control and russet was more severe when LS was one of the applications. Bloom thinning applications of LS and R did not reduce powdery mildew leaf infection compared with the nontreated control. Cedar apple rust incidence was reduced by all bloom thinning treatments, though some lesions were detected in all treatments. There were minimal quince rust infections in any of the treatments, including the nontreated control. These results suggest that when LS and/or Regalia® are mixed with JMS Stylet-Oil and applied as bloom thinners, they can reduce crop load, and, as a secondary benefit, they can also decrease cedar apple rust incidence from infections that occur during bloom.

Effects of Carriers, Emulsifiers, and Biopesticides for Direct Silk Treatments on Caterpillar Feeding Damage and Ear Development in Sweet Corn.

In the northeastern United States, control of Lepidopteran pests of sweet corn, particularly corn earworm [Helicoverpa zea (Boddie)], is difficult using organic methods. The direct application of corn oil and Bacillus thuringiensis (Bt) to corn silk has been shown to reduce ear damage from corn earworm in past studies; these studies sought to optimize this method by evaluating additional carrier and biopesticide mixtures that comply with the United States Federal Insecticide, Fungicide, and Rodenticide Act and National Organic Standards. Carriers, which are liquids used to dissolve the biopesticide and deliver it into the tip of the ear, may have phytotoxic or insecticidal properties. Experiments conducted from 2001 to 2005 evaluated caterpillar damage and ear development effects from carriers (vegetable and paraffinic oils and carrageenan), biopesticides (Bt, spinsosad, and neem), and three emulsifiers in various combinations when applied directly to the tips of the ears 5-7 d after silk initiation. There were no effects of emulsifiers on ear quality, except for slight reduction in caterpillar damage in one of the two years. There were no differences among corn, soy, canola, and safflower oils in corn earworm control or tip development. The carrageenan carrier had the least effect upon ear development as measured by the length of nonpollinated kernels at the tip, compared to corn oil or paraffinic oil (JMS Stylet Oil), which caused the greatest tip damage as well as an oily discoloration. The carrier-pesticide combinations with the best ear quality overall were spinosad in carrageenan or corn oil, and Bt in carrageenan.

Polyoxin D and Other Biopesticides Reduce Gummy Stem Blight But Not Anthracnose on Melon Seedlings

Biopesticides may be useful to prevent fungal foliar diseases on cucurbit seedlings in greenhouses because of the short re-entry intervals, normally 4 h. Bacillus subtilis QST 713 (Serenade ASO), root extract of Reynoutria sachalinensis (Regalia), hydrogen dioxide (Oxidate), paraffinic oil (JMS Stylet Oil), polyoxin D (Oso), and 92% edible fish oil + 5% sesame oil (Organocide) were evaluated against gummy stem blight on muskmelon seedlings and anthracnose on watermelon seedlings. Polyoxin D applied alone, B. subtilis QST 713 followed by polyoxin D, and R. sachalinensis extract followed by B. subtilis QST 713 reduced the severity of gummy stem blight and were as effective as mancozeb. None of the biopesticides applied alone or sequentially were effective against anthracnose. Polyoxin D could be used to prevent outbreaks of gummy stem blight on watermelon and muskmelon seedlings grown for use as transplants. Accepted for publication 1 July 2016. Published 4 August 2016.

Aspects of the epidemiology and control of powdery mildew (Oidium neolycopersici) on tomato in Ontario, Canada

