Induced systemic resistance in Trichoderma harzianum T39 biocontrol of Botrytis cinerea

Biocontrol of Botrytis cinerea with Trichoderma spp. is generally believed to result from direct interaction of the biocontrol agent with the pathogen or from a Trichoderma-induced change in environmental conditions that affects B. cinerea development. In this work we provide arguments for the participation of induced plant defence in T. harzianum T39 control of B. cinerea. In tomato, lettuce, pepper, bean and tobacco, T. harzianum T39 application at sites spatially separated from the B. cinerea inoculation resulted in a 25–100%percnt; reduction of grey mould symptoms, caused by a delay or suppression of spreading lesion formation. Given the spatial separation of both micro-organisms, this effect was attributed to the induction of systemic resistance by T. harzianum T39. The observation that in bean the effect of T. harzianum T39 was similar to that of the rhizobacterium Pseudomonas aeruginosa KMPCH, a reference strain for the induction of systemic resistance, confirmed this hypothesis. Since B. cinerea control on tobacco leaves sprayed with T. harzianum T39 was similar to the control on leaves from T. harzianum T39 soil-treated plants, induction of plant defence might also participate in biocontrol on treated leaves.     

The Role of Trichoderma harzianum Protease in the Biocontrol of Botrytis cinerea

The role of protease of Trichoderma harzianum in the biocontrol of Botrytis cinerea was examined. Two isolates of T. harzianum were compared for their ability to produce protease in liquid culture medium and on the surface of bean leaves. The biocontrol agent T. harziaum T39 produced 58mU/ml of protease and T. harzianum NCIM1185 produced 54mU/ml on the 5th day of growth in liquid culture medium. On bean leaves, combinations of B. cinerea and T. harzianum isolates were examined for the synthesis of protease. The protease activities were 0.9 and 0.6mU/ml for T. harzianum T39 and NCIM1185, respectively, and 0.5mU/ml for B. cinerea alone after 48h of incubation. In the presence of T. harzianum T39 culture liquid containing protease, a 55% reduction in B. cinerea germination and a 80% reduction in the germ tube length were observed after 17h of incubation in vitro. When T. harzianum isolates were added to B. cinerea on bean leaves, increased synthesis of protease was observed (1.0 and 1.2mU/ml for T39 and NCIM1185, respectively). In the presence of T. harzianum NCIM1185 protease, although the rate of germination was reduced, B. cinerea attained 98% germination after 17h of incubation. The hydrolytic enzymes produced by B. cinerea, endo-polygalacturonase (PG) and exoPG were partially deactivated by protease from the T. harzianum isolates. Carboxymethyl cellulase was deactivated only by protease of NCIM1185. On the surface of bean leaves, the protease (obtained from liquid culture medium of T. harzianum isolates) resulted in 56–100% reduction of disease severity. The culture liquid containing protease synthesized on the surface of bean leaves treated with B. cinerea and with T. harzianum was collected and added to fresh leaves infected by B. cinerea. There was 56–100% and 30–75% reduction of disease severity with liquid droplet collected from the leaves treated with T. harzianum T39 and NCIM1185, respectively. Increased control of disease was obtained by combining the conidia of T. harzianum isolates with protease obtained from culture media. Protease inhibitors, trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E64), antipain hydrochloride, and a mixture of inhibitors, but not pepstatin A, fully or partially nullified the biocontrol effect of T39. T39 was found to be a poor producer of chitinase and -1,3-glucanase in vitro. These enzymes were not detected on leaves treated with T39. Involvement of protease in biocontrol of B. cinerea is suggested.     

