Control of lettuce drop disease, caused by Sclerotinia sclerotiorum, with metham-sodium soil treatment and foliar application of benomyl

The effects of metham-sodium (MES) soil treatment, a varying number of benomyl foliar sprays (two, three and six) and combined treatments on control of lettuce drop disease were studied at two sites in Israel naturally infested with the pathogen Sclerotinia sclerotiorum. MES killed 85% of the S. sclerotiorum sclerotia in the top 10 cm of soil where initial populations were 0.6 and 1.6 viable sclerotia per kg soil at the two sites. Of the remaining viable sclerotia. only 30% produced apothecia. MES treatment alone reduced numbers of apothecia to 5% of those counted in the unsprayed control treatment. Numbers of ascospores deposited on the crop in the MES-treated plots were 7-20% of those deposited on control plots. Lettuce drop decreased the total yield by 30% in unsprayed control plots; MES application reduced the loss to 4% and also increased the number of marketable plants. Benomyl sprays alone also significantly reduced numbers of apothecia and disease development and consequently increased yield, although not to the extent observed with the MES treatment alone. Combined treatments produced the best disease control, but this improvement was not accompanied by any major increase in yield compared to that with MES treatment alone.     

Effect of inoculum type and timing of application of Coniothyrium minitans on Sclerotinia sclerotiorum: control of sclerotinia disease in glasshouse lettuce

The effects of Coniothyrium minitans inoculum quality and an 8-week interval between inoculum application and crop planting on sclerotinia ( Sclerotinia sclerotiorum ) disease in three successive lettuce crops were investigated in a glasshouse trial. Spore suspensions of three isolates of C. minitans (Conio, IVT1 and Contans) applied at 10⁸ CFU m⁻² and a standard Conio maizemeal–perlite application (06 L m⁻², 10¹¹ CFU m⁻²) were assessed for their ability to control S. sclerotiorum . Only the maizemeal–perlite inoculum (isolate Conio) consistently reduced sclerotinia disease. In the third lettuce crop only, isolates IVT1 and Contans formulated by Prophyta and isolate IVT as an oil–water formulation, all applied as spore suspensions, reduced disease at harvest compared with the untreated control. Recovery, viability and C. minitans infection of sclerotia buried during the 8-week period prior to each of the three lettuce crops, and of sclerotia formed on the crop, were tested. Only the maizemeal–perlite inoculum (isolate Conio) reduced the recovery of sclerotia buried in soil for weeks between inoculum application and crop planting, reducing their viability and increasing infection by C. minitans . Eight weeks was sufficient to enable C. minitans to infect sclerotia of S. sclerotiorum , and may account for disease control. After harvest of the second and third crops, maizemeal–perlite treatment (isolate Conio) reduced the number and viability of sclerotia recovered on the soil surface and increased infection by C. minitans compared with spore-suspension treatments. The effect of inoculum concentration and the influence of soil temperature (varying with time of year) on infection of sclerotia by C. minitans are discussed.     

Effect of foliar salicylic acid and methyl jasmonate applications on protection against pill-bugs in lettuce plants (Lactuca sativa)

The effects were examined of plant-response signaling compounds, salicylic acid (SA) and methyl jasmonate (MeJA), on resistance to pill-bugs (Armadillidium vulgare) attack in lettuce plants. Foliar SA and MeJA applications were made at weekly intervals from the emergence of the plant until one week before harvesting. SA and MeJA induced detectable levels of hydrogen peroxide (H₂O₂) at least during 5 days post-application in these plants throughout their cultivation. On the whole, SA and MeJA in the concentrations and application scheme evaluated in this research did not significantly influence the dry and fresh weight matter of plants, or the chlorophyll and nitrate contents. In addition, both signal elicitors significantly diminished lettuce mortality due to pill-bugs, which was positively correlated with phenolics and flavonoids contents. Our results suggest that SA and MeJA, especially in low concentrations, should be further evaluated in lettuce production and priming resistance.     

Estimation of secondary metabolites of indigenous medicinal plant extracts and their in vitro and in vivo efficacy against tomato early blight disease in Pakistan

Journal of Plant Diseases and Protection - Fifteen Pakistan’s indigenous medicinal plant extracts were investigated for various secondary metabolites and their potential against tomato early...     