The epidemiology and control of powdery mildew (Oidium neolycopersici) of tomato (Solanum lycopersicum L.) was studied in greenhouse, growth chamber, and field experiments at Harrow, Ontario. Greenhouse environmental conditions were more favourable for disease development, with higher disease progress rates than in the field. Symptoms were more severe on older, lower leaves where the air temperature was slightly lower and relative humidity higher than on young leaves at the top of the canopy. A temperature of 22°C with 16 or 24 h of leaf wetness was optimal for disease development in a growth chamber experiment. Early inoculation resulted in significantly greater final disease severity and area under the disease progress curve than later inoculations. Disease progress in greenhouse and growth chamber trials was best described by the Gompertz model, while the logistic model was best for disease progress in field studies and for sections of plants in greenhouse studies. No yield loss occurred in field studies. The best disease control was obtained with acibenzolar-S-methyl (Actigard®), trifloxystrobin (Flint®), JMS-Stylet Oil®, azoxystrobin (Quadris®) and sulphur applied as protectants. Some phytotoxicity occurred with Actigard in greenhouse studies. Serenade® (Bacillus subtilis) was less effective while Kaligreen, Sporodex® (Pseudozyma flocculosa), copper octanoate and fumed silica were ineffective. Quinoxyfen was phytotoxic at the rate applied. Several tobacco cultivars, jimsonweed, American and black nightshade were susceptible to infection by O. neolycopersici. Eggplant, hairy nightshade and bittersweet were less susceptible, while no visible symptoms developed on pepper, potato and tomato ‘Grace’, and only trace levels of sporulation occurred on cucumber.

MANAGEMENT OF POWDERY MILDEW IN GREENHOUSE TOMATO PRODUCTION WITH BIORATIONAL PRODUCTS AND FUNGICIDES

Powdery mildew (Oidium sp.) is an important disease of greenhouse-produced tomatoes. The severity of the disease, the widespread distribution of the pathogen, and its ability to develop insensitivity to fungicides with a narrow mode of action requires the identification of viable alternatives to conventional fungicides. Various products are available or in development that have the potential to contribute to the management of powdery mildew of tomato. Biorational products and fungicides including Cease and Serenade ASO (Bacillus subtilis QST 713 strain), Actinovate (Streptomyces lydicus), JMS stylet oil (paraffinic oil), Kocide 3000 (copper hydroxide), Microthiol Disperss (sulfur), Milstop (potassium bicarbonate), OxiDate (hydrogen dioxide), Rally 40WSP (myclobutanil), Regalia (extract of Reynoutria sachalinensis), Nufarm-Cuproxat concentrate (copper sulfate), cedar oil, citronella, clove oil, cottonseed oil, lemongrass, Ortho-Eco sense 3-in-1 Rose and Flower Care (sulfur and pyrethrin), Ortho-Eco sense Garden Disease Control (copper octanoate), whole milk, Prestop (Gliocladium catenulatum J1446), and Quintec (quinoxyfen) were tested. The experiments were done twice, each with four replicates per treatment. The severity of powdery mildew on foliage and phytotoxicity were evaluated using a scale of 0-100% foliage affected. In both experiments the severity of powdery mildew was moderate (~20% foliage affected). Cottonseed oil, Rally 40WSP, whole milk and Microthiol Disperss provided >87% control of powdery mildew compared to the non-treated control in both experiments, with little or no phytotoxicity. Cedar oil, lemongrass, Regalia, citronella, both Ortho-Eco sense products, clove oil, Milstop, JMS stylet oil, and Quintec reduced the severity of powdery mildew at least 39% in the first experiment and 62% in the second experiment. Many of the products were slightly phytotoxic on tomato foliage, but JMS stylet oil, cedar oil and citronella damaged foliage significantly compared to the non-treated control in both experiments.

Management of powdery mildew (Podosphaera xanthii) on greenhouse cucumber in Ontario

Cucumber powdery mildew (Podosphaera xanthii) causes significant annual yield and quality losses in greenhouse production in Canada. Management of the disease was evaluated in various research trials conducted at Harrow, ON from 1999–2007 and at two commercial greenhouse operations in Leamington, ON in 2005–2006. Products evaluated included biological control agents, new classes of fungicides, and materials derived from natural products as well as several traditional fungicides with multi-site modes of action. Best control in the research greenhouse was obtained with applications of Nova, Quintec, strobilurin derivatives (Quadris, Flint, Sovran), Procure, Pristine, JMS Stylet-Oil®, V-10118, Prev-AM, copper soap, Actigard and sulphur. Disease control was also obtained with Milstop, two fermented milk by-products (Lactosan, Yo-K-San) + surfactant formulations (Agral 90), and Agral 90 only. Applications of K2HPO4 + Agral 90, CaCl2 + Agral 90, and Siliforce were significantly better than the water check while fumed silica was not effective. Among biological control products, Sporodex (Pseudozyma flocculosa) was effective in control of P. xanthii while Serenade (Bacillus subtilis) was not. Actinovate (Streptomyces lydicus) provided control also. Under commercial greenhouse conditions, Milstop, and Lactosan + Agral 90 when applied weekly suppressed powdery mildew development at least equal to that of Nova. Resistance in P. xanthii to high rates of Nova and Pristine was detected in 3 of 17 and 2 of 8 commercial greenhouse cucumber operations, respectively, near Leamington. None of the locations had resistance to both fungicides at commercial rates of application, although one site showed consistently greater resistance of P. xanthii to both fungicides.