Biological control ofBotrytis cinerea on tomato stem wounds withTrichoderma harzianum

The effectiveness ofTrichoderma harzianum in suppression of tomato stem rot caused byBotrytis cinerea was examined on tomato stem pieces and on whole plants. Ten days after simultanous inoculation withB. cinerea andT. harzianum, the incidence of infected stem pieces was reduced by 62–84%, the severity of infection by 68–71% and the intensity of sporulation by 87%. Seventeen days after inoculation of wounds on whole plants, the incidence of stem rot was reduced by 50 and 33% at 15 and 26 °C, respectively, and the incidence of rot at leaf scar sites on the main stem was reduced by 60 and 50%, respectively. Simultanous inoculation and pre-inoculation withT. harzianum gave good control ofB. cinerea (50 and 90% disease reduction, 10 days after inoculation). The rate of rotting was not reduced by the biocontrol agent once infection was established. However, sporulation byB. cinerea was specifically reduced on these rotting stem pieces. Temperature had a greater effect than vapour pressure deficit (VPD) on the efficacy of biocontrol. Suppression ofB. cinerea incidence byT. harzianum on stem pieces was significant at 10 °C and higher temperatures up to 26 °C. Control of infection was significantly lower at a VPD of 1.3 kPa (60% reduction), than at VPD<1.06 kPa (90–100% control). Reductions in the severity of stem rotting and the sporulation intensity of grey mould were generally not affected by VPD in the range 0.59–1.06 kPa. Survival ofT. harzianum on stems was affected by both temperature and VPD and was greatest at 10 °C at a low VPD and at 26 ° C at a high VPD.     

Trichoderma Biocontrol of Colletotrichum acutatum and Botrytis cinerea and Survival in Strawberry

Trichoderma isolates are known for their ability to control plant pathogens. It has been shown that various isolates of Trichoderma, including T. harzianum isolate T-39 from the commercial biological control product TRICHODEX, were effective in controlling anthracnose (Colletotrichum acutatum) and grey mould (Botrytis cinerea) in strawberry, under controlled and greenhouse conditions. Three selected Trichoderma strains, namely T-39, T-161 and T-166, were evaluated in large-scale experiments using different timing application and dosage rates for reduction of strawberry anthracnose and grey mould. All possible combinations of single, double or triple mixtures of Trichoderma strains, applied at 0.4% and 0.8% concentrations, and at 7 or 10 day intervals, resulted in reduction of anthracnose severity; the higher concentration (0.8%) was superior in control whether used with single isolates or as a result of combined application of two isolates, each at 0.4%. Only a few treatments resulted in significant control of grey mould. Isolates T-39 applied at 0.4% at 2 day intervals, T-166 at 0.4%, or T-161 combined with T-39 at 0.4% were as effective as the chemical fungicide fenhexamide. The survival dynamics of populations of the Trichoderma isolates (T-39, T-105, T-161 and T-166) applied separately was determined by dilution plating and isolates in the mixtures calculated according to the polymerase chain reaction (PCR) using repeat motif primers. The biocontrol isolates were identified to the respective species T. harzianum (T-39), T. hamatum (T-105), T. atroviride (T-161) and T. longibrachiatum (T-166), according to internal transcribed spacer sequence analysis.     

Resistance profiles of Botrytis cinerea populations to several fungicide classes on greenhouse tomato and strawberry in Lebanon

Tomato and strawberry are the most important protected crops in Lebanon and are seriously affected by grey mould disease, caused by Botrytis cinerea. In the present study, the fungicide sensitivity assays revealed medium to high frequencies of B. cinerea isolates resistant to benzimidazoles, dicarboximides, and anilinopyrimidines on tomato and strawberry. Fludioxonil- and boscalid-resistant mutants were uncommonly found at generally low frequency on both crops. Resistance to fenhexamid was detected in only one site on tomato but in most sites on strawberry with high frequencies, and the occurrence of resistance to QoI fungicides was ascertained on both crops. The majority of the tested isolates (>90%) exhibited multiple fungicide resistance, and isolates resistant to the seven antibotrydial fungicide classes were detected on strawberry in three locations. A high level of resistance was shown by B. cinerea mutants resistant to boscalid, fenhexamid, and QoI fungicides, while two levels of moderate and high resistance to anilinopyrimidines were identified. Genetic analysis revealed point mutations in the target genes commonly associated with resistance in B. cinerea isolates, with all mutants resistant to dicarboximides, fenhexamid, boscalid, and QoI fungicides carrying single-nucleotide polymorphims in BcOS1 (I365S/N, Q369P, and N373S), Erg27 (F412V/I), SdhB (H272R/Y), and cytb (G143A) genes, respectively. The general incorrect use of fungicides has caused the development and spread of fungicide resistance as a widespread phenomenon on protected tomato and strawberry in Lebanon. The implementation of appropriate antiresistance strategies is highly recommended.     