Antifeedant activity of solvent extracts of neem seed kernel against Spodoptera litura F. and their persistency against sunlight through encapsulation

Abstract

Different solvent extracts of neem seed kernels were evaluated against Spodoptera litura F. on cauliflower, Brassica oleracea var. botrytis leaves. Based on this evaluation, aqueous extract was dissolved in ethanol, and methanol extract in ethanol, and dissolved parts were designated as fraction I and fraction II, respectively. The extracts having more antifeedant activity were encapsulated to achieve stability against the sunlight. Among the solvent extracts tested at 1.0% concentration, methanol extract provided maximum protection (100%) of the leaves followed by ethanol (98.39%) and aqueous (93.01%) extracts. Fraction I and fraction 11 were equally effective at 0.1 % concentration against S. litura larvae and checked more than 70% of leaf damage. However, such extracts were found to be unstable when exposed to sunlight. The pre‐gelatinized starch‐encapsulated products, viz. ρre‐gel I and pre‐gel II were quite stable and afforded more than 68.0% protection to the cauliflower leaves even after 6 days of exposure to sunlight.     

Impact of consumer-driven changes to crop production practices on lettuce drop caused by Sclerotinia sclerotiorum and S. minor

Increasing demands for value-added salad products have triggered revolutionary changes in the production practices of vegetable salad crops in recent years. One of the pivotal changes is the adaptation of 2-m-wide beds for increased vegetable biomass per unit area. The move away from the traditional 1-m-wide raised beds in cool-season vegetable production and the associated irrigation practices potentially can have a major influence on diseases affecting cool-season vegetables. To assess the potential impacts of this shift on lettuce drop caused by Sclerotinia minor and S. sclerotiorum, the two bed widths and different irrigation frequencies within each were compared in two separate field experiments over four lettuce crops in 2 years. Treatments included 1- and 2-m bed widths with twice-weekly, weekly and biweekly drip irrigation serving as subplot treatments that were begun immediately following thinning. Incidence of lettuce drop was evaluated weekly thereafter until maturity. For S. sclerotiorum, 36 half-liter soil samples were also collected once each season and assayed for the number of sclerotia, and apothecia were counted weekly in a 10-m(2) area for each plot. Regardless of the species, the effects of bed width and irrigation frequency were both significant. Twice-weekly irrigation and 2-m bed width resulted in higher lettuce drop incidence than other treatments. For S. sclerotiorum, twice-weekly irrigation and 2-m bed width also significantly increased the number of apothecia per unit area and the accumulation of soilborne sclerotia over multiple cropping seasons. Results demonstrated that the 2-m bed width combined with the practiced frequency of irrigations can result in higher lettuce drop caused by S. minor and increased incidence of airborne infection by S. sclerotiorum in the Salinas Valley where, historically, it has not been a serious threat. Increased incidence of S. sclerotiorum infection in commercial lettuce fields in the Salinas Valley between 2001 and 2006 validates these experimental results. These relatively new crop production practices can alter the balance of the two Sclerotinia spp. that has long existed in California.     

Antimicrobial activity of essential oils and their components against the three major pathogens of the cultivated button mushroom, Agaricus bisporus

Essential oils of Matricaria chamommilla, Mentha piperita, M. spicata, Lavandula angusti folia, Ocimum basilicum, Thymus vulgaris, Origanum vulgare, Salvia officinalis, Citrus limon and C. aurantium and their components; linalyl acetate, linalool, limonene, α-pinene, β-pinene, 1,8-cineole, camphor, carvacrol, thymol and menthol were assayed for inhibitory activity against the three major pathogens of the button mushroom, Agaricus bisporus, i.e. the fungi Verticillium fungicola and Trichoderma harzianum and the bacterium Pseudomonas tolaasii. The highest and broadest activity was shown by the Origanum vulgare oil. Carvacrol possessed the highest antifungal activity among the components tested.     