Powdery mildew (Leveillula taurica) on greenhouse and field peppers in Ontario – host range, cultivar response and disease management strategies

Leveillula taurica was observed on field pepper at various sites in south-western Ontario in 2005–2007. The field isolates collected from these sites were similar to a greenhouse isolate based on morphological observations. Host range of greenhouse and field isolates was similar, with minor sporulation on potato, carrot and several weeds. The greenhouse pepper cultivar ‘Samanta’ was the most susceptible to L. taurica while ‘Triple 4’, ‘Duplo’ and ‘Bosanova’ were the least susceptible to infection. Best control of pepper powdery mildew in the greenhouse was obtained with applications of myclobutanil, triflumizole, pyraclostrobin + boscalid, quinoxyfen, strobilurin derivatives (azoxystrobin, trifloxystrobin, kresoxim-methyl), copper soap, JMS Stylet-Oil®, Valent-10118, acibenzolar-S-methyl and sulphur. Disease reduction was also obtained with applications of potassium bicarbonate, citrus oil + borax, Bacillus subtilis and a fermented milk byproduct + surfactant. K2HPO4 + surfactant was effective in reducing disease whereas CaCl2 + surfactant, fumed silica and Sporothrix flocculosa were not effective. In field plots, best disease control was achieved with applications of myclobutanil and the fermented milk byproduct + surfactant in 2006 whereas in 2007, citrus oil + borax and potassium bicarbonate were most effective. There were no significant differences in pepper yield among the treatments in field plots. In vitro survival studies showed that the fungus was able to survive in infected pepper leaves after exposure to temperatures of −10 °C for 2 months.

Spray treatments combined with climate modification for the management of Leveillula taurica in sweet pepper

The effects of several spray and climate treatments on Leveillula taurica were tested under controlled and commercial greenhouse conditions either alone or combined with a climate treatment. Ampelomyces quisqualis AQ10 inhibited the germination of conidia on leaves, but not on glass. Trichoderma harzianum T39 inhibited germination on both surfaces. Neither the examined biological control agents (BCAs) nor the two tested mineral oils (AddQ and JMS Stylet-Oil) affected the viability of conidia. Sulphur drastically limited the germination and viability of L. taurica. In experiments at 15–25°C, AQ10 alone reduced hyphal leaf colonisation at 25°C. T. harzianum T39 significantly reduced leaf colonisation at all temperatures but significantly reduced disease only at 20–25°C. The oils significantly reduced leaf colonisation and sulphur reduced both leaf colonisation and disease at all temperatures. Results were confirmed in an experimental greenhouse. In a field experiment, azoxystrobin, polyoxin AL, neem extract, and T39 were effective; sulphur was superior to them. Under severe epidemic conditions the disease had a negative impact on yield; late fungicide treatments at spring-time were found unnecessary. Chemical sprays applied in alternation was compared with the ‘friendly’ spray regime (alternation of Heliosoufre, T. harzianum T39 + JMS Stylet oil, A. quisqualis AQ10+AddQ oil and Neemgard) in two climates i.e. (i.) day warm climate and (ii.) regular (cool) day climate regimes. In the warm climate, there was no significant difference in the performance of the ‘friendly’ spray regime and the chemical spray regime. However, in the cooler climate, the ‘friendly’ spray programme was not as effective as the chemical spray programme. It was concluded that a change in the greenhouse climate may affect the development of powdery mildew and, at the same time, promote the activity of BCAs and render a pathogen more vulnerable to these control agents, allowing for better disease suppression.