Colonization of red raspberry flowers and fruit by Botrytis cinerea under commercial production conditions in northwestern Washington,USA

Colonization of red raspberry flowers and fruit by Botrytis cinerea was determined during 2017–2018 growing seasons under commercial fungicide application programmes used for grey mould management in northwestern Washington, USA. Colonization of flowers and fruit was assessed qualitatively (incidence, %) and quantitatively (abundance, number of colonies) by recovering B. cinerea from surface-disinfested samples. Both incidence and abundance of flower colonization were significantly lower than fruit colonization in both untreated and fungicide-treated plots. Incidence of flower colonization did not differ significantly between untreated and fungicide-treated plots (43% vs. 45%, respectively). In contrast, significantly greater colonization incidence was detected at green fruit stage in untreated compared to fungicide-treated plots (96% vs. 77%, respectively). Ripe fruit had the greatest colonization incidence among the three stages sampled and colonization was not significantly different between untreated and fungicide-treated plots (100% vs. 92%, respectively). Similarly, colonization abundance of flowers did not differ significantly between untreated and fungicide-treated plots (1.0 colonies per colonized flower in both treatments), but colonization abundance of green and ripe fruit was decreased 2.3- and 2.1-fold, respectively, in fungicide-treated plots. DNA fingerprinting analysis of the pathogen revealed that different multilocus genotypes colonized flowers and fruit within the same inflorescence and that genotypic diversity increased through time, suggesting independent infection events. Overall, our results demonstrate that under current environmental conditions, raspberry flowers may not be the exclusive or major route of infection for grey mould of red raspberry in northwestern Washington. Implications of current findings for management and further research are discussed.     

Survival in the phylloplane of an introduced biocontrol agent (Trichoderma harzianum) and populations of the plant pathogenBotrytis cinerea as modified by abiotic conditions

Leaf populations ofTrichoderma were studied on tomato, pepper and geranium plants incubated under various conditions. Treatments involved high (>90%) or lower (75–85%) relative humidity (r.h.), temperatures of 15±3°C or 25±3°C, and soil fertilization with formulations of 2,2,5%, 3,3,8% or 5,3,8% NPK. The size of populations on leaves treated with the fungusTrichoderma harzianum differed according to plant species, leaf age, length of incubation, atmospheric conditions, and plant nutrition.T. harzianum populations were promoted in many cases by high r.h. and by 3,3,8% NPK. Interactions of introduced populations ofBotrytis cinerea with populations ofT. harzianum on tomato leaves under combinations of the above conditions showed that the population ofB. cinerea wasca tenfold lower in the presence ofT. harzianum than in the absence of this fungus.     

河南省番茄灰霉病菌对3种杀菌剂的抗药性检测

为了明确河南省番茄灰霉病菌对苯并咪唑类杀菌剂多菌灵、二甲酰亚胺类杀菌剂腐霉利和氨基甲酸酯类杀菌剂乙霉威的抗药性状况,2013年从河南省不同保护地中采集番茄灰霉病病果或病叶,经单孢分离共获得番茄灰霉病菌菌株139株。采用最低抑制浓度法（MIC）测定了其对多菌灵、腐霉利和乙霉威的抗药性。结果显示：番茄灰霉病菌对多菌灵、腐霉利和乙霉威产生抗性菌株的频率分别为81. 29%、80.58%和93.53%; 所测菌株对3类杀菌剂的抗性类型有BenRDicSNPCS、BenRDicRNPCS、BenRDicSNPCR、BenSDicRNPCR、BenSDicSNPCR和BenRDicRNPCR 6种,所占比例分别为2. 88%、3.60%、3.60%、5.04%、13.67%和71. 22%。表明河南省番茄灰霉病菌已对多菌灵、腐霉利和乙霉威产生抗药性,迫切需要筛选新的杀菌剂防治番茄灰霉病。     