Activity of neem (Azadirachta indica A. Juss) seed kernel extracts against the mustard aphid,Lipaphis erysimi

An aqueous, an ethanolic and a hexane extract obtained from neem(Azadirachta indica A. Juss) seed kernels were tested for insecticidal activity against the mustard aphid,Lipaphis erysimi Kalt. The hexane extract, which exhibited a much higher activity than the two other extracts, had an LC50 of 0.674%. When the hexane extract was partitioned with ethanol, the ethanol-soluble fraction had an LC₅₀ of 0.328%, whereas the ethanol-insoluble part showed no activity even at 1%. Column chromatography of the ethanol-soluble fraction yielded eight compounds: nimbin, epinimbin, desacetylnimbin, salannin, desacetyl-salannin, azadirachtin and two unidentified compounds — a salannin derivative and a nonterpenoid. Of these, only five could be tested. Nimbin and epinimbin exhibited no toxicity at 0.3%, whereas salannin, a salannin derivative and the non-terpenoid gave LC₅₀ values of 0.055, 0.096 and 0.104%, respectively.     

Chemical analysis of three herbal extracts and observation of their activity against adults of Acanthoscelides obtectus and Leptinotarsa decemlineata using a video tracking system

Journal of Plant Diseases and Protection - Ethanol extracts of Rosmarinus officinalis, Lavandula angus-tifolia and Ruta graveolens were tested against adults of Acanthoscelides obtectus and...     

紫苏和薄荷提取物对茶炭疽病病菌(Gloeosporium theae sinesis)的抑制作用

采用95%乙醇浸提紫苏和薄荷获得其提取物,用菌丝生长速率法测定了提取物对茶炭疽病病菌菌丝的抑制作用,采用水琼脂培养法测定提取物对病菌分生孢子萌发的抑制效果,并在显微镜下观察菌丝生长和孢子萌发的状态。结果表明,2种植物提取物对茶病疽病病菌菌丝和分生孢子萌发均有较好的抑制作用。在40 mg/m L浓度下,2种植物提取物对茶病疽病病菌菌丝生长抑制率均在75%以上,紫苏提取物在48 h内抑制率达100%,对其病菌孢子萌发的抑制率最高可达84.28%。显微观察发现,各浓度下茶病疽病病菌菌丝生长和孢子萌发形态均有不同程度畸变,紫苏提取物浓度越高畸变越严重。     

Temporal and quantitative analyses of stem lesion development and foliar disease progression of peach rust in california

ABSTRACT The development of rust epidemics caused by Tranzschelia discolor on leaves and stems of cling peach was studied in California orchards. Sporulating stems lesions were only detected from late March until July in 1997 and 1998. When rust was present in the fall, the quadratic equation Y = -82.51 + 1.97JD - 0.01JD(2) using Julian day (JD) described the incidence of sporulating lesions on stems of cv. Andross (R(2) = 0.73; P /=117.3 mm of total precipitation and maximum temperatures of 相似文献   

Behaviour of alkyl oleates following foliar application in relation to their influence on the penetration of phenmedipham and quizalofop-P-ethyl

The foliar penetration of four alkyl oleates (methyl to butyl) and their influence on the penetration of phenmedipham and quizalofop-P-ethyl was studied in barley ( Hordeum vulgare L.), cleavers ( Galium aparine L.) and pea ( Pisum sativum L.). Loss of alkyl oleates from glass and plant surfaces was inversely related to the length of the alkyl chains and was assumed to be due to volatilization. All four alkyl oleates after application alone, readily penetrated into pea and barley leaves but much less into G. aparine . Penetration of methyl oleate appeared to be faster than that of butyl oleate. Both alkyl oleates were completely metabolized in barley and pea in 27 h, but not in G. aparine . The penetration of herbicides was from 2% to 10% in the absence of alkyl oleates. The penetration of phenmedipham was increased in the presence of all four aikyl oleates: to the greatest extent into pea (55-80% after 27 h), to the lowest into G. aparine (20-45%). In all three species, the effect of butyl oleate was higher than that of methyl oleate. The penetration of quizalofop-P-ethyl was increased to 10%, 30-35% and 50% on G. aparine , pea and barley respectively. The length of the alkyl chains did not influence the effects of the alkyl oleates on the foliar penetration of quizalofop-P-ethyl.     