Evaluation of a Disease Warning System for Phomopsis Cane and Leaf Spot of Grape: A Field Study.

A field evaluation of a warning system for Phomopsis cane and leaf spot of grape (Vitis spp.), caused by Phomopsis viticola, was conducted in Ohio over 3 years (2002 to 2004) by applying fungicides and fungicide-adjuvant combinations based on predicted infection events. Three different criteria for risk-light, moderate, and high-were evaluated with the warning system. The warning system is based on measured weather conditions (temperature and wetness duration following rain) and a model for risk of leaf and internode infection. Vines were sprayed with fungicides based on either the warning system or a calendar-based 7-day protectant program, from 2.5-cm shoot growth (Eichhorn-Lorenz [E-L] stage 7) to the end of the broom (E-L stage 27). Fungicides were tested with or without an adjuvant (JMS Stylet-Oil or Regulaid). In the controls, the mean percentage of leaves and internodes with infections ranged from 36 to 100%, the number of lesions per leaf ranged from 1 to 28, and percentage of internodes covered by lesions ranged from 1 to 12%. Both the calendar-based protectant treatment (based on use of mancozeb) and the warning system treatment based on spraying in response to light or moderate predicted infection events (especially with mancozeb + Regulaid) resulted in significantly less disease incidence and severity compared with the controls. The mean percent control (relative difference in disease between a treatment and the control) was higher for the protectant schedule (˜55% and ˜80% for incidence and severity, respectively, based on application of mancozeb) than for the warning system (˜36% and ˜60% for incidence and severity, respectively, based on application of mancozeb + Regulaid), but there were two to three times more fungicide applications with the protectant schedule than with the warning system.

Factors Affecting Reductions in Photosynthesis Caused by Applying Horticultural Oil to Grapevine Leaves

Phytotoxicity of horticultural oil, applied shortly before antifungal sulfur, was evaluated for 23 grape cultivars. Oil application significantly reduced accumulation of soluble solids in berries of 9 of 23 cultivars, but there was no relationship with visible foliar injury. Treatment of leaves of Vitis labrusca `Catawba' with 1.5% JMS Stylet-Oil reduced leaf net photosynthesis (Pn) by 50% to 60% and of Vitis vinifera `Chardonnay' by 20% to 30% 1 day after application. Pn was reduced only when the lower (abaxial) leaf surface was treated; treatment of only the adaxial leaf surface had little effect. The Pn depression in `Catawba' persisted 3 to 4 weeks, whereas reductions in `Chardonnay' persisted less than 2 weeks. The Pn-depressing effect of oil was not significantly ameliorated by real or simulated rainfall, and washing the lower leaf surfaces with water and detergent also had only limited effect. There was no significant difference in Pn depression from oil applications made in the middle of the day (stomata open) compared to application in the evening (stomata closed), or from oil applied at higher versus lower application pressure. The greater sensitivity of `Catawba' than `Chardonnay' to Pn depression by oil may be related to the amount of oil retained by the leaves; the pubescent lower leaf surfaces of `Catawba' retained more than twice as much spray emulsion as did the more glabrous leaves of `Chardonnay'. Visible injury was mild in both cultivars, with small water-soaked lesions developing more commonly on `Chardonnay' than on `Catawba' leaves. Spray oil retention data for additional cultivars suggested that differences in retention can explain a portion of the differences in horticultural oil phytotoxicity.

Control of Cucurbit Powdery Mildew with JMS Stylet-Oil.