Studies on the Inherent Resistance Risk to Fenhexamid in Botrytis cinerea

After chemical mutagenesis with N-methyl-N-nitrosoguanidine (MNNG) two phenotypes that were highly or moderately resistant to fenhexamid, were isolated from a wild-type strain of Botrytis cinerea, at a mutation frequency of 0.9 × 10^–5. Resistance factors, based on EC⁵⁰ values, were 460–570 and 10–15, respectively. The mutation(s) for resistance to fenhexamid did not affect the sensitivity of mutant strains to the benzimidazole benomyl, the phenylpyridinamine fluazinam, the anilinopyrimidine cyprodinil, the guanidine iminoctadine or to the sterol-biosynthesis-inhibiting fungicides fenarimol, fenpropimorph and tridemorph. On the contrary, an increased sensitivity (EC⁵⁰ ratios of 0.2–0.6) of fenhexamid-resistant strains to the phenylpyrrole fludioxonil and the dicarboximide iprodione was observed. Study of fitness parameters of fenhexamid-resistant isolates of both phenotypic classes showed that these mutation(s) had no effect on mycelial growth and sensitivity to high osmolarity, but they did affect one or more of some other characteristics, such as sporulation, conidial germination and sclerotia production. In tests on cucumber seedlings under greenhouse conditions, all highly fenhexamid-resistant isolates tested presented decreased infection ability compared with the wild-type. Preventive applications of a commercial formulation of fenhexamid, Teldor 50 WP, were effective against lesion development on cotyledons by the wild-type, but ineffective, even in high concentrations, against disease caused by the fenhexamid-resistant isolates. The risk of resistance problems arising during commercial use of fenhexamid is discussed.     

Control of infection and sporulation ofBotrytis cinerea on bean and tomato by saprophytic bacteria and fungi

Sixty isolates of saprophytic microorganisms were screened for their ability to reduce the severity of grey mould (Botrytis cinerea) infection and sporulation. Isolates of the bacteriaXanthomonas maltophilia, Bacillus pumilus, Lactobacillus sp., andPseudomonas sp. and the fungusGliocladium catenulatum reduced germination of conidia of the pathogen and controlled disease on bean and tomato plants. Their activity under growth room conditions was good, consistent, and similar to the activity of the known biocontrol agent,Trichoderma harzianum T39 (non-formulated). Although the tested isolates may for nutrients with the germinating conidia ofB. cinerea, resistance induced in the host by live or dead cells were also found to be involved. Inhibitory compounds were not detected on treated leaves. Sporulation ofB. cinerea after its establishment on leaves was also reduced by the above mentioned isolates and byPenicillium sp.,Arthrinium montagnei, Ar. phaeospermum, Sesquicillium candelabrum, Chaetomium globosum, Alternaria alternata, Ulocladium atrum, andT. viride. These sporulation-inhibiting fungi did not reduce the infection of leaves byB. cinerea. Most of these selected fungi and bacteria were capable of reducing lesion expansion.     

Survey of mutations of a histidine kinase gene BcOS1 in dicarboximide-resistant field isolates of Botrytis cinerea

Previously, we cloned a putative osmosensing histidine kinase gene (BcOS1) and revealed that a single amino acid substitution, isoleucine to serine at codon 365, conferred dicarboximide resistance in field isolates of Botrytis cinerea. This point mutation (type I) occurred within the restriction enzyme TaqI site of the wild-type BcOS1 gene. Thus, a procedure was developed for detecting the type I mutation of the BcOS1 gene using a polymerase chain reaction (PCR) in combination with restriction fragment-length polymorphism (RFLP). Diagnosis by PCR-RFLP was conducted on the 105 isolates isolated from 26 fields in Japan. All dicarboximide-sensitive isolates (49 isolates) had the wild-type BcOS1 gene, and the 43 isolates with the type I mutation were resistant to dicarboximides without exception. These data indicate that dicarboximide-resistant isolates with type I mutation are widespread throughout Japan. However, other types of dicarboximide resistance were detected among isolates from Osaka; among the 24 resistant isolates from Osaka, 12 had the BcOS1 gene without the type I mutation. BcOS1 gene sequencing of these resistant isolates classified them into two groups, type II and type III. The type II isolates have three amino acid substitutions within BcOS1p (³⁶⁸Val to Phe, ³⁶⁹Gln to His, and ⁴⁴⁷Thr to Ser). The type III isolates have two amino acid substitutions within BcOS1p (³⁶⁹Gln to Pro and ³⁷³Asn to Ser). These amino acid changes are located on the amino acid repeat domain in BcOS1p. The three types of resistant isolates were all moderately resistant to dicarboximides without significant osmotic sensitivity, and their pathogenicity on cucumber leaves was also very similar to that of the wild-type isolate.     