In vitro and in vivo antimicrobial activity of propolis extracts against various plant pathogens

Journal of Plant Diseases and Protection - A mixture of the isolates of Fusarium graminearum, Alternaria brassicicola, Verticillium dahliae, and Pythium ultimum was examined to determine...     

The relation of mansonones to resistance against dutch elm disease and their accumulation,as induced by several agents

No evidence was found that mansonones E and F, which accumulated in elms after infection withCeratocystis ulmi, were responsible for resistance against Dutch elm disease inUlmus hollandica cl. 390. Furthermore, production of mansonones inU. americana was only about one-fifteenth of that inU. hollandica cl. Belgica. Yet both are susceptible to Dutch elm disease.Induction of these compounds was not specific, for accumulation occurred not only after introduction of crude toxin ofC. ulmi, but also after inoculation withVerticillium albo-atrum and after introduction of H₂SO₄ or ethanol.The dark discolouration of the wood after toxin treatment was restricted to the lower part of the stem. No mansonones could be detected in the non-discoloured higher parts of the stem or from the necrotic or wilted leaves.Samenvatting Er werd geen aanwijzing gevonden dat mansononen E en F, die na infectie metC. ulmi gevormd worden, verantwoordelijk zijn voor de resistentie tegen de iepziekte inU. hollandica cl. 390 (Tabel 1). U. americana bevat ongeveer 15 maal zo weinig van deze stoffen alsU. hollandica cl. Belgica, terwijl beide vatbaar zijn.De inductie van de synthese van deze stoffen bleek niet specifiek te zijn, omdat bij chemische beschadiging met H₂SO₄ of ethanol ook mansononen gevormd werden.De donkere verkleuring van het hout bleek na toxine toediening beperkt tot het onderste gedeelte van de stam. Geen mansononen werden gevonden in hoger gelegen, niet verkleurde stamgedeelten of in de necrotische en verwelkte bladeren.     

Activity against rust and powdery mildew of somepara phenylenediamines and related compounds

Twenty-fivepara phenylenediamines and related compounds were tested for activity against powdery mildew on cucumber and against rust on bean. Some remarkable changes in activity resulted from minor changes in the chemical structure of the compounds. It is suggested that the fungicidal activity of the phenylenediamines is correlated with the polarographic halfwave potentials. This might indicate that one of the oxidation products, probably the semiquinone ion, is responsible for activity.     

Activity of adjuvants in ‘aliette’ against Botryotinia fuckeliana (botrytis cinered) and their cross-resistance with benzimidazole fungicides

‘Aliette’, a formulation of the fungicide fosetyl-aluminium, is moderately active in vitro against the ascomycete Botryotinia fuckeliana (Botrytis cinerea). In contrast, fosetyl-aluminium and related chemicals, such as phosphonic acid and sodium phosphonate, have low efficacy, although it is enhanced by media with low phosphate content. This indicates that the effectiveness of ‘Aliette’ against B. fuckeliana is not due to fosetyl-aluminium but to adjuvants included in the formulation. The genetic basis of differences in sensitivity to ‘Aliette’ was investigated in field and laboratory isolates of B. fuckeliana. Genetic analysis showed that reduced sensitivity to ‘Aliette’ always co-segregated with resistance to benzimidazole fungicides in meiotic progeny of sexual crosses. This indicates that differences in sensitivity to ‘Aliette’ in B. fuckeliana are due to the major gene Mbcl of resistance to benzimidazole fungicides and active adjuvant(s) present in ‘Aliette’ are linked to benzimidazoles by cross-resistance.     