Laboratory and greenhouse studies were conducted to determine the effect of JMS Stylet-Oil on cucurbit powdery mildew. In laboratory studies, JMS Stylet-Oil (1.5%) applied with a low-pressure sprayer (138 kPa) significantly reduced colony size, but did not eradicate pre-existing mildew colonies. Applying oil every 4 days was more effective than a single application. Oil did not significantly reduce spore viability, since spores taken from sprayed colonies readily formed new colonies. Although oil appeared to cause abnormalities of conidiophores and spores immediately after application, this effect was temporary. Tween 20 had an inhibitory effect on mildew growth and increased the effectiveness of oil when the two were applied together. Efficacy of oil was increased by using a high-pressure sprayer (1380 kPa). In the greenhouse experiment, JMS Stylet-Oil (0.75%) applied once to summer squash either 4 h before transfer of conidia to inoculation sites or 5 days after inoculation suppressed the size of the area infected by 48 to 60%. A single application of oil 5 days before inoculation was not effective. A 4-day spray program beginning 5 days after inoculation was effective. Compared with nontreated plants, oil-treated plants had fewer symptomatic leaves (71 vs. 34%, excluding leaf 1 and inoculated leaves) and fewer colonies (244 vs. 26) 20 days after inoculation.

Trichoderma harzianum T39 Preparation for Biocontrol of Plant Diseases-Control of Botrytis cinerea , Sclerotinia sclerotiorum and Cladosporium fulvum

Isolate T39 of Trichoderma harzianum (TRICHODEX) is a commercial biocontrol agent. It controls Botrytis cinerea (grey mould) in greenhouse crops and in vineyards, Sclerotinia sclerotiorum (white mould) in various greenhouse and field crops, Cladosporium fulvum (leaf mould) in tomato, and the powdery mildews Sphaerotheca fusca in cucurbits and Leveillula taurica in pepper. T. harzianum T39 was applied in vineyards and greenhouses as part of grey mould management programmes in alternation with chemical fungicides. In the present study, the effect of T39 on diseases of greenhouse crops was demonstrated. The biocontrol agent was applied in formulations containing two concentrations of the active ingredient, or in the presence of oil in cucumber and tomato greenhouses. Suppression of B. cinerea , C. fulvum and S. sclerotiorum was similar when T39 was applied at final active ingredient rates of 0.2 or 0.4 g l -1 , except for one sampling date in one experiment. The addition of JMS Stylet-Oil did not contribute to the control of the above mentioned diseases achieved by T39.

Evaluation of biocompatible products for managing cucurbit powdery mildew

The biocompatible products AQ10 (hyperparasitic fungus Ampelomyces quisqualis), JMS Stylet-Oil (medium viscosity mineral oil), M-Pede (potassium salts of fatty acids) and Kaligreen (82% potassium bicarbonate) suppressed powdery mildew ( Sphaerotheca fusca) on winter squash, muskmelon, and pumpkin and increased yield compared with nontreated plants under field conditions. Applications were started after disease detection. JMS Stylet-Oil most effectively controlled powdery mildew. However, these products did not provide the degree of full-season control or yield increase obtained with the conventional fungicide program of Bravo (chlorothalonil) plus Nova (myclobutanil). For example, in muskmelon on 17 August 1995, 7 days after the third application, powdery mildew severity on upper and lower (under) leaf surfaces was 66 and 80% for untreated, 3 and 13% for Bravo plus Nova, 43 and 44% for JMS Stylet-Oil, 38 and 65% for AQ10, and 53 and 65% for Kaligreen, respectively. Yield (ton/ha) was 22.8, 44.2, 36.4, 40.6, and 38.5, respectively. Sucrose content was 3.5%, 6.6%, 4.6%, 3.2%, and 4.0%, respectively.

The Efficacy of JMS Stylet-Oil on Grape Powdery Mildew and Botrytis Bunch Rot and Effects on Fermentation

The use of JMS Stylet-Oil as a control for powdery mildew and bunch rot of grapes was investigated under California vineyard conditions. Stylet-Oil at 2% (v/v) was compared in commercial vineyards with commonly used fungicides including fenarimol, myclobutanil, triflumizole, and sulfur for powdery mildew control, or iprodione for bunch rot control. Stylet-Oil gave control of powdery mildew comparable to the demethylation inhibitor fungicides. Botrytis bunch rot was significantly reduced with Stylet-Oil alone, and when Stylet-Oil was mixed with iprodione a further reduction in bunch rot occurred. Grape juice fermentation as measured by yeast growth and sugar consumption was not affected by Stylet-Oil concentrations that ranged from 0 to 3.6 mL/L.