Chitosan Stimulates Defense Reactions in Grapevine Leaves and Inhibits Development of Botrytis Cinerea

Chitosan (β-1,4-linked glucosamine oligomer) derived from crab shells conferred a high protection of grapevine leaves against grey mould caused by Botrytis cinerea. Under controlled conditions, it was shown to be an efficient elicitor of some defense reactions in grapevine leaves and to inhibit directly the in vitro development of B. cinerea. Treatment of grapevine leaves by chitosan led to marked induction of lipoxygenase (LOX), phenylalanine ammonia-lyase (PAL) and chitinase activities, three markers of plant defense responses. Dose-response curves show that maximum defense reactions (PAL and chitinase activities) and strong reduction of B. cinerea infection were achieved with 75–150 mg l⁻¹ chitosan. However, greater concentrations of chitosan did not protect grapevine leaves with the same efficiency, but inhibited mycelial growth in vitro. Present results underlined the potency of chitosan in inducing some defense responses in grapevine leaves which in turn might improve resistance to grey mould.     

Biological control of <Emphasis Type="Italic">Botrytis cinerea</Emphasis> by selected grapevine-associated bacteria and stimulation of chitinase and β-1,3 glucanase activities under field conditions

In this study, the biocontrol ability of seven grapevine-associated bacteria, previously reported as efficient against Botrytis cinerea under in vitro conditions, was evaluated in two vineyard orchards with the susceptible cv. Chardonnay during four consecutive years (2002–2005). It was shown that the severity of disease on grapevine leaves and berries was reduced to different levels, depending on the bacterial strain and inoculation method. Drenching the plant soil with these bacteria revealed a systemic resistance to B. cinerea, even without renewal of treatment. Accordingly, this resistance was associated with a stimulation of some plant defense responses such as chitinase and β-1,3-glucanase activities in both leaves and berries. In leaves, chitinase activity increased before veraison (end-July) while β-1,3-glucanase reached its maximum activity at ripening (September). Reverse patterns were observed in berries, with β-1,3-glucanase peaking at full veraison (end-August) and chitinase at a later development stage. Highest activities were observed with Acinetobacter lwoffii PTA-113 and Pseudomonas fluorescens PTA-CT2 in leaves, and with A. lwoffii PTA-113 and Pantoea agglomerans PTA-AF1 in berries. These results have demonstrated an induced protection of grapevine against B. cinerea by selected bacteria under field conditions, and suggest that induced resistance could be related to a stimulation of plant defense reactions in a successive manner.     

Effects of Host and Microbial Factors on Development of Clonostachys rosea and Control of Botrytis cinerea in Rose

Development of Clonostachys rosea in rose leaves and petals and control of Botrytis cinerea by the agent were investigated. C. rosea germinated, established endophytic growth, and sporulated abundantly whether the tissues were mature, senescent or dead when inoculated. Germination incidence was moderate on mature and senescent leaves (47% and 35%) and petals (31% and 43%), and high (>98%) on dead tissues. Sporulation of C. rosea in tissues inoculated when mature, senescent or dead averaged 41%, 61%, and 75% in leaves, and 48%, 87% and 53% in petals. When leaves were wounded with needles before inoculation, germination of C. rosea increased from 45–56% to 90–92%, but sporulation became high (>75%) regardless of wounds. When leaves were inoculated with C. rosea at 0–24h after wounding and subsequently with B. cinerea, germination of the pathogen was reduced by 25–41% and sporulation by 99%. A humid period prior to inoculation of senescent or dead leaves promoted communities of indigenous fungi, reduced sporulation of C. rosea and B. cinerea, and, in dead leaves, increased control of the pathogen associated with C. rosea. Applied at high density, isolates of indigenous Penicillium sp. and Alternaria alternata from rose interacted with C. rosea and reduced control of the pathogen by 16% and 21%, respectively. In conclusion, C. rosea markedly suppressed sporulation of B. cinerea in rose leaves and petals regardless of developmental stage, minor wounds, and natural densities of microflora. This versatility should allow C. rosea to effectively control inoculum production of B. cinerea in rose production systems.     