Comparison of root and foliar applications of potassium silicate in potentiating post‐infection defences of melon against powdery mildew

The application of silicon to the roots or leaves reduces the severity of powdery mildew (Podosphaera xanthii) in melon but the latter treatment is less effective. This study compared key biochemical defence responses of melon triggered by P. xanthii after root or foliar treatment with potassium silicate (PS). Treatments consisted of pathogen‐inoculated or mock‐inoculated plants supplied with PS via roots or foliarly, as well as a non‐treated control. The activity of defence enzymes and the concentration of phenolic compounds, lignin and malondialdehyde were determined from leaf samples at different time points after inoculation. Pathogen‐inoculated plants irrigated with PS showed both an accumulation of silicon and primed defence responses in leaves that were not observed in pathogen‐inoculated plants either sprayed with PS or not treated. These responses included the anticipated activity of peroxidase and accumulation of soluble phenols, the activation of chitinase and repression of catalase, and the stronger activation of superoxide dismutase, peroxidase and β‐1,3‐glucanase. Moreover, the lignin concentration increased in response to inoculation, whereas the malondialdehyde concentration decreased. For the foliar treatment, however, only an increase in lignin deposition was observed compared with the control plants. The results show that silicon strongly plays an active role in modulating the defence responses of melon against P. xanthii when supplied to the roots as opposed to the foliage.     

Biocontrol activity and primed systemic resistance by compost water extracts against anthracnoses of pepper and cucumber

We investigated direct and indirect effects of compost water extracts (CWEs) from Iljuk-3, Iljuk-7, Shinong-8, and Shinong-9 for the control of anthracnoses caused by Colletotrichum coccodes on pepper and C. orbiculare on cucumber. All tested CWEs significantly (P < 0.05) inhibited in vitro conidial germination and appressorium formation of the fungal pathogens; however, DL-β-amino-n-butyric acid (BABA) failed to inhibit the conidial development of the pathogens. Direct treatments of the CWEs and BABA on pepper and cucumber leaves at 1 and 3 days before or after inoculation significantly (P < 0.05) reduced anthracnose severities; Iljuk-3, Shinong-9, and BABA for pepper and Iljuk-7 for cucumber had more protective activities than curative activities. In addition, root treatment of CWEs suppressed anthracnoses on the plants by the pathogens; however, CWE treatment on lower leaves failed to reduce the diseases on the upper leaves of the plants. The CWE root treatments enhanced not only the expression of the pathogenesis-related (PR) genes CABPR1, CABGLU, CAChi2, CaPR-4, CAPO1, and CaPR-10 in pepper and PR1-1a, PR-2, PR-3, and APOX in cucumber but also the activity of β-1,3-glucanase, chitinase, and peroxidase and the generation of hydrogen peroxide in pepper and cucumber under pathogen-inoculated conditions. However, the CWE treatments failed to induce the plant responses under pathogen-free conditions. These results indicated that the CWEs had direct effects, reducing anthracnoses by C. coccodes on pepper leaves and C. orbiculare on cucumber leaves through protective and curative effects. In addition, CWE root treatments could induce systemic resistance in the primed state against pathogens on plant leaves that enhanced PR gene expression, defense-related enzyme production, and hydrogen peroxide generation rapidly and effectively immediately after pathogen infection. Thus, the CWEs might suppress anthracnoses on leaves of both pepper and cucumber through primed (priming-mediated) systemic resistance.     

Differences in light stability of some carboxylic acid anilide fungicides in relation to their applicability for seed and foliar treatment

Irradiation of carboxin, furcarbanil, pyracarbolid, cyclafuramid, benodanil, mebenil and oxycarboxin by u.v. light (254 nm) for 4 h resulted in 97, 64, 58, 50, 20, 18 and 15% inactivation, respectively. Photoinactivation of the different compounds in aqueous solution or in the solid state was much slower in sunlight than in u.v. light and stability increased in the following order: carboxin < furcarbanil ≤ cyclafuramid ≤ pyracarbolid < mebenil ≤ benodanil < oxycarboxin. The residues of carboxin and furcarbanil on the leaf surface of bean plants were almost completely inactivated after 40 h exposure to sunlight; cyclafuramid lost 85% of its activity. The toxicity of leaf deposits of pyracarbolid, mebenil, benodanil and oxycarboxin decreased by 83, 53, 50 and 41%, respectively after 80 h in sunlight. The compounds with low photostability (e.g. carboxin, furcarbanil and cyclafuramid) are recommended mainly for controlling seed- and soil-borne fungi; pyracarbolid, mebenil, oxycarboxin and benodanil, which proved to be more photostable, appear to be useful fungicides to control rust diseases. Among several photochemical decomposition products of carboxin detected, the sulphoxide and sulphone were identified.