Botrytis cinerea in greenhouse vegetables: chemical,cultural, physiological and biological controls and their integration

Botrytis cinerea is an ubiquitous pathogen which causes severe losses in many fruit, vegetable and ornamental crops. The pathogen infects leaves, stems, flowers and fruits. The complexity of diseases caused by B. cinerea in greenhouses makes this pathogen one of the most important diseases of vegetable crops in greenhouse in many countries. In general, epidemics occur in cool and humid conditions, which favour infection and may also predispose the host to become susceptible. High relative humidity in the greenhouse and free moisture on plant surfaces are considered the most important environmental factors which influence infection by B. cinerea. In this review we specify the factors affecting the development of diseases incited by B. cinerea and discuss different approaches for its suppression. Chemical and non-chemical controls are outlined and their integration is discussed. Finally, achievements, gaps in knowledge, and future needs are indicated. The most common means for disease management is by application of chemical fungicides. Both spraying of fungicides and application of fungicides directly to sporulating wounds is practiced. However, high activity of several fungicides is being lost, at least in part, due to the development of resistance. As fungicides still remain an important tool for control of epidemics caused by B. cinerea, it is important to monitor populations of the pathogen for their resistance towards potential fungicides. Cultural measures can be a powerful means to suppress plant diseases in greenhouses where the value of crops is high and the farmers make considerable efforts during long cropping seasons. Such measures are usually aimed at altering the microclimate in the canopy and around susceptible plant organs, prevention of inoculum entrance into the greenhouse and its build up, and, rendering the host plants less susceptible to diseases. Calcium loading of plant tissues and alteration of nitrogen fertilization reduce susceptibility to Botrytis. Cultivars resistant to B. cinerea are not available. Another alternative methods to control B. cinerea is by means of biological control agents. At least one preparation is already available in the market and in many cases it was as effective as the conventional fungicides. A decision support system was recently developed for integration of chemical and biological controls. Adaquate suppression of B. cinerea diseases in greenhouse crops is an attainable goal. In our opinion this goal can be reached by considering the ecology of the pathosystem in its broader sense and by integration of all possible control measures. This implies optimization of plant nutrition, microlimate and control (cultural, biological, physiological and, if necessary, chemical) measures. Moreover, Botrytis management must be incorporated in a more holistic system that is compatible with insect control, crop production systems and profitability of the crop.     

Comparative Analysis of the Role of Substrate Specificity in Biological Control of Botrytis Elliptica in Lily and B. Cinerea in Cyclamen with Ulocladium Atrum

Biological control of Botrytis spp. by the fungal antagonist Ulocladium atrum is based on their interaction in plant tissue. U. atrum is effective against B. cinerea in commercial cyclamen crops but not effective against B. elliptica in lily crops. Based on the necrotrophic nature of the Botrytis spp. and the saprophytic nature of U. atrum it is hypothesised, and experimentally confirmed, that the interaction between Botrytis spp. and U. atrum, resulting in a biocontrol effect, only takes place in necrotic plant tissue. The role of necrotic tissue in the epidemiology of B. cinerea in cyclamen and B. elliptica in lily was found to be different. Removal of symptomless senescing leaves resulted in a significant reduction of the area under the disease severity progress curve (AUDPC) for B. cinerea in cyclamen but had no effect on the disease severity in lily. U. atrum applications significantly reduced B. cinerea AUDPC values in cyclamen but were less efficient than the removal of senescing leaves. In lily, disease severity was not affected by applications of U. atrum. It is concluded that necrotic cyclamen tissue, not killed by B. cinerea, plays an important role in the onset of disease. Colonisation of this tissue by U. atrum prevents saprophytic colonisation of those leaves by B. cinerea. In contrast, conidia of B. elliptica directly infect healthy lily leaf tissue. U. atrum applications aimed at blocking the infection pathway from a saprophytic base are therefore not effective against B. elliptica. Control options based on competitive interactions in and around B. elliptica lesions resulted in a reduced production of conidia by B. elliptica but proved ineffective against disease development. The potential of U. atrum as a biocontrol agent against Botrytis spp. and possibly against other necrotrophs appears to be determined by the competitive saprophytic ability of the antagonist in mutual substrates of pathogen and antagonist and by the role of these substrates in disease epidemiology.     

Effect of label and sublabel rates of metam sodium in combination with<Emphasis Type="Italic">Trichoderma hamatum,T. harzianum,T. virens,T. viride</Emphasis> on survival and growth of<Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

This work was undertaken to determine the effects ofTrichoderma spp. combined with label and sublabel rates of metam sodium on survival ofRhizoctonia solani in soil. Soils were infested with wheat bran preparations ofTrichoderma hamatum Tri-4,T. harzianum Th-58,T. virens Gl-3, andT. viride Ts-1-R3. Soil was also infested with sterile beet seeds that were colonized withR. solani. Beet seeds were later recovered, plated onto water agar plus antibiotics, and the growth ofR. solani was recorded. Preliminary experiments showed thatT. hamatum andT. virens reduced survival and saprophytic activity ofR. solani when the biocontrol fungi were incorporated into soil at 1.5% (w:w) or greater. Based on these data, biocontrol fungi in subsequent experiments were incorporated into soil at 2%. Metam sodium at label rate killed all biocontrol fungi andR. solani. At 1:2 and 1:5 dilutions, metam sodium reduced survival ofR. solani and allTrichoderma spp. When biocontrol fungi plus the label rate of metam sodium and 1:5, 1:10, 1:50 or 1:100 dilutions of the label rate were tested together, there were no interactions between any biocontrol agent and the fumigant with respect to colony diameter, reflecting that allTrichoderma isolates tested reacted similarly to increasing concentrations of metam sodium. At the label rate of metam sodium, allTrichoderma spp. significantly reduced colony diameter, but not growth rate, ofR. solani from beet seed. For the levels of metam sodium tested in combination withTrichoderma, it does not appear feasible to use a reduced rate of metam sodium to controlR. solani. However, the combination ofTrichoderma with metam sodium does reduce growth ofR. solani in comparison with that provided by metam sodium at the label rate. http://www.phytoparasitica.org posting Feb. 11, 2004.     

Note: Evaluating insecticides for the control of overwintered adults ofEurygaster integriceps under field conditions in Turkey

The Sunn pestEurygaster integriceps Puton is the most harmful pest of cereals in Turkey and the surrounding countries. Chemical control has been employed against the nymph stages of the pest. The efficacy of six products [acetamiprid (SL, soluble concentrate), chlorpyrifosethyl (EC, emulsifiable concentrate), lambda-cyhalothrin (CS, capsule suspension), monocrotophos (SC, suspension concentrate), thiacloprid (SC) and zeta-cypermethrin (EC)] was tested on overwintered adults ofE. integriceps, with applications to wheat at the shooting stage. In a study conducted at Siverek, Şanlıurfa in the southeastern Anatolia Region, the most effective insecticide was found to be lambda-cyhalothrin. It gave very promising results in controlling the pest and reduced subsequent egg laying and the appearance of nymphs in the trial area. The results showed that chemical control of overwintered adults of the Sunn pest in early spring is possible with lambda-cyhalothrin. http://www.phytoparasitica.org posting Sept. 18, 2006.     

The effect of three irrigation practices on phytophthora crown and root rot of apple trees under field conditions

The effect of microjet, drip, and two durations of sprinkler irrigation systems on phytophthora crown and root rot of apple trees was examined under field conditions. This eight year study indicates that crown and root rot caused byPhytophthora cactorum was most severe where young MM. 106 rootstock trees were watered by microjet irrigation for 2.3 h each day. There was no difference in infection byP. cactorum when trees were irrigated either by drip or sprinkler irrigation systems. The MM.106 apple rootstock trees watered by drip irrigation for 2.6 h each day were least affected by phytophthora crown and root rot.